Developing highly effective and stable non-noble metalbased bifunctional catalyst working at high current density is an urgent issue for water electrolysis(WE).Herein,we prepare the N-doped graphene-decorated NiCo all...Developing highly effective and stable non-noble metalbased bifunctional catalyst working at high current density is an urgent issue for water electrolysis(WE).Herein,we prepare the N-doped graphene-decorated NiCo alloy coupled with mesoporous NiCoMoO nano-sheet grown on 3D nickel foam(NiCo@C-NiCoMoO/NF)for water splitting.NiCo@C-NiCoMoO/NF exhibits outstanding activity with low overpotentials for hydrogen and oxygen evolution reaction(HER:39/266 mV;OER:260/390 mV)at±10 and±1000 mA cm^(−2).More importantly,in 6.0 M KOH solution at 60℃ for WE,it only requires 1.90 V to reach 1000 mA cm−2 and shows excellent stability for 43 h,exhibiting the potential for actual application.The good performance can be assigned to N-doped graphene-decorated NiCo alloy and mesoporous NiCoMoO nano-sheet,which not only increase the intrinsic activity and expose abundant catalytic activity sites,but also enhance its chemical and mechanical stability.This work thus could provide a promising material for industrial hydrogen production.展开更多
Oxygen evolution reaction(OER)is the key step involved both in water splitting devices and rechargeable metal-air batteries,and hence,there is an urgent need for a stable and low-cost material for efficient OER.In the...Oxygen evolution reaction(OER)is the key step involved both in water splitting devices and rechargeable metal-air batteries,and hence,there is an urgent need for a stable and low-cost material for efficient OER.In the present investigation,Co-Fe-Ga-NiZn(CFGNZ)high entropy alloy(HEA)has been utilized as a low-cost electrocatalyst for OER.Herein,after cyclic voltammetry activation,CFGNZ-nanoparticles(NPs)are covered with oxidized surface and form high entropy(oxy)hydroxides(HEOs),exhibiting a low overpotential of 370 mV to achieve a current density of 10 mA/cm^(2)with a small Tafel slope of 71 mV/dec.CFGNZ alloy has higher electrochemical stability in comparison to state-of-the art RuO2 electrocatalyst as no degradation has been observed up to 10 h of chronoamperometry.Transmission electron microscopy(TEM)studies after 10 h of long-term chronoamperometry test showed no change in the crystal structure,which confirmed the high stability of CFGNZ.The density functional theory(DFT)based calculations show that the closeness of d(p)-band centers to the Fermi level(EF)plays a major role in determining active sites.This work highlights the tremendous potential of CFGNZ HEA for OER,which is the primary reaction involved in water splitting.展开更多
基金supported by the National Natural Science Foundation of China(21872040)the Hundred Talents Program of Guangxi Universitiesthe Excellent Scholars and Innovation Team of Guangxi Universities。
文摘Developing highly effective and stable non-noble metalbased bifunctional catalyst working at high current density is an urgent issue for water electrolysis(WE).Herein,we prepare the N-doped graphene-decorated NiCo alloy coupled with mesoporous NiCoMoO nano-sheet grown on 3D nickel foam(NiCo@C-NiCoMoO/NF)for water splitting.NiCo@C-NiCoMoO/NF exhibits outstanding activity with low overpotentials for hydrogen and oxygen evolution reaction(HER:39/266 mV;OER:260/390 mV)at±10 and±1000 mA cm^(−2).More importantly,in 6.0 M KOH solution at 60℃ for WE,it only requires 1.90 V to reach 1000 mA cm−2 and shows excellent stability for 43 h,exhibiting the potential for actual application.The good performance can be assigned to N-doped graphene-decorated NiCo alloy and mesoporous NiCoMoO nano-sheet,which not only increase the intrinsic activity and expose abundant catalytic activity sites,but also enhance its chemical and mechanical stability.This work thus could provide a promising material for industrial hydrogen production.
基金the Institute of Eminence(IoE)MHRD grant of the Indian Institute of Science.N.K.K.acknowledges the Newton Fellowship award from the Royal Society UK(NIF\R1\191571)the core research grant and Ramanujan Fellowship.C.S.T.acknowledges AOARD grant no.FA2386-19-1-4039.
文摘Oxygen evolution reaction(OER)is the key step involved both in water splitting devices and rechargeable metal-air batteries,and hence,there is an urgent need for a stable and low-cost material for efficient OER.In the present investigation,Co-Fe-Ga-NiZn(CFGNZ)high entropy alloy(HEA)has been utilized as a low-cost electrocatalyst for OER.Herein,after cyclic voltammetry activation,CFGNZ-nanoparticles(NPs)are covered with oxidized surface and form high entropy(oxy)hydroxides(HEOs),exhibiting a low overpotential of 370 mV to achieve a current density of 10 mA/cm^(2)with a small Tafel slope of 71 mV/dec.CFGNZ alloy has higher electrochemical stability in comparison to state-of-the art RuO2 electrocatalyst as no degradation has been observed up to 10 h of chronoamperometry.Transmission electron microscopy(TEM)studies after 10 h of long-term chronoamperometry test showed no change in the crystal structure,which confirmed the high stability of CFGNZ.The density functional theory(DFT)based calculations show that the closeness of d(p)-band centers to the Fermi level(EF)plays a major role in determining active sites.This work highlights the tremendous potential of CFGNZ HEA for OER,which is the primary reaction involved in water splitting.
