Vanadium redox flow battery(VRFB)exhibits a great potential for application in large-scale and long-term energy storage systems due to its high safety,longevity,and environmental friendliness.However,the poor electroc...Vanadium redox flow battery(VRFB)exhibits a great potential for application in large-scale and long-term energy storage systems due to its high safety,longevity,and environmental friendliness.However,the poor electrocatalytic activity of the pristine graphite felt electrode seriously hinders the energy density and efficiency of VRFB.To address the issue,in this work,the rich active site-NiMoO_(4)nanorods were used to in situ modify graphite felt for high-performance VRFB.The rod-to-diameter ratio and deposition of NiMoO_(4)were controlled by adjusting the ratio of water/ethanol and concentration of the precursor solution to obtain the optimal length of NiMoO_(4)nanorods uniformly deposited on the graphite felt surface.This abundant micropores,dual active sites of Mo-O-Ni,and additional oxygen vacancies effectively increase the specific surface area,the number of active sites,and the hydrophilicity for graphite felt,which boosts the charge transfer and mass transfer for VO^(2+)/VO_(2)^(+)and V^(3+)/V^(2+)redox reactions.The modified battery exhibits an energy efficiency of 71.1%at 150 mA·cm^(-2),which is 19.8%higher than the blank battery.Furthermore,the modified battery shows excellent stability during 100 cycles.This work will promote the development and application of binary metal oxides with rich active sites in VRFB.展开更多
Developing non-noble-metal oxygen evolution reaction(OER) electrocatalysts with high performance is critical to electrocatalytic water splitting. In this work, we fabricated Co Fe-layered double hydroxide(LDH) nanowir...Developing non-noble-metal oxygen evolution reaction(OER) electrocatalysts with high performance is critical to electrocatalytic water splitting. In this work, we fabricated Co Fe-layered double hydroxide(LDH) nanowire arrays on graphite felt(Co Fe-LDH/GF) via a hydrothermal method. The Co Fe-LDH/GF, as a robust integrated 3 D OER anode, exhibits excellent catalytic activity with the need of low overpotential of 252 and 285 mV to drive current densities of 10 and 100 mA/cm^(2) in 1.0 mol/L KOH, respectively. In addition, it also maintains electrochemical durability for at least 24 h. This work would open up avenues for the development of GF like attractive catalyst supports for oxygen evolution applications.展开更多
The scarcity of wettability,insufficient active sites,and low surface area of graphite felt(GF)have long been suppressing the performance of vanadium redox flow batteries(VRFBs).Herein,an ultra-homogeneous multipledim...The scarcity of wettability,insufficient active sites,and low surface area of graphite felt(GF)have long been suppressing the performance of vanadium redox flow batteries(VRFBs).Herein,an ultra-homogeneous multipledimensioned defect,including nano-scale etching and atomic-scale N,O codoping,was used to modify GF by the molten salt system.NH_(4)Cl and KClO_(3) were added simultaneously to the system to obtain porous N/O co-doped electrode(GF/ON),where KClO_(3) was used to ultra-homogeneously etch,and O-functionalize electrode,and NH4Cl was used as N dopant,respectively.GF/ON presents better electrochemical catalysis for VO_(2)+/VO_(2)+ and V3+/V2+ reactions than only O-functionalized electrodes(GF/O)and GF.The enhanced electrochemical properties are attributed to an increase in active sites,surface area,and wettability,as well as the synergistic effect of N and O,which is also supported by the density functional theory calculations.Further,the cell using GF/ON shows higher discharge capacity,energy efficiency,and stability for cycling performance than the pristine cell at 140 mA cm^(−2) for 200 cycles.Moreover,the energy efficiency of the modified cell is increased by 9.7% from 55.2% for the pristine cell at 260 mA cm^(−2).Such an ultra-homogeneous etching with N and O co-doping through“boiling”molten salt medium provides an effective and practical application potential way to prepare superior electrodes for VRFB.展开更多
Hydrogen peroxide synthesis by electro-reduction of O_(2) to substitute the current anthraquinone process has attracted a great deal of attention. Low oxygen utilization rate and low hydrogen peroxide production remai...Hydrogen peroxide synthesis by electro-reduction of O_(2) to substitute the current anthraquinone process has attracted a great deal of attention. Low oxygen utilization rate and low hydrogen peroxide production remain obstacles to electro-Fenton application. In situ H_(2)O_(2) generated by electrochemical reaction depends on the electrochemical performance of the cathode and the structure of the reactor. Here, novel graphite felt(GF) modified by La-doped CeO_(2)(La-CeO_(2)) was developed as a cathode. A new double chamber electro-Fenton reactor was proposed, where an organic ultrafiltration membrane was used to prevent H_(2)O_(2) from spreading to the anode. The effects of hydrothermal temperature, time and urea concentration on the electrochemical properties of graphite felt were investigated. The accumulated concentration of H_(2)O_(2) on the modified cathode reached 218.4 mg·L^(-1)in 1 h when the optimal conditions of hydrothermal temperature 120 ℃ and urea concentration 0.55%(mass) in 24 h. The degradation rate of methyl orange reached 98.29%. The new electro-Fenton reactor can efficiently produce hydrogen peroxide to degrade various organic substances and has a high potential for treating wastewater in the chemical industry.展开更多
The cerium-based redox flow battery(RFB)is regarded as a compelling gridscale energy storage technology to revolutionize the utilization of renewable energy by storing the energy in liquid electrolytes.However,its wid...The cerium-based redox flow battery(RFB)is regarded as a compelling gridscale energy storage technology to revolutionize the utilization of renewable energy by storing the energy in liquid electrolytes.However,its widespread implementation is impeded by the cerium redox reactions that exhibit slow kinetics on commercial graphite felt(GF)electrodes.Surface functionalization may be an available activation strategy to achieve a significant boost in the electrochemical performance of GFs.However,conventional chemical and/or electrochemical routes for the surface functionalization of GFs suffer from the issues of complication,and the deterioration of the resulting modified electrode surface over long-term cycle processes leads to catalytic activity decline.Here,we develop a facile and general strategy for introducing the functional groups to the electrode through the addition of L-cysteine into electrolytes.The-COOH,-NH_(2),and-SH groups in L-cysteine can induce oxygen/nitrogen/sulfur trifunctional doping on GF surfaces with lower deterioration rates,which enables the activated GFs to demonstrate a promising electrocatalytic activity toward cerium redox reactions and excellent durability when used as a cerium-based RFB electrode.This study proposes a rational strategy to overcome the intrinsic limitations of existing modification techniques for GFs and provides a potential pathway toward high-performance RFBs.展开更多
PAN-based graphite felt （PGF） treated in 98% sulphuric acid for 5 h and then kept at 450 ℃ for 2 h was evaluated for their electrochemical performance as electrodes of vanadium redox battery （VRB）. Structure and ...PAN-based graphite felt （PGF） treated in 98% sulphuric acid for 5 h and then kept at 450 ℃ for 2 h was evaluated for their electrochemical performance as electrodes of vanadium redox battery （VRB）. Structure and characteristic of treated PAN-based graphite felt （TPGF） were determined by means of Fourier Transform Infi-ared Spectroscopy, Scanning Electron Microscopy, Brunauer-Emmett-Teller surface area analysis and VRB test system. The results show that the acid and heat synergistic effect increase the number of --COOH functional groups on the PGF surface, and the PGF is eroded by sulphuric acid oxidation, resulting in the surface area increases from 0.31 m^2/g to 0.45 m^2/g. The V（ Ⅱ ）/V（Ⅲ） redox reaction is electrochemically reversible on the TPGF electrode, while the V（Ⅳ）/V（Ⅴ） couple is a quasi reversible process. The diffusion coefficients of the oxidation for V（Ⅳ）/V（Ⅴ） obtained from the scope of peak current Ip vs scan rate v^1/2 is 4.4×10^-5 cm^2/s. The improvement of electrochemical activity for the electrode is mainly ascribed to the increase of the number of ---COOH groups on the TPGF, which behaves as active sites catalyzing the vanadium species reactions and accelerating electron transfer reaction and oxygen transfer.展开更多
The development of efficient electrocatalysts from Earth-abundant elements for the oxygen evolution reaction (OER) is highly desired.Here,we report the electrodeposition of a NiCo layered double hydroxide nanosheet ar...The development of efficient electrocatalysts from Earth-abundant elements for the oxygen evolution reaction (OER) is highly desired.Here,we report the electrodeposition of a NiCo layered double hydroxide nanosheet array on graphite felt (NiCo LDHs/GF) as a 3D OER electrocatalyst.Such NiCo LDHs/GF exhibits superior electrocatalytic activity with the need for an overpotential of 249 mV to drive a current density of 20 mA cm^(-2) in 1.0 M KOH.It also shows strong long-term electrochemical durability with its activity being maintained for at least 24 h.展开更多
Zinc-polyiodide redox flow battery(RFB)systems with highly soluble triiodide/iodide(I_(3)^(-)/I^(-))couples have demonstrated significantly enhanced energy densities.However,their low power density has limited their b...Zinc-polyiodide redox flow battery(RFB)systems with highly soluble triiodide/iodide(I_(3)^(-)/I^(-))couples have demonstrated significantly enhanced energy densities.However,their low power density has limited their broad application.In this work,MoS_(2)nanoplates were in situ grafted onto graphite felt(GF)surfaces to accelerate the I_(3)^(-)/I^(-)redox reaction.The hexagonal phase MoS_(2)with enlarged interlayer spacing can facilitate the diffusion of the electrolyte,and the defects on the MoS_(2)nanoplates can serve as very effective catalytic active sites.Cyclic voltammetry testing revealed the high catalytic performance of MoS_(2)in the I_(3)^(-)/I^(-)redox reaction.A non-flow cell with the MoS_(2)-modified GF serving as a positive electrode showed a higher energy efficiency than that of pristine GF;increases of about 10.2%and 10.9%at current densities of 30 mA cm^(-2)and 40 mA cm^(-2)were obtained with the optimized electrode,respectively.展开更多
A mild and simple synthesis process for large-scale vanadium redox flow batteries(VRFBs)energy storage systems is desirable.A graphite felt/Mn O_2(GF-MNO)composite electrode with excellent electrocatalytic activity to...A mild and simple synthesis process for large-scale vanadium redox flow batteries(VRFBs)energy storage systems is desirable.A graphite felt/Mn O_2(GF-MNO)composite electrode with excellent electrocatalytic activity towards VO^(2+)/VO_2^+redox couples in a VRFB was synthesized by a one-step hydrothermal process.The resulting GF-MNO electrodes possess improved electrochemical kinetic reversibility of the vanadium redox reactions compared to pristine GF electrodes,and the corresponding energy efficiency and discharge capacity at 150 m A cm^(-2)are increased by 12.5%and 40%,respectively.The discharge capacity is maintained at 4.8 A h L^(-1)at the ultrahigh current density of 250 m A cm^(-2).Above all,80%of the energy efficiency of the GF-MNO composite electrodes is retained after 120 charge-discharge cycles at 150 m A cm^(-2).Furthermore,these electrodes demonstrated that more evenly distributed catalytic active sites were obtained from the Mn O_2particles under acidic conditions.The proposed synthetic route is facile,and the raw materials are low cost and environmentally friendly.Therefore,these novel GF-MNO electrodes hold great promise in large-scale vanadium redox flow battery energy storage systems.展开更多
E-peroxone(EP)was one of the most attractive AOPs for removing refractory organic compounds from water,but the high energy consumption for in situ generating H_(2)O_(2) and its low reaction efficiency for activating O...E-peroxone(EP)was one of the most attractive AOPs for removing refractory organic compounds from water,but the high energy consumption for in situ generating H_(2)O_(2) and its low reaction efficiency for activating O_(3) under acidic conditions made the obstacles for its practical application.In this study,cerium oxide was loaded on the surface of graphite felt(GF)by the hydrothermal method to construct the efficient electrode(CeO_(x)/GF)for mineralizing carbamazepine(CBZ)via EP process.CeO_(x)/GF was an efficient cathode,which led to 69.4%TOC removal in CeO_(x)/GF-EP process with current intensity of 10 mA in 60 min.Moreover,CeO_(x)/GF had the flexible application in the pH range from 5.0 to 9.0,TOC removal had no obvious decline with decrease of pH.Comparative characterizations showed that CeO_(x)could enhance surface hydrophilicity and reduce the charge-transfer resistance of GF.About 5.4 mg/L H_(2)O_(2) generated in CeO_(x)/GF-EP process,which was 2.1 times as that in GF-EP process.The greater ozone utility was also found in CeO_(x)/GF-EP process.More O_(3) was activated into hydroxyl radicals,which accounted for the mineralization of CBZ.An interfacial electron transfer process was revealed,which involved the function of oxygen vacancies and Ce^(3+)/Ce^(4+)redox cycle.CeO_(x)/GF had the good recycling property in fifth times'use.展开更多
Electrode materials with good redox kinetics,excellent mass transfer characteristics and ultra-high stability play a crucial role in reducing the life-cycle cost and prolonging the maintenance-free time of the vanadiu...Electrode materials with good redox kinetics,excellent mass transfer characteristics and ultra-high stability play a crucial role in reducing the life-cycle cost and prolonging the maintenance-free time of the vanadium flow batteries(VFB).Herein,a nitrogen-doped porous graphite felt electrode(N-PGF)is proposed by growing ZIF-67 nanoparticles on carbon fibers and then calcinating and acid etching.The multi-scale structure of“carbon fiber gap(electrolyte flow),micro/nano pore(active species diffusion)and Nitrogen active center(reaction site)”in N-PGF electrode effectively increases the catalytic sites and promotes mass transfer characteristics.Reasonable electrode design makes the battery show excellent rate performance and ultra-high cycling stability.The peak power density of the battery reaches 1006 mW cm^(-2).During 1000 cycles at 150 mA cm^(-2),the average discharge capacity and average discharge energy of N-PGF increase substantially by 11.6%and 23.4%compared with the benchmark thermal activated graphite felt,respectively.More excitingly,after ultra-long term(5000 cycles)operation at an ultra-high current density(300 mA cm^(-2)),N-PGF exhibits an unprecedented energy efficiency retention(99.79%)and electrochemical performance stability.展开更多
Vanadium flow battery （VFB） is a fast going and promising system for large-scale stationary energy stor- age. However, drawbacks such as low power density and narrow temperature window caused by poor catalytic activ...Vanadium flow battery （VFB） is a fast going and promising system for large-scale stationary energy stor- age. However, drawbacks such as low power density and narrow temperature window caused by poor catalytic activity of graphite felt （GF） electrodes limit its worldwide application. In this paper, bismuth, as a low-cost, no-toxic and high-activity electrocatalyst, is used to modify the thermal activated GF （TGF） via a facile hydrothermal method. Bismuth can effectively inhibit the side reaction of hydrogen evolution in wide temperature range, while promoting the V2＋/V3＋ redox reaction. As a result, the VFB assembled with Bi/TGF as negative electrode demonstrates outstanding rate performance under the current density up to 400 mAcm-2, as well as a long-term stability over 600 charging/discharging cycles at a high cur- rent density of 150mA cm-2. Moreover, it also shows excellent temperature adaptability from -10 ℃ to 50 ℃ and high durability for life test at the temperature of 50 ℃.展开更多
The electrode is one of the main components in redox flow batteries(RFBs), as it provides the reactions sites for redox couples and can influence the cell performance through its effect on cell voltage losses associat...The electrode is one of the main components in redox flow batteries(RFBs), as it provides the reactions sites for redox couples and can influence the cell performance through its effect on cell voltage losses associated with activation overpotential, concentration overpotential and ohmic losses. Extensive research has thus been carried out on material selection, structural design and modification of electrodes as well as electrocatalysis for redox reactions. This review provides an historical overview of the screening and modification of electrode materials together with recent progress in novel electrode architectures, electrode modification and electrocatalysis methods. RFB systems such as iron/chromium, polysulfide/bromine and all vanadium batteries are discussed in detail.展开更多
An electrocatalytic nitrate reduction reaction(NO_(3)RR)is an attractive strategy to maintain the nitrogen neutral.Fe nanoparticles(Fe NPs)are among the most promising electrocatalysts for the NO_(3)RR with low cost a...An electrocatalytic nitrate reduction reaction(NO_(3)RR)is an attractive strategy to maintain the nitrogen neutral.Fe nanoparticles(Fe NPs)are among the most promising electrocatalysts for the NO_(3)RR with low cost and high performance.However,the durability of Fe-based catalysts is poor owing to the aggrega-tion and oxidation of iron.Herein,a series of self-supported Fe/support catalysts has been synthesized by a simple hydrothermal and in situ thermal reduction strategy,exhibiting strong metal–support interaction(SMSI)between Fe active sites and supports.Remarkably,the iron nanoparticles loaded on graphite felt(Fe/GF)exhibited an optimal electrochemical NO_(3)RR performance with NO_(3)^(−)conversion of 67.7%and N_(2) selectivity of 96.6%,which is attributed to the enhanced dispersity and conductivity.This study not only provides a universal method for SMSI composite catalysts but also lays the foundation for their large-scale application.展开更多
Ammonia(NH3)is an ideal nitrogen source in terms of availability,reactivity,safety,atom economy,environmental compatibility,and ease of isolation.However,its utility for amine synthesis is limited by its high bond dis...Ammonia(NH3)is an ideal nitrogen source in terms of availability,reactivity,safety,atom economy,environmental compatibility,and ease of isolation.However,its utility for amine synthesis is limited by its high bond dissociation energy,its strong coordination ability,and the difference between its reactivity and that of the product amines.Herein,we reported the first electrochemical protocol for direct syntheses of unprotected tetrasubstituted aziridines with NH3 and alkenes in the absence of an oxidant,which are highly challenging to achieve by other methods.The combination of graphite felt as the anode material and MeOH as the solvent was the key to the success of the protocol,and the effects of these factors were investigated by means of cyclic voltammetry and density functional theory calculations.展开更多
基金financially supported by National Natural Science Foundation of China(Nos.51872090 and 51772097)Hebei Natural Science Fund for Distinguished Young Scholar(No.E2019209433)+4 种基金Youth Talent Program of Hebei Provincial Education Department(No.BJ2018020)Natural Science Foundation of Hebei Province(Nos.E2020209151 and E2024209029)National Key R&D Plan Project(No.2022YFB4200305)Research Projects of CNPC(Nos.2024ZG50 and 2023DQ03-04)Innovation Capacity Enhancement Projects of Hebei Province(No.22567608H)
文摘Vanadium redox flow battery(VRFB)exhibits a great potential for application in large-scale and long-term energy storage systems due to its high safety,longevity,and environmental friendliness.However,the poor electrocatalytic activity of the pristine graphite felt electrode seriously hinders the energy density and efficiency of VRFB.To address the issue,in this work,the rich active site-NiMoO_(4)nanorods were used to in situ modify graphite felt for high-performance VRFB.The rod-to-diameter ratio and deposition of NiMoO_(4)were controlled by adjusting the ratio of water/ethanol and concentration of the precursor solution to obtain the optimal length of NiMoO_(4)nanorods uniformly deposited on the graphite felt surface.This abundant micropores,dual active sites of Mo-O-Ni,and additional oxygen vacancies effectively increase the specific surface area,the number of active sites,and the hydrophilicity for graphite felt,which boosts the charge transfer and mass transfer for VO^(2+)/VO_(2)^(+)and V^(3+)/V^(2+)redox reactions.The modified battery exhibits an energy efficiency of 71.1%at 150 mA·cm^(-2),which is 19.8%higher than the blank battery.Furthermore,the modified battery shows excellent stability during 100 cycles.This work will promote the development and application of binary metal oxides with rich active sites in VRFB.
基金supported by the National Natural Science Foundation of China (No.22072015)。
文摘Developing non-noble-metal oxygen evolution reaction(OER) electrocatalysts with high performance is critical to electrocatalytic water splitting. In this work, we fabricated Co Fe-layered double hydroxide(LDH) nanowire arrays on graphite felt(Co Fe-LDH/GF) via a hydrothermal method. The Co Fe-LDH/GF, as a robust integrated 3 D OER anode, exhibits excellent catalytic activity with the need of low overpotential of 252 and 285 mV to drive current densities of 10 and 100 mA/cm^(2) in 1.0 mol/L KOH, respectively. In addition, it also maintains electrochemical durability for at least 24 h. This work would open up avenues for the development of GF like attractive catalyst supports for oxygen evolution applications.
基金supported by the National Natural Science Foundation of China(No.51872090)Natural Science Foundation of Hebei Province(No.E2019209433,E2022209158)Colleges and Universities in Hebei Province Science and Technology Research Project(No.JZX2024026).
文摘The scarcity of wettability,insufficient active sites,and low surface area of graphite felt(GF)have long been suppressing the performance of vanadium redox flow batteries(VRFBs).Herein,an ultra-homogeneous multipledimensioned defect,including nano-scale etching and atomic-scale N,O codoping,was used to modify GF by the molten salt system.NH_(4)Cl and KClO_(3) were added simultaneously to the system to obtain porous N/O co-doped electrode(GF/ON),where KClO_(3) was used to ultra-homogeneously etch,and O-functionalize electrode,and NH4Cl was used as N dopant,respectively.GF/ON presents better electrochemical catalysis for VO_(2)+/VO_(2)+ and V3+/V2+ reactions than only O-functionalized electrodes(GF/O)and GF.The enhanced electrochemical properties are attributed to an increase in active sites,surface area,and wettability,as well as the synergistic effect of N and O,which is also supported by the density functional theory calculations.Further,the cell using GF/ON shows higher discharge capacity,energy efficiency,and stability for cycling performance than the pristine cell at 140 mA cm^(−2) for 200 cycles.Moreover,the energy efficiency of the modified cell is increased by 9.7% from 55.2% for the pristine cell at 260 mA cm^(−2).Such an ultra-homogeneous etching with N and O co-doping through“boiling”molten salt medium provides an effective and practical application potential way to prepare superior electrodes for VRFB.
基金supported by the Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project (TSBICIP-KJGG003)Qinglan Plan of the Jiangsu Education Department。
文摘Hydrogen peroxide synthesis by electro-reduction of O_(2) to substitute the current anthraquinone process has attracted a great deal of attention. Low oxygen utilization rate and low hydrogen peroxide production remain obstacles to electro-Fenton application. In situ H_(2)O_(2) generated by electrochemical reaction depends on the electrochemical performance of the cathode and the structure of the reactor. Here, novel graphite felt(GF) modified by La-doped CeO_(2)(La-CeO_(2)) was developed as a cathode. A new double chamber electro-Fenton reactor was proposed, where an organic ultrafiltration membrane was used to prevent H_(2)O_(2) from spreading to the anode. The effects of hydrothermal temperature, time and urea concentration on the electrochemical properties of graphite felt were investigated. The accumulated concentration of H_(2)O_(2) on the modified cathode reached 218.4 mg·L^(-1)in 1 h when the optimal conditions of hydrothermal temperature 120 ℃ and urea concentration 0.55%(mass) in 24 h. The degradation rate of methyl orange reached 98.29%. The new electro-Fenton reactor can efficiently produce hydrogen peroxide to degrade various organic substances and has a high potential for treating wastewater in the chemical industry.
基金Natural Science Foundation of Liaoning Province,Grant/Award Number:2020-MZLH-40High-Level Talent Innovation Support Program of Dalian City,Grant/Award Number:2019RQ076National Natural Science Foundation of China,Grant/Award Numbers:21801034,51732007,51872033。
文摘The cerium-based redox flow battery(RFB)is regarded as a compelling gridscale energy storage technology to revolutionize the utilization of renewable energy by storing the energy in liquid electrolytes.However,its widespread implementation is impeded by the cerium redox reactions that exhibit slow kinetics on commercial graphite felt(GF)electrodes.Surface functionalization may be an available activation strategy to achieve a significant boost in the electrochemical performance of GFs.However,conventional chemical and/or electrochemical routes for the surface functionalization of GFs suffer from the issues of complication,and the deterioration of the resulting modified electrode surface over long-term cycle processes leads to catalytic activity decline.Here,we develop a facile and general strategy for introducing the functional groups to the electrode through the addition of L-cysteine into electrolytes.The-COOH,-NH_(2),and-SH groups in L-cysteine can induce oxygen/nitrogen/sulfur trifunctional doping on GF surfaces with lower deterioration rates,which enables the activated GFs to demonstrate a promising electrocatalytic activity toward cerium redox reactions and excellent durability when used as a cerium-based RFB electrode.This study proposes a rational strategy to overcome the intrinsic limitations of existing modification techniques for GFs and provides a potential pathway toward high-performance RFBs.
基金Project (03GKY3015) supported by the Foundation of Hunan Provincial Department of Science and Technology
文摘PAN-based graphite felt （PGF） treated in 98% sulphuric acid for 5 h and then kept at 450 ℃ for 2 h was evaluated for their electrochemical performance as electrodes of vanadium redox battery （VRB）. Structure and characteristic of treated PAN-based graphite felt （TPGF） were determined by means of Fourier Transform Infi-ared Spectroscopy, Scanning Electron Microscopy, Brunauer-Emmett-Teller surface area analysis and VRB test system. The results show that the acid and heat synergistic effect increase the number of --COOH functional groups on the PGF surface, and the PGF is eroded by sulphuric acid oxidation, resulting in the surface area increases from 0.31 m^2/g to 0.45 m^2/g. The V（ Ⅱ ）/V（Ⅲ） redox reaction is electrochemically reversible on the TPGF electrode, while the V（Ⅳ）/V（Ⅴ） couple is a quasi reversible process. The diffusion coefficients of the oxidation for V（Ⅳ）/V（Ⅴ） obtained from the scope of peak current Ip vs scan rate v^1/2 is 4.4×10^-5 cm^2/s. The improvement of electrochemical activity for the electrode is mainly ascribed to the increase of the number of ---COOH groups on the TPGF, which behaves as active sites catalyzing the vanadium species reactions and accelerating electron transfer reaction and oxygen transfer.
基金supported by the National Natural Science Foundation of China(no.22072015).
文摘The development of efficient electrocatalysts from Earth-abundant elements for the oxygen evolution reaction (OER) is highly desired.Here,we report the electrodeposition of a NiCo layered double hydroxide nanosheet array on graphite felt (NiCo LDHs/GF) as a 3D OER electrocatalyst.Such NiCo LDHs/GF exhibits superior electrocatalytic activity with the need for an overpotential of 249 mV to drive a current density of 20 mA cm^(-2) in 1.0 M KOH.It also shows strong long-term electrochemical durability with its activity being maintained for at least 24 h.
基金National Key R&D Program of China(2016YFB0901500,2016YFB0101201)National Natural Science Foundation of China(21805141,11704114,61427901 and 51771094)+1 种基金Ministry of Education of China(B12015)Tianjin High-Tech(No.18JCZDJC31500)。
文摘Zinc-polyiodide redox flow battery(RFB)systems with highly soluble triiodide/iodide(I_(3)^(-)/I^(-))couples have demonstrated significantly enhanced energy densities.However,their low power density has limited their broad application.In this work,MoS_(2)nanoplates were in situ grafted onto graphite felt(GF)surfaces to accelerate the I_(3)^(-)/I^(-)redox reaction.The hexagonal phase MoS_(2)with enlarged interlayer spacing can facilitate the diffusion of the electrolyte,and the defects on the MoS_(2)nanoplates can serve as very effective catalytic active sites.Cyclic voltammetry testing revealed the high catalytic performance of MoS_(2)in the I_(3)^(-)/I^(-)redox reaction.A non-flow cell with the MoS_(2)-modified GF serving as a positive electrode showed a higher energy efficiency than that of pristine GF;increases of about 10.2%and 10.9%at current densities of 30 mA cm^(-2)and 40 mA cm^(-2)were obtained with the optimized electrode,respectively.
基金supported by the Ministry of Science and Technology of China (2016YFA0202500)the National Natural Science Foundation of China (51772093)the National key Research and Development Program of China (2017YFD0301507)
文摘A mild and simple synthesis process for large-scale vanadium redox flow batteries(VRFBs)energy storage systems is desirable.A graphite felt/Mn O_2(GF-MNO)composite electrode with excellent electrocatalytic activity towards VO^(2+)/VO_2^+redox couples in a VRFB was synthesized by a one-step hydrothermal process.The resulting GF-MNO electrodes possess improved electrochemical kinetic reversibility of the vanadium redox reactions compared to pristine GF electrodes,and the corresponding energy efficiency and discharge capacity at 150 m A cm^(-2)are increased by 12.5%and 40%,respectively.The discharge capacity is maintained at 4.8 A h L^(-1)at the ultrahigh current density of 250 m A cm^(-2).Above all,80%of the energy efficiency of the GF-MNO composite electrodes is retained after 120 charge-discharge cycles at 150 m A cm^(-2).Furthermore,these electrodes demonstrated that more evenly distributed catalytic active sites were obtained from the Mn O_2particles under acidic conditions.The proposed synthetic route is facile,and the raw materials are low cost and environmentally friendly.Therefore,these novel GF-MNO electrodes hold great promise in large-scale vanadium redox flow battery energy storage systems.
基金funded by the National Natural Science Foundation(No.51978288)Natural Science Foundation of Guangdong Province(No.2019A1515012202)Major Science and Technology Program for Water Pollution Control and Treatment in China(No.2017ZX07202-004).
文摘E-peroxone(EP)was one of the most attractive AOPs for removing refractory organic compounds from water,but the high energy consumption for in situ generating H_(2)O_(2) and its low reaction efficiency for activating O_(3) under acidic conditions made the obstacles for its practical application.In this study,cerium oxide was loaded on the surface of graphite felt(GF)by the hydrothermal method to construct the efficient electrode(CeO_(x)/GF)for mineralizing carbamazepine(CBZ)via EP process.CeO_(x)/GF was an efficient cathode,which led to 69.4%TOC removal in CeO_(x)/GF-EP process with current intensity of 10 mA in 60 min.Moreover,CeO_(x)/GF had the flexible application in the pH range from 5.0 to 9.0,TOC removal had no obvious decline with decrease of pH.Comparative characterizations showed that CeO_(x)could enhance surface hydrophilicity and reduce the charge-transfer resistance of GF.About 5.4 mg/L H_(2)O_(2) generated in CeO_(x)/GF-EP process,which was 2.1 times as that in GF-EP process.The greater ozone utility was also found in CeO_(x)/GF-EP process.More O_(3) was activated into hydroxyl radicals,which accounted for the mineralization of CBZ.An interfacial electron transfer process was revealed,which involved the function of oxygen vacancies and Ce^(3+)/Ce^(4+)redox cycle.CeO_(x)/GF had the good recycling property in fifth times'use.
基金supported by the National Natural Science Foundation of China(21576154)the Natural Science Foundation of Guangdong Province(2022A1515011999 and 2019A1515011955)the Shenzhen Basic Research Project(20200829101039001 and GXWD20201231165806004)。
文摘Electrode materials with good redox kinetics,excellent mass transfer characteristics and ultra-high stability play a crucial role in reducing the life-cycle cost and prolonging the maintenance-free time of the vanadium flow batteries(VFB).Herein,a nitrogen-doped porous graphite felt electrode(N-PGF)is proposed by growing ZIF-67 nanoparticles on carbon fibers and then calcinating and acid etching.The multi-scale structure of“carbon fiber gap(electrolyte flow),micro/nano pore(active species diffusion)and Nitrogen active center(reaction site)”in N-PGF electrode effectively increases the catalytic sites and promotes mass transfer characteristics.Reasonable electrode design makes the battery show excellent rate performance and ultra-high cycling stability.The peak power density of the battery reaches 1006 mW cm^(-2).During 1000 cycles at 150 mA cm^(-2),the average discharge capacity and average discharge energy of N-PGF increase substantially by 11.6%and 23.4%compared with the benchmark thermal activated graphite felt,respectively.More excitingly,after ultra-long term(5000 cycles)operation at an ultra-high current density(300 mA cm^(-2)),N-PGF exhibits an unprecedented energy efficiency retention(99.79%)and electrochemical performance stability.
基金financial support from the National Natural Science Foundation of China (No. 21576154)the Open Fund of The State Key Laboratory of Refractories and Metallurgy (No. G201809)the Shenzhen Basic Research Project (Nos. JCYJ20170412170756603 and JCYJ20170307152754218)
文摘Vanadium flow battery （VFB） is a fast going and promising system for large-scale stationary energy stor- age. However, drawbacks such as low power density and narrow temperature window caused by poor catalytic activity of graphite felt （GF） electrodes limit its worldwide application. In this paper, bismuth, as a low-cost, no-toxic and high-activity electrocatalyst, is used to modify the thermal activated GF （TGF） via a facile hydrothermal method. Bismuth can effectively inhibit the side reaction of hydrogen evolution in wide temperature range, while promoting the V2＋/V3＋ redox reaction. As a result, the VFB assembled with Bi/TGF as negative electrode demonstrates outstanding rate performance under the current density up to 400 mAcm-2, as well as a long-term stability over 600 charging/discharging cycles at a high cur- rent density of 150mA cm-2. Moreover, it also shows excellent temperature adaptability from -10 ℃ to 50 ℃ and high durability for life test at the temperature of 50 ℃.
文摘The electrode is one of the main components in redox flow batteries(RFBs), as it provides the reactions sites for redox couples and can influence the cell performance through its effect on cell voltage losses associated with activation overpotential, concentration overpotential and ohmic losses. Extensive research has thus been carried out on material selection, structural design and modification of electrodes as well as electrocatalysis for redox reactions. This review provides an historical overview of the screening and modification of electrode materials together with recent progress in novel electrode architectures, electrode modification and electrocatalysis methods. RFB systems such as iron/chromium, polysulfide/bromine and all vanadium batteries are discussed in detail.
基金supported by the National Natural Science Foundation of China(No.52172291,52122312,22022608)“Shuguang Program”supported by the Shanghai Education Development Foundation and Shanghai Municipal Education Commission(22SG31)the State Key Laboratory for Modification of Chemical Fibers and Polymer Materials(Donghua University).
文摘An electrocatalytic nitrate reduction reaction(NO_(3)RR)is an attractive strategy to maintain the nitrogen neutral.Fe nanoparticles(Fe NPs)are among the most promising electrocatalysts for the NO_(3)RR with low cost and high performance.However,the durability of Fe-based catalysts is poor owing to the aggrega-tion and oxidation of iron.Herein,a series of self-supported Fe/support catalysts has been synthesized by a simple hydrothermal and in situ thermal reduction strategy,exhibiting strong metal–support interaction(SMSI)between Fe active sites and supports.Remarkably,the iron nanoparticles loaded on graphite felt(Fe/GF)exhibited an optimal electrochemical NO_(3)RR performance with NO_(3)^(−)conversion of 67.7%and N_(2) selectivity of 96.6%,which is attributed to the enhanced dispersity and conductivity.This study not only provides a universal method for SMSI composite catalysts but also lays the foundation for their large-scale application.
基金supported by the National Natural Science Foundation of China(nos.22071105,22031008,21803030,and 22001089)QingLan Project of Jiangsu Education Department,and the Jiangsu Innovation&Entrepreneurship Talents Plan in China.J.L.appreciates the support from the Nature Science Foundation of Jiangsu Province(no.BK20191046).
文摘Ammonia(NH3)is an ideal nitrogen source in terms of availability,reactivity,safety,atom economy,environmental compatibility,and ease of isolation.However,its utility for amine synthesis is limited by its high bond dissociation energy,its strong coordination ability,and the difference between its reactivity and that of the product amines.Herein,we reported the first electrochemical protocol for direct syntheses of unprotected tetrasubstituted aziridines with NH3 and alkenes in the absence of an oxidant,which are highly challenging to achieve by other methods.The combination of graphite felt as the anode material and MeOH as the solvent was the key to the success of the protocol,and the effects of these factors were investigated by means of cyclic voltammetry and density functional theory calculations.
