Effects of Reduction Methods on the Performance of Shewanella oneidensis MR-1 Palladium/Carbon Catalyst for Oxygen Reduction Reaction

The influence of the reduction method on the morphology and performance of the catalyst still controversial. In this study, hydrogen, Shewanella oneidensis MR-1 (MR-1), MR-1 and hydrogen coreduction are used to reduce the palladium ions adsorbed by MR-1 to obtain Pd/C-H2 , Pd/C-M, and Pd/CH2+M catalyst, respectively. It is found that the palladium nanoparticles (Pd NPs) in Pd/CH2+M are the largest, while the Pd NPs in Pd/C-M are the smallest. This is due to the reduction of Pd NPs in Pd/CH2+M under anaerobic conditions to form smaller Pd NPs that will further aggregate and grow in H-2. In addition, Pd/C-M exhibited the best catalytic performance with a mass activity of 0.31 A mg(-1), better than that of Pd/C-H2 (0.06 A mg(-1)) and Pd/CH2+M (0.13 A mg(-1)). This study provides a meaningful reference for the selection of reduction methods in metal catalysts.