Engineering highly active Ag/Nb2O5@Nb2CTx (MXene) photocatalysts via steering charge kinetics strategy

Abstract Steering charge kinetics is one of the most urgent unsolved issues in photocatalysis. The effective spatial separation of photogenerated electron-hole pairs is particularly important in the design and controllable preparation of nano-photocatalysts. Herein, one-dimensional Nb2O5 nanorod arrays with [001] orientation were grown in-situ on two-dimensional Nb2CTx MXenes through a facile hydrothermal method for the first time. Ag nanoparticles were then photodeposited on the Nb2O5 nanorods to form hierarchical 0D/1D/2D nanohybrids. It was experimentally demonstrated that -OH is predominantly adsorbed on Nb2CTx as termination groups, which resulted in a low work function (2.7 eV). Thanks to the unique structure, the highly active [001] Nb2O5 nanorods afford high-efficiency photogeneration of electron-hole pairs, while the low-work-function -OH terminated Nb2CTx allows for trapping holes, and Ag nanoparticles act as electron reservoir and sites of hydrogen evolution reaction (HER). The ternary Ag/Nb2O5@Nb2CTx nanohybrids reached a record HER activity (682.2 and 824.2 μmol·g-1h-1 use methanol and glycerol as sacrificial agents, respectively) among the niobium-based photocatalysts, demonstrating the potential of MXenes as a platform for the synthesis of high-performance heterojunction structures, where the tunable electronic property is a key factor.