Study On Fabrication And Electrocatalytic Properties Of Ternary Alloy Supported Carbon-based Catalyst

Driven by the rapid depletion of petroleum resources and increasing global warming issues,there is a growing necessity for developing highly efficient and sustainable alternative energy-storage and conversion technologies.Fuel cell,as an electrochemical device for direct conversion the chemical energy of fuel and oxidant into electric energy,due to the high efficiency,no environmental pollution,and unlimited sources of reactants,It is expected to come into widespread commercial use in the areas of transportation,portable electronic products,and communications equipment.Currently,platinum and its alloys are well-known oxygen reduction reaction electrocatalysts,efficient oxygen evolution reaction catalysts are iridium and ruthenium oxide.However,the high cost and scarcity of these metals severely limits their development.Therefore,from a long-term perspective,reducing noble metal loading and developing non-noble metal catalysts is very important.Based on the above analysis,in this dissertation,we carry out the two following works,focusing on the preparation of efficient and stable oxygen reduction catalyst with low-platium content and non-noble metal oxygen evolution catalyst.(1)Twin-like ternary PtCoFe alloy in nitrogen-doped graphene nanopores composite material has been prepared by hydrothermal and calcination method using platinum phthalocyanine(PtPc),iron phthalocyanine(FePc),and cobalt phthalocyanine(CoPc)as precursors.These metal Pc provided abundant nitrogen sources and facilitated carbon supports doped with nitrogen during calcination.The results showed that most PtFeCo alloy nanoparticles are uniformly confined in graphene nanopores.This composite markedly decreases Pt usage,the mass activity of PtCoFe/NPG 700 exhibits 7.6 times higher than that of commercial 20% Pt/C catalyst in alkaline solution,and the electrochemical durability of PtCoFe/NPG exhibits slow decay with high current retention of 94.6% after 2000 potential cycles.The improved ORR catalytic activity of the PtCoFe/NPG could be attributed to the synergy and strong electronic interaction between twin-like PtCoFe alloy and graphene nanopores,in addition,the large surface area and the formation of particular N-M bonds positively affected its ORR activity.(2)An nikel-cobalt nanorod compsite as precursor were synthesized by hydrothermal method,and then it was used as the precursor to synthetize an molybdenum-doped carbon-coated nickel-cobalt nanowire composite(Mo-NiCo@C)by coating with dopamine,doping molybdenum and followed by calcination.It has better OER activity and durability by comparing with carbon-coated nickel-cobalt nanorod composite,which without doping molybdenum.The electrochemical test results show that the doping of molybdenum can significantly improve the catalytic activity of catalytic materials.Preliminary judgment of the reasons: first,the metal dopant can enlarge the specific surface,the second is new active sites formed due to metal doping.As the work is still in progress,so the appropriate amount of molybdenum doping and the specific reasons for the improved catalytic performance need to be further verified.