Ultraviolet‐Assisted Construction of Nitrogen‐Rich Ag@Ti3C2Tx MXene for Highly Efficient Hydrogen Evolution Electrocatalysis and Supercapacitor

Abstract To achieve highly efficient energy storage and conversion in electrochemical energy devices, the research of rationally designed method is crucial to improve performances of MXene‐based catalysts and electrodes. Herein, an ultraviolet‐assisted strategy is demonstrated to synthesize Ag@N‐doping Ti 3 C 2 T x (Ag@N‐Ti 3 C 2 T x ) composites and N‐promoted free electron number and the electron bound in Mxene are used to generally boost the hydrogen evolution reaction (HER) catalysis and supercapacitor performance. The prepared Ag@N‐Ti 3 C 2 T x catalyst displays a high catalytic ability with an overpotentials of −153 mV and corresponding Tafel slopes (137.9 mV dec −1 ) lower than pristine Ti 3 C 2 T x catalysts (−156.7 mV dec −1 ). Theoretical analysis and refined structural characterization indicate that the HER activity correlates well with the structural characteristic, active components, and electronic structure. As an electrode material for supercapacitors, the nano‐Ag@N‐Ti 3 C 2 T x exhibits high specific capacity of 223.3 F g −1 , outstanding capacity retention rate of about 68% from 1 to 10 A g −1 in rate performance and 96% capacity retention after 2000 cycles in stable performance. The synthetic approach offers a new vision for tuning the electrocatalytic activities of N‐rich Ag@MXene materials.