The Passive Effect of MXene on Electrocatalysis: A Case of Ti₃C₂T_x/CoNi−MOF nanosheets for Oxygen Evolution Reaction

Herein, CoNi bimetallic metal-organic framework nanosheets (CoNi−MOFNs) in-situ grown on Ti₃C₂T_x MXene (CoNi−MOFNs@MX) were explored as a typical nanocomposite to study the impact of MXene on the electrocatalytic activity of MOF for oxygen evolution reaction (OER). In contrast to previous reports, we observed a passive effect of Ti₃C₂T_x MXene on the OER performance of CoNi−MOFNs although the electronic conductivity of the nanocomposites was improved. The combined analysis of electrochemical results and atomic valence state characterization demonstrates that the decreased OER activity is likely ascribed to the unfavorable electron donation from Ti₃C₂T_x MXene, which suppresses the formation of active species for OER from the oxidation of Co²⁺ and Ni²⁺ to higher valence states in the nanocomposite. Consequently, more attention needs to be paid to the rational design of nanocomposites with MXenes for electrocatalytic applications.