Achieving low charge overpotentials represents one of the most critical challenges for pursuing highperformance lithium-oxygen(Li-O_(2))batteries.Herein,we propose a strategy to realize low charge overpotentials by co...Achieving low charge overpotentials represents one of the most critical challenges for pursuing highperformance lithium-oxygen(Li-O_(2))batteries.Herein,we propose a strategy to realize low charge overpotentials by confining the growth of lithium peroxide(Li_(2)O_(2))inside mesoporous channels of cathodes(CMK-8).The CMK-8 cathode with tortuous pore structures can extend the diffusion distance of lithium superoxide(LiO_(2))in the mesoporous channels,facilitating the further reduction of LiO_(2) to lithium peroxide(Li_(2)O_(2))inside the pores and preventing them to be diffused out of the pores.Therefore,Li_(2)O_(2) is trapped in the mesoporous channels of CMK-8 cathodes,ensuring a good Li_(2)O_(2)/CMK-8 contact interface.The CMK-8 electrode exhibits a low charge overpotential of 0.43 V and a good cycle life for 72 cycles with a fixed capacity of 500 m Ah g^(-1) at 0.1 A g^(-1).This study proposes a strategy to achieve a low charge overpotential by confining Li_(2)O_(2) growth in the mesoporous channels of cathodes.展开更多
The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fi...The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fitting methods often overestimate the charge transfer overpotential,leading to substantial errors in reaction rate constant measurements.These inaccuracies hinder the accurate prediction of voltage profiles and overall cell performance.In this study,we propose the characteristic time-decomposed overpotential(CTDO)method,which employs a single-layer particle electrode(SLPE)structure to eliminate interference overpotentials.By leveraging the distribution of relaxation times(DRT),our method effectively isolates the characteristic time of the charge transfer process,enabling a more precise determination of the reaction rate constant.Simulation results indicate that our approach reduces measurement errors to below 2%,closely aligning with theoretical values.Furthermore,experimental validation demonstrates an 80% reduction in error compared to the conventional galvanostatic intermittent titration technique(GITT)method.Overall,this study provides a novel voltage-based approach for determining the reaction rate constant,enhancing the applicability of theoretical analysis in electrode structural design and facilitating rapid battery optimization.展开更多
The lithium-oxygen battery(LOB)is a promising source of green energy due to its energy density.However,the development of this technology is limited by the insoluble discharge product it produces.In this work,a cathod...The lithium-oxygen battery(LOB)is a promising source of green energy due to its energy density.However,the development of this technology is limited by the insoluble discharge product it produces.In this work,a cathode material with a p-n heterostructure of polyaniline(PANI)/ZnS is prepared to trap visible light,utilizing a ZnS quantum dot(ZnS QD)network to form a large number of photogenerated electron–hole pairs,thus promoting the generation and decomposition of Li_(2)O_(2).The prepared PANI/ZnS has an ultra-low overpotential of 0.06 V under illumination.Furthermore,density functional theory theoretical calculation has demonstrated the ability of the heterostructures to adsorb oxygen-containing intermediates,which not only facilitates the growth of Li_(2)O_(2),but also reduces the reaction energy required to decompose Li_(2)O_(2).The present work provides a solution to the problem of insolubility of discharge products in photo-assisted LOB.展开更多
It is well known that transition metal sulfides(TMS)(i.e.,NiS_(2))undergo electrochemical reconstructions to generate highly active Ni_(3)S_(2) during the process of hydrogen evolution reaction(HER)under overpotential...It is well known that transition metal sulfides(TMS)(i.e.,NiS_(2))undergo electrochemical reconstructions to generate highly active Ni_(3)S_(2) during the process of hydrogen evolution reaction(HER)under overpotentials of<500 mV.However,at higher overpotentials,Ni_(3)S_(2) can theoretically be further restructured into Ni and thus form Ni/Ni_(3)S_(2) heterogeneous interface structures,which may provide opportunities to further enhance HER activity of NiS_(2).Here,we selected NiS_(2) as a model electrocatalyst and investigated the influence of the reconstruction results induced from regular to ultrahigh overpotentials on its electrocatalytic hydrogen precipitation performance.The experimental results showed that the most significant enhancement of hydrogen precipitation performance was obtained for the NiS_(2)@CC-900(900 means 900 mV overpotential)sample after the ultra-high overpotential induced reconstruction.Compared with the initial overpotential of 161 mV(10 mA cm^(-2)),the overpotential of the reconstructed sample reduced by 67 mV(42%).The characterization results showed that an ultra-high overpotential of 900 mV induced deep reconstruction of NiS_(2),formed highly reactive Ni/Ni_(3)S_(2) heterogeneous interfaces,which is more conducive to improved HER performance and match well with theoretical calculations results.We demonstrated ultrahigh overpotential was an effective strategy to induce NiS_(2) deeply reconstruction and significantly improve its HER performance,and this strategy was also applicable to CoS_(2) and FeS_(2).This study provides an extremely simple and universal pathway for the reasonable construction of efficient electrocatalysts by induced TMS deeply reconstruction.展开更多
Rechargeable lithium-carbon dioxide(Li-CO_(2))batteries have emerged as a highly promising approach to simultaneously address energy shortages and the greenhouse effect.However,certain limitations exist in Li-CO_(2)ba...Rechargeable lithium-carbon dioxide(Li-CO_(2))batteries have emerged as a highly promising approach to simultaneously address energy shortages and the greenhouse effect.However,certain limitations exist in Li-CO_(2)batteries like high charge overpotential and unstable Li metal interface,which adversely affect the energy efficiency and cycling life.The incorporation of soluble redox mediators(RMs)has proven effective in enhancing the charge transfer between lithium carbonate(Li_(2)CO_(3))and cathode,thereby substantially reducing the charge overpotential.Nevertheless,the severe shuttle effect of RMs results in the reactions with Li anode,not only exacerbating the corrosion of Li anode but also leading to the depletion of RMs and electrical energy efficiency.In this work,an organic compound containing large cation group,1-ethyl-3-methylimidazole bromide(EMIBr)is proposed as the defense donor RM for Li anode in Li-CO_(2)batteries to address the above problems simultaneously.During charging,Li_(2)CO_(3)oxidation kinetics can be accelerated by bromide anion pair(Br_(3)^(−)/Br^(−)).Meanwhile,the cations(EMI^(+))are preferentially adsorbed around the protruding tips of Li anode through electrostatic interaction driven by surface free energy,forming protective layers that effectively inhibit further Li deposition at these tips,which is verified by DFT calculations.Additionally,Li dendrites growth is inhibited by the electrostatic repulsion of polar groups in EMIBr,resulting in uniform Li deposition.Consequently,a lower overpotential(∼1.17 V)and a longer cycle life(∼200 cycles)have been obtained for Li-CO_(2)battery incorporating EMIBr.展开更多
The oxygen evolution reaction(OER)is a key process in water splitting for hydrogen production,yet its sluggish kinetics pose significant challenges for catalyst development.In this work,we present the first systematic...The oxygen evolution reaction(OER)is a key process in water splitting for hydrogen production,yet its sluggish kinetics pose significant challenges for catalyst development.In this work,we present the first systematic study on isostructural 2D coordination polymers(CPs)based on 1,10-ferrocenediyl-bis(H-phosphinic)acid,with cobalt,manganese,and cadmium metals as electrocatalysts for OER.These polymers were synthesized via a facile solution reaction,yielding crystalline materials with excellent structural integrity.The electrocatalytic performance of CPs composites,prepared with carbon and phosphonium ionic liquid,was evaluated in 0.1 M KOH using a three-electrode system.Notably,the Co-and Cd-based CPs demonstrated exceptional OER activity,achieving an overpotential as low as 236–255 mV at 10 mA cm^(-2),surpassing those of many previously reported CP-based OER catalysts.Furthermore,these materials exhibited high stability over prolonged electrolysis,maintaining their activity without significant degradation.This work not only introduces a new class of ferrocenyl phosphinatebased CPs as highly active and durable OER catalysts but also provides valuable insights into their structureactivity relationships,paving the way for future advancements in electrocatalysis.展开更多
In the quest for high-efficiency and cost-effective catalysts for the oxygen evolution reaction(OER),a novel biomass-driven strategy is developed to fabricate a unique one-dimensional rod-arrays@two-dimensional interl...In the quest for high-efficiency and cost-effective catalysts for the oxygen evolution reaction(OER),a novel biomass-driven strategy is developed to fabricate a unique one-dimensional rod-arrays@two-dimensional interlaced-sheets(C_(1D@2D))network.A groundbreaking chemical fermentation(CF)pore-generation mechanism,proposed for the first time for creating nanopores within carbon structures,is based on the optimal balance between gasification and solidification.This mechanism not only results in a distinctive C_(1D@2D) multilevel network with nanoscale,intersecting and freely flowing channels but also introduces a novel concept for in situ,extensive and hierarchical pore formation.The unique architecture,combined with the homogeneous dispersion of Ni-Fe nanoparticles,facilitates easy electrolyte penetration and provides abundant active sites for the anchoring and dispersion of reactive molecules or ions.Consequently,the Ni-Fe@C_(1D@2D) porous network demonstrates an exceptional OER electrocatalytic performance,achieving a record-low overpotential of 165 mV at 10 mA cm^(−2)and maintaining long-term stability for over 90 h.Theoretical calculations reveal that the porous structure markedly strengthens the interaction between alloy nanoparticles and the carbon matrix,thereby significantly boosting their electrocatalytic activity and stability.These findings unequivocally validate the CF pore-generation mechanism as a powerful and innovative strategy for designing highly efficient functional nanostructures.展开更多
ZnO with good lithiophilicity has widely been employed to modify the lithiophobic substrates and facilitate uniform lithium(Li)deposition.The overpotential of ZnO-derived Li anode during cycling depends on the lithiop...ZnO with good lithiophilicity has widely been employed to modify the lithiophobic substrates and facilitate uniform lithium(Li)deposition.The overpotential of ZnO-derived Li anode during cycling depends on the lithiophilicity of both LiZn and Li_(2)O products upon lithiation of ZnO.However,the striking differences in the lithiophilicity between Li_(2)O and LiZn would result in a high overpotential during cycling.In this research,the Al_(2)O_(3)/nZnO(n≥1)hybrid layers were precisely fabricated by atomic layer deposition(ALD)to regulate the lithiophilicity of ZnO phase and Li_(2)O/LiZn configuration—determining the actual Li loading amount and Li plating/stripping processes.Theoretically,the Li adsorption energy(E_(a))values of LiZn and Li_(2)O in the LiZn/Li_(2)O configuration are separately predicted as-2.789 and-3.447 eV.In comparison,the E_(a) values of LiZn,LiAlO_(2),and Li_(2)O in the LiZn/LiAlO_(2)/Li_(2)O configuration upon lithiation of Al_(2)O_(3)/8ZnO layer are calculated as-2.899,-3.089,and-3.208 eV,respectively.Importantly,a novel introduction of LiAlO_(2)into the LiZn/Li_(2)O configuration could enable the hierarchical Li plating/stripping and reduce the overpotentials during cycling.Consequently,the Al_(2)O_(3)/8ZnO-derived hybrid Li-metal anode could exhibit electrochemical performances superior to these of ZnO-derived Li anode in both symmetrical and full cells paired with a LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)cathode.展开更多
CO_(2)electroreduction to formate is technically feasible and economically viable,but still suffers from low selectivity and high overpotential at industrial current densities.Here,lattice-distorted metallic nanosheet...CO_(2)electroreduction to formate is technically feasible and economically viable,but still suffers from low selectivity and high overpotential at industrial current densities.Here,lattice-distorted metallic nanosheets with disorder-engineered metal sites are designed for industrial-current-density CO_(2)-to-formate conversion at low overpotentials.As a prototype,richly lattice-distorted bismuth nanosheets are first constructed,where abundant disorder-engineered Bi sites could be observed by high-angle annular dark-field scanning transmission electron microscopy image.In-situ Fourier-transform infrared spectra reveal the CO_(2)•−*group is the key intermediate,while theoretical calculations suggest the electron-enriched Bi sites could effectively lower the CO_(2)activation energy barrier by stabilizing the CO_(2)•−*intermediate,further affirmed by the decreased formation energy from 0.49 to 0.39 eV.As a result,the richly lattice-distorted Bi nanosheets exhibit the ultrahigh current density of 800 mA·cm^(−2)with 91%Faradaic efficiencies for CO_(2)-to-formate electroreduction,and the formate selectivity can reach nearly 100%at the current density of 200 mA·cm^(−2)with a very low overpotential of ca.570 mV,outperforming most reported metal-based electrocatalysts.展开更多
Biomass electrooxidation has garnered much attention in recent years,owing to its potential to circumvent greenhouse gas emissions.Substituting the sluggish water oxidation with biomass oxidizable species such as lign...Biomass electrooxidation has garnered much attention in recent years,owing to its potential to circumvent greenhouse gas emissions.Substituting the sluggish water oxidation with biomass oxidizable species such as lignin at anode is thermodynamically more favorable,enabling energy efficient hydrogen production and concomitant fine chemicals.The present study shows the organosolv lignin electrooxidation in an additively manufactured 3D printed reactor(3DPR)consisting of platinized nickel foam(PtNF)as anode and cathode and compared with commercial hardware electrolyzer(CHE).The electrolysis of organosolv lignin in 3DPR outperformed CHE by achieving 1.23 times higher current at an applied voltage range from 0 to 2.2 V with a membrane(Nafion 115)interposed between anode and cathode under a continuous flow of lignin feed at the anode.The chronoamperometry study reveals a mixture of diverse aromatic compounds,including vanillic acid,syringic acid,3,5-dimethoxy-4-hydroxyacetophenone,2-hydroxyacetophenone,4-ethycathecol,and 2,6-dimethoxyphenol in anolyte,and sinapic acid and vanillin acetate in catholyte.Thus,realizing renewable biomass electrolysis in the 3DPR is an intriguing strategy for the co-production of hydrogen and fine aromatic chemicals.展开更多
Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and selectivity.In this work,by means of the density functional theory(DFT) calculations,...Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and selectivity.In this work,by means of the density functional theory(DFT) calculations,the catalytic activities of transition metal clusters with precise numbers of atoms supported on graphdiyne(TM_(1-4)@GDY,TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Pd,Ir,Pt) were investigated for oxygen evolution reactions(OER),oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER).The computed results reveal that the Pd_(2),Pd_(4) and Pt_(1) anchored graphdiyne can serve as trifunctional catalysts for OER/ORR/HER with the overpotentials of 0.49/0.37/0.06,0.45/0.33/0.12 and 0.37/0.43/0.01 V,respectively,while Pd_(1) and Pt_(2)@graphdiyne can exhibit excellent catalytic performance for water splitting(OER/HER) with the overpotentials of 0.55/0.17 and 0.43/0.03 V.In addition,Ni_(1) and Pd_(3) anchored GDY can perform as bifunctional catalysts for metal-air cells(OER/ORR) and fuels cells(ORR/HER) with the overpotentials of 0.34/0.32 and 0.42/0.04 V,respectively.Thus,by precisely controlling the numbers of atoms in clusters,the TM_(1-4) anchored graphdiyne can serve as promising multifunctional electrocatalysts for OER/ORR/HER,which may provide an instructive strategy to design catalysts for the energy conversation and storage devices.展开更多
Nano-CeO2 （RE） particles were co-deposited into Ni-P binary composite coatings by applying pulse current （PC） under ultrasonic （U） field. Morphology, chemical content and crystal microstructure were characterize...Nano-CeO2 （RE） particles were co-deposited into Ni-P binary composite coatings by applying pulse current （PC） under ultrasonic （U） field. Morphology, chemical content and crystal microstructure were characterized by environmental scanning electron microscopy （E-SEM） with energy dispersive X-ray analysis （EDXA）, XRD diffractometry and transmission electron microscopy （TEM）. Experimental results show that Ni-P coating reinforced with 15g/L nano-CeO2, in amorphous state and with compact structure, can be improved in the microhardness from HV0.2580 to HV0.2780 by annealing at 600 °C for 2 h. The highest content of codeposited Ce and deposition rate can reach 2.3% and 68 μm/h, respectively. Furthermore, the effect of RE adsorption and pulse overpotential on depositional mechanism was investigated. n-CeO2 particles or Ce4＋ ions with strong adsorption capacity acted as the catalytic nucleus to improve densification effectively. During annealing at 600 °C for 2 h, n-CeO2 particles will uniformly adsorb on crystal grain to preferentially pad and heal up gaps of cracking Ni boundaries, promoting dispersion strengthening with refiner-grained structure.展开更多
Lithium-oxygen(Li-O_(2)) batteries are considered as the next generation for energy storages systems due to the higher theoretical energy density than that of Li-ion batteries. However, the high charge overpotential c...Lithium-oxygen(Li-O_(2)) batteries are considered as the next generation for energy storages systems due to the higher theoretical energy density than that of Li-ion batteries. However, the high charge overpotential caused by the insulated Li_(2)O_(2)results in low energy efficiency, side reaction from electrolyte and cathode, and therefore poor battery performance. Designing noble metal-based catalysts can be an effective strategy to develop high-performance Li-O_(2)batteries with low charge overpotentials and outstanding cycle stability. However, the charge mechanism for noble metal-based catalysts is not clear and even contradictory. Herein, several charge mechanisms of Li_(2)O_(2)are first discussed. Subsequently, the possible charge processes of Li-O_(2)batteries with noble metal-based catalysts are illustrated. In addition, the future development for noble metal-based catalysts is outlined.展开更多
Kinetics of dissociative O2 adsorption, OHad desorption, and oxygen reduction reaction （ORR） at Pt（111） electrode in 0.1 mol/L HClO4 has been investigated. Reversible OHad adsorption/desorption occurs at potential...Kinetics of dissociative O2 adsorption, OHad desorption, and oxygen reduction reaction （ORR） at Pt（111） electrode in 0.1 mol/L HClO4 has been investigated. Reversible OHad adsorption/desorption occurs at potentials from 0.6 V to 1.0 V （vs. RHE） with the exchange current density of ca. 50 mA/cm^2 at 0.8 V, the fast kinetics of OHad desorption indicates that it should not be the rate determining step for ORR. In the kineticor kinetic-mass transport mix controlled potential region, ORR current at constant potential displays slight decrease with reaction time. ORR current in the positive-going potential scan is slightly larger than that in the subsequent negative-going scan with electrode rotation speed （〉800 r/min） and slow potential scan rate （〈100 mV/s）. The open circuit potential of Pt/0.1 mol/L HClO4 interface increases promptly from 0.9 V to 1.0 V after switch from O2 free- to O2-saturated solution. The increase of open circuit potential as well as ORR current decays under potential control due to the accumulation of OHad from dissociative adsorption of O2. It indicates that at Pt（111） the net rate for O2 decomposition to OHad is slightly faster than that for OHad removal, one cannot simply use the assumption of rate determining step to discuss ORR kinetics. Instead, the ORR kinetics is determined by both the kinetics for O2 decomposition to OHad as well as the thermo-equilibrium of OHad＋H^＋＋e→←H2O.展开更多
Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-bas...Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR electrocatalysis.The delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based nanomaterials.In this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic performance.We start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based nanoparticles.Then,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support effects.Last but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.展开更多
Exploration of cost-effective electrocatalysts for boosting the overall water-splitting efficiency is vitally important for obtaining renewable fuels such as hydrogen.Here,earth-abundant CoxNi1-xO nanowire arrays were...Exploration of cost-effective electrocatalysts for boosting the overall water-splitting efficiency is vitally important for obtaining renewable fuels such as hydrogen.Here,earth-abundant CoxNi1-xO nanowire arrays were used as a structural framework to dilute Ir incorporation for fabricating electrocatalysts for water splitting.Minimal Ir-incorporated CoxNi1-xO nanowire arrays were synthesized through the facile hydrothermal method with subsequent calcination by using Ni foam(NF)as both the substrate and source of Ni.The electrocatalytic water-splitting performance was found to crucially depend on the Ir content of the parent CoxNi1-xO nanowire arrays.As a result,for a minimal Ir content,as low as 0.57 wt%,the obtained Ir-CoxNi1-xO/NF electrodes exhibited optimal catalytic activity in terms of a low overpotential of 260 mV for the oxygen evolution reaction and 53 mV for the hydrogen evolution reaction at 10 mA cm?2 in 1 mol L–1 KOH.When used as bifunctional electrodes in water splitting,the current density of 10 mA cm–2 was obtained at a low cell voltage of 1.55 V.Density functional theory calculations revealed that the Ir-doped CoxNi1-xO arrays exhibited enhanced electrical conductivity and low Gibbs free energy,which contributed to the improved electrocatalytic activity.The present study presents a new strategy for the development of transition metal oxide electrocatalysts with low levels of Ir incorporation for efficient water splitting.展开更多
In this study,commercial copper(Cu)foil and Cu foam are used as the working electrodes to systematically investigate the electrochemical deposition and dissolution processes of metallic lithium(Li)on these electrodes;...In this study,commercial copper(Cu)foil and Cu foam are used as the working electrodes to systematically investigate the electrochemical deposition and dissolution processes of metallic lithium(Li)on these electrodes;Li metal deposited on the Cu foil electrode is porous and loose.The surface solid electrolyte interface(SEI)film after dissolution from Li dendrites maintains a dendritic porous structure,resulting in a large volume effect of the electrode during the cycle.The Cu foam electrode provides preferential nucleation and deposition sites near the side surface of the separator;the difference in Li affinity results in a heterogeneous deposition and dendrite growth of metallic Li.展开更多
Electrocatalytic nitrogen reduction reaction(NRR)at ambient conditions holds great promise for sustainably synthesizing ammonia(NH3),while developing highly-efficient,long-term stable,and inexpensive catalysts to acti...Electrocatalytic nitrogen reduction reaction(NRR)at ambient conditions holds great promise for sustainably synthesizing ammonia(NH3),while developing highly-efficient,long-term stable,and inexpensive catalysts to activate the inert N≡N bond is a key scientific issue.In this work,on the basis of the concept"N-heterocyclic carbenes(NHCs)",we propose a carbon decorated graphitic-carbon nitride(C/g-C3N4)as novel metal-free NRR electrocatalyst by means of density functional theory(DFT)computations.Our results reveal that the introduced C atom in g-C3N4 surface can be regarded as NHCs and catalytic sites for activating N≡N bond,and are stabilized by the g-C3N4 substrate due to sterically disfavored dimerization.Especially,this NHCs-based heterogeneous catalysis can efficiently reduce the activated N2 molecule to NH3 with a low overpotential of 0.05 V via an enzymatic mechanism.Our work is the first report of NHCs-based electrocatalyst for N2 fixation,thus opening an alternative avenue for advancing sustainable NH3 production.展开更多
The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to prod...The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to produce high purity hydrogen. Cobalt-based catalysts are well-known electrocatalysts for oxygen evolution reaction（OER）. In this article, all these merits indicate that the present cobalt nanocomposite is a promising electrocatalyst for OER. C–CoO-nanorods catalyst with nanorod structure was synthesized by hydrothermal treatment of CoCl·6HO/dextrose/urea mixture at 180 °C for 18 h and then calcined at400 °C for 3.5 h. The role of dextrose percentage in solution to achieve the uniform coating of carbon on the surface of CoO-nanorods has been demonstrated. The prepared materials were characterized by X-ray diffraction（XRD）, X-ray photoelectron spectrum（XPS）, field emission scanning electron microscopy（FE-SEM）, high-resolution transmission electron microscopy（HR-TEM）, and Brunauer–Emmett–Teller instrument（BET）. Due to its unique morphology, the C–CoO-nanorods catalyst exhibited better activity than CoO-microplates catalyst for OER in 1 M KOH aqueous solution. The results showed a highly efficient, scalable, and low-cost method for developing highly active and stable OER electrocatalysts in alkaline solution.展开更多
基金the financial support from the National Natural Science Foundation of China(91645102)the Singapore MOE grant(R143-000-A29-112)the Hundred Talents Sailing Project of Jiangxi province,China。
文摘Achieving low charge overpotentials represents one of the most critical challenges for pursuing highperformance lithium-oxygen(Li-O_(2))batteries.Herein,we propose a strategy to realize low charge overpotentials by confining the growth of lithium peroxide(Li_(2)O_(2))inside mesoporous channels of cathodes(CMK-8).The CMK-8 cathode with tortuous pore structures can extend the diffusion distance of lithium superoxide(LiO_(2))in the mesoporous channels,facilitating the further reduction of LiO_(2) to lithium peroxide(Li_(2)O_(2))inside the pores and preventing them to be diffused out of the pores.Therefore,Li_(2)O_(2) is trapped in the mesoporous channels of CMK-8 cathodes,ensuring a good Li_(2)O_(2)/CMK-8 contact interface.The CMK-8 electrode exhibits a low charge overpotential of 0.43 V and a good cycle life for 72 cycles with a fixed capacity of 500 m Ah g^(-1) at 0.1 A g^(-1).This study proposes a strategy to achieve a low charge overpotential by confining Li_(2)O_(2) growth in the mesoporous channels of cathodes.
基金supported by the National Key R&D Program of China 2022YFB2404300the National Natural Science Foundation of China U22B2069the China Postdoctoral Science Foundation 2024M761006。
文摘The reaction rate constant is a crucial kinetic parameter that governs the charge and discharge performance of batteries,particularly in high-rate and thick-electrode applications.However,conventional estimation or fitting methods often overestimate the charge transfer overpotential,leading to substantial errors in reaction rate constant measurements.These inaccuracies hinder the accurate prediction of voltage profiles and overall cell performance.In this study,we propose the characteristic time-decomposed overpotential(CTDO)method,which employs a single-layer particle electrode(SLPE)structure to eliminate interference overpotentials.By leveraging the distribution of relaxation times(DRT),our method effectively isolates the characteristic time of the charge transfer process,enabling a more precise determination of the reaction rate constant.Simulation results indicate that our approach reduces measurement errors to below 2%,closely aligning with theoretical values.Furthermore,experimental validation demonstrates an 80% reduction in error compared to the conventional galvanostatic intermittent titration technique(GITT)method.Overall,this study provides a novel voltage-based approach for determining the reaction rate constant,enhancing the applicability of theoretical analysis in electrode structural design and facilitating rapid battery optimization.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.52171206 and52271209)Key Project of Hebei Natural Science Foundation(Nos.F2024201031 and E20202201030)+4 种基金Beijing-Tianjin-Hebei Collaborative Innovation Community Construction Project(No.21344301D)the Second Batch of Young Talent of Hebei Province(Nos.70280016160250 and 70280011808)Key Fund in Hebei Province Department of Education China(No.ZD2021014)the Central Government Guide Local Funding Projects for Scientific and Technological Development(Nos.216Z4404G and 206Z4402G)Interdisciplinary Research Program of Natural Science of Hebei University(No.DXK202107)。
文摘The lithium-oxygen battery(LOB)is a promising source of green energy due to its energy density.However,the development of this technology is limited by the insoluble discharge product it produces.In this work,a cathode material with a p-n heterostructure of polyaniline(PANI)/ZnS is prepared to trap visible light,utilizing a ZnS quantum dot(ZnS QD)network to form a large number of photogenerated electron–hole pairs,thus promoting the generation and decomposition of Li_(2)O_(2).The prepared PANI/ZnS has an ultra-low overpotential of 0.06 V under illumination.Furthermore,density functional theory theoretical calculation has demonstrated the ability of the heterostructures to adsorb oxygen-containing intermediates,which not only facilitates the growth of Li_(2)O_(2),but also reduces the reaction energy required to decompose Li_(2)O_(2).The present work provides a solution to the problem of insolubility of discharge products in photo-assisted LOB.
文摘It is well known that transition metal sulfides(TMS)(i.e.,NiS_(2))undergo electrochemical reconstructions to generate highly active Ni_(3)S_(2) during the process of hydrogen evolution reaction(HER)under overpotentials of<500 mV.However,at higher overpotentials,Ni_(3)S_(2) can theoretically be further restructured into Ni and thus form Ni/Ni_(3)S_(2) heterogeneous interface structures,which may provide opportunities to further enhance HER activity of NiS_(2).Here,we selected NiS_(2) as a model electrocatalyst and investigated the influence of the reconstruction results induced from regular to ultrahigh overpotentials on its electrocatalytic hydrogen precipitation performance.The experimental results showed that the most significant enhancement of hydrogen precipitation performance was obtained for the NiS_(2)@CC-900(900 means 900 mV overpotential)sample after the ultra-high overpotential induced reconstruction.Compared with the initial overpotential of 161 mV(10 mA cm^(-2)),the overpotential of the reconstructed sample reduced by 67 mV(42%).The characterization results showed that an ultra-high overpotential of 900 mV induced deep reconstruction of NiS_(2),formed highly reactive Ni/Ni_(3)S_(2) heterogeneous interfaces,which is more conducive to improved HER performance and match well with theoretical calculations results.We demonstrated ultrahigh overpotential was an effective strategy to induce NiS_(2) deeply reconstruction and significantly improve its HER performance,and this strategy was also applicable to CoS_(2) and FeS_(2).This study provides an extremely simple and universal pathway for the reasonable construction of efficient electrocatalysts by induced TMS deeply reconstruction.
基金financially supported by National Natural Science Foundation of China(No.22075171).
文摘Rechargeable lithium-carbon dioxide(Li-CO_(2))batteries have emerged as a highly promising approach to simultaneously address energy shortages and the greenhouse effect.However,certain limitations exist in Li-CO_(2)batteries like high charge overpotential and unstable Li metal interface,which adversely affect the energy efficiency and cycling life.The incorporation of soluble redox mediators(RMs)has proven effective in enhancing the charge transfer between lithium carbonate(Li_(2)CO_(3))and cathode,thereby substantially reducing the charge overpotential.Nevertheless,the severe shuttle effect of RMs results in the reactions with Li anode,not only exacerbating the corrosion of Li anode but also leading to the depletion of RMs and electrical energy efficiency.In this work,an organic compound containing large cation group,1-ethyl-3-methylimidazole bromide(EMIBr)is proposed as the defense donor RM for Li anode in Li-CO_(2)batteries to address the above problems simultaneously.During charging,Li_(2)CO_(3)oxidation kinetics can be accelerated by bromide anion pair(Br_(3)^(−)/Br^(−)).Meanwhile,the cations(EMI^(+))are preferentially adsorbed around the protruding tips of Li anode through electrostatic interaction driven by surface free energy,forming protective layers that effectively inhibit further Li deposition at these tips,which is verified by DFT calculations.Additionally,Li dendrites growth is inhibited by the electrostatic repulsion of polar groups in EMIBr,resulting in uniform Li deposition.Consequently,a lower overpotential(∼1.17 V)and a longer cycle life(∼200 cycles)have been obtained for Li-CO_(2)battery incorporating EMIBr.
文摘The oxygen evolution reaction(OER)is a key process in water splitting for hydrogen production,yet its sluggish kinetics pose significant challenges for catalyst development.In this work,we present the first systematic study on isostructural 2D coordination polymers(CPs)based on 1,10-ferrocenediyl-bis(H-phosphinic)acid,with cobalt,manganese,and cadmium metals as electrocatalysts for OER.These polymers were synthesized via a facile solution reaction,yielding crystalline materials with excellent structural integrity.The electrocatalytic performance of CPs composites,prepared with carbon and phosphonium ionic liquid,was evaluated in 0.1 M KOH using a three-electrode system.Notably,the Co-and Cd-based CPs demonstrated exceptional OER activity,achieving an overpotential as low as 236–255 mV at 10 mA cm^(-2),surpassing those of many previously reported CP-based OER catalysts.Furthermore,these materials exhibited high stability over prolonged electrolysis,maintaining their activity without significant degradation.This work not only introduces a new class of ferrocenyl phosphinatebased CPs as highly active and durable OER catalysts but also provides valuable insights into their structureactivity relationships,paving the way for future advancements in electrocatalysis.
基金supported by the National Natural Science Foundation of China(Grant No.22275082 and 22175084).
文摘In the quest for high-efficiency and cost-effective catalysts for the oxygen evolution reaction(OER),a novel biomass-driven strategy is developed to fabricate a unique one-dimensional rod-arrays@two-dimensional interlaced-sheets(C_(1D@2D))network.A groundbreaking chemical fermentation(CF)pore-generation mechanism,proposed for the first time for creating nanopores within carbon structures,is based on the optimal balance between gasification and solidification.This mechanism not only results in a distinctive C_(1D@2D) multilevel network with nanoscale,intersecting and freely flowing channels but also introduces a novel concept for in situ,extensive and hierarchical pore formation.The unique architecture,combined with the homogeneous dispersion of Ni-Fe nanoparticles,facilitates easy electrolyte penetration and provides abundant active sites for the anchoring and dispersion of reactive molecules or ions.Consequently,the Ni-Fe@C_(1D@2D) porous network demonstrates an exceptional OER electrocatalytic performance,achieving a record-low overpotential of 165 mV at 10 mA cm^(−2)and maintaining long-term stability for over 90 h.Theoretical calculations reveal that the porous structure markedly strengthens the interaction between alloy nanoparticles and the carbon matrix,thereby significantly boosting their electrocatalytic activity and stability.These findings unequivocally validate the CF pore-generation mechanism as a powerful and innovative strategy for designing highly efficient functional nanostructures.
基金supported by the National Key Research and Development Program of China(2021YFB2400202)the National Natural Science Foundation of China(52104313)+1 种基金the Key Research and Development Plan of Shaanxi(2024GH-YBXM-11)the Foshan Science and Technology Innovation Team Project(1920001004098).
文摘ZnO with good lithiophilicity has widely been employed to modify the lithiophobic substrates and facilitate uniform lithium(Li)deposition.The overpotential of ZnO-derived Li anode during cycling depends on the lithiophilicity of both LiZn and Li_(2)O products upon lithiation of ZnO.However,the striking differences in the lithiophilicity between Li_(2)O and LiZn would result in a high overpotential during cycling.In this research,the Al_(2)O_(3)/nZnO(n≥1)hybrid layers were precisely fabricated by atomic layer deposition(ALD)to regulate the lithiophilicity of ZnO phase and Li_(2)O/LiZn configuration—determining the actual Li loading amount and Li plating/stripping processes.Theoretically,the Li adsorption energy(E_(a))values of LiZn and Li_(2)O in the LiZn/Li_(2)O configuration are separately predicted as-2.789 and-3.447 eV.In comparison,the E_(a) values of LiZn,LiAlO_(2),and Li_(2)O in the LiZn/LiAlO_(2)/Li_(2)O configuration upon lithiation of Al_(2)O_(3)/8ZnO layer are calculated as-2.899,-3.089,and-3.208 eV,respectively.Importantly,a novel introduction of LiAlO_(2)into the LiZn/Li_(2)O configuration could enable the hierarchical Li plating/stripping and reduce the overpotentials during cycling.Consequently,the Al_(2)O_(3)/8ZnO-derived hybrid Li-metal anode could exhibit electrochemical performances superior to these of ZnO-derived Li anode in both symmetrical and full cells paired with a LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM622)cathode.
基金the National Key Research and Development Program of China(No.2019YFA0210004)the National Natural Science Foundation of China(Nos.22125503,21975242,U2032212,and 21890754)+5 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Youth Innovation Promotion Association of CAS(No.CX2340007003)the Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-SLH011)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP003)Users with Excellence Program of Hefei Science Center CAS(No.2020HSC-UE001)the University Synergy Innovation Program of Anhui Province(No.GXXT-2020-001)。
文摘CO_(2)electroreduction to formate is technically feasible and economically viable,but still suffers from low selectivity and high overpotential at industrial current densities.Here,lattice-distorted metallic nanosheets with disorder-engineered metal sites are designed for industrial-current-density CO_(2)-to-formate conversion at low overpotentials.As a prototype,richly lattice-distorted bismuth nanosheets are first constructed,where abundant disorder-engineered Bi sites could be observed by high-angle annular dark-field scanning transmission electron microscopy image.In-situ Fourier-transform infrared spectra reveal the CO_(2)•−*group is the key intermediate,while theoretical calculations suggest the electron-enriched Bi sites could effectively lower the CO_(2)activation energy barrier by stabilizing the CO_(2)•−*intermediate,further affirmed by the decreased formation energy from 0.49 to 0.39 eV.As a result,the richly lattice-distorted Bi nanosheets exhibit the ultrahigh current density of 800 mA·cm^(−2)with 91%Faradaic efficiencies for CO_(2)-to-formate electroreduction,and the formate selectivity can reach nearly 100%at the current density of 200 mA·cm^(−2)with a very low overpotential of ca.570 mV,outperforming most reported metal-based electrocatalysts.
基金This project received financial support from Natural Sciences and Engineering Research Council of Canada via a Discovery Grant(2022-00058)Canada Research Chair Fund(3266004)+1 种基金The Fonds de recherche du Quebec-Nature et technologies FRQNT(NCR-327419)We would also like to thank Intlvac Thin Film team for the support.
文摘Biomass electrooxidation has garnered much attention in recent years,owing to its potential to circumvent greenhouse gas emissions.Substituting the sluggish water oxidation with biomass oxidizable species such as lignin at anode is thermodynamically more favorable,enabling energy efficient hydrogen production and concomitant fine chemicals.The present study shows the organosolv lignin electrooxidation in an additively manufactured 3D printed reactor(3DPR)consisting of platinized nickel foam(PtNF)as anode and cathode and compared with commercial hardware electrolyzer(CHE).The electrolysis of organosolv lignin in 3DPR outperformed CHE by achieving 1.23 times higher current at an applied voltage range from 0 to 2.2 V with a membrane(Nafion 115)interposed between anode and cathode under a continuous flow of lignin feed at the anode.The chronoamperometry study reveals a mixture of diverse aromatic compounds,including vanillic acid,syringic acid,3,5-dimethoxy-4-hydroxyacetophenone,2-hydroxyacetophenone,4-ethycathecol,and 2,6-dimethoxyphenol in anolyte,and sinapic acid and vanillin acetate in catholyte.Thus,realizing renewable biomass electrolysis in the 3DPR is an intriguing strategy for the co-production of hydrogen and fine aromatic chemicals.
基金financially supported by Fundamental Research Funds for Heilongjiang Province universities (No.2021-KYYWF-0184)Harbin Normal University Graduate Student Innovation Project (No.HSDSSCX2023-30)。
文摘Subnanometer metal clusters play an increasingly important role in heterogeneous catalysis due to their high catalytic activity and selectivity.In this work,by means of the density functional theory(DFT) calculations,the catalytic activities of transition metal clusters with precise numbers of atoms supported on graphdiyne(TM_(1-4)@GDY,TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Pd,Ir,Pt) were investigated for oxygen evolution reactions(OER),oxygen reduction reactions(ORR) and hydrogen evolution reactions(HER).The computed results reveal that the Pd_(2),Pd_(4) and Pt_(1) anchored graphdiyne can serve as trifunctional catalysts for OER/ORR/HER with the overpotentials of 0.49/0.37/0.06,0.45/0.33/0.12 and 0.37/0.43/0.01 V,respectively,while Pd_(1) and Pt_(2)@graphdiyne can exhibit excellent catalytic performance for water splitting(OER/HER) with the overpotentials of 0.55/0.17 and 0.43/0.03 V.In addition,Ni_(1) and Pd_(3) anchored GDY can perform as bifunctional catalysts for metal-air cells(OER/ORR) and fuels cells(ORR/HER) with the overpotentials of 0.34/0.32 and 0.42/0.04 V,respectively.Thus,by precisely controlling the numbers of atoms in clusters,the TM_(1-4) anchored graphdiyne can serve as promising multifunctional electrocatalysts for OER/ORR/HER,which may provide an instructive strategy to design catalysts for the energy conversation and storage devices.
基金Project (CXLX12_0151) supported by Jiangsu Innovation program for Graduate Education and Fundamental Research Funds for Central Unibersities, China
文摘Nano-CeO2 （RE） particles were co-deposited into Ni-P binary composite coatings by applying pulse current （PC） under ultrasonic （U） field. Morphology, chemical content and crystal microstructure were characterized by environmental scanning electron microscopy （E-SEM） with energy dispersive X-ray analysis （EDXA）, XRD diffractometry and transmission electron microscopy （TEM）. Experimental results show that Ni-P coating reinforced with 15g/L nano-CeO2, in amorphous state and with compact structure, can be improved in the microhardness from HV0.2580 to HV0.2780 by annealing at 600 °C for 2 h. The highest content of codeposited Ce and deposition rate can reach 2.3% and 68 μm/h, respectively. Furthermore, the effect of RE adsorption and pulse overpotential on depositional mechanism was investigated. n-CeO2 particles or Ce4＋ ions with strong adsorption capacity acted as the catalytic nucleus to improve densification effectively. During annealing at 600 °C for 2 h, n-CeO2 particles will uniformly adsorb on crystal grain to preferentially pad and heal up gaps of cracking Ni boundaries, promoting dispersion strengthening with refiner-grained structure.
基金the financial support from the National Natural Science Foundation of China (No. 12175098)Hundred Talents Sailing Project of Jiangxi Province, China。
文摘Lithium-oxygen(Li-O_(2)) batteries are considered as the next generation for energy storages systems due to the higher theoretical energy density than that of Li-ion batteries. However, the high charge overpotential caused by the insulated Li_(2)O_(2)results in low energy efficiency, side reaction from electrolyte and cathode, and therefore poor battery performance. Designing noble metal-based catalysts can be an effective strategy to develop high-performance Li-O_(2)batteries with low charge overpotentials and outstanding cycle stability. However, the charge mechanism for noble metal-based catalysts is not clear and even contradictory. Herein, several charge mechanisms of Li_(2)O_(2)are first discussed. Subsequently, the possible charge processes of Li-O_(2)batteries with noble metal-based catalysts are illustrated. In addition, the future development for noble metal-based catalysts is outlined.
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20773116）, the National Instrumentation Program （No.2011YQ03012416）, and 973 Program from the Ministry of Science and Technology of China （No.2010CB923302）.
文摘Kinetics of dissociative O2 adsorption, OHad desorption, and oxygen reduction reaction （ORR） at Pt（111） electrode in 0.1 mol/L HClO4 has been investigated. Reversible OHad adsorption/desorption occurs at potentials from 0.6 V to 1.0 V （vs. RHE） with the exchange current density of ca. 50 mA/cm^2 at 0.8 V, the fast kinetics of OHad desorption indicates that it should not be the rate determining step for ORR. In the kineticor kinetic-mass transport mix controlled potential region, ORR current at constant potential displays slight decrease with reaction time. ORR current in the positive-going potential scan is slightly larger than that in the subsequent negative-going scan with electrode rotation speed （〉800 r/min） and slow potential scan rate （〈100 mV/s）. The open circuit potential of Pt/0.1 mol/L HClO4 interface increases promptly from 0.9 V to 1.0 V after switch from O2 free- to O2-saturated solution. The increase of open circuit potential as well as ORR current decays under potential control due to the accumulation of OHad from dissociative adsorption of O2. It indicates that at Pt（111） the net rate for O2 decomposition to OHad is slightly faster than that for OHad removal, one cannot simply use the assumption of rate determining step to discuss ORR kinetics. Instead, the ORR kinetics is determined by both the kinetics for O2 decomposition to OHad as well as the thermo-equilibrium of OHad＋H^＋＋e→←H2O.
基金financially supported by the National Natural Science Foundation of China (No.52172058)。
文摘Oxygen reduction reaction(ORR) occurs at the cathode of fuel cells and metal-air batteries,but usually suffers from sluggish kinetics.To solve this issue,efficient electrocatalysts are highly desired.Palladium(Pd)-based nanomaterials,as the most promising substitute of platinum(Pt),exhibit superior activity and stability in ORR electrocatalysis.The delicate regulation of the structure and/or composition shows great potential in improving the electrocatalytic ORR performance of Pd-based nanomaterials.In this review,we retrospect the recent advance of Pdbased ORR electrocatalysts,and analyses the relationship between nanostructure and catalytic performance.We start with the ORR mechanism and indicators of ORR performance in both alkaline and acidic media,followed by the synthetic methods for Pd-based nanoparticles.Then,we emphasize the design strategies of efficient Pd-based ORR catalysts from the perspective of composition,crystal phase,morphology,and support effects.Last but not least,we conclude with possible opportunities and outlook on Pd-based nanomaterials toward ORR.
基金financially supported by the National Natural Science Foundation of China (51772255)the Hunan Provincial Innovation Foundation For Postgraduate (CX2017B274)+1 种基金the National Basic Research Program of China (2015CB921103)the Program for Changjiang Scholars and Innovative Research Team in University (IRT13093)~~
文摘Exploration of cost-effective electrocatalysts for boosting the overall water-splitting efficiency is vitally important for obtaining renewable fuels such as hydrogen.Here,earth-abundant CoxNi1-xO nanowire arrays were used as a structural framework to dilute Ir incorporation for fabricating electrocatalysts for water splitting.Minimal Ir-incorporated CoxNi1-xO nanowire arrays were synthesized through the facile hydrothermal method with subsequent calcination by using Ni foam(NF)as both the substrate and source of Ni.The electrocatalytic water-splitting performance was found to crucially depend on the Ir content of the parent CoxNi1-xO nanowire arrays.As a result,for a minimal Ir content,as low as 0.57 wt%,the obtained Ir-CoxNi1-xO/NF electrodes exhibited optimal catalytic activity in terms of a low overpotential of 260 mV for the oxygen evolution reaction and 53 mV for the hydrogen evolution reaction at 10 mA cm?2 in 1 mol L–1 KOH.When used as bifunctional electrodes in water splitting,the current density of 10 mA cm–2 was obtained at a low cell voltage of 1.55 V.Density functional theory calculations revealed that the Ir-doped CoxNi1-xO arrays exhibited enhanced electrical conductivity and low Gibbs free energy,which contributed to the improved electrocatalytic activity.The present study presents a new strategy for the development of transition metal oxide electrocatalysts with low levels of Ir incorporation for efficient water splitting.
基金the National Natural Science Foundation of China(No.51874361)the National Natural Science Foundation of China Youth Fund(51904343)for supporting this work.
文摘In this study,commercial copper(Cu)foil and Cu foam are used as the working electrodes to systematically investigate the electrochemical deposition and dissolution processes of metallic lithium(Li)on these electrodes;Li metal deposited on the Cu foil electrode is porous and loose.The surface solid electrolyte interface(SEI)film after dissolution from Li dendrites maintains a dendritic porous structure,resulting in a large volume effect of the electrode during the cycle.The Cu foam electrode provides preferential nucleation and deposition sites near the side surface of the separator;the difference in Li affinity results in a heterogeneous deposition and dendrite growth of metallic Li.
基金financially supported in China by the National Natural Science Foundation of China(21103224 and 21878227)Natural Science Funds for Distinguished Young Scholar of Heilongjiang Province(No.JC2018004)+2 种基金Natural Science Foundation of Hebei Province of China(B2019202210)in USA by NSF-CREST Center for Innovation,Research and Education in Environmental Nanotechnology(CIRE2N)(Grant Number HRD-1736093)supported by the Supercomputing Center in Harbin Normal University and Lvliang。
文摘Electrocatalytic nitrogen reduction reaction(NRR)at ambient conditions holds great promise for sustainably synthesizing ammonia(NH3),while developing highly-efficient,long-term stable,and inexpensive catalysts to activate the inert N≡N bond is a key scientific issue.In this work,on the basis of the concept"N-heterocyclic carbenes(NHCs)",we propose a carbon decorated graphitic-carbon nitride(C/g-C3N4)as novel metal-free NRR electrocatalyst by means of density functional theory(DFT)computations.Our results reveal that the introduced C atom in g-C3N4 surface can be regarded as NHCs and catalytic sites for activating N≡N bond,and are stabilized by the g-C3N4 substrate due to sterically disfavored dimerization.Especially,this NHCs-based heterogeneous catalysis can efficiently reduce the activated N2 molecule to NH3 with a low overpotential of 0.05 V via an enzymatic mechanism.Our work is the first report of NHCs-based electrocatalyst for N2 fixation,thus opening an alternative avenue for advancing sustainable NH3 production.
基金supported by the National Research Foundation of Korea(NRF)–Grants funded by the Ministry of Science,ICT and Future Planning(2014R1A2A2A01004352),Republic of Korea
文摘The design of cost-effective, highly active catalysts for hydrogen energy production is a vital element in the societal pursuit of sustainable energy. Water electrolysis is one of the most convenient processes to produce high purity hydrogen. Cobalt-based catalysts are well-known electrocatalysts for oxygen evolution reaction（OER）. In this article, all these merits indicate that the present cobalt nanocomposite is a promising electrocatalyst for OER. C–CoO-nanorods catalyst with nanorod structure was synthesized by hydrothermal treatment of CoCl·6HO/dextrose/urea mixture at 180 °C for 18 h and then calcined at400 °C for 3.5 h. The role of dextrose percentage in solution to achieve the uniform coating of carbon on the surface of CoO-nanorods has been demonstrated. The prepared materials were characterized by X-ray diffraction（XRD）, X-ray photoelectron spectrum（XPS）, field emission scanning electron microscopy（FE-SEM）, high-resolution transmission electron microscopy（HR-TEM）, and Brunauer–Emmett–Teller instrument（BET）. Due to its unique morphology, the C–CoO-nanorods catalyst exhibited better activity than CoO-microplates catalyst for OER in 1 M KOH aqueous solution. The results showed a highly efficient, scalable, and low-cost method for developing highly active and stable OER electrocatalysts in alkaline solution.
