S-Scheme and Schottky Junction Synchronous Regulation Boost Hierarchical CdS@Nb 2 O 5 /Nb 2 C T x (MXene) Heterojunction for Photocatalytic H 2 Production.

Photocatalytic water cracking hydrogen (H 2 ) production is a promising clean energy production technology. Therefore, a ternary CdS@Nb 2 O 5 /Nb 2 C T x (MXene) heterojunction with hierarchical structure was designed to promote photocatalytic H 2 evolution. When Na 2 S/Na 2 SO 3 and lactic acid were used as sacrificial agents, the hydrogen evolution reaction (HER) rates of the optimized photocatalyst were 1501.7 and 2715.8 μmol g -1 h -1 , with 12.4% and 26.1% apparent quantum efficiencies (AQE) at 420 nm, respectively. Its HER performance was 10.9-fold higher than that of pure CdS and remained 87% activity after five rounds of cycle tests. Such an enhancement stems from the excellent light absorption properties, tight interfacial contact, fast charge transfer channel, and sufficient active sites. Mechanism analysis demonstrates that S-scheme and Schottky junction synchronous regulation boost hierarchical CdS@Nb 2 O 5 /Nb 2 C T x for photocatalytic H 2 production. This work creates possibilities for manufacturing Nb-based MXene photocatalysts for converting solar energy and other applications.