The effects of deposited Pt and its deposition route on the photocatalytic reforming of glycerol for H ₂ evolution over Pt/TiO ₂ were investigated. Intimately loaded Pt(0) particles are the key active sites for the reaction, the formation of which was favored by an in situ photo-deposition route.

Noble metal-modified CdS is one of the most promising photocatalysts for solar H₂ production due to its intrinsic band structure merits. It is highly desirable to develop an effective preparation route to pursue a high photocatalytic performance and to minimize the use of costly noble metals. For the first time, a simple and convenient one-pot solvothermal (OPS) method was developed to prepare platinized CdS nanorods (Pt/CdS-N) in this work. The formation of a hexagonal 1D structure CdS and the deposition of Pt(0) can be achieved simultaneously by the method, which is more efficient than the conventional post-deposition routes, such as photochemical reduction and impregnation–reduction methods, to enhance the photocatalytic activity of CdS-N for the H₂ evolution reaction (HER). The H₂ evolution rate (r H₂ ) of CdS-N could be remarkably improved from 2.10 to 10.29 mmol h⁻¹ g⁻¹ by loading with only 0.06% Pt (wt%) under visible light irradiation (λ > 400 nm, 300 W Xe lamp). No deactivation of the sample was observed in cyclic experiments for 20 h reaction. This loading amount of Pt is substantially lower than the reported optimal values (commonly in the range of 0.5–2%) by more than one order of magnitude. A criterion of enhancement coefficient was proposed to identify the ideal loading amount of Pt. The result indicates that, considering the improvement efficiency of r H₂ and the loading amount of Pt, this ultra-low amount of Pt is more practical than the optimal amount (determined to be 0.5%). The high and stable activity of Pt/CdS-N can be attributed to the hexagonal 1D structure of CdS and the high dispersion of Pt in the Pt(0) state. Besides Pt, the OPS method is also valid for the deposition of Pd or Ru on CdS and r H₂ decreases in the order Ru/CdS-N (12.89) > Pt/CdS-N (10.29) > Pd/CdS-N (6.72 mmol h⁻¹ g⁻¹) with a loading amount of 0.06%. It reveals that the use of noble metal co-catalysts can be significantly reduced without unduly sacrificing the HRE efficiency. The developed OPS route provides a new insight into the preparation of highly efficient and stable chalcogenide photocatalysts for the HER.

Development of semiconductor photocatalysts with simultaneous high photooxidation and photoreduction performance is always a hot topic in the photocatalytic field. In this article, a highly active Z-scheme NaNbO₃/WO₃ photocatalyst was prepared by a facile ball milling method, even though either NaNbO₃ or WO₃ exhibited relatively much lower photocatalytic activity. The photocatalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron spin resonance technology (ESR), photoluminescence (PL) spectra and UV–Vis diffuse reflection spectroscopy (DRS). The OH radicals produced during the photocatalytic process were detected by a terephthalic acid photoluminescence probing technique (TA-PL). The photocatalytic activity was evaluated by photocatalytic oxidation of rhodamine B (RhB), methylene blue (MB) and reduction of Cr₂O₇ ²⁻. The results showed that the photocatalytic activity of the composite was much higher than that of single NaNbO₃ and WO₃. The first-order kinetic constant of photocatalytic degradation of RhB and MB for NaNbO₃/WO₃ is 4.9 times and 3.4 times that of pure WO₃. The optimum amount of NaNbO₃ is 0.5 wt%. The composite photocatalyst shows good stability. It is proposed that the photoexcited electrons in the CB of WO₃ and photogenerated holes in the VB of NaNbO₃ are quickly combined, so the accumulated rich electrons in the CB of NaNbO₃ and holes in the VB of WO₃ have powerful potential to produce ˙O₂ ⁻ and ˙OH, respectively. The ˙OH, ˙O₂ ⁻ and direct h⁺ oxidation of WO₃ play major roles in the degradation of RhB or MB in the NaNbO₃/WO₃ system.