Rational reconstruction of oxygen evolution reaction(OER)precatalysts and performance index of OER catalysts are crucial but still challenging for universal water electrolysis.Herein,we develop a double-cation etching...Rational reconstruction of oxygen evolution reaction(OER)precatalysts and performance index of OER catalysts are crucial but still challenging for universal water electrolysis.Herein,we develop a double-cation etching strategy to tailor the electronic structure of NiMoO_(4),where the prepared NiMoO_(4) nanorods etched by H_(2)O_(2) reconstruct their surface with abundant cation deficiencies and lattice distortion.Calculation results reveal that the double cation deficiencies can make the upshift of d-band center for Ni atoms and the active sites with better oxygen adsorption capacity.As a result,the optimized sample(NMO-30M)possesses an overpotential of 260 mV at 10 mA cm−2 and excellent long-term durability of 162 h.Importantly,in situ Raman test reveals the rapid formation of high-oxidation-state transition metal hydroxide species,which can further help to improve the catalytic activity of NiMoO_(4) in OER.This work highlights the influence of surface remodification and shed some light on activating catalysts.展开更多
Field-assisted electrocatalytic reactions are demonstrated to be sufficient strategies in enhancing the electrocatalyst activities for oxygen evolution reaction(OER).Here,we report the in-situ magnetic field enhanced ...Field-assisted electrocatalytic reactions are demonstrated to be sufficient strategies in enhancing the electrocatalyst activities for oxygen evolution reaction(OER).Here,we report the in-situ magnetic field enhanced electrocatalytic activity in ferromagnetic FeCo_(2)O_(4)nanofibers.Our results demonstrate that the overpotential of FeCo_(2)O_(4)nanofibers at 10 mA cm^(-2)shows a left-shift of 40 mV for the OER by applying an external magnetic field,and no obvious change has been observed in the non-ferromagnetic-order Co3O4nanofibers.Calculation results indicate that there are more overlaps between the density of states for Co3d and O 2p by applying an external magnetic field.Accordingly,the spin hybridization of 3d-2p and the kinetics of spin charge transfer are optimized in ferromagnetic FeCo_(2)O_(4),which can promote the adsorption of oxygen-intermediates and electron transfer,significantly improving its electrocatalytic efficiency.What’s more,the maximum power density of the FeCo_(2)O_(4)nanofibers based Zn-air battery(ZAB)increases from 97.3 mW cm^(-2)to 108.2 mW cm^(-2)by applying an external magnetic field,providing a new idea for the application of magnetic cathode electrocatalysts in ZABs.展开更多
The development of e cient earth-abundant electrocatalysts for oxygen reduction, oxygen evolution, and hydrogen evolution reactions(ORR, OER, and HER) is important for future energy conversion and energy storage devic...The development of e cient earth-abundant electrocatalysts for oxygen reduction, oxygen evolution, and hydrogen evolution reactions(ORR, OER, and HER) is important for future energy conversion and energy storage devices, for which both rechargeable Zn–air batteries and water splitting have raised great expectations. Herein, we report a single-phase bimetallic nickel cobalt sulfide((Ni,Co)S_2) as an e cient electrocatalyst for both OER and ORR. Owing to the synergistic combination of Ni and Co, the(Ni,Co)S_2 exhibits superior electrocatalytic performance for ORR, OER, and HER in an alkaline electrolyte, and the first principle calculation results indicate that the reaction of an adsorbed O atom with a H_2O molecule to form a *OOH is the potential limiting step in the OER. Importantly, it could be utilized as an advanced air electrode material in Zn–air batteries, which shows an enhanced charge–discharge performance(charging voltage of 1.71 V and discharge voltage of 1.26 V at 2 mA cm^(-2)), large specific capacity(842 mAh g_(Zn)^(-1) at 5 mA cm^(-2)), and excellent cycling stability(480 h). Interestingly, the(Ni,Co)S_2-based Zn–air battery can e ciently power an electrochemical water-splitting unit with(Ni,Co)S_2 serving as both the electrodes. This reveals that the prepared(Ni,Co)S_2 has promising applications in future energy conversion and energy storage devices.展开更多
One approach to accelerate the stagnant kinetics of both the oxygen reduction and evolution reactions(ORR/OER)is to develop a rationally designed multiphase nanocomposite,where the functions arising from each of the c...One approach to accelerate the stagnant kinetics of both the oxygen reduction and evolution reactions(ORR/OER)is to develop a rationally designed multiphase nanocomposite,where the functions arising from each of the constituent phases,their interfaces,and the overall structure are properly controlled.Herein,we successfully synthesized an oxygen electrocatalyst consisting of Ni nanoparticles purposely interpenetrated into mesoporous NiO nanosheets(porous Ni/NiO).Benefiting from the contributions of the Ni and NiO phases,the well-established pore channels for charge transport at the interface between the phases,and the enhanced conductivity due to oxygen-deficiency at the pore edges,the porous Ni/NiO nanosheets show a potential of 1.49 V(10 mA cm^-2)for the OER and a half-wave potential of 0.76 V for the ORR,outperforming their noble metal counterparts.More significantly,a Zn-air battery employing the porous Ni/NiO nanosheets exhibits an initial charging-discharging voltage gap of 0.83 V(2 mA cm^-2),specific capacity of 853 mAh gZn^-1 at 20 mA cm^-2,and long-time cycling stability(120 h).In addition,the porous Ni/NiO-based solid-like Zn-air battery shows excellent electrochemical performance and flexibility,illustrating its great potential as a next-generation rechargeable power source for flexible electronics.展开更多
A Zn-air battery is a potential next-generation energy storage device owing to its extremely high theoretical energy density. Currently, it is important to explore non-precious metal electrocatalysts with high electro...A Zn-air battery is a potential next-generation energy storage device owing to its extremely high theoretical energy density. Currently, it is important to explore non-precious metal electrocatalysts with high electroactivity and stability in the oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) for the development of Zn-air batteries. In this work, porous(Ni,Co)Se2 nanosheets were synthesized by selenizing Ni Co2O4 nanosheets. By regulating the conductivity and morphology of the sample, the prepared porous(Ni,Co)Se2 nanosheets show enhanced electrocatalytic activity for OER and ORR compared to Ni Co2O4 nanosheets. The aqueous Zn-air battery using porous(Ni,Co)Se2 nanosheets as the air cathode exhibits superior charge and discharge performance(1.98 V for charging and 1.17 V for discharging), high specific capacity(770 m Ah/g), and excellent cycle stability(140 h). These results indicate that the porous(Ni,Co)Se2 nanosheets are suitable as a bifunctional electrocatalyst for future Zn-air batteries.展开更多
基金supported by the National Natural Science Foundation of China(No.12004146)Natural Science Foundation of Gansu Province,China(Nos.20JR5RA303 and 20JR10RA648)the Fundamental Research Funds for the Central Universities(No.LZUMMM2022007).
文摘Rational reconstruction of oxygen evolution reaction(OER)precatalysts and performance index of OER catalysts are crucial but still challenging for universal water electrolysis.Herein,we develop a double-cation etching strategy to tailor the electronic structure of NiMoO_(4),where the prepared NiMoO_(4) nanorods etched by H_(2)O_(2) reconstruct their surface with abundant cation deficiencies and lattice distortion.Calculation results reveal that the double cation deficiencies can make the upshift of d-band center for Ni atoms and the active sites with better oxygen adsorption capacity.As a result,the optimized sample(NMO-30M)possesses an overpotential of 260 mV at 10 mA cm−2 and excellent long-term durability of 162 h.Importantly,in situ Raman test reveals the rapid formation of high-oxidation-state transition metal hydroxide species,which can further help to improve the catalytic activity of NiMoO_(4) in OER.This work highlights the influence of surface remodification and shed some light on activating catalysts.
基金financially supported by the Natural Science Foundation(NSF) of China(91963201 and 12174163)the Creation of Science and Technology of Northwest Normal University,China(NWNU-LKQN2020-22)。
文摘Field-assisted electrocatalytic reactions are demonstrated to be sufficient strategies in enhancing the electrocatalyst activities for oxygen evolution reaction(OER).Here,we report the in-situ magnetic field enhanced electrocatalytic activity in ferromagnetic FeCo_(2)O_(4)nanofibers.Our results demonstrate that the overpotential of FeCo_(2)O_(4)nanofibers at 10 mA cm^(-2)shows a left-shift of 40 mV for the OER by applying an external magnetic field,and no obvious change has been observed in the non-ferromagnetic-order Co3O4nanofibers.Calculation results indicate that there are more overlaps between the density of states for Co3d and O 2p by applying an external magnetic field.Accordingly,the spin hybridization of 3d-2p and the kinetics of spin charge transfer are optimized in ferromagnetic FeCo_(2)O_(4),which can promote the adsorption of oxygen-intermediates and electron transfer,significantly improving its electrocatalytic efficiency.What’s more,the maximum power density of the FeCo_(2)O_(4)nanofibers based Zn-air battery(ZAB)increases from 97.3 mW cm^(-2)to 108.2 mW cm^(-2)by applying an external magnetic field,providing a new idea for the application of magnetic cathode electrocatalysts in ZABs.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11474137 and 11674143)Program for Changjiang Scholars and Innovative Research Team in University (IRT 16R35)+1 种基金the Fundamental Research Funds for the Central Universities (Grant Nos. LZUMMM2018017, lzujbky-2018-121)the support of Ministry of Education (MOE2016-T2-2-138,Singapore),for research conducted at the National University of Singapore
文摘The development of e cient earth-abundant electrocatalysts for oxygen reduction, oxygen evolution, and hydrogen evolution reactions(ORR, OER, and HER) is important for future energy conversion and energy storage devices, for which both rechargeable Zn–air batteries and water splitting have raised great expectations. Herein, we report a single-phase bimetallic nickel cobalt sulfide((Ni,Co)S_2) as an e cient electrocatalyst for both OER and ORR. Owing to the synergistic combination of Ni and Co, the(Ni,Co)S_2 exhibits superior electrocatalytic performance for ORR, OER, and HER in an alkaline electrolyte, and the first principle calculation results indicate that the reaction of an adsorbed O atom with a H_2O molecule to form a *OOH is the potential limiting step in the OER. Importantly, it could be utilized as an advanced air electrode material in Zn–air batteries, which shows an enhanced charge–discharge performance(charging voltage of 1.71 V and discharge voltage of 1.26 V at 2 mA cm^(-2)), large specific capacity(842 mAh g_(Zn)^(-1) at 5 mA cm^(-2)), and excellent cycling stability(480 h). Interestingly, the(Ni,Co)S_2-based Zn–air battery can e ciently power an electrochemical water-splitting unit with(Ni,Co)S_2 serving as both the electrodes. This reveals that the prepared(Ni,Co)S_2 has promising applications in future energy conversion and energy storage devices.
基金the National Natural Science Foundation of China(Grant Nos.11474137,11674143)the Fundamental Research Funds for the Central Universities(Grant No.Lzujbky-2019-cd02).
文摘One approach to accelerate the stagnant kinetics of both the oxygen reduction and evolution reactions(ORR/OER)is to develop a rationally designed multiphase nanocomposite,where the functions arising from each of the constituent phases,their interfaces,and the overall structure are properly controlled.Herein,we successfully synthesized an oxygen electrocatalyst consisting of Ni nanoparticles purposely interpenetrated into mesoporous NiO nanosheets(porous Ni/NiO).Benefiting from the contributions of the Ni and NiO phases,the well-established pore channels for charge transport at the interface between the phases,and the enhanced conductivity due to oxygen-deficiency at the pore edges,the porous Ni/NiO nanosheets show a potential of 1.49 V(10 mA cm^-2)for the OER and a half-wave potential of 0.76 V for the ORR,outperforming their noble metal counterparts.More significantly,a Zn-air battery employing the porous Ni/NiO nanosheets exhibits an initial charging-discharging voltage gap of 0.83 V(2 mA cm^-2),specific capacity of 853 mAh gZn^-1 at 20 mA cm^-2,and long-time cycling stability(120 h).In addition,the porous Ni/NiO-based solid-like Zn-air battery shows excellent electrochemical performance and flexibility,illustrating its great potential as a next-generation rechargeable power source for flexible electronics.
基金supported by the National Natural Science Foundation of China (Grant nos.11474137)the Fundamental Research Funds for the Central Universities (Grant nos.LZUMMM2018017,lzujbky-2018-121)+1 种基金Key Research and Development Plan of Gansu Province (No.18YF1GA088)Scientific research project of colleges and universities in gansu province (No.2018A-205)
文摘A Zn-air battery is a potential next-generation energy storage device owing to its extremely high theoretical energy density. Currently, it is important to explore non-precious metal electrocatalysts with high electroactivity and stability in the oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) for the development of Zn-air batteries. In this work, porous(Ni,Co)Se2 nanosheets were synthesized by selenizing Ni Co2O4 nanosheets. By regulating the conductivity and morphology of the sample, the prepared porous(Ni,Co)Se2 nanosheets show enhanced electrocatalytic activity for OER and ORR compared to Ni Co2O4 nanosheets. The aqueous Zn-air battery using porous(Ni,Co)Se2 nanosheets as the air cathode exhibits superior charge and discharge performance(1.98 V for charging and 1.17 V for discharging), high specific capacity(770 m Ah/g), and excellent cycle stability(140 h). These results indicate that the porous(Ni,Co)Se2 nanosheets are suitable as a bifunctional electrocatalyst for future Zn-air batteries.
基金This work is supported by the National Natural Science Foundation of China (Nos. 11474137 and 11674143), and Program for Changjiang Scholars and Innovative Research Team in University (IRT 16R35). J. W. thanks for the support of MOE (MOE2016-T2-2-138) for research conducted at the National University of Singapore.