Investigation of MXenes as oxygen reduction electrocatalyst for selective H2O2 generation

Two-electron oxygen reduction reaction (ORR) catalysts are essential for the electrosynthesis of hydrogen peroxide (H2O2). MXenes, a rising family of two-dimensional (2D) transition metal carbides, have been extensively studied for energy storage and (photo)electrocatalysis due to their rich chemical compositions and tunable electronic structures. In this work, three representative MXenes of Ti3C2Tx, V2CTx, and Nb2CTx were selected for H2O2 electrosynthesis and we found that MXenes are inherent two-electron ORR catalysts with high H2O2 selectivity. In addition, this work critically evaluates their electrocatalytic activity and stability. Interestingly, Nb2CTx catalyst maintains better electrocatalytic activity and higher stability for a long time test, although the stability of Ti3C2Tx and V2CTx catalysts is poor owing to the metal dissolution property of Ti and V in alkaline media. Moreover, the assembled device based on Nb2CTx catalyst presents a high H2O2 production and a rapid organic dye decoloration ability.