Releasing Au Electrons to Mo Site for Weakened Mo─H Bond of MoC MXene Cocatalyst Toward Improved Photocatalytic H Production.

MoC MXene (MoCT) is one of the most promising noble-metal-free cocatalysts for photocatalytic H production because of its excellent electron transport capacity and abundant Mo sites. However, MoCT typically exhibits a strong Mo─H bond, resulting in that the produced H difficultly desorbs from the Mo surface for the limited activity. To effectively weaken the Mo─H bond, in this paper, a regulation strategy of electron donor Au releasing electrons to the d-orbitals of Mo sites in MoCT is proposed. Herein, the MoCT-Au/CdS photocatalysts are prepared through a two-step process, including the initial loading of Au nanoparticles on the MoCT surface and the subsequent in situ growth of CdS onto the MoCT-Au surface. Photocatalytic measurements indicate that the maximal H-production rate of MoCT-Au/CdS reaches up to 2799.44 µmol g h, which is 30.99 and 3.60 times higher than that of CdS and MoCT/CdS, respectively. Experimental and theoretical data corroborate that metallic Au can transfer free electrons to MoCT to generate electron-enriched Mo sites, thus causing the increased antibonding-orbital occupancy state and the weakened Mo─H bond for the boosted H-production efficiency. This research provides a promising approach for designing MoCT-based cocatalysts by regulating the antibonding-orbital occupancy of Mo sites for improved photocatalytic performance.