Tandem supported, high metal-loading, non-PGM electrocatalysts for oxygen reduction reaction

Abstract

Developing non-platinum group metal (non-PGM) electrocatalysts for the oxygen reduction reaction (ORR) is a critical effort toward low-cost fuel cells and metal–air batteries. Such catalysts require a uniform dispersion of metal atoms on a solid support, typically consisting of nitrogen doped carbon. However, the synthesis of non-PGM electrocatalysts is often complex, and metal loadings are typically below 10 wt. %, limiting the number of active sites and, therefore, the catalytic activity. In this work, we overcome these limits by synthesizing tandem supported, copper loaded electrocatalysts. Through one-pot pyrolysis, we make carbon black/Cu-doped graphitic carbon nitride (g-C3N4) core–shell structures to optimize the trade-off between conductivity and metal-loading capacity and achieve a Cu loading larger than 20 wt. %. By controlling the pyrolysis temperature, we systematically modulate the catalyst composition, structure, electrocatalytic activity, and stability. At a low pyrolysis temperature of only 600 °C, we achieve an onset potential of 0.90 V and a half-wave potential of 0.81 V vs RHE for alkaline ORR and negligible current loss after 10 000 potential cycles. These results demonstrate an effective approach to realize non-PGM electrocatalysts with optimum metal-loading, activity, and stability, thus unlocking their potential for real-world applications.