Enhanced Photocatalytic Hydrogen Production of ZnIn(2)S(4) by Using Surface-Engineered Ti(3)C(2)T(x) MXene as a Cocatalyst

Developing efficient and stable photocatalysts is crucial for photocatalytic hydrogen production. Cocatalyst loading is one of the effective strategies for improving photocatalytic efficiency. Here, Ti(3)C(2)T(x) (T(x) = F, OH, O) nanosheets have been adopted as promising cocatalysts for photocatalytic hydrogen production due to their metallic conductivity and unique 2D characterization. In particular, surface functionalized Ti(3)C(2)(OH)(x) and Ti(3)C(2)O(x) cocatalysts were synthesized through the alkalization treatment with NaOH and a mild oxidation treatment of Ti(3)C(2)F(x), respectively. ZnIn(2)S(4)/Ti(3)C(2)T(x) composites, which were fabricated by the in-situ growth of ZnIn(2)S(4) nanosheets on the Ti(3)C(2)T(x) surface, exhibited the promoted photocatalytic performance, compared with the parent ZnIn(2)S(4). The enhanced photocatalytic performance can be further optimized through the surface functionalization of Ti(3)C(2)F(x). As a result, the optimized ZnIn(2)S(4)/Ti(3)C(2)O(x) composite with oxygen functionalized Ti(3)C(2)O(x) cocatalyst demonstrated excellent photocatalytic hydrogen evolution activity. The characterizations and density functional theory calculation suggested that O-terminated Ti(3)C(2)O(x) could effectively facilitate the transfer and separation of photogenerated electrons and holes due to the formation of a Schottky junction, with the largest difference in work function between ZnIn(2)S(4) and Ti(3)C(2)O(x). This work paves the way for photocatalytic applications of MXene-based photocatalysts by tuning their surface termination groups.