Component-Dependent Electrocatalytic Activity of Ultrathin PdRh Alloy Nanocrystals for the Formate Oxidation Reaction

The direct formate fuel cells in alkaline medium is attracting more and more attention, because of their reasonable power density, facile power system, and low formate crossover. Herein, we successfully prepare the XC-72 carbon-supported PdRh alloy nanocrystals (PdRh/XC-72 nanocomposites) with different Pd/Rh atomic ratios by precipitation–reduction strategy. The as-prepared Pd5Rh1/XC-72 nanocomposites show the excellent electrocatalytic mass activity (4.5 A mg–1) for the formate oxidation reaction (FOR) in a KOH medium, which is 2.3-fold mass activity enhancement over commercial Pd/C anodic catalyst (1.9 A mg–1) for the FOR in a KOH medium. The obvious activity enhancement can be ascribed to the high dispersibility, the electronic effect, and the suitable OHad species. Meanwhile, the Rh atoms in the PdRh alloy also can weaken the CO accumulation during the FOR and simultaneously enhance the electrochemical self-stability of catalyst, resulting in excellent electrocatalytic durability of Pd5Rh1/XC-72 nanocomposites for the FOR. This work demonstrates that the Pd5Rh1/XC-72 nanocomposites are promising high-performance electrocatalysts for the FOR.