Consciously Constructing Heterojunction or Direct Z-Scheme Photocatalysts by Regulating Electron Flow Direction

摘要

Heterojunction and direct Z-scheme nanostructures are two typical representatives of an efficient photo catalyst, which is composed of two semiconductors. However, it is a great challenge to construct each of them on purpose. The photodeposition technique can be a potentially powerful tool to regulate the electron flow direction for constructing these nanostructures. In this report, CdS nanoparticles were deposited on the g-C3N4 nanosheets by photodeposition and chemical deposition methods for comparison. In the photodeposition case, PL and charge flow tracking demonstrate that a type II heterojunction is constructed because CdS is selectively deposited at the electron transfer site of g-C3N4, which leads to the photoexcited electron from g_C3N4 tending to transfer to CdS in the composites. In the latter, the CdS is randomly deposited onto the g-C3N4 nanosheets through chemical deposition. There is no preferred site for deposition or charge transfer in the composite. The results illustrate that the electron of CdS tends to recombine with the hole from g-C3N4. The direct Z-scheme is predominant for the CdS/g-C3N4 prepared by the chemical deposition route. Furthermore, the photocatalytic performance and stability also confirm the above results. On the of these, we can deduce that the photodeposition method can be used to regulating the electron transfer route. We expect this report to shed light on the rational design of heterojunction or direct Z-scheme type composites.