Preparation Of Platinum-based Nanocatalysts And Their Alcohol Oxidation Properties

The energy structure of our country is mainly dominated by traditional fossil fuels.The non-renewable characteristics of fossil fuels and the pollution caused by combustion will lead to increasingly serious energy crisis and environmental pollution.Therefore,vigorously developing direct alcohol fuel cells(DAFCs)are one of the most competitive solutions.This is because DAFCs are a device that can directly convert chemical energy into electrical energy.Their high energy conversion rate can significantly improve fuel utilization efficiency and reduce CO₂ emissions.However,the slow anodic reaction kinetics of DAFCs hinders their commercial development.Therefore,this paper intends to synthesize Pt-based catalyst with a highly catalytic activity and a long-term stability for the alcohol oxidation reaction.Firstly,Pt_x/PVA catalysts were synthesized by one-step hydrothermal method with the assistance of polyvinyl alcohol(PVA)as a green reducing agent,structure guiding agent,dispersing agent,and binder.And then the structure characterization and electrochemical performance test of Pt_x/PVA catalysts were carried out.The structural characterization results show that Pt_1.2/PVA catalyst has the smallest average particle size of Pt NPs(4.97 nm),which can provide a highly active surface area(30.9 m² g^-1)and a large number of active sites.Also,the electrochemical test results show that the mass activity of Pt_1.2/PVA catalyst for methanol oxidation is 2.6 times higher than that of commercial Pt/C catalyst.In addition,the electrocatalytic activities of Pt_1.2/PVA catalyst for ethanol oxidation,ethylene glycol oxidation and glycerol oxidation are also much higher than that of commercial Pt/C catalyst.Then chain-like Pt_xPd_y/PVA catalysts were synthesized by two-step hydrothermal method with the assistance of polyvinyl alcohol as a green reducing agent,structure guiding agent,dispersing agent,and binder.And then the structure characterization and electrochemical performance test of Pt_xPd_y/PVA catalysts were carried out.The structural characterization results show that Pt₁Pd₅/PVA catalyst has a unique chain structure.Also,the electrochemical test results show that Pt₁Pd₅/PVA catalyst displays the highest mass activity(3774.2 m A mg_pt^-1)for methanol oxidation reaction.Moreover,the residual activity of Pt₁Pd₅/PVA catalyst after chronoamperometry test of 28 h is close to that of commercial Pt/C catalyst after CA test of 5000 s.Those results indicate that Pt₁Pd₅/PVA catalyst has the best electrocatalytic activity and stability for methanol oxidation.In addition,Pt₁Pd₅/PVA catalyst has excellent electrocatalytic performance for the oxidation of ethanol,ethylene glycol and glycerol.The excellently electrocatalytic performance of Pt₁Pd₅/PVA catalyst is mainly attributed to the synergistic effect between Pt and Pd which reduces the adsorption of CO-like species over the Pt surface by optimizing the surface electronic structure.Besides,the unique chain network structure of Pt Pd forms a conductive network of self-conducting electrons.Meanwhile,the coating for Pt Pd catalyst of PVA and the interaction with PVA and Pt Pd hinder the migration and agglomeration of Pt Pd nanoparticles,resulting in the ultra-long stability of the catalyst.