Releasing Au Electrons to Mo Site for Weakened Mo<i>─</i>H Bond of Mo<sub>2</sub>C MXene Cocatalyst Toward Improved Photocatalytic H<sub>2</sub> Production
Xiaochun Ke, Ping Wang, Xuefei Wang, Feng Chen, Huogen Yu
Abstract
Abstract Mo 2 C MXene (Mo 2 CT x ) is one of the most promising noble‐metal‐free cocatalysts for photocatalytic H 2 production because of its excellent electron transport capacity and abundant Mo sites. However, Mo 2 CT x typically exhibits a strong Mo ─ H ads bond, resulting in that the produced H 2 difficultly desorbs from the Mo surface for the limited activity. To effectively weaken the Mo ─ H ads bond, in this paper, a regulation strategy of electron donor Au releasing electrons to the d‐orbitals of Mo sites in Mo 2 CT x is proposed. Herein, the Mo 2 CT x ‐Au/CdS photocatalysts are prepared through a two‐step process, including the initial loading of Au nanoparticles on the Mo 2 CT x surface and the subsequent in situ growth of CdS onto the Mo 2 CT x ‐Au surface. Photocatalytic measurements indicate that the maximal H 2 ‐production rate of Mo 2 CT x ‐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 Mo 2 CT x /CdS, respectively. Experimental and theoretical data corroborate that metallic Au can transfer free electrons to Mo 2 CT x to generate electron‐enriched Mo δ‐ sites, thus causing the increased antibonding‐orbital occupancy state and the weakened Mo ─ H ads bond for the boosted H 2 ‐production efficiency. This research provides a promising approach for designing Mo 2 CT x ‐based cocatalysts by regulating the antibonding‐orbital occupancy of Mo sites for improved photocatalytic performance.