Heterojunction and direct Z-scheme nanostructures are two typical representatives of an efficient photocatalyst, 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.

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Defects (Ti or oxygen vacancies) have been demonstrated to promote the charge separation process in TiO based photocatalysts. Particularly, the bulk defects within a certain concentration can give a great enhancement for both light absorption and charge separation efficiency. In this report, we explored a one-step molten salts route to synthesize SrTiO nanocubes with bulk defects (Ti doped) by using SrCO as a Sr source, and TiO and Ti powder as Ti sources. The amount of defects can be tuned by changing the molar ratio of Ti/TiO. The corresponding bandgap of SrTiO can be changed from 3.29 to 2.73 eV with the increase of defects. X-ray diffraction and electron microscopy disclose that SrTiO is highly crystalline and has a cubic morphology. X-ray photoelectron spectroscopy and electron paramagnetic resonance indicate that the as-prepared SrTiO is close to the Ti doped SrTiO. Surface photovoltage spectroscopy (SPS) and field-induced SPS confirm that Ti doping in the SrTiO turns it from an n-type semiconductor to p-type. The SrTiO with an optimal amount of defects exhibits highly enhanced photocatalytic performance. An excess amount of defects results in a weak SPS response and photocatalytic performance.

The FeCo@N-GCNT-FD catalyst exhibits enhanced intrinsic activities and excellent durability for the oxygen reduction reaction.