Facilitating Oriented Electron Transfer from Cu to Mo2C MXene for Weakened Mo─H Bond Toward Enhanced Photocatalytic H2 Generation

Abstract Mo 2 C MXene (Mo 2 CT x ) is recognized as an excellent cocatalyst due to unique physicochemical properties and platinum‐like d‐band of Mo active sites. However, Mo sites of Mo 2 CT x with high‐density empty d‐orbitals exhibit strong Mo─H ads bonds during photocatalytic hydrogen evolution, leading to easy adsorption of hydrogen ions from solution and unfavorable desorption of H 2 from Mo sites. To weaken the Mo─H ads bond, a strategy of oriented electron transfer from Cu to Mo 2 CT x to increase the antibonding orbital occupancy of Mo─H ads hybrid orbitals is implemented by introducing Cu into Mo 2 CT x interlayers to form Cu‐Mo 2 CT x . The Cu‐Mo 2 CT x is synthesized from Mo 2 Ga 2 C and CuCl 2 via a one‐step molten salt method and combined with TiO 2 to form Cu‐Mo 2 CT x /TiO 2 photocatalyst through an ultrasound‐assisted approach. Hydrogen production tests reveal that an exceptional performance of Cu‐Mo 2 CT x /TiO 2 (6446 µmol h −1 g −1 , AQE = 18.3%) is 8.4 fold higher than that of Mo 2 CF 2 /TiO 2 (Mo 2 CF 2 by the conventional etchant NH 4 F+HCl). Density functional theory (DFT) calculations and characterization results corroborate that the oriented electron transfer from Cu to Mo 2 CT x increases the Mo─H ads antibonding occupancy in Cu‐Mo 2 CT x , thereby weakening Mo─H ads bonds and accelerating the hydrogen evolution rate of TiO 2 . This research offers valuable insights into optimizing H‐adsorption capabilities at active sites on MXene materials.