Tailoring the Electronic Structure of Transition Metals by the VC MXene Support: Excellent Oxygen Reduction Performance Triggered by Metal-Support Interactions.

The enhancement of oxygen reduction reaction (ORR) activity can significantly boost the performance of fuel cells. MXene-supported transition metals with strong metal-support interactions (SMSI) are an effective strategy to increase the catalytic activity and durability while decreasing the usage of noble metals. Herein, a series of composites of transition-metal atoms (Ni, Pd, Pt, Cu, Ag, and Au) deposited on VC MXene are designed as potential catalysts for ORR using density functional theory. The calculation results demonstrate that all the transition metals prefer to form a monolayer on VC (TM/VC) with high thermodynamic stability because of SMSI, in which the Pd, Pt, Ag, and Au monolayers exhibit high chemical stability during the ORR process. Pt/VC exhibits the highest activity toward ORR with the overpotential down to 0.38 V and the largest energy barrier of 0.48 eV. The excellent catalytic performance originates from the modification of the electronic structure by the VC support because of SMSI. Our studies elucidate the SMSI between transition-metal atoms and VC MXene from the atomic level and thus rationally design the ORR catalyst at the cathode of fuel cells to enhance the activity while possessing high stability and less Pt usage.