The exploration of cheap,efficient,and durable bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is highly desired to push forward the commercialization of rechargeable ...The exploration of cheap,efficient,and durable bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is highly desired to push forward the commercialization of rechargeable metal–air batteries.Here,bifunctional ORR/OER electrocatalysts based on CoxP(0<x<2,i.e.,Co_(2)P,Co_(2)P/CoP mixture,and CoP)nanoparticles(NPs)anchored on N,P-doped carbon framework(Co_(x)P@NPC)are developed via one-step carbonization of the mixture of as-synthesized ZIF-67 and melamine–phytic acid supermolecular aggregate(MPSA).The stoichiometric ratio of resultant Co_(x)P NPs can be rationally designed by adjusting the introduced ratio of ZIF-67 to MPSA,enabling their fabrication in a controlled manner.It is found that the as-synthesized Co_(2)P@NPC exhibits the best bifunctional ORR/OER activity among the Co_(x)P@NPC analogues,with a reversible oxygen electrode index(ΔE=E_(j10)−E_(1/2))down to~0.75 V.The constructed Zn–air battery based on Co_(2)P@NPC delivers a peak power density of 157 mW cm^(−2) and an excellent charge-discharge stability with negligible voltage decay for 140 h at 10 mA cm^(−2),superior to those based on Pt/C+RuO_(2) and most Co_(x)P-based electrodes ever reported.展开更多
The efficient energy conversion of fuel cells is greatly constrained by the slow oxygen reduction reac tion(ORR)kinetics,which necessitates the use of highly active metal catalysts such as platinum(Pt).The critical ch...The efficient energy conversion of fuel cells is greatly constrained by the slow oxygen reduction reac tion(ORR)kinetics,which necessitates the use of highly active metal catalysts such as platinum(Pt).The critical challenge limiting large-scale usage of Pt is the capital cost that can be addressed through a pro totypical approach by embedding metal nanoparticles(NPs),e.g.,Pt NPs,in the conductive framework However,previously reported embedding approaches are sophisticated and suffer from limited yields leading to higher chemical process costs and remaining distant from commercial viability.Here,we re port a facile,cost-effective and time-efficient structural tuning approach to synthesizing ultrafine Pt NP impregnated within a conductive and highly porous carbon framework via a microwave-assisted polyo reduction method.Pt NPs with a uniform size of~2.27 nm can be successfully integrated within the pore of the carbon framework,enabling homogeneous dispersion.Benefiting from these highly dispersed and ultrafine Pt NPs,the electrochemical surface area(ECSA)is improved to 142.98 m^(2)/gPt,2.25 times highe than that of the commercial counterpart(63.52 m^(2)/gPt).Furthermore,our structurally optimized catalys composite features a remarkably catalytic activity with a high half-wave potential(E_(1/2))of 0.895 V and an improved mass activity(MA)of 0.2289 A/mgPt,2.39-fold improvement compared to the commercia counterpart.In addition,orthogonal experiments were designed to identify the key process parameter for fabricating Pt/C catalysts,offering insights for scaled-up and industrial production.展开更多
Comprehensive Summary Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))from air and water presents a sustainable and efficient alternative to the traditional anthraquinone method.Therefore,the design and synth...Comprehensive Summary Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))from air and water presents a sustainable and efficient alternative to the traditional anthraquinone method.Therefore,the design and synthesis of efficient photocatalysts for H_(2)O_(2) production are important.In this work,we apply a nitrogen-site engineering strategy to achieve high-performance photocatalysts by synthesizing three imine-linked oligo(phenylenevinylene)-based covalent organic frameworks(OPV-COFs)doped with different numbers of nitrogen atoms(denoted as COF-920-nN,n=0,1,3).Comprehensive characterization confirmed the high crystallinity and porosity of the COFs,critical for efficient photocatalysis.Each OPV-COF exhibited the ability to rapidly synthesize H_(2)O_(2) using air and water,with COF-920-1N achieving the highest rate of 4288μmol·g^(–1)·h^(–1) under visible light,higher than those of most of other reported COFs.Mechanism studies demonstrated that the introduction of pyridine nitrogen atoms at the junction changes the electronic structure and electron transfer path within the COFs,enhancing the photogenerated electron mobility and reducing the rate of electron-hole recombination.This study not only pioneers the class of OPV-COFs for photocatalytic synthesis of H2O2,but also sets a foundational strategy for the rational design of COFs in photocatalytic applications.展开更多
Although the oxygen reduction process to hydrogen peroxide(H_(2)O_(2))is a green option for H_(2)O_(2)generation,the low activity and selectivity hindered the industry's process.In recent years,the electrochemical...Although the oxygen reduction process to hydrogen peroxide(H_(2)O_(2))is a green option for H_(2)O_(2)generation,the low activity and selectivity hindered the industry's process.In recent years,the electrochemical synthesis of H_(2)O_(2)through a 2e-transfer method of oxygen reduction reaction(ORR)has piqued the interest of both academics and industry.Metal oxide catalysts have emerged as a novel family of electrochemical catalysts due to their unusual physical,chemical,and electrical characteristics.In this work,we first developed a Ruddlesden-Popper perovskite oxide(Pr_(2)NiO_(4+δ))as a highly selective and active catalyst for 2e-ORR to produce H_(2)O_(2).Molybdenum was introduced here to adjust the oxidation states of these transition metals with successful substitution into Ni-site to prepare Pr_(2)Ni1-xMoxO_(4+δ),and the molybdenum substitution improves the H_(2)O_(2)selectivity during the ORR process,in 0.1 M KOH,from 60%of Pr_(2)NiO_(4+δ)to 79%of Pr_(2)Ni_(0.8)Mo_(0.2)O_(4+δ)at 0.55 V versus RHE.A limiting H_(2)O_(2)concentration of_0.24 mM for Pr_(2)NiO_(4+δ)and 0.42 mM for Pr_(2)Ni_(0.8)Mo_(0.2)O_(4+δ)was obtained at a constant current of 10 mA/cm2 using a flow-cell reactor using a gas-diffusion electrode.展开更多
基金supported by National Natural Science Foundation of China(NSFC,Grant Nos.51702176,51572133,and 51972178)Zhejiang Provincial Nature Science Foundation(Grant No.LY20E020009)。
文摘The exploration of cheap,efficient,and durable bifunctional electrocatalysts for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is highly desired to push forward the commercialization of rechargeable metal–air batteries.Here,bifunctional ORR/OER electrocatalysts based on CoxP(0<x<2,i.e.,Co_(2)P,Co_(2)P/CoP mixture,and CoP)nanoparticles(NPs)anchored on N,P-doped carbon framework(Co_(x)P@NPC)are developed via one-step carbonization of the mixture of as-synthesized ZIF-67 and melamine–phytic acid supermolecular aggregate(MPSA).The stoichiometric ratio of resultant Co_(x)P NPs can be rationally designed by adjusting the introduced ratio of ZIF-67 to MPSA,enabling their fabrication in a controlled manner.It is found that the as-synthesized Co_(2)P@NPC exhibits the best bifunctional ORR/OER activity among the Co_(x)P@NPC analogues,with a reversible oxygen electrode index(ΔE=E_(j10)−E_(1/2))down to~0.75 V.The constructed Zn–air battery based on Co_(2)P@NPC delivers a peak power density of 157 mW cm^(−2) and an excellent charge-discharge stability with negligible voltage decay for 140 h at 10 mA cm^(−2),superior to those based on Pt/C+RuO_(2) and most Co_(x)P-based electrodes ever reported.
基金the support from Warwick Manufacturing Group at the University of WarwickCITIC Dameng Mining Industries Limited-Guangxi University Joint Research Institute of Manganese Resources Utilization and Advanced Materials Technology+4 种基金Guangxi University-CITIC Dameng Mining Industries Limited Joint base of Postgraduate CultivationState Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite StructuresNational Natural Science Foundation of China(Nos.11364003 and 52102470)Guangxi Innovation Driven Development Project(Nos.AA17204100 and AA18118052)the Natural Science Foundation of Guangxi Province(No.2018GXNSFAA138186)。
文摘The efficient energy conversion of fuel cells is greatly constrained by the slow oxygen reduction reac tion(ORR)kinetics,which necessitates the use of highly active metal catalysts such as platinum(Pt).The critical challenge limiting large-scale usage of Pt is the capital cost that can be addressed through a pro totypical approach by embedding metal nanoparticles(NPs),e.g.,Pt NPs,in the conductive framework However,previously reported embedding approaches are sophisticated and suffer from limited yields leading to higher chemical process costs and remaining distant from commercial viability.Here,we re port a facile,cost-effective and time-efficient structural tuning approach to synthesizing ultrafine Pt NP impregnated within a conductive and highly porous carbon framework via a microwave-assisted polyo reduction method.Pt NPs with a uniform size of~2.27 nm can be successfully integrated within the pore of the carbon framework,enabling homogeneous dispersion.Benefiting from these highly dispersed and ultrafine Pt NPs,the electrochemical surface area(ECSA)is improved to 142.98 m^(2)/gPt,2.25 times highe than that of the commercial counterpart(63.52 m^(2)/gPt).Furthermore,our structurally optimized catalys composite features a remarkably catalytic activity with a high half-wave potential(E_(1/2))of 0.895 V and an improved mass activity(MA)of 0.2289 A/mgPt,2.39-fold improvement compared to the commercia counterpart.In addition,orthogonal experiments were designed to identify the key process parameter for fabricating Pt/C catalysts,offering insights for scaled-up and industrial production.
基金support by the National Natural Science Foundation of China(52473217,52273211)the Sichuan Science and Technology Program(2023NSFSc0085)the Fundamental Research Funds for the Central Universities.
文摘Comprehensive Summary Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))from air and water presents a sustainable and efficient alternative to the traditional anthraquinone method.Therefore,the design and synthesis of efficient photocatalysts for H_(2)O_(2) production are important.In this work,we apply a nitrogen-site engineering strategy to achieve high-performance photocatalysts by synthesizing three imine-linked oligo(phenylenevinylene)-based covalent organic frameworks(OPV-COFs)doped with different numbers of nitrogen atoms(denoted as COF-920-nN,n=0,1,3).Comprehensive characterization confirmed the high crystallinity and porosity of the COFs,critical for efficient photocatalysis.Each OPV-COF exhibited the ability to rapidly synthesize H_(2)O_(2) using air and water,with COF-920-1N achieving the highest rate of 4288μmol·g^(–1)·h^(–1) under visible light,higher than those of most of other reported COFs.Mechanism studies demonstrated that the introduction of pyridine nitrogen atoms at the junction changes the electronic structure and electron transfer path within the COFs,enhancing the photogenerated electron mobility and reducing the rate of electron-hole recombination.This study not only pioneers the class of OPV-COFs for photocatalytic synthesis of H2O2,but also sets a foundational strategy for the rational design of COFs in photocatalytic applications.
基金The authors are grateful for the FWO(12ZV320N)and NNSF(22005250).O.M.M.thanks CONACYT-Mexico.K.W.is grateful to Guangzhou Elite Project.W.Z.,W.G,S.X.,and Q.L.are grateful to CSC.
文摘Although the oxygen reduction process to hydrogen peroxide(H_(2)O_(2))is a green option for H_(2)O_(2)generation,the low activity and selectivity hindered the industry's process.In recent years,the electrochemical synthesis of H_(2)O_(2)through a 2e-transfer method of oxygen reduction reaction(ORR)has piqued the interest of both academics and industry.Metal oxide catalysts have emerged as a novel family of electrochemical catalysts due to their unusual physical,chemical,and electrical characteristics.In this work,we first developed a Ruddlesden-Popper perovskite oxide(Pr_(2)NiO_(4+δ))as a highly selective and active catalyst for 2e-ORR to produce H_(2)O_(2).Molybdenum was introduced here to adjust the oxidation states of these transition metals with successful substitution into Ni-site to prepare Pr_(2)Ni1-xMoxO_(4+δ),and the molybdenum substitution improves the H_(2)O_(2)selectivity during the ORR process,in 0.1 M KOH,from 60%of Pr_(2)NiO_(4+δ)to 79%of Pr_(2)Ni_(0.8)Mo_(0.2)O_(4+δ)at 0.55 V versus RHE.A limiting H_(2)O_(2)concentration of_0.24 mM for Pr_(2)NiO_(4+δ)and 0.42 mM for Pr_(2)Ni_(0.8)Mo_(0.2)O_(4+δ)was obtained at a constant current of 10 mA/cm2 using a flow-cell reactor using a gas-diffusion electrode.
