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2022 Volume 38 Issue 10
2022, 38(10): 1889-1907
doi: 10.11862/CJIC.2022.208
Abstract:
In recent years, perovskite solar cells (PSCs) have achieved rapid development with the maximum certified power conversion efficiency (PCE) up to 25.7%, which is comparable with the advances obtained for silicon and thin-film solar cells. However, the involvement of lead, which is a cumulative toxicant to human bodies, hampers the pace of their future commercial application. Therefore, it is crucial to seek a new path to reduce or eliminate Pb from PSCs and replace it with other environmentally friendly elements. Recently, the development of lead-free PSCs has attracted great attentions. Tin-based perovskite materials with excellent photoelectric properties are thus by far the most promising alternative. The p-i-n inverted tin-based PSCs have developed rapidly in recent years, which represented an important breakthrough in the field. Their main advantages include low-temperature fabrication, cost-effectiveness, and suppressed hysteresis behavior, alongside a competitive power conversion efficiency of up to 14.8%. Though numerous research efforts have been devoted to inverted Sn-based PSCs, the PCE of these devices still lag far behind Pb-based PSCs. The rapid development of inverted Sn-based PSCs prompted us to review the current progress of inverted p-i-n Sn-based PSCs, focusing mainly on the aspects involving on features p-i-n Sn-based PSCs, interface layers, properties of Sn perovskites, and fabrication of a high-quality Sn perovskite active layer, highlighting the obstacles to further progress and opportunities for future work.
In recent years, perovskite solar cells (PSCs) have achieved rapid development with the maximum certified power conversion efficiency (PCE) up to 25.7%, which is comparable with the advances obtained for silicon and thin-film solar cells. However, the involvement of lead, which is a cumulative toxicant to human bodies, hampers the pace of their future commercial application. Therefore, it is crucial to seek a new path to reduce or eliminate Pb from PSCs and replace it with other environmentally friendly elements. Recently, the development of lead-free PSCs has attracted great attentions. Tin-based perovskite materials with excellent photoelectric properties are thus by far the most promising alternative. The p-i-n inverted tin-based PSCs have developed rapidly in recent years, which represented an important breakthrough in the field. Their main advantages include low-temperature fabrication, cost-effectiveness, and suppressed hysteresis behavior, alongside a competitive power conversion efficiency of up to 14.8%. Though numerous research efforts have been devoted to inverted Sn-based PSCs, the PCE of these devices still lag far behind Pb-based PSCs. The rapid development of inverted Sn-based PSCs prompted us to review the current progress of inverted p-i-n Sn-based PSCs, focusing mainly on the aspects involving on features p-i-n Sn-based PSCs, interface layers, properties of Sn perovskites, and fabrication of a high-quality Sn perovskite active layer, highlighting the obstacles to further progress and opportunities for future work.
2022, 38(10): 1908-1918
doi: 10.11862/CJIC.2022.207
Abstract:
A linear Co-substituted Strandberg-type polyphosphomolybdate (H2en)6{[Co(H2O)4] (P2 Mo5O23)}3·11H2O (abbreviated as CoPM, en=ethylenediamine) has been synthesized and structurally characterized by elemental analyses, IR spectrum, thermogravimetric analysis, and single-crystal X-ray diffraction. Structural analysis reveals that the molecular structural unit of CoPM consists of [P2Mo5O23]6- cluster, and Co-complex [Co(H 2O)4]2+, and they join alternately to form the 1D infinite extension skeleton of CoPM. Furthermore, each cyclic unit of the CoPM chain contains three {[Co(H2O)4](P2Mo5O23)}4- units in solid states based on bond valence sums (BVS) calculation. The intervention of CoPM on the misfolding process of amyloid β-protein (Aβ) was studied by the thioflavin T fluorescence method, turbidimetric method, circular dichroism, and NMR. The results indicate that CoPM can modulate the β-sheet-rich conformation of Aβ aggregates, and thus reduce the formation of toxic species. Moreover, 2', 7'-dichlorofluorescein (DCF) fluorescence and cytotoxicity experiments showed that CoPM could also eliminate reactive oxygen species (ROS) produced by Cu2+-Aβ aggregates. It can inhibit the cytotoxicity of β-sheet-rich species and protect synapses of PC12 cells.
A linear Co-substituted Strandberg-type polyphosphomolybdate (H2en)6{[Co(H2O)4] (P2 Mo5O23)}3·11H2O (abbreviated as CoPM, en=ethylenediamine) has been synthesized and structurally characterized by elemental analyses, IR spectrum, thermogravimetric analysis, and single-crystal X-ray diffraction. Structural analysis reveals that the molecular structural unit of CoPM consists of [P2Mo5O23]6- cluster, and Co-complex [Co(H 2O)4]2+, and they join alternately to form the 1D infinite extension skeleton of CoPM. Furthermore, each cyclic unit of the CoPM chain contains three {[Co(H2O)4](P2Mo5O23)}4- units in solid states based on bond valence sums (BVS) calculation. The intervention of CoPM on the misfolding process of amyloid β-protein (Aβ) was studied by the thioflavin T fluorescence method, turbidimetric method, circular dichroism, and NMR. The results indicate that CoPM can modulate the β-sheet-rich conformation of Aβ aggregates, and thus reduce the formation of toxic species. Moreover, 2', 7'-dichlorofluorescein (DCF) fluorescence and cytotoxicity experiments showed that CoPM could also eliminate reactive oxygen species (ROS) produced by Cu2+-Aβ aggregates. It can inhibit the cytotoxicity of β-sheet-rich species and protect synapses of PC12 cells.
2022, 38(10): 1919-1926
doi: 10.11862/CJIC.2022.191
Abstract:
A series of new Schiff base ligands (BLn, n=1 - 3) and complexes have been synthesized. Binuclear ruthenium complexes [Ru(BLn)(bpy)2]2(ClO4)4, where bpy=2, 2'-bipyridine, BLn=((PyCHN)-Ph-O-C6H4) 2R (PyCHN=N-2-pyridylmethylene, R=none for Ru1, —C(CH3)2 for Ru2 and —SO2 for Ru3), have been prepared and characterized by element analysis, 1H NMR, IR, and mass spectrometry methods. The cytotoxicity to cervical cancer cells (Hela), gastric cancer cells (BGC823), gastric cancer cells (SGC-7901), and human normal embryonic lung fibroblasts cells (MRC-5) of the three complexes in vitro was evaluated using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. It is worth noting that Ru1-Ru3 showed excellent antitumor effects in a cellular study for BGC823 in vitro. However, Ru3 exhibited the highest cytotoxicity to any cancer cells than Ru1 and Ru2.
A series of new Schiff base ligands (BLn, n=1 - 3) and complexes have been synthesized. Binuclear ruthenium complexes [Ru(BLn)(bpy)2]2(ClO4)4, where bpy=2, 2'-bipyridine, BLn=((PyCHN)-Ph-O-C6H4) 2R (PyCHN=N-2-pyridylmethylene, R=none for Ru1, —C(CH3)2 for Ru2 and —SO2 for Ru3), have been prepared and characterized by element analysis, 1H NMR, IR, and mass spectrometry methods. The cytotoxicity to cervical cancer cells (Hela), gastric cancer cells (BGC823), gastric cancer cells (SGC-7901), and human normal embryonic lung fibroblasts cells (MRC-5) of the three complexes in vitro was evaluated using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. It is worth noting that Ru1-Ru3 showed excellent antitumor effects in a cellular study for BGC823 in vitro. However, Ru3 exhibited the highest cytotoxicity to any cancer cells than Ru1 and Ru2.
2022, 38(10): 1927-1938
doi: 10.11862/CJIC.2022.214
Abstract:
Four CyB5Q[5]-Ca complexes (1-4) have been synthesized by the new member of the cucurbituril family (CyB5Q[5]) and calcium ions in different anionic media. Their structures have been characterized by X-ray single-crystal diffraction. Their crystal structures show that complexes of different coordination types are generated in different environments of Cl-, [ZnCl4]2-, [ZnCl4]2-+ClO4-, and ClO4-, respectively. The coordination number of complexes 1, 2, 3, and 4 are 6, 8, 7, and 6, respectively.
Four CyB5Q[5]-Ca complexes (1-4) have been synthesized by the new member of the cucurbituril family (CyB5Q[5]) and calcium ions in different anionic media. Their structures have been characterized by X-ray single-crystal diffraction. Their crystal structures show that complexes of different coordination types are generated in different environments of Cl-, [ZnCl4]2-, [ZnCl4]2-+ClO4-, and ClO4-, respectively. The coordination number of complexes 1, 2, 3, and 4 are 6, 8, 7, and 6, respectively.
2022, 38(10): 1939-1947
doi: 10.11862/CJIC.2022.201
Abstract:
Two iridium(Ⅲ) complexes, [Ir(L1)2(dbr-bpy)]PF6 (Ir1) and [Ir(L2)2(dbr-bpy)]PF6 (Ir2) with 4, 4'-dibromo-2, 2'-bipyridine (dbr-bpy) as neutral ligand, 6-phenylnicotinaldehyde (L1) and 6-(4-trifluoromethylphenyl)pyridine-3-carbaldehyde (L2) as cyclometalated ligands, were synthesized and characterized by 1H NMR, 13C NMR, IR and MS spectra. For the emission spectra in acetonitrile solution, the maximum peaks were located at 584 and 530 nm for complexes Ir1 and Ir2 with quantum efficiencies of 49% and 66%, respectively. The introduction of electronwithdrawing trifluoromethyl and aldehyde groups resulted in an obvious blue shift in the emission spectra of complexes Ir1 and Ir2. The study of cyclic voltammograms indicates trifluoromethyl moieties in the cyclometalated ligands of complexes Ir1 and Ir2 can reduce the energy of the highest occupied molecular orbital (HOMO), and make the oxidation potential shift towards the anode. Density functional theory (DFT) calculations have been carried out to gain insight into their frontier molecular orbital properties and transition details. Complexes Ir1 and Ir2 displayed significant phosphorescence quenching upon binding to cysteine (Cys), and the binding stoichiometry was approximately 1:2 with the detection limit of 35.1 and 18.5 μmol·L-1, respectively. Both complexes showed a good anti-interference ability for the detection of Cys. Upon the addition of OH- into the solution of Ir2 in DMSO/H2O (7∶3, V/V), OH- replaced the bromine substituents on the neutral ligand of Ir2, resulting in a blue shift of the emission peak. The luminescence color of complex Ir2 changed from yellow to green and Ir2 showed a 4-fold enhanced emission in an alkaline environment when compared to neutral pH. In addition, complex Ir2 exhibited high sensitivity and selectivity for OH- and showed good anti-interference ability.
Two iridium(Ⅲ) complexes, [Ir(L1)2(dbr-bpy)]PF6 (Ir1) and [Ir(L2)2(dbr-bpy)]PF6 (Ir2) with 4, 4'-dibromo-2, 2'-bipyridine (dbr-bpy) as neutral ligand, 6-phenylnicotinaldehyde (L1) and 6-(4-trifluoromethylphenyl)pyridine-3-carbaldehyde (L2) as cyclometalated ligands, were synthesized and characterized by 1H NMR, 13C NMR, IR and MS spectra. For the emission spectra in acetonitrile solution, the maximum peaks were located at 584 and 530 nm for complexes Ir1 and Ir2 with quantum efficiencies of 49% and 66%, respectively. The introduction of electronwithdrawing trifluoromethyl and aldehyde groups resulted in an obvious blue shift in the emission spectra of complexes Ir1 and Ir2. The study of cyclic voltammograms indicates trifluoromethyl moieties in the cyclometalated ligands of complexes Ir1 and Ir2 can reduce the energy of the highest occupied molecular orbital (HOMO), and make the oxidation potential shift towards the anode. Density functional theory (DFT) calculations have been carried out to gain insight into their frontier molecular orbital properties and transition details. Complexes Ir1 and Ir2 displayed significant phosphorescence quenching upon binding to cysteine (Cys), and the binding stoichiometry was approximately 1:2 with the detection limit of 35.1 and 18.5 μmol·L-1, respectively. Both complexes showed a good anti-interference ability for the detection of Cys. Upon the addition of OH- into the solution of Ir2 in DMSO/H2O (7∶3, V/V), OH- replaced the bromine substituents on the neutral ligand of Ir2, resulting in a blue shift of the emission peak. The luminescence color of complex Ir2 changed from yellow to green and Ir2 showed a 4-fold enhanced emission in an alkaline environment when compared to neutral pH. In addition, complex Ir2 exhibited high sensitivity and selectivity for OH- and showed good anti-interference ability.
2022, 38(10): 1948-1958
doi: 10.11862/CJIC.2022.213
Abstract:
A 3D CdⅡ -based coordination polymer with the formula of [Cd2(DDBD)(NDC)2]n (JXUST-16) has been solvothermally synthesized by using 4, 7-bis(1H-1, 2, 4-triazol-1-yl)-2, 1, 3-benzothiadiazole (DDBD) as the primary ligand and 1, 4-naphthalenedicarboxylic acid (H2NDC) as the auxiliary ligand, and structurally characterized through single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetry analysis, etc. JXUST-16 belongs to the monoclinic I 2/a space group and the adjacent CdⅡ ions are bridged through the carboxylate ligand NDC2- to form a symmetrical trinuclear CdⅡ cluster, which extends to obtain a 1D chain. The neighboring 1D chains are further linked by DDBD to form a 3D structure. JXUST-16 could keep stable in organic solvents and aqueous solutions with different pH values, and be used as a dual -function fluorescence sensor to identify MnO4- and H2PO4- with obvious naked-eye recognition under a 365 nm UV lamp. In addition, MnO4- showed a turn-off effect on the fluorescence of JXUST-16 due to the competitive absorption mechanism; while H2PO4- had a certain redshift and turn-on effect on the fluorescence of JXUST-16, which can be explained by the absorbance-caused enhancement mechanism.
A 3D CdⅡ -based coordination polymer with the formula of [Cd2(DDBD)(NDC)2]n (JXUST-16) has been solvothermally synthesized by using 4, 7-bis(1H-1, 2, 4-triazol-1-yl)-2, 1, 3-benzothiadiazole (DDBD) as the primary ligand and 1, 4-naphthalenedicarboxylic acid (H2NDC) as the auxiliary ligand, and structurally characterized through single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetry analysis, etc. JXUST-16 belongs to the monoclinic I 2/a space group and the adjacent CdⅡ ions are bridged through the carboxylate ligand NDC2- to form a symmetrical trinuclear CdⅡ cluster, which extends to obtain a 1D chain. The neighboring 1D chains are further linked by DDBD to form a 3D structure. JXUST-16 could keep stable in organic solvents and aqueous solutions with different pH values, and be used as a dual -function fluorescence sensor to identify MnO4- and H2PO4- with obvious naked-eye recognition under a 365 nm UV lamp. In addition, MnO4- showed a turn-off effect on the fluorescence of JXUST-16 due to the competitive absorption mechanism; while H2PO4- had a certain redshift and turn-on effect on the fluorescence of JXUST-16, which can be explained by the absorbance-caused enhancement mechanism.
2022, 38(10): 1959-1969
doi: 10.11862/CJIC.2022.188
Abstract:
The low-cost nickel nanoparticles/towel gourd derived nitrogen-doped porous carbon nanocomposites (Ni/T-dNPCN) were prepared with Ni(Ac)2·4H2O and towel gourd by impregnation and then pyrolysis. The electrocatalytic performance of the nanocomposites for methanol oxidation reaction (MOR) was studied, and the effect of pyrolysis temperature on its structure and properties was also discussed. The results demonstrated that the Ni/T-dNPCN modified glassy carbon electrode (Ni/T-dNPCN/GCE) exhibited well electrocatalytic activity for MOR in alkaline electrolytes. Among them, Ni/T-dNPCN800/GCE possessed the best catalytic performance with the lowest onset potential (0.344 V (vs Ag/AgCl)), the highest catalytic current density (mass activity: 1 902 mA·mgNi-1; specific activity: 1.61 mA·cm-2) and the fastest kinetics process (Tafel slope: 50.23 mV·dec-1), its catalytic activity was about 3.92 times that of the commercial Pt/C catalyst modified glassy carbon electrode. And according to the chronoamperometry test, Ni/T-dNPCN800/GCE displayed good stability.
The low-cost nickel nanoparticles/towel gourd derived nitrogen-doped porous carbon nanocomposites (Ni/T-dNPCN) were prepared with Ni(Ac)2·4H2O and towel gourd by impregnation and then pyrolysis. The electrocatalytic performance of the nanocomposites for methanol oxidation reaction (MOR) was studied, and the effect of pyrolysis temperature on its structure and properties was also discussed. The results demonstrated that the Ni/T-dNPCN modified glassy carbon electrode (Ni/T-dNPCN/GCE) exhibited well electrocatalytic activity for MOR in alkaline electrolytes. Among them, Ni/T-dNPCN800/GCE possessed the best catalytic performance with the lowest onset potential (0.344 V (vs Ag/AgCl)), the highest catalytic current density (mass activity: 1 902 mA·mgNi-1; specific activity: 1.61 mA·cm-2) and the fastest kinetics process (Tafel slope: 50.23 mV·dec-1), its catalytic activity was about 3.92 times that of the commercial Pt/C catalyst modified glassy carbon electrode. And according to the chronoamperometry test, Ni/T-dNPCN800/GCE displayed good stability.
2022, 38(10): 1970-1980
doi: 10.11862/CJIC.2022.186
Abstract:
P-Al/NaX catalyst was in-situ synthesized by hydrothermal method, and its acidity and basicity were controlled by impregnation of NaOH, and its catalytic performance for side-chain alkylation of toluene with methanol was tested. Combined with the characterizations of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, and the catalytic activity data, it was found that the structure of the synthesized Na 13Al24Si13P11O96·H2O showed good catalytic performance of side-chain alkylation of toluene with methanol after in-situ loading of P and Al. With the NaOH loading increasing, the selectivity of ethylbenzene and styrene increased first and then decreased. When the NaOH loading (mass fraction) was 9%, the selectivity of styrene was the highest (45.84%), and the total yield of ethylbenzene and styrene reached 63.08%. This may be because the loading of NaOH was conducive to the increase of the number of strong alkaline sites and weak acidic sites, and the high number of strong alkaline sites and weak acidic sites were conducive to the side chain alkylation of toluene with methanol.
P-Al/NaX catalyst was in-situ synthesized by hydrothermal method, and its acidity and basicity were controlled by impregnation of NaOH, and its catalytic performance for side-chain alkylation of toluene with methanol was tested. Combined with the characterizations of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, and the catalytic activity data, it was found that the structure of the synthesized Na 13Al24Si13P11O96·H2O showed good catalytic performance of side-chain alkylation of toluene with methanol after in-situ loading of P and Al. With the NaOH loading increasing, the selectivity of ethylbenzene and styrene increased first and then decreased. When the NaOH loading (mass fraction) was 9%, the selectivity of styrene was the highest (45.84%), and the total yield of ethylbenzene and styrene reached 63.08%. This may be because the loading of NaOH was conducive to the increase of the number of strong alkaline sites and weak acidic sites, and the high number of strong alkaline sites and weak acidic sites were conducive to the side chain alkylation of toluene with methanol.
2022, 38(10): 1981-1992
doi: 10.11862/CJIC.2022.185
Abstract:
Using copper acetate monohydrate as a copper source, 1D chain coordination polymer {[(Cu(OAc)2)2(L)]·3CH3CN}n (1, OAc-=CH3CO2-) was synthesized using 2, 6-bis(4'-pyridyl)-4-methylaniline (L) as bridged pyridine ligand, and 2D network coordination polymer {[Cu(IPA)(L)(H2O)]2·H2IPA·H2O}n (2) was prepared by L and isophthalic acid (H2IPA) as the co-ligand. It can be seen from the single crystal structure analysis that the copper atoms in complex 1 are located in the center of the tetrahedral coordination environment in the [CuNO4]2 clusters, and the copper atoms in complex 2 are in the [CuNO3] deformed hexahedral coordination environment. The comparative experiments on Fenton - like photocatalytic degradation with methylene blue as substrate show that the catalytic effect of complex 1 with Cu—N and Cu—O coordination environment was better than that of HKUST-1 with the same tetrahedral coordination environment. The comparison of the catalytic performance of complexes 1 and 2 also proves that the photocatalytic degradation activity of the open mononuclear copper coordination center was better than that of the copper coordination center in the cluster complex. Benefiting from the stability of the ligands and the existence of the framework structure, both complexes had higher catalytic activity and recyclability compared with the catalytic performance of the unconstrained copper acetate under the same conditions. The band gaps of the two complexes were calculated through UV-Vis spectra. The stability of the complexes after the reaction was confirmed by X-ray diffraction and inductively coupled plasma mass spectrometry. By adding free radical scavengers benzoquinone, tertiary butanol, and triethanolamine, it is confirmed that the catalytic process is a Fenton-like reaction mechanism of the hydroxyl radical process.
Using copper acetate monohydrate as a copper source, 1D chain coordination polymer {[(Cu(OAc)2)2(L)]·3CH3CN}n (1, OAc-=CH3CO2-) was synthesized using 2, 6-bis(4'-pyridyl)-4-methylaniline (L) as bridged pyridine ligand, and 2D network coordination polymer {[Cu(IPA)(L)(H2O)]2·H2IPA·H2O}n (2) was prepared by L and isophthalic acid (H2IPA) as the co-ligand. It can be seen from the single crystal structure analysis that the copper atoms in complex 1 are located in the center of the tetrahedral coordination environment in the [CuNO4]2 clusters, and the copper atoms in complex 2 are in the [CuNO3] deformed hexahedral coordination environment. The comparative experiments on Fenton - like photocatalytic degradation with methylene blue as substrate show that the catalytic effect of complex 1 with Cu—N and Cu—O coordination environment was better than that of HKUST-1 with the same tetrahedral coordination environment. The comparison of the catalytic performance of complexes 1 and 2 also proves that the photocatalytic degradation activity of the open mononuclear copper coordination center was better than that of the copper coordination center in the cluster complex. Benefiting from the stability of the ligands and the existence of the framework structure, both complexes had higher catalytic activity and recyclability compared with the catalytic performance of the unconstrained copper acetate under the same conditions. The band gaps of the two complexes were calculated through UV-Vis spectra. The stability of the complexes after the reaction was confirmed by X-ray diffraction and inductively coupled plasma mass spectrometry. By adding free radical scavengers benzoquinone, tertiary butanol, and triethanolamine, it is confirmed that the catalytic process is a Fenton-like reaction mechanism of the hydroxyl radical process.
2022, 38(10): 1993-1998
doi: 10.11862/CJIC.2022.190
Abstract:
A fluorescent probe 1 has been synthesized by the Schiff base condensation of 4-(diethylamino)salicylaldehyde with oxamic hydrazide, which has been carefully characterized through 1H NMR, 13C NMR, and electrospray ionization mass spectrometer. Probe 1 exhibited a quite weak emission at 495 nm, which could selectively and sensitively recognize Al3+ from other cations by a notable fluorescence enhancement. The limit of detection of probe 1 for Al3+ was as low as 1.44 μmol·L-1, indicating its high sensitivity. Based on theory calculation results, probe 1 is proposed to coordinate with Al with the ratio of 1∶1 in a tridentate mode. Moreover, the probe was applied to imaging Al3+ in living cells.
A fluorescent probe 1 has been synthesized by the Schiff base condensation of 4-(diethylamino)salicylaldehyde with oxamic hydrazide, which has been carefully characterized through 1H NMR, 13C NMR, and electrospray ionization mass spectrometer. Probe 1 exhibited a quite weak emission at 495 nm, which could selectively and sensitively recognize Al3+ from other cations by a notable fluorescence enhancement. The limit of detection of probe 1 for Al3+ was as low as 1.44 μmol·L-1, indicating its high sensitivity. Based on theory calculation results, probe 1 is proposed to coordinate with Al with the ratio of 1∶1 in a tridentate mode. Moreover, the probe was applied to imaging Al3+ in living cells.
2022, 38(10): 1999-2005
doi: 10.11862/CJIC.2022.210
Abstract:
The AlCo-LDH/NF (layered double hydroxide, LDH) catalyst was obtained by in situ growth on nickel foam (NF) by a one-step hydrothermal method. Benefitting from the transition metal-based LDH, as-synthesized AlCo-LDH in-situ grown on nickel foam (NF) electrocatalyst exhibited outstanding oxygen evolution reaction (OER) performance with an exceptionally low overpotential of 419 mV at 200 mA·cm-2 current density in an alkaline electrolyte, an extremely small Tafel slope (50.04 mV·dec-1) and excellent durability, which is due to its high surface area and optimized phase interfaces.
The AlCo-LDH/NF (layered double hydroxide, LDH) catalyst was obtained by in situ growth on nickel foam (NF) by a one-step hydrothermal method. Benefitting from the transition metal-based LDH, as-synthesized AlCo-LDH in-situ grown on nickel foam (NF) electrocatalyst exhibited outstanding oxygen evolution reaction (OER) performance with an exceptionally low overpotential of 419 mV at 200 mA·cm-2 current density in an alkaline electrolyte, an extremely small Tafel slope (50.04 mV·dec-1) and excellent durability, which is due to its high surface area and optimized phase interfaces.
2022, 38(10): 2006-2018
doi: 10.11862/CJIC.2022.192
Abstract:
B-doped hierarchical porous carbon spheres (BPCS) were prepared by hydrothermal and carbonization method using D-xylose as a carbon source, sodium laurate as a soft template, and boric acid as a dopant. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption test, X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), Fourier infrared spectroscopy (FT - IR), Raman spectroscopy, X-ray powder diffraction (XRD), and thermogravimetric (TG) analysis indicated that the hierachical porous structure with narrow size (2-5 μm) were compounded by spontaneous self-assembly from hydrogen-bond interaction between the carbon source and the soft template. Moreover, sodium laurate was also used as a pore - forming agent (mesopore). Boric acid was doped on the carbon spheres in the form of BC3, BCO2, and BC2O and improved the surface wettability. After CO2 activation, decomposition of sodium laurate and the accumulation of colloidal carbon spheres, micropore (0.5 - 1.2 nm), mesopore (3.14 - 35.00 nm), and macropore (60 - 146 nm) were produced respectively. Electrochemical test results showed that the porous carbon spheres (BPCS - 1) treated with 0.927 5 g boric acid had the optimal supercapacitor performance. In a three-electrode system, BPCS-1 showed a high specific capacitance of 287.12 F·g-1 at a current density of 0.5 A·g-1. In a two-electrode system, BPCS-1 showed an excellent energy density (5.3 Wh·kg-1) and a superior specific capacitance of 151.34 F·g-1 at a current density of 0.5 A·g-1, and outstanding cycling stability of 96.43% capacitance retention after 1 000 cycles at a current density of 5 A·g-1.
B-doped hierarchical porous carbon spheres (BPCS) were prepared by hydrothermal and carbonization method using D-xylose as a carbon source, sodium laurate as a soft template, and boric acid as a dopant. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption test, X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), Fourier infrared spectroscopy (FT - IR), Raman spectroscopy, X-ray powder diffraction (XRD), and thermogravimetric (TG) analysis indicated that the hierachical porous structure with narrow size (2-5 μm) were compounded by spontaneous self-assembly from hydrogen-bond interaction between the carbon source and the soft template. Moreover, sodium laurate was also used as a pore - forming agent (mesopore). Boric acid was doped on the carbon spheres in the form of BC3, BCO2, and BC2O and improved the surface wettability. After CO2 activation, decomposition of sodium laurate and the accumulation of colloidal carbon spheres, micropore (0.5 - 1.2 nm), mesopore (3.14 - 35.00 nm), and macropore (60 - 146 nm) were produced respectively. Electrochemical test results showed that the porous carbon spheres (BPCS - 1) treated with 0.927 5 g boric acid had the optimal supercapacitor performance. In a three-electrode system, BPCS-1 showed a high specific capacitance of 287.12 F·g-1 at a current density of 0.5 A·g-1. In a two-electrode system, BPCS-1 showed an excellent energy density (5.3 Wh·kg-1) and a superior specific capacitance of 151.34 F·g-1 at a current density of 0.5 A·g-1, and outstanding cycling stability of 96.43% capacitance retention after 1 000 cycles at a current density of 5 A·g-1.
2022, 38(10): 2019-2027
doi: 10.11862/CJIC.2022.202
Abstract:
Two ruthenium complexes (Ru-Cl, Ru-NCMe) containing long alkoxy tribipyridine and 2, 2′-bipyridine were synthesized and characterized by mass spectrometry, NMR, single crystal X-ray diffraction analysis, etc. Based on their crystal structural information, it can be found that the sixth coordination position in complex Ru-Cl is Cl- ion, and the sixth coordination position in complex Ru-NCME is N atom in acetonitrile molecule. The interaction of the two complexes with various amino acids and DNA was studied by UV-Vis absorption and fluorescence spectros-copy. It was found that the complexes with long alkyl chains and rigid coordination planes had an obvious specific recognition effect on DNA. Further study found that they could bind DNA in the way of insertion and electrostatic. Both results of the experiments and the theoretical calculation were consistent.
Two ruthenium complexes (Ru-Cl, Ru-NCMe) containing long alkoxy tribipyridine and 2, 2′-bipyridine were synthesized and characterized by mass spectrometry, NMR, single crystal X-ray diffraction analysis, etc. Based on their crystal structural information, it can be found that the sixth coordination position in complex Ru-Cl is Cl- ion, and the sixth coordination position in complex Ru-NCME is N atom in acetonitrile molecule. The interaction of the two complexes with various amino acids and DNA was studied by UV-Vis absorption and fluorescence spectros-copy. It was found that the complexes with long alkyl chains and rigid coordination planes had an obvious specific recognition effect on DNA. Further study found that they could bind DNA in the way of insertion and electrostatic. Both results of the experiments and the theoretical calculation were consistent.
2022, 38(10): 2028-2036
doi: 10.11862/CJIC.2022.187
Abstract:
Double-perovskite oxide Sr2MgMoO6 (SMMO) was prepared as anode material for solid-oxide fuel cells by the sol-gel route. The effect of the material preparation scenario on the phase constituents, transport property, and catalyzing activity for H2 oxidization was investigated. The results show that the preparation process of SMMO requires strict control, and a phase-pure sample with a double-perovskite structure can be hardly synthesized by a one-step annealing reaction, and a high purity grade of SMMO requires the repeated thorough mixing and full annealing. In the meanwhile, impurity phase SrMoO4 in a very small amount is almost unavoidable. The impure substance in samples affects a great deal of the electrical conductivity of this material, and a purer sample exhibits better conductive performance. The purity of SMMO has a tremendous impact on the electrochemical performance of this material, and a purer sample exhibits a lower anode interfacial resistance, a higher catalyzing activity for H2 oxidizing, and a larger power output of the corresponding single cell. At a temperature of 800 ℃, the area-specific resistance of the SMMO anode was as low as 1.07 Ω·cm2, and power output from the corresponding single cell reached to 710 mW·cm-2.
Double-perovskite oxide Sr2MgMoO6 (SMMO) was prepared as anode material for solid-oxide fuel cells by the sol-gel route. The effect of the material preparation scenario on the phase constituents, transport property, and catalyzing activity for H2 oxidization was investigated. The results show that the preparation process of SMMO requires strict control, and a phase-pure sample with a double-perovskite structure can be hardly synthesized by a one-step annealing reaction, and a high purity grade of SMMO requires the repeated thorough mixing and full annealing. In the meanwhile, impurity phase SrMoO4 in a very small amount is almost unavoidable. The impure substance in samples affects a great deal of the electrical conductivity of this material, and a purer sample exhibits better conductive performance. The purity of SMMO has a tremendous impact on the electrochemical performance of this material, and a purer sample exhibits a lower anode interfacial resistance, a higher catalyzing activity for H2 oxidizing, and a larger power output of the corresponding single cell. At a temperature of 800 ℃, the area-specific resistance of the SMMO anode was as low as 1.07 Ω·cm2, and power output from the corresponding single cell reached to 710 mW·cm-2.
2022, 38(10): 2037-2046
doi: 10.11862/CJIC.2022.211
Abstract:
This work reports a bifunctional catalyst consisting of ultra-small Ru nanoclusters anchored onto oxygenvacancy-enriched MoO3-x nanobelts (Ru/MoO3-x). The obtained catalyst exhibited excellent hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER) performances with a low overpotential of -79 and -27 mV at 10 mA·cm-2, respectively. And the assembled hydrazine-assisted overall water splitting (OWS) device required a low cell voltage of only 13 mV, significantly better than commercial 20% Pt/C and some recently reported catalysts. Such excellent performance is mainly attributed to Ru nanoclusters facilitating dehydrogenation of N2H4 in HzOR and balancing of H* adsorption/desorption in HER and the abundant electrochemical active sites, optimized electron transfer kinetics resulting from oxygen vacancies in MoO3-x and Ru/MoO3-x heterostructures.
This work reports a bifunctional catalyst consisting of ultra-small Ru nanoclusters anchored onto oxygenvacancy-enriched MoO3-x nanobelts (Ru/MoO3-x). The obtained catalyst exhibited excellent hydrazine oxidation reaction (HzOR) and hydrogen evolution reaction (HER) performances with a low overpotential of -79 and -27 mV at 10 mA·cm-2, respectively. And the assembled hydrazine-assisted overall water splitting (OWS) device required a low cell voltage of only 13 mV, significantly better than commercial 20% Pt/C and some recently reported catalysts. Such excellent performance is mainly attributed to Ru nanoclusters facilitating dehydrogenation of N2H4 in HzOR and balancing of H* adsorption/desorption in HER and the abundant electrochemical active sites, optimized electron transfer kinetics resulting from oxygen vacancies in MoO3-x and Ru/MoO3-x heterostructures.
2022, 38(10): 2047-2055
doi: 10.11862/CJIC.2022.204
Abstract:
To overcome the shortcomings of carbon nitride (C3N4), such as easily recombination of photogenerated charges and limited photocatalytic activity, this study explored a method to prepare NF-C3N4 via co-doping of N and F into C3N4 with improved photocatalytic performance.Using HF and NH3 produced by the in-situ decomposition of NH4F at high temperature, dual elements doping was achieved while etching C3N4.N-doped C3N4 (N-C3N4) was prepared by using ammonium chloride (NH4Cl) as a control sample.The effects of N and F co-doping on the morphology, composition, structure, and physicochemical properties of C3N4 were studied using scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), specific surface area, and electrochemistry.Compared with C3N4 and N-C3N4, NF-C3N4 had porous and increased specific surface area, and the generation, separation, and transfer of photogenerated charges were promoted.The photocatalytic reduction rate of Cr(Ⅵ) by NF-C3N4 was 2.6 times that of C3N4 and 1.7 times that of N-C3N4, respectively.The influence of different precursors(urea, dicyandiamide, and melamine)on the preparation of C3N4 was further investigated.It was found that when the mass ratio of C3N4 with urea as a precursor to NH4F was 3∶2, NF-C3N4 showed the best photocatalytic performance.Furthermore, the reduction rate of Cr(Ⅵ) can be enhanced with the increase of catalyst dosage, light intensity, hole trapping agent concentration, and decrease in pH.After 40 min visible light irradiation with 0.1 g·L-1 NF-C3N4, pH=3 and cEDTA-2Na=2 mmol·L-1, the Cr(Ⅵ) removal efficiency reached 90%.Five cyclic runs indicated that the optimized NF-C3N4 remained good performance and high stability for photocatalytic reduction of Cr(Ⅵ).
To overcome the shortcomings of carbon nitride (C3N4), such as easily recombination of photogenerated charges and limited photocatalytic activity, this study explored a method to prepare NF-C3N4 via co-doping of N and F into C3N4 with improved photocatalytic performance.Using HF and NH3 produced by the in-situ decomposition of NH4F at high temperature, dual elements doping was achieved while etching C3N4.N-doped C3N4 (N-C3N4) was prepared by using ammonium chloride (NH4Cl) as a control sample.The effects of N and F co-doping on the morphology, composition, structure, and physicochemical properties of C3N4 were studied using scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), specific surface area, and electrochemistry.Compared with C3N4 and N-C3N4, NF-C3N4 had porous and increased specific surface area, and the generation, separation, and transfer of photogenerated charges were promoted.The photocatalytic reduction rate of Cr(Ⅵ) by NF-C3N4 was 2.6 times that of C3N4 and 1.7 times that of N-C3N4, respectively.The influence of different precursors(urea, dicyandiamide, and melamine)on the preparation of C3N4 was further investigated.It was found that when the mass ratio of C3N4 with urea as a precursor to NH4F was 3∶2, NF-C3N4 showed the best photocatalytic performance.Furthermore, the reduction rate of Cr(Ⅵ) can be enhanced with the increase of catalyst dosage, light intensity, hole trapping agent concentration, and decrease in pH.After 40 min visible light irradiation with 0.1 g·L-1 NF-C3N4, pH=3 and cEDTA-2Na=2 mmol·L-1, the Cr(Ⅵ) removal efficiency reached 90%.Five cyclic runs indicated that the optimized NF-C3N4 remained good performance and high stability for photocatalytic reduction of Cr(Ⅵ).
2022, 38(10): 2056-2064
doi: 10.11862/CJIC.2022.189
Abstract:
A new sandwich - type tungstobismuthate containing manganese (Ⅱ), Na9H[(Mn(H2O)3)2(Mn(H2O)2) (WO2) (BiW9O33)2]·30H2O (1), has been synthesized in the aqueous solutions and structurally characterized by elemental analyses, UV-Vis spectroscopy, IR spectroscopy, powder X -ray diffraction, single-crystal X-ray diffraction and ther- mogravimetric analysis. Single crystal X-ray analysis shows that the polyanion of 1 is composed of two trivacant β-B-[BiW9O33]9- Keggin fragments joined together by two [(Mn(H2O)2)0.5(WO2)0.5]2+ moieties and two [Mn(H2O)3]2+ subunits located in the inner and outer positions, respectively. Magnetic measurements indicate that 1 exhibits the antiferro-magnetic couplings between Mn(Ⅱ) centers.
A new sandwich - type tungstobismuthate containing manganese (Ⅱ), Na9H[(Mn(H2O)3)2(Mn(H2O)2) (WO2) (BiW9O33)2]·30H2O (1), has been synthesized in the aqueous solutions and structurally characterized by elemental analyses, UV-Vis spectroscopy, IR spectroscopy, powder X -ray diffraction, single-crystal X-ray diffraction and ther- mogravimetric analysis. Single crystal X-ray analysis shows that the polyanion of 1 is composed of two trivacant β-B-[BiW9O33]9- Keggin fragments joined together by two [(Mn(H2O)2)0.5(WO2)0.5]2+ moieties and two [Mn(H2O)3]2+ subunits located in the inner and outer positions, respectively. Magnetic measurements indicate that 1 exhibits the antiferro-magnetic couplings between Mn(Ⅱ) centers.
2022, 38(10): 2065-2071
doi: 10.11862/CJIC.2022.180
Abstract:
The design and assembly of nanostructured materials are devoted to improving the electrochemical properties of the Li-S batteries (LSBs) by synergistic effect. In this work, a composite of hexagonal Co1-xS nanosheets decorating N-doped carbon nanotube (Co1-xS-CNT) was successfully synthesized and used as a sulfur host for Li-S batteries (LSBs). In Co1-xS-CNT/S, the polar hexagonal Co1-xS nanosheets can absorb the lithium polysulfide through chemisorption, at the same time, the CNT can provide a highly conductive network. Based on the synergy of physical encapsulating and chemical trapping, the Co1-xS-CNT/S cathode exhibited excellent electrochemical performance, especially the superior cycle performance. After 170 cycles, the Co1-xS-CNT/S can maintain a discharge capacity of 405.6 mAh·g-1 at 0.5C, with a stable Coulombic efficiency (over 99.2%).
The design and assembly of nanostructured materials are devoted to improving the electrochemical properties of the Li-S batteries (LSBs) by synergistic effect. In this work, a composite of hexagonal Co1-xS nanosheets decorating N-doped carbon nanotube (Co1-xS-CNT) was successfully synthesized and used as a sulfur host for Li-S batteries (LSBs). In Co1-xS-CNT/S, the polar hexagonal Co1-xS nanosheets can absorb the lithium polysulfide through chemisorption, at the same time, the CNT can provide a highly conductive network. Based on the synergy of physical encapsulating and chemical trapping, the Co1-xS-CNT/S cathode exhibited excellent electrochemical performance, especially the superior cycle performance. After 170 cycles, the Co1-xS-CNT/S can maintain a discharge capacity of 405.6 mAh·g-1 at 0.5C, with a stable Coulombic efficiency (over 99.2%).
2022, 38(10): 2072-2082
doi: 10.11862/CJIC.2022.203
Abstract:
Nitrogen - doped graphene (NG) was synthesized by thermal annealing of graphene oxide (GO) using melamine as the nitrogen source, and NG-loaded manganese (Mn/NG) was prepared using the immersion precipitation method. At 80% relative humidity (RH) and an initial ozone concentration of 85.7 mg·m-3, the decomposition rate of ozone remained above 80% after 24 h of reaction. Under the low RH environment, the catalytic activity can be restored to the initial state again. The nitrogen doping not only created structural defects for the catalyst, but also the lone pair electrons of nitrogen atoms increased the electron density of oxygen vacancies, reduced the adsorption energy of water molecules, and improved the moisture resistance of the catalyst.
Nitrogen - doped graphene (NG) was synthesized by thermal annealing of graphene oxide (GO) using melamine as the nitrogen source, and NG-loaded manganese (Mn/NG) was prepared using the immersion precipitation method. At 80% relative humidity (RH) and an initial ozone concentration of 85.7 mg·m-3, the decomposition rate of ozone remained above 80% after 24 h of reaction. Under the low RH environment, the catalytic activity can be restored to the initial state again. The nitrogen doping not only created structural defects for the catalyst, but also the lone pair electrons of nitrogen atoms increased the electron density of oxygen vacancies, reduced the adsorption energy of water molecules, and improved the moisture resistance of the catalyst.
2022, 38(10): 2083-2090
doi: 10.11862/CJIC.2022.200
Abstract:
We have successfully synthesized two organic-inorganic hybrid crystals, which are (bempy)Br (1) and (bempy)2CdBr4 (2), based on bempy (bempy=1-bromoethyl-1-methylpyrrolidinium) by employing easily disordered amines. Structural phase transitions analysis, dielectric phase transition measurements, and blue-white fluorescence spectroscopy measurements were performed on them. It is notable that, no reversible phase transition was observed in compound 1, and compound 2 exhibited high-temperature dielectric phase transition anomalies at around 357 K by differential scanning calorimetry and dielectric measurements. Both compounds showed blue-white photoluminescence with one emission peak at 538 nm for compound 1 and two emission peaks at 547 and 750 nm for compound 2. Significantly, compound 2 possesses dual functions of dielectric phase transition and blue-white photoluminescence.
We have successfully synthesized two organic-inorganic hybrid crystals, which are (bempy)Br (1) and (bempy)2CdBr4 (2), based on bempy (bempy=1-bromoethyl-1-methylpyrrolidinium) by employing easily disordered amines. Structural phase transitions analysis, dielectric phase transition measurements, and blue-white fluorescence spectroscopy measurements were performed on them. It is notable that, no reversible phase transition was observed in compound 1, and compound 2 exhibited high-temperature dielectric phase transition anomalies at around 357 K by differential scanning calorimetry and dielectric measurements. Both compounds showed blue-white photoluminescence with one emission peak at 538 nm for compound 1 and two emission peaks at 547 and 750 nm for compound 2. Significantly, compound 2 possesses dual functions of dielectric phase transition and blue-white photoluminescence.
2022, 38(10): 2091-2102
doi: 10.11862/CJIC.2022.215
Abstract:
LiNi0.5Mn1.5O4 cathode materials have been considered promising candidates for high energy density Li-ion batteries due to their high operation potential. However, to develop 5 V LiNi0.5Mn1.5O4-based batteries, practical electrolytes with high electrochemical stability are yet to be realized. In this work, tris(trimethylsilyl)-based additives, including tris(trimethylsilyl)borate (TMSB) and tris(trimethylsilyl)phosphite (TMSPi), were selected as electrolyte additives for typical ethylene carbonate (EC)-LiPF6 based electrolyte to develop practical LiNi0.5Mn1.5O4-based batteries. Combining theoretical calculations, physicochemical characterization, and electrochemical measurements, we found that both TMSB and TMSPi can improve the Coulombic efficiency and cycling stability of 5 V LiNi0.5Mn1.5O4-based cells. Specifically, TMSB can act as the stabilizer for PF6- due to its electron deficiency nature, thereby suppressing the increase of cell impedance. In addition, thanks to its high highest occupied molecule orbital (HOMO) energy level, TMSPi can be preferentially oxidized on the surface of charged LiNi0.5Mn1.5O4 electrodes, resulting in a decent rate capacity and high discharge platform. In addition, TMSPi is conducive to the formation of robust solid electrolyte interphase (SEI) on graphite anode through the nucleophilic attack, resulting in enhanced cycle performance. As a result, Graphite||LiNi0.5Mn1.5O4 pouch cells with TMSPi - containing electrolyte displayed capacity retention of 88.9% after 100 cycles at 1C, superior to that in the blank (60.5%) and TMSB - containing (77.4%) electrolytes.
LiNi0.5Mn1.5O4 cathode materials have been considered promising candidates for high energy density Li-ion batteries due to their high operation potential. However, to develop 5 V LiNi0.5Mn1.5O4-based batteries, practical electrolytes with high electrochemical stability are yet to be realized. In this work, tris(trimethylsilyl)-based additives, including tris(trimethylsilyl)borate (TMSB) and tris(trimethylsilyl)phosphite (TMSPi), were selected as electrolyte additives for typical ethylene carbonate (EC)-LiPF6 based electrolyte to develop practical LiNi0.5Mn1.5O4-based batteries. Combining theoretical calculations, physicochemical characterization, and electrochemical measurements, we found that both TMSB and TMSPi can improve the Coulombic efficiency and cycling stability of 5 V LiNi0.5Mn1.5O4-based cells. Specifically, TMSB can act as the stabilizer for PF6- due to its electron deficiency nature, thereby suppressing the increase of cell impedance. In addition, thanks to its high highest occupied molecule orbital (HOMO) energy level, TMSPi can be preferentially oxidized on the surface of charged LiNi0.5Mn1.5O4 electrodes, resulting in a decent rate capacity and high discharge platform. In addition, TMSPi is conducive to the formation of robust solid electrolyte interphase (SEI) on graphite anode through the nucleophilic attack, resulting in enhanced cycle performance. As a result, Graphite||LiNi0.5Mn1.5O4 pouch cells with TMSPi - containing electrolyte displayed capacity retention of 88.9% after 100 cycles at 1C, superior to that in the blank (60.5%) and TMSB - containing (77.4%) electrolytes.
2022, 38(10): 2103-2110
doi: 10.11862/CJIC.2022.206
Abstract:
In this work, a miniature Y-jet mixer was used to enhance the mixing efficiency to prepare strontium carbonate (SrCO3) microspheres by using the co - precipitation method. Ethylenediamine tetraacetic acid disodium (EDTA) was used as the additive to control particle morphology. The effects of EDTA concentration and reactant concentrations on the morphology and particle size distribution (PSD) were investigated. Experimental results demonstrate that orthorhombic-type spherical SrCO3 particles were obtained by using EDTA as an additive. The molar concentration ratio of EDTA to strontium chloride (SrCl2), RE, is the key factor affecting the particle morphology and size. When RE was fixed, reactant concentrations had little effect on the morphology and size. The microspheres prepared under the optimum conditions were 2-3 μm with a very narrow PSD. Without EDTA, only rod-shaped particles were prepared and the particles tend to aggregate into bundles. The mechanism of how EDTA regulates the morphology is also discussed.
In this work, a miniature Y-jet mixer was used to enhance the mixing efficiency to prepare strontium carbonate (SrCO3) microspheres by using the co - precipitation method. Ethylenediamine tetraacetic acid disodium (EDTA) was used as the additive to control particle morphology. The effects of EDTA concentration and reactant concentrations on the morphology and particle size distribution (PSD) were investigated. Experimental results demonstrate that orthorhombic-type spherical SrCO3 particles were obtained by using EDTA as an additive. The molar concentration ratio of EDTA to strontium chloride (SrCl2), RE, is the key factor affecting the particle morphology and size. When RE was fixed, reactant concentrations had little effect on the morphology and size. The microspheres prepared under the optimum conditions were 2-3 μm with a very narrow PSD. Without EDTA, only rod-shaped particles were prepared and the particles tend to aggregate into bundles. The mechanism of how EDTA regulates the morphology is also discussed.
