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2017 Volume 28 Issue 12
2017, 28(12): 2169-2170
doi: 10.1016/j.cclet.2017.11.047
Abstract:
2017, 28(12): 2171-2179
doi: 10.1016/j.cclet.2017.11.039
Abstract:
Lithium metal battery, one of the most promising candidates for high-energy-density storage system, has attracted extensive interest due to its extremely high theoretical specific capacity, low gravimetric density and lowest negative redox potential. However, the formation of lithium dendrites, uncontrolled interfacial reactions, and huge volume change during the cycles of charging and discharging lower the Coulombic efficiency and cause harsh safety issues; they are the major hurdles towards the practical applications of lithium metal batteries. This review presents the recent advances in lithium metal battery and focuses on the functional hybrid electrodes, which are constructed to boost the electrochemical performance of metallic lithium and suppress the growth of lithium dendrites. Their general design rules, fabrication strategies, enhanced performances, and potential applications are summarized and analyzed. An outlook of the challenges and the potentials of lithium metal battery is also provided, which facilitates the future development of lithium metal batteries
Lithium metal battery, one of the most promising candidates for high-energy-density storage system, has attracted extensive interest due to its extremely high theoretical specific capacity, low gravimetric density and lowest negative redox potential. However, the formation of lithium dendrites, uncontrolled interfacial reactions, and huge volume change during the cycles of charging and discharging lower the Coulombic efficiency and cause harsh safety issues; they are the major hurdles towards the practical applications of lithium metal batteries. This review presents the recent advances in lithium metal battery and focuses on the functional hybrid electrodes, which are constructed to boost the electrochemical performance of metallic lithium and suppress the growth of lithium dendrites. Their general design rules, fabrication strategies, enhanced performances, and potential applications are summarized and analyzed. An outlook of the challenges and the potentials of lithium metal battery is also provided, which facilitates the future development of lithium metal batteries
2017, 28(12): 2180-2194
doi: 10.1016/j.cclet.2017.11.038
Abstract:
To meet the ever-increasing energy demands, advanced electrode materials are strongly requested for the exploration of advanced energy storage and conversion technologies, such as Li-ion batteries, Li-S batteries, Li-/Zn-air batteries, supercapacitors, dye-sensitized solar cells, and other electrocatalysis process (e.g., oxygen reduction/evolution reaction, hydrogen evolution reaction). Transition metal chalcogenides (TMCs, i.e., sulfides and selenides) are forcefully considered as an emerging candidate, owing to their unique physical and chemical properties. Moreover, the integration of TMCs with conductive graphene host has enabled the significant improvement of electrochemical performance of devices. In this review, the recent research progress on TMC/graphene composites for applications in energy storage and conversion devices is summarized. The preparation process of TMC/graphene nanocomposites is also included. In order to promote an in-depth understanding of performance improvement for TMC/graphene materials, the operating principle of various devices and technologies are briefly presented. Finally, the perspectives are given on the design and construction of advanced electrode materials.
To meet the ever-increasing energy demands, advanced electrode materials are strongly requested for the exploration of advanced energy storage and conversion technologies, such as Li-ion batteries, Li-S batteries, Li-/Zn-air batteries, supercapacitors, dye-sensitized solar cells, and other electrocatalysis process (e.g., oxygen reduction/evolution reaction, hydrogen evolution reaction). Transition metal chalcogenides (TMCs, i.e., sulfides and selenides) are forcefully considered as an emerging candidate, owing to their unique physical and chemical properties. Moreover, the integration of TMCs with conductive graphene host has enabled the significant improvement of electrochemical performance of devices. In this review, the recent research progress on TMC/graphene composites for applications in energy storage and conversion devices is summarized. The preparation process of TMC/graphene nanocomposites is also included. In order to promote an in-depth understanding of performance improvement for TMC/graphene materials, the operating principle of various devices and technologies are briefly presented. Finally, the perspectives are given on the design and construction of advanced electrode materials.
2017, 28(12): 2195-2206
doi: 10.1016/j.cclet.2017.11.010
Abstract:
The lithium metal silicates (Li2MSiO4) (where M=Mn, Fe, and Co) have a great potential in rechargeable lithium ion batteries as polyanion cathodes, due to the immanent merits such as superior electrochemical properties, low cost, and abundance. However, these merits are suffered from lower electrical and ionic conductivities, owing to the effect of poor lithium ion extraction/insertion kinetics. By building hybrid architectures, the integrated composites may afford much promoting activities towards lithium ion batteries compared with the bare ones. Kinds of synthetic methods such as template method, sol-gel method, and hydrothermal method have been successfully applied to prepare lithium metal silicates based compounds and composite materials. In this review, we aim to present a general view of Li2MSiO4 for the recent progress. The relationship between nanoarchitectures and electrochemical performances is discussed. In the end, we also summarize the opportunities and challenges about Li2MSiO4 nanomaterials recently.
The lithium metal silicates (Li2MSiO4) (where M=Mn, Fe, and Co) have a great potential in rechargeable lithium ion batteries as polyanion cathodes, due to the immanent merits such as superior electrochemical properties, low cost, and abundance. However, these merits are suffered from lower electrical and ionic conductivities, owing to the effect of poor lithium ion extraction/insertion kinetics. By building hybrid architectures, the integrated composites may afford much promoting activities towards lithium ion batteries compared with the bare ones. Kinds of synthetic methods such as template method, sol-gel method, and hydrothermal method have been successfully applied to prepare lithium metal silicates based compounds and composite materials. In this review, we aim to present a general view of Li2MSiO4 for the recent progress. The relationship between nanoarchitectures and electrochemical performances is discussed. In the end, we also summarize the opportunities and challenges about Li2MSiO4 nanomaterials recently.
2017, 28(12): 2207-2211
doi: 10.1016/j.cclet.2017.11.037
Abstract:
Given the proper band gap, low cost and good stability, hematite (α-Fe2O3) has been considered as a promising candidate for photoelectrochemical (PEC) water splitting, however suffers from the sluggish surface water oxidation reaction kinetics. In this study, a simple dip-coating process was used to modify the surface of α-Fe2O3 nanorod arrays with cobalt oxide (CoOx) and carbon (C) for the improved PEC performance, with a photocurrent density at 1.6 V (vs. reversible hydrogen electrode, RHE) increased from 0.10 mA/cm2 for the pristine α-Fe2O3 to 0.37 mA/cm2 for the CoOx/C modified α-Fe2O3 nanorods. As revealed by electrochemical analysis, thanks to the synergistic effect of CoOx and C, the PEC enhancement could be attributed to the enhanced charge transfer ability, decreased surface charge recombination, and accelerated water oxidation reaction kinetics. This study serves as a good example for improving PEC water splitting performance via a simple method.
Given the proper band gap, low cost and good stability, hematite (α-Fe2O3) has been considered as a promising candidate for photoelectrochemical (PEC) water splitting, however suffers from the sluggish surface water oxidation reaction kinetics. In this study, a simple dip-coating process was used to modify the surface of α-Fe2O3 nanorod arrays with cobalt oxide (CoOx) and carbon (C) for the improved PEC performance, with a photocurrent density at 1.6 V (vs. reversible hydrogen electrode, RHE) increased from 0.10 mA/cm2 for the pristine α-Fe2O3 to 0.37 mA/cm2 for the CoOx/C modified α-Fe2O3 nanorods. As revealed by electrochemical analysis, thanks to the synergistic effect of CoOx and C, the PEC enhancement could be attributed to the enhanced charge transfer ability, decreased surface charge recombination, and accelerated water oxidation reaction kinetics. This study serves as a good example for improving PEC water splitting performance via a simple method.
2017, 28(12): 2212-2218
doi: 10.1016/j.cclet.2017.08.013
Abstract:
Three-dimensional (3D) carbonaceous materials derived from bacterial cellulose (BC) has been introduced as electrode for supercapacitors in recent. Here, we report a simple strategy for the synthesis of functional carbon frameworks through 2, 2, 6, 6-tetramethylpilperidine l-oxyl radical (TEMPO) mediated oxidation of bacterial cellulose (BC) followed by carbonization. TEMPO-mediated oxidation can efficiently convert the hydroxyls on the surface of BC to carboxylate groups to improve electrochemical activity. Because of its high porosity, good hydrophilicity, rich oxygen groups, and continuous ion transport in-between sheet-like porous network, the TEMPO-oxidized BC delivers a much higher gravimetric capacitance (137.3 F/g) at low annealing temperature of 500℃ than that of pyrolysis BC (31 F/g) at the same annealing temperature. The pyrolysis modified BC obtained at 900℃ shows specific capacitance (160.2 F/g), large current stability and long-term stability (84.2% of its initial capacitance retention after 10, 000 cycles).
Three-dimensional (3D) carbonaceous materials derived from bacterial cellulose (BC) has been introduced as electrode for supercapacitors in recent. Here, we report a simple strategy for the synthesis of functional carbon frameworks through 2, 2, 6, 6-tetramethylpilperidine l-oxyl radical (TEMPO) mediated oxidation of bacterial cellulose (BC) followed by carbonization. TEMPO-mediated oxidation can efficiently convert the hydroxyls on the surface of BC to carboxylate groups to improve electrochemical activity. Because of its high porosity, good hydrophilicity, rich oxygen groups, and continuous ion transport in-between sheet-like porous network, the TEMPO-oxidized BC delivers a much higher gravimetric capacitance (137.3 F/g) at low annealing temperature of 500℃ than that of pyrolysis BC (31 F/g) at the same annealing temperature. The pyrolysis modified BC obtained at 900℃ shows specific capacitance (160.2 F/g), large current stability and long-term stability (84.2% of its initial capacitance retention after 10, 000 cycles).
2017, 28(12): 2219-2222
doi: 10.1016/j.cclet.2017.11.031
Abstract:
Construction of advanced high-rate anodes is critical for the development of high-power lithium ion batteries (LIBs). In this work, we report a binder-free carbon fiber (CF)/titanium niobium oxide (TiNb2O7 (TNO)) composite electrode via a simple solvothermal method combined with heat treatment. Continuous TNO film consisting of cross-linked TNO nanoparticles of 30-50 nm is strongly anchored on the carbon fiber forming integrated CF/TNO composite electrode. Owing to the intimate threedimensional structure, the as-prepared CF/TNO electrode presents exceptional high-rate performance (245 mAh/g at 1 C, and 138 mAh/g at 80 C) and enhanced cyclability with a capacity of 150 mAh/g at the current density of 10 C after 1000 cycles. Our results demonstrate the CF/TNO electrode as efficient anode for application in high-power lithium ion batteries.
Construction of advanced high-rate anodes is critical for the development of high-power lithium ion batteries (LIBs). In this work, we report a binder-free carbon fiber (CF)/titanium niobium oxide (TiNb2O7 (TNO)) composite electrode via a simple solvothermal method combined with heat treatment. Continuous TNO film consisting of cross-linked TNO nanoparticles of 30-50 nm is strongly anchored on the carbon fiber forming integrated CF/TNO composite electrode. Owing to the intimate threedimensional structure, the as-prepared CF/TNO electrode presents exceptional high-rate performance (245 mAh/g at 1 C, and 138 mAh/g at 80 C) and enhanced cyclability with a capacity of 150 mAh/g at the current density of 10 C after 1000 cycles. Our results demonstrate the CF/TNO electrode as efficient anode for application in high-power lithium ion batteries.
2017, 28(12): 2223-2226
doi: 10.1016/j.cclet.2017.08.009
Abstract:
A series of low band gap terpolymers based on 4, 8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1, 2-b:4, 5-b']dithiophene (BDTT) and diketopyrrolopyrrole (DPP) with varied solubilizing groups (i.e., tert-butoxycarbonyl, t-Boc and 2-octyldodecyl) are developed as electron donors for bulk heterojunction (BHJ) polymer solar cells (PSCs). The results reveal that the one with 50% t-Boc concentration (P3) performs better than the other terpolymers used in this study in conventional PSC devices with a power conversion efficiency of 2.92%
A series of low band gap terpolymers based on 4, 8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1, 2-b:4, 5-b']dithiophene (BDTT) and diketopyrrolopyrrole (DPP) with varied solubilizing groups (i.e., tert-butoxycarbonyl, t-Boc and 2-octyldodecyl) are developed as electron donors for bulk heterojunction (BHJ) polymer solar cells (PSCs). The results reveal that the one with 50% t-Boc concentration (P3) performs better than the other terpolymers used in this study in conventional PSC devices with a power conversion efficiency of 2.92%
2017, 28(12): 2227-2230
doi: 10.1016/j.cclet.2017.09.009
Abstract:
Developing porous carbon materials with low-cost, sustainable and eco-friendly natural resources is emerging as an ever important research field in the application of high-performance supercapacitor. In this paper, a simple synthetic method to fabricate nitrogen doped porous carbon (NPC) is developed via a one-pot carbonization of sodium alginate and urea. The as-prepared NPC annealed at 700℃ with mesoand macro-porous structure exhibits excellent specific capacitance (180.2 F/g at 1 A/g) and superior cycling life when serves as electrode materials for supercapacitor. Moreover, the investigation on the annealing temperature demonstrates that NPC pyrolysis at 700℃ possesses relatively high pyrrole nitrogen and pyridine nitrogen, which is favorable for enhancing supercapacitor performance. This work extends biomass derived carbon materials in energy storage applications.
Developing porous carbon materials with low-cost, sustainable and eco-friendly natural resources is emerging as an ever important research field in the application of high-performance supercapacitor. In this paper, a simple synthetic method to fabricate nitrogen doped porous carbon (NPC) is developed via a one-pot carbonization of sodium alginate and urea. The as-prepared NPC annealed at 700℃ with mesoand macro-porous structure exhibits excellent specific capacitance (180.2 F/g at 1 A/g) and superior cycling life when serves as electrode materials for supercapacitor. Moreover, the investigation on the annealing temperature demonstrates that NPC pyrolysis at 700℃ possesses relatively high pyrrole nitrogen and pyridine nitrogen, which is favorable for enhancing supercapacitor performance. This work extends biomass derived carbon materials in energy storage applications.
2017, 28(12): 2231-2234
doi: 10.1016/j.cclet.2017.11.027
Abstract:
Reduced graphene oxide wrapped hollow molybdenum trioxide nanorods (MoO3@rGO) have been fabricated by a facile process. The MoO3@rGO shows improved lithium storage performance. It could deliver a high reversible capacity (842 mAh/g at 0.1 A/g), excellent cycling stability (778 mAh/g at 0.1 A/g after 200 cycles) and excellent rate capability (455 mAh/g at 2 A/g). The excellent electrochemical performance could be attributed as the special core (MoO3)/sheath (rGO) structure, which could accommodate the volume change of MoO3 during lithiation/delithiation process. In addition, the rGO coating layer could improve the electronic conductivity of MoO3.
Reduced graphene oxide wrapped hollow molybdenum trioxide nanorods (MoO3@rGO) have been fabricated by a facile process. The MoO3@rGO shows improved lithium storage performance. It could deliver a high reversible capacity (842 mAh/g at 0.1 A/g), excellent cycling stability (778 mAh/g at 0.1 A/g after 200 cycles) and excellent rate capability (455 mAh/g at 2 A/g). The excellent electrochemical performance could be attributed as the special core (MoO3)/sheath (rGO) structure, which could accommodate the volume change of MoO3 during lithiation/delithiation process. In addition, the rGO coating layer could improve the electronic conductivity of MoO3.
2017, 28(12): 2235-2238
doi: 10.1016/j.cclet.2017.09.065
Abstract:
Lithium-sulfur batteries have been considered as one of the most promising battery system for their high theoretical energy density. However, the lithium-sulfur batteries suffer from the dissolution and diffusion of polysulfides, which induce parasitic reactions with lithium metal anodes. The safety of lithium-sulfur batteries is also concerned with the risk of dendrite growth on lithium metal anodes. To simultaneously address the challenges in the shuttle effect and safety problems, we demonstrate herein a two-dimensional vermiculite separator. With the assembly of the 2D exfoliated vermiculite sheets, the vermiculite separator can suppress the diffusion of polysulfides across the separator through electrostatic interaction and steric hindrance. Meanwhile, the inorganic sheets with high strength and Young's modulus prevent the penetration of lithium metal dendrite and potentially improve the safety of the system. This work elucidates a promising strategy for safe and stable lithium sulfur batteries, and can also be extended to other electrochemical systems based on metal anodes.
Lithium-sulfur batteries have been considered as one of the most promising battery system for their high theoretical energy density. However, the lithium-sulfur batteries suffer from the dissolution and diffusion of polysulfides, which induce parasitic reactions with lithium metal anodes. The safety of lithium-sulfur batteries is also concerned with the risk of dendrite growth on lithium metal anodes. To simultaneously address the challenges in the shuttle effect and safety problems, we demonstrate herein a two-dimensional vermiculite separator. With the assembly of the 2D exfoliated vermiculite sheets, the vermiculite separator can suppress the diffusion of polysulfides across the separator through electrostatic interaction and steric hindrance. Meanwhile, the inorganic sheets with high strength and Young's modulus prevent the penetration of lithium metal dendrite and potentially improve the safety of the system. This work elucidates a promising strategy for safe and stable lithium sulfur batteries, and can also be extended to other electrochemical systems based on metal anodes.
2017, 28(12): 2239-2243
doi: 10.1016/j.cclet.2017.08.031
Abstract:
A visible-light driven photoelectrochemical (PEC) cell comprised of nanostructured BiVO4 photoanode and Pt cathode was established for organic compounds degradation with simultaneous H2 generation. BiVO4 electrode film fabricated by a simple drip-coating method showed a porous nanostructure and an intense absorption in visible light range. The PEC process possesses a rate of about 0.3207 h-1 for MO degradation, which is 8 times and 64 times faster than electrocatalytic (EC) and photocatalytic (PC) process, respectively. A simultaneous H2 generation via the PEC process was also observed and a rate of 34.44 μmol h-1 cm-2 for H2 generation was measured, which is 3 folds more efficient than the EC process. The nanostructured BiVO4 photoanode shows outstanding PEC photocurrent density and recycle performance. The proposed PEC system would be a promising strategy for wastewater treatment and energy recovery with an outstanding stability and recyclability performance.
A visible-light driven photoelectrochemical (PEC) cell comprised of nanostructured BiVO4 photoanode and Pt cathode was established for organic compounds degradation with simultaneous H2 generation. BiVO4 electrode film fabricated by a simple drip-coating method showed a porous nanostructure and an intense absorption in visible light range. The PEC process possesses a rate of about 0.3207 h-1 for MO degradation, which is 8 times and 64 times faster than electrocatalytic (EC) and photocatalytic (PC) process, respectively. A simultaneous H2 generation via the PEC process was also observed and a rate of 34.44 μmol h-1 cm-2 for H2 generation was measured, which is 3 folds more efficient than the EC process. The nanostructured BiVO4 photoanode shows outstanding PEC photocurrent density and recycle performance. The proposed PEC system would be a promising strategy for wastewater treatment and energy recovery with an outstanding stability and recyclability performance.
2017, 28(12): 2244-2250
doi: 10.1016/j.cclet.2017.09.017
Abstract:
Heterostructure photocatalyst fabrication is of great significance for promoting the photoreactivity and solar-energy utilization efficiencies. In this work, AgI/BiOIO3 heterostructure photocatalysts are synthesized by a facile in-situ crystallization of AgI on BiOIO3. The photocatalytic performance is first surveyed by decomposition of model dye methyl orange (MO) separately with illumination of UV light and visible-light (λ > 420 nm). It indicates that AgI/BiOIO3 shows highly improved photocatalytic activity regardless of the light source, which should be attributed to the matchable band energy levels between AgI and BiOIO3, benefiting the efficient charge separation. Notably, AgI/BiOIO3 shows a universal photocatalytic activity for treating diverse antibiotics and phenols, including tetracycline hydrochloride, chlortetracycline hydrochloride, 2, 4-dichlorophenol (2, 4-DCP), phenol and bisphenol A (BPA), and the strong mineralization ability of AgI/BiOIO3 was also demonstrated. Additionally, the different mechanisms under UV and visible light irradiation are investigated in detail. This work provides a new reference for design and manipulation of high-performance nonselective heterostructure photocatalyst for environmental purification.
Heterostructure photocatalyst fabrication is of great significance for promoting the photoreactivity and solar-energy utilization efficiencies. In this work, AgI/BiOIO3 heterostructure photocatalysts are synthesized by a facile in-situ crystallization of AgI on BiOIO3. The photocatalytic performance is first surveyed by decomposition of model dye methyl orange (MO) separately with illumination of UV light and visible-light (λ > 420 nm). It indicates that AgI/BiOIO3 shows highly improved photocatalytic activity regardless of the light source, which should be attributed to the matchable band energy levels between AgI and BiOIO3, benefiting the efficient charge separation. Notably, AgI/BiOIO3 shows a universal photocatalytic activity for treating diverse antibiotics and phenols, including tetracycline hydrochloride, chlortetracycline hydrochloride, 2, 4-dichlorophenol (2, 4-DCP), phenol and bisphenol A (BPA), and the strong mineralization ability of AgI/BiOIO3 was also demonstrated. Additionally, the different mechanisms under UV and visible light irradiation are investigated in detail. This work provides a new reference for design and manipulation of high-performance nonselective heterostructure photocatalyst for environmental purification.
2017, 28(12): 2251-2253
doi: 10.1016/j.cclet.2017.11.028
Abstract:
Vanadium pentoxide (V2O5·nH2O) nanoribbons are synthesized via a hydrothermal process. These ribbons are 20 nm thick, 200 nm to 1 μm wide and several tens of micrometers long. Free-standing binder-free films are prepared by using these nanoribbons with multi-walled carbon nanotubes (MWCNTs) and used as the cathode for rechargeable sodium batteries. The large interlayer space between the V2O5 bilayers can enhance the kinetics of sodium ion intercalation/deintercalation. In addition, the intertwining network of the V2O5·0.34H2O film provides efficient electron conduction pathways and shortens diffusion distances of sodium ion. The electrochemical tests prove that the freestanding V2O5·0.34H2O film cathode delivers high reversible specific capacities (190 mAh/g) and good cycling stabilities (170 mAh/g after 150 cycles) in the voltage range between 1.5 V and 3.5 V.
Vanadium pentoxide (V2O5·nH2O) nanoribbons are synthesized via a hydrothermal process. These ribbons are 20 nm thick, 200 nm to 1 μm wide and several tens of micrometers long. Free-standing binder-free films are prepared by using these nanoribbons with multi-walled carbon nanotubes (MWCNTs) and used as the cathode for rechargeable sodium batteries. The large interlayer space between the V2O5 bilayers can enhance the kinetics of sodium ion intercalation/deintercalation. In addition, the intertwining network of the V2O5·0.34H2O film provides efficient electron conduction pathways and shortens diffusion distances of sodium ion. The electrochemical tests prove that the freestanding V2O5·0.34H2O film cathode delivers high reversible specific capacities (190 mAh/g) and good cycling stabilities (170 mAh/g after 150 cycles) in the voltage range between 1.5 V and 3.5 V.
2017, 28(12): 2254-2258
doi: 10.1016/j.cclet.2017.10.025
Abstract:
Converting solar energy into valuable hydrogen and hydrocarbon fuels through photoelectrocatalytic water splitting and CO2 reduction is highly promising in addressing the growing demand for renewable and clean energy resources. However, the solar-to-fuel conversion efficiency is still very low due to limited light absorption and rapid bulk recombination of charge carriers. In this work, we present chlorophyll (Chl) and its derivative sodium copper chlorophyllin (ChlCuNa), as dye sensitizers, modified BiVO4 to improve the photoelectrochemical (PEC) performance. The photocurrent of BiVO4 is surprisingly decreased after a direct sensitization of Chl while the sensitization of ChlCuNa obviously enhances photocurrent of BiVO4 electrodes by improved surface hydrophilicity and extended light absorption. ChlCuNa-sensitized BiVO4 achieves an improved H2 evolution rate of 5.43 μmol h-1 cm-2 in water splitting and an enhanced HCOOH production rate of 2.15 μmol h-1 cm-2 in CO2 PEC reduction, which are 1.9 times and 2.4 times higher than pristine BiVO4, respectively. It is suggested that the derivative ChlCuNa is a more effective sensitizer for solar-to-fuel energy conversion and CO2 utilization than Chl.
Converting solar energy into valuable hydrogen and hydrocarbon fuels through photoelectrocatalytic water splitting and CO2 reduction is highly promising in addressing the growing demand for renewable and clean energy resources. However, the solar-to-fuel conversion efficiency is still very low due to limited light absorption and rapid bulk recombination of charge carriers. In this work, we present chlorophyll (Chl) and its derivative sodium copper chlorophyllin (ChlCuNa), as dye sensitizers, modified BiVO4 to improve the photoelectrochemical (PEC) performance. The photocurrent of BiVO4 is surprisingly decreased after a direct sensitization of Chl while the sensitization of ChlCuNa obviously enhances photocurrent of BiVO4 electrodes by improved surface hydrophilicity and extended light absorption. ChlCuNa-sensitized BiVO4 achieves an improved H2 evolution rate of 5.43 μmol h-1 cm-2 in water splitting and an enhanced HCOOH production rate of 2.15 μmol h-1 cm-2 in CO2 PEC reduction, which are 1.9 times and 2.4 times higher than pristine BiVO4, respectively. It is suggested that the derivative ChlCuNa is a more effective sensitizer for solar-to-fuel energy conversion and CO2 utilization than Chl.
2017, 28(12): 2259-2262
doi: 10.1016/j.cclet.2017.09.067
Abstract:
PNIPAM@ZnO/C composite photocatalyst was prepared by cross-linking polymerization technology with N-isopropylacrylamide used as functional monomer, N, N'-methylenebis (acrylamide) used as crosslinking agent, ammonium persulfate used as initiator, and 3-(trimethoxysilyl) propyl methacrylate used as surface modification reagent. The morphology, structure, electrochemical and photocatalytic properties of as-prepared samples were characterized via the serial tests. The temperature-response performances of PNIPAM@ZnO/C were evaluated by the photocatalytic degradation of tetracycline (TC) under different temperatures. The results show that the synthesized composite photocatalysts possess the excellent and switchable photocatalytic activity. The photocatalytic degradation activity of PNIPAM@ZnO/C is suppressed above the lower critical solution temperature (LCST), and it is enhanced below the LCST.
PNIPAM@ZnO/C composite photocatalyst was prepared by cross-linking polymerization technology with N-isopropylacrylamide used as functional monomer, N, N'-methylenebis (acrylamide) used as crosslinking agent, ammonium persulfate used as initiator, and 3-(trimethoxysilyl) propyl methacrylate used as surface modification reagent. The morphology, structure, electrochemical and photocatalytic properties of as-prepared samples were characterized via the serial tests. The temperature-response performances of PNIPAM@ZnO/C were evaluated by the photocatalytic degradation of tetracycline (TC) under different temperatures. The results show that the synthesized composite photocatalysts possess the excellent and switchable photocatalytic activity. The photocatalytic degradation activity of PNIPAM@ZnO/C is suppressed above the lower critical solution temperature (LCST), and it is enhanced below the LCST.
2017, 28(12): 2263-2268
doi: 10.1016/j.cclet.2017.09.064
Abstract:
The peony-like CuO micro/nanostructures were fabricated by a facile hydrothermal approach. The peonylike CuO micro/nanostructures about 3-5 μm in diameter were assembled by CuO nanoplates. These CuO nanoplates, as the building block, were self-assembled into multilayer structures under the action of ethidene diamine, and then grew into uniform peony-like CuO architecture. The novel peony-like CuO micro/nanostructures exhibit a high cycling stability and improved rate capability. The peony-like CuO micro/nanostructures electrodes show a high reversible capacity of 456 mAh/g after 200 cycles, much higher than that of the commercial CuO nanocrystals at a current 0.1 C. The excellent electrochemical performance of peony-like CuO micro/nanostructures might be ascribed to the unique assembly structure, which not only provide large electrode/electrolyte contact area to accelerate the lithiation reaction, but also the interval between the multilayer structures of CuO nanoplates electrode could provide enough interior space to accommodate the volume change during Li+ insertion and de-insertion process.
The peony-like CuO micro/nanostructures were fabricated by a facile hydrothermal approach. The peonylike CuO micro/nanostructures about 3-5 μm in diameter were assembled by CuO nanoplates. These CuO nanoplates, as the building block, were self-assembled into multilayer structures under the action of ethidene diamine, and then grew into uniform peony-like CuO architecture. The novel peony-like CuO micro/nanostructures exhibit a high cycling stability and improved rate capability. The peony-like CuO micro/nanostructures electrodes show a high reversible capacity of 456 mAh/g after 200 cycles, much higher than that of the commercial CuO nanocrystals at a current 0.1 C. The excellent electrochemical performance of peony-like CuO micro/nanostructures might be ascribed to the unique assembly structure, which not only provide large electrode/electrolyte contact area to accelerate the lithiation reaction, but also the interval between the multilayer structures of CuO nanoplates electrode could provide enough interior space to accommodate the volume change during Li+ insertion and de-insertion process.
2017, 28(12): 2269-2273
doi: 10.1016/j.cclet.2017.10.024
Abstract:
Covalent organic frameworks (COFs) were nano-coated onto single-walled carbon nanotubes (SWCNTs) by in situ polymerization of TpPa-COFs together with SWCNTs under solvothermal conditions. At the molecular level, the COF/SWCNT interface can be efficiently controlled. Thus, the TpPa-COF-SWCNTs nano-hybrid wire, which combines the excellent conductivity of SWCNTs and the high porosity and good redox activity of TpPa-COFs, was employed as active electrode materials for supercapacitors. The strategy reported in this work can give guidance for the design of other similar COF-based electrodes, and hold a great potential in energy storages
Covalent organic frameworks (COFs) were nano-coated onto single-walled carbon nanotubes (SWCNTs) by in situ polymerization of TpPa-COFs together with SWCNTs under solvothermal conditions. At the molecular level, the COF/SWCNT interface can be efficiently controlled. Thus, the TpPa-COF-SWCNTs nano-hybrid wire, which combines the excellent conductivity of SWCNTs and the high porosity and good redox activity of TpPa-COFs, was employed as active electrode materials for supercapacitors. The strategy reported in this work can give guidance for the design of other similar COF-based electrodes, and hold a great potential in energy storages
2017, 28(12): 2274-2276
doi: 10.1016/j.cclet.2017.11.034
Abstract:
Carbon-coated Li4Ti5O12 sample was synthesized by a sol-gel method. The Li4Ti5O12 powders were obtained by calcinations of the gels at 750, 800, 850, 900℃ at N2 atmosphere. The structure, morphology and electrochemical properties of the materials were characterized by SEM, XRD and charge and discharge. The final product sintered at 850℃ demonstrates excellent performance with a specific capacity of 163.5 mAh/g after 100 cycles at 1 C. Furthermore, the discharge specific capacity of the sample can retain 80 mAh/g at 10 C.
Carbon-coated Li4Ti5O12 sample was synthesized by a sol-gel method. The Li4Ti5O12 powders were obtained by calcinations of the gels at 750, 800, 850, 900℃ at N2 atmosphere. The structure, morphology and electrochemical properties of the materials were characterized by SEM, XRD and charge and discharge. The final product sintered at 850℃ demonstrates excellent performance with a specific capacity of 163.5 mAh/g after 100 cycles at 1 C. Furthermore, the discharge specific capacity of the sample can retain 80 mAh/g at 10 C.
2017, 28(12): 2277-2280
doi: 10.1016/j.cclet.2017.11.026
Abstract:
Sulfur-decorated nanomesh graphene (S@G) has been synthesized by a 155℃ heat treatment of a mixture of nanomesh graphene and S. The as-obtained S@G materials keep a high specific surface area, and exhibit obviously enhanced conductivity and hydrophilicity as compared to the pristine graphene. X-ray photoelectron spectroscopy and thermogravimetric analysis indicate that most S atoms in the S@G samples are stably combined with nanomesh graphene via covalent bonds rather than exist as free elemental S. As an electrode material for aqueous supercapacitors, the S@G with a S content of 5 wt% delivers a specific capacitance up to 257 F/g at the current density of 0.25 A/g, which is 23.6% higher than that of the undoped graphene. Our results provide a simple approach to scalable synthesis of S-doped porous carbon materials, which have potential applications in the high-performance capacitive energy storage devices.
Sulfur-decorated nanomesh graphene (S@G) has been synthesized by a 155℃ heat treatment of a mixture of nanomesh graphene and S. The as-obtained S@G materials keep a high specific surface area, and exhibit obviously enhanced conductivity and hydrophilicity as compared to the pristine graphene. X-ray photoelectron spectroscopy and thermogravimetric analysis indicate that most S atoms in the S@G samples are stably combined with nanomesh graphene via covalent bonds rather than exist as free elemental S. As an electrode material for aqueous supercapacitors, the S@G with a S content of 5 wt% delivers a specific capacitance up to 257 F/g at the current density of 0.25 A/g, which is 23.6% higher than that of the undoped graphene. Our results provide a simple approach to scalable synthesis of S-doped porous carbon materials, which have potential applications in the high-performance capacitive energy storage devices.
2017, 28(12): 2281-2284
doi: 10.1016/j.cclet.2017.11.032
Abstract:
A novel porous silicon was synthesized through a magnesiothermic reduction method of molecular sieve for the first time, Si/C composite was synthesized by using pitch as carbon source. The porous Si/C composite shows a high initial specific capacity of 2018.5 mAh/g with current density of 0.1 A/g. When the current density increases to 2 A/g, it still exhibits high average specific capacity of 640.3 mAh/g. The porous structure can remit the Si particle pulverization during the lithiation/delithiation process. This article can provide a reference for the research of the porous Si anode for the high performance rechargeable lithium-ion battery.
A novel porous silicon was synthesized through a magnesiothermic reduction method of molecular sieve for the first time, Si/C composite was synthesized by using pitch as carbon source. The porous Si/C composite shows a high initial specific capacity of 2018.5 mAh/g with current density of 0.1 A/g. When the current density increases to 2 A/g, it still exhibits high average specific capacity of 640.3 mAh/g. The porous structure can remit the Si particle pulverization during the lithiation/delithiation process. This article can provide a reference for the research of the porous Si anode for the high performance rechargeable lithium-ion battery.
2017, 28(12): 2285-2289
doi: 10.1016/j.cclet.2017.10.031
Abstract:
We demonstrate an efficient and cost-effective strategy to improve electrochemical properties of AC based electrode materials. A series of graphene oxide (GO)-modified activated carbon (AC) composites (GO@ACs) have been prepared as electrode materials for supercapacitors (SCs). In GO@ACs, AC particles anchored on the surface of GO sheets which were synchronously reduced during charge/discharge process, and formed a 3D-conductive network. Electrochemical analyses revealed that 2.5 wt% GO@AC, which exhibited improved electrical conductivity and high specific capacitance at large current density in organic electrolyte, is a promising electrode material for high-performance SCs. At 6 A/g, the specific capacitance of 2.5 wt% GO@AC increased by 249.5% in comparison with that of AC.
We demonstrate an efficient and cost-effective strategy to improve electrochemical properties of AC based electrode materials. A series of graphene oxide (GO)-modified activated carbon (AC) composites (GO@ACs) have been prepared as electrode materials for supercapacitors (SCs). In GO@ACs, AC particles anchored on the surface of GO sheets which were synchronously reduced during charge/discharge process, and formed a 3D-conductive network. Electrochemical analyses revealed that 2.5 wt% GO@AC, which exhibited improved electrical conductivity and high specific capacitance at large current density in organic electrolyte, is a promising electrode material for high-performance SCs. At 6 A/g, the specific capacitance of 2.5 wt% GO@AC increased by 249.5% in comparison with that of AC.
Analysis of graphene-like activated carbon derived from rice straw for application in supercapacitor
2017, 28(12): 2290-2294
doi: 10.1016/j.cclet.2017.11.004
Abstract:
Activated carbons with large surface area, abundant microporosity and low cost are the most commonly used electrode materials for energy storage devices. However, activated carbons are conventionally made from fossil precursors, such as coal and petroleum, which are limited resources and easily aggregate large block in high temperature carbonization processes. In this novel work, we examined the use of rice straw as a potential alternative carbon source precursor for the production of graphene-like active carbon. A very slack activated carbon with ultra-thin two-dimensional (2D) layer structure was prepared by our proposed approach in this work, which includes a pre-treatment process and potassium hydroxide activation at high temperatures. The obtained active carbon derived from rice straw exhibited a capacitance of 255 F/g at 0.5 A/g, excellent rate capability, and long cycling capability (98% after 10, 000 cycles).
Activated carbons with large surface area, abundant microporosity and low cost are the most commonly used electrode materials for energy storage devices. However, activated carbons are conventionally made from fossil precursors, such as coal and petroleum, which are limited resources and easily aggregate large block in high temperature carbonization processes. In this novel work, we examined the use of rice straw as a potential alternative carbon source precursor for the production of graphene-like active carbon. A very slack activated carbon with ultra-thin two-dimensional (2D) layer structure was prepared by our proposed approach in this work, which includes a pre-treatment process and potassium hydroxide activation at high temperatures. The obtained active carbon derived from rice straw exhibited a capacitance of 255 F/g at 0.5 A/g, excellent rate capability, and long cycling capability (98% after 10, 000 cycles).
2017, 28(12): 2295-2297
doi: 10.1016/j.cclet.2017.10.041
Abstract:
In this paper, a direction carbonization method was used to prepare porous carbon from Allium cepa for supercapacitor applications. In this method, calcium acetate was used to assist carbonization process. Scanning electron microscope (SEM) and N2 adsorption/desorption method were used to characterize the morphology, Brunauer-Emmett-Teller (BET) specific surface area and pore size distribution of porous carbon derived from Allium cepa (onion derived porous carbon, OPC). OPC is of hierarchical porous structure with high specific surface area and relatively high specific capacitance. OPC possesses relatively high specific surface area of 533.5 m2/g. What's more, OPC possesses a specific capacitance of 133.5 F/g at scan rate of 5 mV/s.
In this paper, a direction carbonization method was used to prepare porous carbon from Allium cepa for supercapacitor applications. In this method, calcium acetate was used to assist carbonization process. Scanning electron microscope (SEM) and N2 adsorption/desorption method were used to characterize the morphology, Brunauer-Emmett-Teller (BET) specific surface area and pore size distribution of porous carbon derived from Allium cepa (onion derived porous carbon, OPC). OPC is of hierarchical porous structure with high specific surface area and relatively high specific capacitance. OPC possesses relatively high specific surface area of 533.5 m2/g. What's more, OPC possesses a specific capacitance of 133.5 F/g at scan rate of 5 mV/s.
