Constructing active sites and Type-II-like heterojunctions to promote efficient photoreforming of cellulose by CdS for co-production of hydrogen and formic acid

Here, CdS/ZnS/Pt (CZP), Zn 0.4 Cd 0.6 S/ZnS/Pt (ZCSZP), and CdS/ZnS/1T-WS 2 /CNTs (CZWC) composites are constructed through co-catalyst modification and heterojunction engineering strategies. The CZWC-10 with an innovative structure exhibits the optimal photocatalytic hydrogen production performance (37.83 mmol/g/h) for lactic acid, while the CZP photoreforming of cellulose achieves yields of 13.22 and 5.27 mmol/g/h for hydrogen and formic acid, respectively. 1T-WS 2 /CNTs not only exposes more active sites but also expands the photoresponse range. The synergistic effect of the built-in electric field within the heterojunction of ZnS/CdS and the co-catalysts (1T-WS 2 /CNTs and Pt) enables the spatial separation and directed aggregation of photogenerated charge carriers, thereby simultaneously triggering redox half-reactions. The formation of heterojunctions reduces the Δ G H∗ value at the S site in 1T-WS 2 and is smaller than the absolute value of Δ G H∗ at the Pt site in CZP, thereby promoting hydrogen formation. This study provides insights for rationally designing photocatalysts to achieve highly efficient photoreforming reactions.