Improved Oxygen Reduction Reaction Performance of PGM-Free Catalyst Through Change in Surface Structure

Over the past decades, extensive research and development have been conducted to replace platinum group metal (PGM), the key material for oxygen reduction reaction (ORR) catalysts, with various non-platinum and carbon-based catalysts. However, non-platinum nanoparticle catalysts have faced significant commercialization barriers due to their lower ORR performance compared to commercial platinum catalyst and their severe dissolution issues in acidic electrolytes. In this context, M-N-C (M = 3d-transition metal) catalysts, which disperse transition metals at the atomic level, have shown considerable promise due to their substantial performance in both acidic and alkaline electrolytes, making them attractive candidates. Also, recent studies have reported that the M-Nx structures on the surface of M-N-C catalysts exhibit electron withdrawing/donating effects depending on the type of core metal or doped elements. Based on these, we have developed novel PGM-free catalysts with anchoring M-Nx structures onto carbon shells of non-platinum metal nanoparticles. As a result, we confirmed the enhancement of the catalytic performance by controlling the electron withdrawing/donating effects between the core metal and the M-Nx sites of the carbon shell. Therefore, we expect these results significantly contribute to the development of novel PGM-free catalysts for fuel cells.