Releasing Au Electrons to Mo Site for Weakened Mo─H Bond of Mo₂C MXene Cocatalyst Toward Improved Photocatalytic H₂ Production

Abstract

Mo2C MXene (Mo2CTx) is one of the most promising noble‐metal‐free cocatalysts for photocatalytic H2 production because of its excellent electron transport capacity and abundant Mo sites. However, Mo2CTx typically exhibits a strong Mo─Hads bond, resulting in that the produced H2 difficultly desorbs from the Mo surface for the limited activity. To effectively weaken the Mo─Hads bond, in this paper, a regulation strategy of electron donor Au releasing electrons to the d‐orbitals of Mo sites in Mo2CTx is proposed. Herein, the Mo2CTx‐Au/CdS photocatalysts are prepared through a two‐step process, including the initial loading of Au nanoparticles on the Mo2CTx surface and the subsequent in situ growth of CdS onto the Mo2CTx‐Au surface. Photocatalytic measurements indicate that the maximal H2‐production rate of Mo2CTx‐Au/CdS reaches up to 2799.44 µmol g−1 h−1, which is 30.99 and 3.60 times higher than that of CdS and Mo2CTx/CdS, respectively. Experimental and theoretical data corroborate that metallic Au can transfer free electrons to Mo2CTx to generate electron‐enriched Moδ‐ sites, thus causing the increased antibonding‐orbital occupancy state and the weakened Mo─Hads bond for the boosted H2‐production efficiency. This research provides a promising approach for designing Mo2CTx‐based cocatalysts by regulating the antibonding‐orbital occupancy of Mo sites for improved photocatalytic performance.