Ultrafine rhodium selenides enable efficient oxygen reduction reaction catalysis

The promotion of the oxygen reduction reaction (ORR) catalytic activity strongly depends on the binding strength between active sites and oxygen molecules. In this work, we report rhodium selenide (Rh3Se4) nanoparticles as a promising ORR electrocatalyst due to the incorporation of Se atoms that weakened the binding strength between Rh and oxygen. Also, the formed Rh-Se bonds yield more positively charged Rh atoms favorable for breaking the *OOH intermediate to *O species due to the higher oxophilicity. Moreover, negligible degradation in ORR performance is recorded after 5000 potential cycles owing to the overly strong electronic interplay between Se and Rh atoms. A 3 times higher zinc-air battery performance is recorded compared to that of Pt/C, demonstrating the superior ORR performance of Rh3Se4/C.