Tungsten-Doping-Induced Surface Reconstruction of Porous Ternary Pt-Based Alloy Electrocatalyst for Oxygen Reduction

Surface engineering has been found to be effective in promoting the catalytic activities of noble-metal-based nanocatalysts. In this contribution, by using the PtCu _x Ni ternary alloy nanocrystal (NC) as the model catalyst, a surface tungsten(W)-doping strategy, combining a surface oxidative acid treatment protocol, can effectively boost the electrocatalytic activities of the NCs in oxygen reduction reaction. The W-doped PtCu _x Ni alloy catalysts show obvious enhancement in electrochemical surface area and mass activity and slightly enhanced specific activity compared with the undoped catalyst. Based on the experimental evidence, it is proposed that the W doping involves a surface reconstruction by first removing the surface Pt atoms from the NC and then reducing them back to the surface. The existence of surface Ni atoms may be crucial in promoting the catalytic activities possibly through their electronic interactions to the active sites. The durability of the W-doped PtCu _x Ni catalysts is also enhanced possibly due to the pinning effect of surface W atoms. Therefore, the surface engineering of PtCu _x Ni ternary alloy by W atoms can effectively modulate its activity and durability.