Preparation Of Nanoporous Pt-based Alloy By Dealloying And Its Catalytic Performance

Dealloying is one of the important method to fabricate nanoporous metals,and the precursor composition,phase constitution and the dealloying conditions play important roles in the pore formation of nanoporous metals during dealloying process.However,the formation mechanism of nanoporous metals during dealloying in micro-nanoparticles systems still need to be further investigated.The Al-and Cu-based alloy systems have been selected as the precursor alloys.We investigate the inherent law of nanoporous structures of the multicomponent alloy micro-nanoparticles systems during dealloying.The influence and action mechanisms of factors including particle size,composition,phase constitution,microstructure and dealloying conditions on the formation and evolution of nanopores have also been investigated.Furthermore,we probe the formation mechanism of nanoporous metals during dealloying in the multicomponent micro/nano-alloy systems.We also study the electro-catalytic properties of nanoporous metals towards oxidation of small organic molecules like methanol.The relationship between the microstructures of nanoporous metals and their electro-catalytic properties has also been illuminated.In this research,the Al-based and Cu-based precursor alloys containing Pt were fabricated by rapid solidification process,and one-step or two-step dealloying treatment was carried out to study the formation and evolution mechanism of pores in the process of multi-component alloy dealloying,and a series of nanoporous Pt based alloy catalysts with high electro-catalytic performance were prepared.Through rapid solidification and two-step dealloying method,nanoporous Pt₂Cu alloys have been successfully fabricated Electrochemical tests indicate that the obtained np-Pt₂Cu alloys exhibit superior MOR and stability compared to the commercial Pt C catalyst Due to alloying with Cu,the nanoporous structure and connecting ligaments of the np-Pt₂Cu(np-Pt₂Cu)alloy are much favorable for the mass and electron transport in three-dimension,which greatly accelerates the reaction kinetics on the nanoporous alloy modified electrode surfaces.Furthermore,by adjusting the composition of precursor alloy Al-Cu-Pt,the evolution of pores and the formation of nano-structures in the process of dealloying can be controlled,and the catalytic effect of methanol,ethanol and formic acid on organic small molecules can be further optimized.The results show that under the condition of Al content greater than 50%,the precursor alloy strip can obtain a double-continuous porous ligament-channel structure through two-step dealloying process.Electrochemical tests showed that the nanoporous PtCu alloy samples with discontinuous structure had good catalytic activity,which has important guiding significance for elucidating the microstructure mechanism of multi-component alloy process and the formation mechanism of nanoporous metal.Different dealloying processes were performed on CuZrPt,CuCePt and CuAgPt ribbons fabricated by rapid solidification process,and nanoporous PtCuZr/Ce/Ag alloy can be successfully obtained through optimizing the dealloying process parameters.The composition and dealloying process have important influence on the formation of nanoporous structure.The results of the proposed project will provide novel routes to develop new multicomponent alloy systems and fabricate high-performance nanoporous metals,and will give experiment and theory instructions on the microstructure and functional design of nanoporous metals.