The Design, Preparation And Electrocatalytic Performance Of Pt-based Multi-element Nano-catalysts

Platinum(Pt)nanocrystals have been considered as the most efficient electrocatalysts for fuel cells.Unfortunately,the scarce reserves,high cost and poor stability of Pt nanoparticles that are vulnerable to CO poisoning severely impede the large-scale commercialization and widespread applications of fuel cells.Therefore,it is highly urgent to develop more effective electrocatalysts having a relatively lower Pt content with retained high activity and enhanced poisoning resistance.It has been found that increasing the number of active sites on a given electrode and increasing the intrinsic activity could address these issues.Based on the two strategies,three Pt-based nanomaterials with different morphology and composition have been synthesized in this paper,and the growth mechanism is also investigated by control experiments.Furthermore,the relationship between the morphology and composition of Pt-based electrocatalysts and eclctrocatalytic performance has been investigated as well.The main results are summarized as follows:1.In this work,porous Pd3Pt nanobowls and Pd3Pt nanocages are synthesized by using urea as guiding surfactant.It was proved that urea played a key role in the formation of the porous architecture.And the surface structure and the size of pores could be controlled by the decomposition rate of urea which is affected by the pH value of the reaction environment.When used as an electrocatalyst toward the formic acid oxidation reaction(FAOR),the hollow porous Pd3Pt nanobowls exhibited great electrocatalytic performance and anti-poisoning capability.More specifically,the mass activity of porous Pd3Pt nanobowls is 1.9 and 1.5 times greater than those of commercial Pd black and Pd3Pt nanocages,respectively.And for the porous Pd3Pt nanobowls,the dehydrogenation pathway was dramatically enhanced compared with commercial Pt black,which is manifested by the much higher ratio value between the dehydrogenation path peak and dehydration path peak of porous Pd3Pt nanobowls(1.86)than that of commercial Pt black(0.16).2.In this work,triangular AgAu@Pt core-shell nanoframes with a dendritic Pt shell were synthesized by employing Ag nanoprisms as sacrificial templates due to the unique anisotropic structure.Notably,the gold coating process and the introduction of CTAB are indispensable for the successful generation of triangular AgAu@Pt nanoframes.The thin layer of Au coating not only prevents the AgAu@Pt nanoframes from deformation,but also greatly contributes to the electrocatalytic performance.The CTAB exerts dual functions as an etching agent for removing free Ag and a surfactant for controlling Pt growth.Due to the intriguing hollow framework structure with a dendritic surface and compositional synergy,the well-designed AgAu@Pt nanoframes exhibit excellent electrocatalytic performance toward the methanol oxidation reaction(MOR)with a much lower onset potential,2 times higher activity,and better anti-poisoning capability compared with the commercial Pt/C catalyst.3.In this work,a novel temperature-controllable smart electrocatalyst by binding thermosensitive PNIPAM-NH2 polymers to the external surface of the ultrathin bimetallic CuPt3 wavy nanowires was synthesized by one-pot hydrothermal method.The PNIPAM-NH2 functionalized CuPt3 nanowires exhibited the sharply different electrocatalytic activity toward the methanol oxygen reaction(MOR)in response to temperature changes from below to above low critical solution temperature(Tt=35?),which is attributed to the thermal behavior of PNIPAM-NH2.In addition,owing to the unique structural advantages and bimetallic synergetic effect of the CuPt3 wavy nanowires,the surface "clean" CuPt3 wavy nanowires exhibit 3 times higer activity and better anti-poisoning capability compared with commercial Pt black.