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2021 Volume 40 Issue 4
2021, 40(4): 409-414
doi: 10.14102/j.cnki.0254-5861.2011-2954
Abstract:
The nitro-substituted derivatives of guanine are designed and calculated to explore novel high energy density materials. To explore the thermal stability of title molecules, the heat of formation (HOF), bond dissociation energy (BDE), and bond order of the trigger bond are calculated. To predict the possibility used as high energy density compounds, the detonation pressure (P), detonation velocity (D), explosive heat (Q), and crystal density (ρ) are calculated by using the classical Kamlet-Jacobs (K-J) equation. Based on our calculations, E (D = 8.93 km/s, P = 37.21 GPa) is confirmed as the potential high energy density compound.
The nitro-substituted derivatives of guanine are designed and calculated to explore novel high energy density materials. To explore the thermal stability of title molecules, the heat of formation (HOF), bond dissociation energy (BDE), and bond order of the trigger bond are calculated. To predict the possibility used as high energy density compounds, the detonation pressure (P), detonation velocity (D), explosive heat (Q), and crystal density (ρ) are calculated by using the classical Kamlet-Jacobs (K-J) equation. Based on our calculations, E (D = 8.93 km/s, P = 37.21 GPa) is confirmed as the potential high energy density compound.
2021, 40(4): 415-423
doi: 10.14102/j.cnki.0254-5861.2011-2956
Abstract:
Density functional theory (DFT) calculations are performed to investigate recent experimentally studied ring-closing sulfoxide imidation catalyzed by Fe(Ⅱ)-phthalocyanine (FeⅡPc). Our results reveal that the ground state of iron phthalocyanine nitrene intermediate (PcFeNR, R = (CH2)3(SO)Ph), which is believed to mediate the intramolecular imitation, is triplet state featuring a diradical structure. The formation of PcFeNR is the result of a denitrification process with a calculated high-barrier of 23.4 kcal/mol which is in good agreement with the experimentally observed high reaction temperature of 100 ℃. The generated PcFeNR undergoes a low-barrier intramolecular nucleophilic attack by proximal nitrogen atom on the sulfur accomplishing the cyclization of sulfoxide. This study provides theoretical insights into the mechanism-based design of useful catalysts for nitrene transfer reactions.
Density functional theory (DFT) calculations are performed to investigate recent experimentally studied ring-closing sulfoxide imidation catalyzed by Fe(Ⅱ)-phthalocyanine (FeⅡPc). Our results reveal that the ground state of iron phthalocyanine nitrene intermediate (PcFeNR, R = (CH2)3(SO)Ph), which is believed to mediate the intramolecular imitation, is triplet state featuring a diradical structure. The formation of PcFeNR is the result of a denitrification process with a calculated high-barrier of 23.4 kcal/mol which is in good agreement with the experimentally observed high reaction temperature of 100 ℃. The generated PcFeNR undergoes a low-barrier intramolecular nucleophilic attack by proximal nitrogen atom on the sulfur accomplishing the cyclization of sulfoxide. This study provides theoretical insights into the mechanism-based design of useful catalysts for nitrene transfer reactions.
2021, 40(4): 424-430
doi: 10.14102/j.cnki.0254-5861.2011-2937
Abstract:
1,2,4-Triazolo[4,3-a]pyridine (TP) is a key intermediate in pesticides, materials and medicines. The title compound 4-(((8-chloro-3-oxo-[1,2,4]triazolo[4,3-a]pyridin-2(3H)-yl)thio)methyl)benzonitrile was synthesized via three steps, and its structure was characterized by 1H NMR, HRMS and X-ray diffraction. Single-crystal X-ray diffraction reveals that it crystallizes in the monoclinic system, space group P21/c. Four TP molecules in the symmetric unit are linked through the O–H···O and O–H···N hydrogen bonding interactions via two H2O molecules along with two π-π interactions. The preliminary antifungal activity results indicated that the compound TP exhibited good activities. Theoretical calculation was carried out by DFT method using the 6-31G basis set.
1,2,4-Triazolo[4,3-a]pyridine (TP) is a key intermediate in pesticides, materials and medicines. The title compound 4-(((8-chloro-3-oxo-[1,2,4]triazolo[4,3-a]pyridin-2(3H)-yl)thio)methyl)benzonitrile was synthesized via three steps, and its structure was characterized by 1H NMR, HRMS and X-ray diffraction. Single-crystal X-ray diffraction reveals that it crystallizes in the monoclinic system, space group P21/c. Four TP molecules in the symmetric unit are linked through the O–H···O and O–H···N hydrogen bonding interactions via two H2O molecules along with two π-π interactions. The preliminary antifungal activity results indicated that the compound TP exhibited good activities. Theoretical calculation was carried out by DFT method using the 6-31G basis set.
2021, 40(4): 431-442
doi: 10.14102/j.cnki.0254-5861.2011-2966
Abstract:
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gained tremendous attention due to its high infectivity and pathogenicity. The 3-chymotrypsin-like hydrolase protease (Mpro) of SARS-CoV-2 has been proven to be an important target for anti-SARS-CoV-2 activity. To better identify the drugs with potential in treating coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 and according to the crystal structure of Mpro, we conducted a virtual screening of FDA-approved drugs and chemical agents that have entered clinical trials. As a result, 9 drug candidates with therapeutic potential for the treatment of COVID-19 and with good docking scores were identified to target SARS-CoV-2. Consequently, molecular dynamics (MD) simulation was performed to explore the dynamic interactions between the predicted drugs and Mpro. The binding mode during MD simulation showed that hydrogen bonding and hydrophobic interactions played an important role in the binding processes. Based on the binding free energy calculated by using MM/PBSA, Lopiravir, an inhibitor of human immunodeficiency virus (HIV) protease, is under investigation for the treatment of COVID-19 in combination with ritionavir, and it might inhibit Mpro effectively. Moreover, Ombitasvir, an inhibitor for non-structural protein 5A of hepatitis C virus (HCV), has good inhibitory potency for Mpro. It is notable that the GS-6620 has a binding free energy, with respect to binding Mpro, comparable to that of ombitasvir. Our study suggests that ombitasvir and lopinavir are good drug candidates for the treatment of COVID-19, and that GS-6620 has good anti-SARS-CoV-2 activity.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gained tremendous attention due to its high infectivity and pathogenicity. The 3-chymotrypsin-like hydrolase protease (Mpro) of SARS-CoV-2 has been proven to be an important target for anti-SARS-CoV-2 activity. To better identify the drugs with potential in treating coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 and according to the crystal structure of Mpro, we conducted a virtual screening of FDA-approved drugs and chemical agents that have entered clinical trials. As a result, 9 drug candidates with therapeutic potential for the treatment of COVID-19 and with good docking scores were identified to target SARS-CoV-2. Consequently, molecular dynamics (MD) simulation was performed to explore the dynamic interactions between the predicted drugs and Mpro. The binding mode during MD simulation showed that hydrogen bonding and hydrophobic interactions played an important role in the binding processes. Based on the binding free energy calculated by using MM/PBSA, Lopiravir, an inhibitor of human immunodeficiency virus (HIV) protease, is under investigation for the treatment of COVID-19 in combination with ritionavir, and it might inhibit Mpro effectively. Moreover, Ombitasvir, an inhibitor for non-structural protein 5A of hepatitis C virus (HCV), has good inhibitory potency for Mpro. It is notable that the GS-6620 has a binding free energy, with respect to binding Mpro, comparable to that of ombitasvir. Our study suggests that ombitasvir and lopinavir are good drug candidates for the treatment of COVID-19, and that GS-6620 has good anti-SARS-CoV-2 activity.
2021, 40(4): 443-452
doi: 10.14102/j.cnki.0254-5861.2011-3075
Abstract:
Two new thioantimonates, (NH4)2Sb10S16 (1) and K1.4(NH4)0.6Sb10S16 (2), have been synthesized by solvothermal method with the yields of 80% and 85%, respectively. Single-crystal X-ray diffraction (SCXRD) study reveals that 1 crystallizes in the monoclinic space group of Pn with a = 8.1284(4), b = 19.4587(9), c = 9.1030(4) Å, β = 91.736(5)°, V = 1439.14(12) Å3, Z = 2, Dc = 4.077 g·cm-3, F(000) = 1576, μ = 10.389 mm-1, R = 0.0343 and wR = 0.0624 (I > 2σ(I)); 2 also crystallizes in the monoclinic space group of Pn with a = 8.0989(6), b = 19.3730(17), c = 9.0411(6) Å, β = 91.879(6)°, V = 1417.79(19) Å3, Z = 2, Dc = 4.207 g·cm-3, F(000) = 1598, μ = 10.748 mm-1, R = 0.0323 and wR = 0.0664 (I > 2σ(I)). The anionic frameworks of two compounds both feature two-dimensional (2D) [Sb10S16]n2n- layers. The stabilities and optoelectronic properties of 1 and 2 have been characterized. In particular, they are stable under acidic or alkaline conditions (pH = 0 or 12.5), showing excellent acid-based resistance.
Two new thioantimonates, (NH4)2Sb10S16 (1) and K1.4(NH4)0.6Sb10S16 (2), have been synthesized by solvothermal method with the yields of 80% and 85%, respectively. Single-crystal X-ray diffraction (SCXRD) study reveals that 1 crystallizes in the monoclinic space group of Pn with a = 8.1284(4), b = 19.4587(9), c = 9.1030(4) Å, β = 91.736(5)°, V = 1439.14(12) Å3, Z = 2, Dc = 4.077 g·cm-3, F(000) = 1576, μ = 10.389 mm-1, R = 0.0343 and wR = 0.0624 (I > 2σ(I)); 2 also crystallizes in the monoclinic space group of Pn with a = 8.0989(6), b = 19.3730(17), c = 9.0411(6) Å, β = 91.879(6)°, V = 1417.79(19) Å3, Z = 2, Dc = 4.207 g·cm-3, F(000) = 1598, μ = 10.748 mm-1, R = 0.0323 and wR = 0.0664 (I > 2σ(I)). The anionic frameworks of two compounds both feature two-dimensional (2D) [Sb10S16]n2n- layers. The stabilities and optoelectronic properties of 1 and 2 have been characterized. In particular, they are stable under acidic or alkaline conditions (pH = 0 or 12.5), showing excellent acid-based resistance.
2021, 40(4): 453-458
doi: 10.14102/j.cnki.0254-5861.2011-3049
Abstract:
A new binuclear copper(Ⅱ) complex [Cu2(MBBA)2(HPT)2(H2O)2]·2H2O (1) was synthesized with copper acetate, 2-(4-methylbenzoyl) benzoic acid (MBBA) and 3-(pyridin-2-yl)-1H-1,2,4-triazole (HPT). It crystallizes in the monoclinic space group P21/c with a = 14.722(2), b = 8.8907(12), c = 18.5565(18) Å, β = 116.820(7)º, V = 2167.6(5) Å3, Mr = 483.96, Dc = 1.483 g/cm3, Z = 4, μ(MoKa) = 1.049 mm-1, F(000) = 981, the final GOOF = 0.952, R = 0.0586 and wR = 0.0823. The whole molecule consists of two copper ions bridged by two HPT molecules. The central Cu(Ⅱ) ion is coordinated by six atoms to give a distorted octahedral coordination geometry. The structure of 1 has been determined by X-ray diffraction, IR spectrum and thermal stability analysis. The solid-state fluorescence displays an obvious emission band at 412 nm upon excitation at 330 nm. Magnetic properties indicate that 1 exhibits antiferromagnetic properties.
A new binuclear copper(Ⅱ) complex [Cu2(MBBA)2(HPT)2(H2O)2]·2H2O (1) was synthesized with copper acetate, 2-(4-methylbenzoyl) benzoic acid (MBBA) and 3-(pyridin-2-yl)-1H-1,2,4-triazole (HPT). It crystallizes in the monoclinic space group P21/c with a = 14.722(2), b = 8.8907(12), c = 18.5565(18) Å, β = 116.820(7)º, V = 2167.6(5) Å3, Mr = 483.96, Dc = 1.483 g/cm3, Z = 4, μ(MoKa) = 1.049 mm-1, F(000) = 981, the final GOOF = 0.952, R = 0.0586 and wR = 0.0823. The whole molecule consists of two copper ions bridged by two HPT molecules. The central Cu(Ⅱ) ion is coordinated by six atoms to give a distorted octahedral coordination geometry. The structure of 1 has been determined by X-ray diffraction, IR spectrum and thermal stability analysis. The solid-state fluorescence displays an obvious emission band at 412 nm upon excitation at 330 nm. Magnetic properties indicate that 1 exhibits antiferromagnetic properties.
2021, 40(4): 459-464
doi: 10.14102/j.cnki.0254-5861.2011-2970
Abstract:
A 2D layer Cu(Ⅱ) coordination polymer [Cu(npth)(H2O)]n (1) was crystallized from a mixture of 3-nitrophthalic acid and Cu(OAc)2·H2O in water under room temperature and structurally characterized by single-crystal X-ray diffraction, FT-IR and TGA. Compound 1 was applied to make a nanocomposite with graphene oxide (GO). A highly dispersible and stable nanocomposite of Cu(npth)-GO was successfully synthesized by a simple ultrasonication method. SEM, TEM, UV-vis, FT-IR and TGA were used to characterize the morphology and structure of the prepared composite. In accordance with the characterization results, we suspected that the binding mechanism of Cu(npth) and GO was assigned to be the cooperative interaction of Cu–O coordination, π-π stacking and hydrogen bonding.
A 2D layer Cu(Ⅱ) coordination polymer [Cu(npth)(H2O)]n (1) was crystallized from a mixture of 3-nitrophthalic acid and Cu(OAc)2·H2O in water under room temperature and structurally characterized by single-crystal X-ray diffraction, FT-IR and TGA. Compound 1 was applied to make a nanocomposite with graphene oxide (GO). A highly dispersible and stable nanocomposite of Cu(npth)-GO was successfully synthesized by a simple ultrasonication method. SEM, TEM, UV-vis, FT-IR and TGA were used to characterize the morphology and structure of the prepared composite. In accordance with the characterization results, we suspected that the binding mechanism of Cu(npth) and GO was assigned to be the cooperative interaction of Cu–O coordination, π-π stacking and hydrogen bonding.
2021, 40(4): 465-472
doi: 10.14102/j.cnki.0254-5861.2011-2957
Abstract:
A new ligand [1-{2-(2-pyridyl)-benzo[d]imidazole}-2-(5-hydroxyisophthalic acid) ethane] was used to synthesize cadmium and cobalt based florescent organic frameworks successfully under solvothermal conditions. Single-crystal X-ray crystallography of both complexes as well as their thermal stability and luminescence properties was investigated. Much emphasis was placed on the newly synthesized Cd-complex which shows great sensitivity for the detection of Fe3+ ions and could be used as a potential probe to detect the Fe3+ ions.
A new ligand [1-{2-(2-pyridyl)-benzo[d]imidazole}-2-(5-hydroxyisophthalic acid) ethane] was used to synthesize cadmium and cobalt based florescent organic frameworks successfully under solvothermal conditions. Single-crystal X-ray crystallography of both complexes as well as their thermal stability and luminescence properties was investigated. Much emphasis was placed on the newly synthesized Cd-complex which shows great sensitivity for the detection of Fe3+ ions and could be used as a potential probe to detect the Fe3+ ions.
2021, 40(4): 473-481
doi: 10.14102/j.cnki.0254–5861.2011–2946
Abstract:
Two mixed-ligand compounds, namely [Mn2(bimb)(PA)2]n (1) and [Zn(bimb)(PA)]n (2) (H2PA = pamoic acid, bimb = 1,4-bis(imidazol-1-yl)-butane) have been synthesized under the same solvothermal conditions. Compound 1 can be described as (4,4) topology based on the 4-connected [Mn2(COO)4] paddle-wheel units, which contains both rotaxane- and catenane-like motifs. For 2, the 2D wavy-like network interlocked with each other and resulted in a 2-fold interpenetrated 2D → 3D architecture. The structural differences of the two compounds are mainly due to the differences of metal ions and coordination modes of the PA2- ligand. In addition, the magnetism and photoluminescent properties of them have also been explored.
Two mixed-ligand compounds, namely [Mn2(bimb)(PA)2]n (1) and [Zn(bimb)(PA)]n (2) (H2PA = pamoic acid, bimb = 1,4-bis(imidazol-1-yl)-butane) have been synthesized under the same solvothermal conditions. Compound 1 can be described as (4,4) topology based on the 4-connected [Mn2(COO)4] paddle-wheel units, which contains both rotaxane- and catenane-like motifs. For 2, the 2D wavy-like network interlocked with each other and resulted in a 2-fold interpenetrated 2D → 3D architecture. The structural differences of the two compounds are mainly due to the differences of metal ions and coordination modes of the PA2- ligand. In addition, the magnetism and photoluminescent properties of them have also been explored.
2021, 40(4): 482-486
doi: 10.14102/j.cnki.0254–5861.2011–2940
Abstract:
A new Cu(Ⅱ) complex, [Cu4Cl6O(1-TrTz)4] where 1-TrTz is 1-trityl-1H-[1,2,4]triazole, was synthesized by the reaction of 1-trityl-1H-[1,2,4]triazole with two hydrated cupric chlorides, and its structure was characterized by X-ray single-crystal diffraction. [Cu4Cl6O(1-TrTz)4] is of monoclinic system, space group P21/c, a = 12.5024(13), b = 26.400(3), c = 28.588(3) Å, β = 112.807(4)°, V = 8698.1(16) Å3, Z = 4, ρcalc = 1.411 g/cm3, μ = 1.265 mm–1, F(000) = 3772, the final R = 0.1293 and wR = 0.3644 for 55774 observed reflections (I > 2σ(I)), R(all data) = 0.1972, wR(all data) = 0.3989, completeness to theta of 25.242 is 99.9% and GOF = 1.103. In the structure of [Cu4Cl6O(1-TrTz)4], the central O atom is tetrahedral and is coordinated with four Cu atoms. The distance between copper and oxygen bond is 1.909(6) Å. In addition, the catalytic property of this complex was investigated and it could effectively catalyze the Ullmann coupling reaction of various (hetero)aryl chlorides with azoles.
A new Cu(Ⅱ) complex, [Cu4Cl6O(1-TrTz)4] where 1-TrTz is 1-trityl-1H-[1,2,4]triazole, was synthesized by the reaction of 1-trityl-1H-[1,2,4]triazole with two hydrated cupric chlorides, and its structure was characterized by X-ray single-crystal diffraction. [Cu4Cl6O(1-TrTz)4] is of monoclinic system, space group P21/c, a = 12.5024(13), b = 26.400(3), c = 28.588(3) Å, β = 112.807(4)°, V = 8698.1(16) Å3, Z = 4, ρcalc = 1.411 g/cm3, μ = 1.265 mm–1, F(000) = 3772, the final R = 0.1293 and wR = 0.3644 for 55774 observed reflections (I > 2σ(I)), R(all data) = 0.1972, wR(all data) = 0.3989, completeness to theta of 25.242 is 99.9% and GOF = 1.103. In the structure of [Cu4Cl6O(1-TrTz)4], the central O atom is tetrahedral and is coordinated with four Cu atoms. The distance between copper and oxygen bond is 1.909(6) Å. In addition, the catalytic property of this complex was investigated and it could effectively catalyze the Ullmann coupling reaction of various (hetero)aryl chlorides with azoles.
2021, 40(4): 487-494
doi: 10.14102/j.cnki.0254–5861.2011–2941
Abstract:
A novel zinc complex (ZnE) has been designed and synthesized based on the derivative of 2-(2'-hydroxyphenyl)-1-H-benzimidazole (HBI) and the neutral nitrogen-containing ligand (phen). The crystal of the title complex crystallizes in the monoclinic system, space group P21/n with a = 10.2631(2), b = 34.2166(6), c = 11.4103(3) Å, β = 96.771(2)°, Mr = 844.24, V = 3978.99(14) Å3, Z = 4, the final R = 0.0400 and wR = 0.1001 for 8107 observed reflections (I > 2σ(I)). In the title complex, the free protonated phenoxide moiety (4-OH) is successfully retained to realize pseudo-intramolecular hydrogen bonds with the coordinated O atom from the other ligand.
A novel zinc complex (ZnE) has been designed and synthesized based on the derivative of 2-(2'-hydroxyphenyl)-1-H-benzimidazole (HBI) and the neutral nitrogen-containing ligand (phen). The crystal of the title complex crystallizes in the monoclinic system, space group P21/n with a = 10.2631(2), b = 34.2166(6), c = 11.4103(3) Å, β = 96.771(2)°, Mr = 844.24, V = 3978.99(14) Å3, Z = 4, the final R = 0.0400 and wR = 0.1001 for 8107 observed reflections (I > 2σ(I)). In the title complex, the free protonated phenoxide moiety (4-OH) is successfully retained to realize pseudo-intramolecular hydrogen bonds with the coordinated O atom from the other ligand.
2021, 40(4): 495-500
doi: 10.14102/j.cnki.0254–5861.2011–2942
Abstract:
One hexanuclear cobalt cluster [Co2ⅢCo4Ⅱ(L)4(CH3COO)2(MeO)4]·MeOH (1) was synthesized by the reaction of H2L (H2L = 2-((2-hydroxy-4-methoxy-benzylideneamino)methyl)phenol) and Co(OAc)2·4H2O in MeOH under solvothermal conditions. Complex 1 crystalizes in the triclinic space group P\begin{document}$ \overline 1 $\end{document}
One hexanuclear cobalt cluster [Co2ⅢCo4Ⅱ(L)4(CH3COO)2(MeO)4]·MeOH (1) was synthesized by the reaction of H2L (H2L = 2-((2-hydroxy-4-methoxy-benzylideneamino)methyl)phenol) and Co(OAc)2·4H2O in MeOH under solvothermal conditions. Complex 1 crystalizes in the triclinic space group P
2021, 40(4): 501-506
doi: 10.14102/j.cnki.0254–5861.2011–2951
Abstract:
A novel nickel complex [Ni2L2Phen3]·3H2O (HL = 3-hydroxy-2-methylquioline-4-carboxylic acid) has been synthesized by a hydrothermal approach and is structurally determined by single-crystal X-ray diffraction. The title complex crystallizes in triclinic space group P\begin{document}$ \overline 1 $\end{document}
A novel nickel complex [Ni2L2Phen3]·3H2O (HL = 3-hydroxy-2-methylquioline-4-carboxylic acid) has been synthesized by a hydrothermal approach and is structurally determined by single-crystal X-ray diffraction. The title complex crystallizes in triclinic space group P
2021, 40(4): 507-511
doi: 10.14102/j.cnki.0254–5861.2011–2969
Abstract:
A new europium(Ⅲ) complex Eu(C20H14O3N)3(2, 2'-bipy)(H2O)·H2O has been synthesized with 2-diphenylanine carbonyl benzoic acid and 2, 2'-bipyridine as ligands. Crystal data for the complex are as follows: triclinic, space group P\begin{document}$ \overline 1 $\end{document}
A new europium(Ⅲ) complex Eu(C20H14O3N)3(2, 2'-bipy)(H2O)·H2O has been synthesized with 2-diphenylanine carbonyl benzoic acid and 2, 2'-bipyridine as ligands. Crystal data for the complex are as follows: triclinic, space group P
2021, 40(4): 512-518
doi: 10.14102/j.cnki.0254–5861.2011–2934
Abstract:
Molybdenum disulphide (MoS2) has emerged as a promising candidate for low-power digital applications. However, grain boundaries play a decisive role in determining the carrier mobility and performance of MoS2-FETs. In this work, we report a systematic study on the grain boundary of chemical vapor deposition (CVD) MoS2. We found that in the ON-state, if current flows across a grain boundary that is aligned perpendicular to the channel length, the current of CVD MoS2-FETs can be significantly reduced, while in the OFF-state, the effect is negligible. Metal-insulator-transition is clearly observed, indicating the high quality of our CVD samples, and it is also shown that grain boundaries increase the metal-insulator-transition crossover-voltage in MoS2-FETs. Thereby, this work provides useful information and guidance in understanding the nature of carrier transport in synthesized MoS2 devices, and the developed framework can be applied to other 2D semiconductors in general, as well as in optimizing the CVD process and device design with 2D materials.
Molybdenum disulphide (MoS2) has emerged as a promising candidate for low-power digital applications. However, grain boundaries play a decisive role in determining the carrier mobility and performance of MoS2-FETs. In this work, we report a systematic study on the grain boundary of chemical vapor deposition (CVD) MoS2. We found that in the ON-state, if current flows across a grain boundary that is aligned perpendicular to the channel length, the current of CVD MoS2-FETs can be significantly reduced, while in the OFF-state, the effect is negligible. Metal-insulator-transition is clearly observed, indicating the high quality of our CVD samples, and it is also shown that grain boundaries increase the metal-insulator-transition crossover-voltage in MoS2-FETs. Thereby, this work provides useful information and guidance in understanding the nature of carrier transport in synthesized MoS2 devices, and the developed framework can be applied to other 2D semiconductors in general, as well as in optimizing the CVD process and device design with 2D materials.
2021, 40(4): 519-526
doi: 10.14102/j.cnki.0254–5861.2011–2975
Abstract:
Electrochemical fixation of nitrogen to ammonia with highly active, highly selective and low cost electrocatalysts is a sustainable alternative to the extremely energy- and capital-intensive Haber-Bosch process. Herein, we demonstrate a near electroneutral WO3 nanobelt catalyst to be a promising electrocatalyst for selective and efficient nitrogen reduction. The concept of near electroneutral interface is demonstrated by fabricating WO3 nanobelts with small zeta potential value on carbon fiber paper, which ensures a loose double layer structure of the electrode/electrolyte interface and allows nitrogen molecules access the active sites more easily and regulates proton transfer to increase the catalytic selectivity. The WO3/CFP electrode with optimal surface charge achieves a NH3 yield rate of 4.3 μg·h−1·mg−1 and a faradaic efficiency of 37.3% at −0.3 V vs. RHE, rivalling the performance of the state-of-the-art nitrogen reduction reaction electrocatalysts. The result reveals that an unobstructed gas-diffusion pathway for continually supplying enough nitrogen to the active catalytic sites is of great importance to the overall catalytic performance.
Electrochemical fixation of nitrogen to ammonia with highly active, highly selective and low cost electrocatalysts is a sustainable alternative to the extremely energy- and capital-intensive Haber-Bosch process. Herein, we demonstrate a near electroneutral WO3 nanobelt catalyst to be a promising electrocatalyst for selective and efficient nitrogen reduction. The concept of near electroneutral interface is demonstrated by fabricating WO3 nanobelts with small zeta potential value on carbon fiber paper, which ensures a loose double layer structure of the electrode/electrolyte interface and allows nitrogen molecules access the active sites more easily and regulates proton transfer to increase the catalytic selectivity. The WO3/CFP electrode with optimal surface charge achieves a NH3 yield rate of 4.3 μg·h−1·mg−1 and a faradaic efficiency of 37.3% at −0.3 V vs. RHE, rivalling the performance of the state-of-the-art nitrogen reduction reaction electrocatalysts. The result reveals that an unobstructed gas-diffusion pathway for continually supplying enough nitrogen to the active catalytic sites is of great importance to the overall catalytic performance.
