Synthesis Of P-doped Pt/Pd-based And Ni-Fe-S Ultrathin Nanostructures And Their Electrocatalytic Performance

Energy and environmental issues are the major challenges in 21 st century.Therefore,the development of new energy sources and energy conversion technology with clean,highly effective,and sustainable characteristics has become a research hotpot.Nanomaterials as catalysts play a significant role in the field of new energy sources,however,how to improve the catalytic activity and stability as well as simultaneously decrease the cost of electrocatalysts still remains an important scientific problem that needs to be solved.In this thesis,we direct proton exchange membrane fuel cell and oxygen evolution reaction as oriented applications,and aim at developing effective synthetic methods for fabricating ultrathin nanomaterials with controlled morphology,structure and composition,exploring the dependencies between these parameters and the experimental conditions as well as studying structure-dependent electrocatalytic performance.The main works in this thesis are summarized as follows:1.We develop a facile and efficient one-step soft-templateassisted strategy to prepare 3D Pd-P alloy nanoparticle networks(NNs)with sub-10 nm ultrathin nanoparticles as building blocks.The as-prepared Pd-P NNs possess large surface area,abundant active sites and strong structural stability.They are found to exhibit excellent electrocatalytic activity(specific activity and mass activity),stability and antipoisoning ability towards formic acid electrooxidation.2.We report a room-temperature seed-mediated co-reduction strategy to fabricate dendritic Pt-Ni-P alloy nanoparticles(NPs)with ultrathin branches(~ 3 nm)as subunits,in which these nanobranches grow in various directions.The dendritic Pt-Ni-P alloy NPs own an open and porous structure,large surface area and strong structural stability.The dendritic Pt-Ni-P alloy NPs exhibit higher electrocatalytic activity(specific activity and mass activity),stability and antipoisoning ability towards methanol oxidation reaction and formic acid oxidation reaction.3.We demonstrate an electrodeposition method to synthesize amorphous-like Ni-Fe-S ultrathin nanosheets supported on Ti plate,followed by oxygen incorporation and electrochemical tuning as an efficient oxygen evolution reaction(OER)electrocatalysts.The strategy combining the oxygen incorporation with electrochemical tuning can be conducive to increase electric conductivity and modulate electronic structure as well as the active sites.The as-prepared catalyst shows excellent electrochemical activity(large current densities of 500 and 3000 m A cm-2 with low overpotentials of 300 and 435 m V,respectively)and stability,offering new possibilities to meet the industrial demand of highly efficient OER catalysts.