Insights into the synergy of platinum and nickel carbonate hydroxide for efficient methanol electro-oxidation

Abstract

Pt-based nanostructures are an indispensable component in the anodic electrocatalysts of direct methanol fuel cells (DMFCs). Unfortunately, they often suffer from severe operational durability issues, due to CO poisoning. Here, a ternary hybrid consisting of Pt nanocrystals, ultrathin nanoflower-like nickel carbonate hydroxide (NiCH) and porous carbon is designed and fabricated to overcome this issue. Owing to the abundance of defects and large surface area of the NiCH, water molecules are easily dissociated to form OH adspecies, which could assist the oxidative removal of carbonaceous poisons from nearby Pt nanoparticles by the L-H mechanism. Porous carbon offsets the poor conductivity of NiCH and accelerates charge transfer. Impressively, this hybrid electrocatalyst could maintain over 39% of the initial activity after 5000 s of stability testing, and the MOR peak current was reduced by only 25% after 8000 CV cycles. CO stripping experiments demonstrate this incredible CO tolerance. DFT calculations further elucidate that the electronic interactions between H atom from NiCH and Pt downshifts the d-band center of Pt atom and accelerates the release of CO adsorbed on its surface. This work offers a promising candidate for the design of DMFCs anodic electrocatalysts.