Activating and optimizing activity of CdS@g-C3N4 heterojunction for photocatalytic hydrogen evolution through the synergistic effect of phosphorus doping and defects

The CdS@g-C3N4 heterojunction photocatalyst has attracted tremendous attention in photocatalytic hydrogen evolution, but how to further enhance its photoactivity is still a huge challenge. Herein, we develop a facile strategy to form a double-modified CdS@g-C3N4 heterojunction through the simultaneous phosphorus (P) doping and defects creation in one-step process. Various characterization results confirmed the intimate heterojunction, P doped via P-N bond formation and abundant defects on the double-modified CdS@g-C3N4. The optimized photocatalyst showed a remarkable H-2 evolution rate of similar to 383.59 mu mol/h, which was similar to 52.05, similar to 4.11, and 1.52 times higher than those of pristine g-C3N4 CdS, and unmodified CdS@g-C3N4 respectively. The superior H-2 evolution performance can be attributed to the following factors: (1) P doping induced a mid-gap state, resulting in the improved ability to harvest visible light and prolong the lifetime of photogenerated electrons; (2) defects could narrow bandgap and trap electrons, accelerating the transfer of these electrons to H+; (3) core-shell nanostructures and intimate interfacial contact promote the separation and transfer of interface charges owing to improved charge transport pathways. This work highlights a feasible strategy for developing superior photocatalysts by heteroatom doping and defect engineering. (C) 2020 Elsevier B.V. All rights reserved.