Synthesis Of (Pt,Pd) CoNi Trimetallic Electrocatalyst And Application In Alcohol Oxidation And Hydrogen Evolution Reaction

The development of clean,high-efficiency,low-pollution new energy is one of the means to solve the energy shortage and ease the pressure on the environment.Direct alcohol fuel cells can be used as portable mobile power sources for new energy vehicles,aviation,etc.Due to their fast start-up,high efficiency and mild working conditions.Hydrogen energy has received a lot of attention due to its zero pollution,wide sources,and easy transportation.Hydrogen production by electrolysis of water is one of the most environmentally friendly and efficient methods of hydrogen production,so it is favored.At present,the catalysts for hydrogen evolution of alcohol fuel cells and electrolyzed water are mainly platinum group precious metal catalysts.Therefore,the development of low-cost precious metal electrocatalysts without sacrificing catalytic performance is a current research focus.For example,the use of precious metal-non-precious metal synergy can solve the above problems.Therefore,this topic mainly focuses on the above problems.Starting from improving the activity and stability of electrocatalysts for the catalytic oxidation of alcohols and electrolysis of water for hydrogen evolution,and for the purpose of reducing the amount of precious metals,we designed and constructed a series of electrocatalysts for the efficient electrocatalytic oxidation of alcohols.PdCoNi/rG,Pt/rGNP for water electrolysis and bifunctional Pt Co Ni/rGNP series electrocatalysts.This paper mainly obtains the following research results:1.PdCoNi/rG（PdCo/rG,PdNi/rG,Co Ni/rG,Pd/rG,Co/rG and Ni/rG）for efficient electrocatalytic oxidation of methanol and ethanol under alkaline conditions were synthesized by Na BH₄ reduction and replacement series electrocatalysts,the mass activity of PdCoNi/rG catalyst for methanol oxidation at 1 M KOH is 8.65 A mg _Pd^-1,which are 24.37 times and 43.23 times that of commercial 20 wt%Pt/C,respectively.The mass activity of oxidized ethanol was 19.6 A mg _Pd^-1,which were 81.59 times and 25.71 times that of commercial 20 wt%Pt/C and 25.71 times that of commercial 20 wt%Pd/C,respectively.In addition,the PdCoNi/rG catalyst has high stability and retains high electrocatalytic performance（higher than commercial 20 wt%Pt/C,Pd/C several times）in the chronoamperometry test of 200,000 s in the catalytic oxidation of methanol and ethanol under alkaline conditions,and the electrocatalytic performance of PdCoNi/rG catalyst is higher than that of PdCo/rG,PdNi/rG,Co Ni/rG,Pd/rG-1,Pd/rG-2,Ni/rG and Co/rG catalyst.Combined with ICP,TEM,XRD,XPS and other characterization techniques and electrochemical test results,it is shown that the synergistic effect of Pd and Co Ni alloy nanoparticles in the PdCoNi/rG catalyst improves the activity and stability of the catalyst in electrocatalytic methanol and ethanol.2.Graphene was doped with N and P to synthesize rGNP catalyst supports,and Pt/rGNPs（rGNP,Ir/rGNP,Ru/rGNP,Co/rGNP,Ni/rGNP）were successfully constructed with precious metal,non-precious metal,supported rGNP in 0.5 M H₂SO₄ electrolysis of water for hydrogen evolution.series electrocatalysts,and realized the preparation of Pt/rGNP catalysts with low loading and low hydrogen evolution overpotential.The Pt/rGNP electrocatalyst exhibitsη₁₀₀=10.6 m V in 0.5 M H₂SO₄,compared withη₁₀₀=66.5 m V for commercial 20 wt%Pt/C.The Tafel slope of the Pt/rGNP electrocatalyst is 14.53 m V dec^-1 smaller than that of commercial 20 wt%Pt/C(21.73 m V dec^-1).And the Pt/rGNP catalyst has lower HER overpotential and Tafel slope than rGNP,Ir/rGNP,Ru/rGNP,Co/rGNP,and Ni/rGNP catalysts under the same conditions.It is shown that the modification of heteroatoms（N,P）can greatly improve the hydrogen evolution performance of M/rGNP catalysts.3.Based on the excellent performance of the above precious metal/non-precious metal/graphene and metal/doped NP graphene catalysts,we designed and synthesized low-cost,high-efficiency and stable Pt Co Ni/rGNP（Pt Co/rGNP,Pt Ni/rGNP,Co Ni/rGNP,Pt/rGNP,Co/rGNP,Ni/rGNP）series electrocatalysts.The effect of the synergistic effect between precious metals and non-precious metals and non-metals on the electrocatalytic methanol oxidation and the hydrogen evolution performance of electrolyzed water was studied,and a low-load bifunctional precious metal catalyst was prepared through a simple synthetic route.The mass activity of Pt Co Ni/rGNP catalyst for methanol oxidation in 1.0 M KOH is 1.31 A mg _Pt^-1,which is 3.74 times that of commercial 20 wt%Pt/C,and its activity remains unchanged in the 4000 s timed discharge test,while the commercial 20 wt%Pt/C decays to 25%of the initial activity.The hydrogen evolution overpotential of Pt Co Ni/rGNP catalyst at 100 m A cm in 0.5 M H₂SO₄ is 51 m V lower than that of commercial 20 wt%Pt/C,only 15 m V.The Tafel slope of Pt Co Ni/rGNP electrocatalyst of 6.46 m V dec^-1 is also smaller than that of commercial 20 wt%Pt/C(17.15 m V dec^-1),and Pt Co Ni/rGNP electrocatalyst also maintains strong stability in 0.5 M H₂SO₄,in the 72 h uninterrupted chronopotential test at 100 m A cm^-2,the overpotential increased by only 13.8 m V,which was still better than that of commercial 20 wt%Pt/C(66 m V@100 m A cm^-2);After 2000 cycles in the hydrogen evolution potential range,the overpotential increases by only 8 m V at 10 m A cm^-2,which is still better than that of commercial 20 wt%Pt/C(20 m V@10 m A cm^-2).And the electrocatalytic methanol oxidation and HER performance of Pt Co Ni/rGNP is better than that of Pt Co/rGNP,Pt Ni/rGNP,Co Ni/rGNP,Pt/rGNP,Co/rGNP and Ni/rGNP catalysts.Combining ICP,TEM,XRD,XPS and other characterization techniques and electrochemical test results,it is shown that the synergistic effect of multimetallic components in the Pt Co Ni/rGNP catalyst plays an important role in promoting the catalyst in alkaline methanol oxidation and acidic hydrogen evolution.