Highly efficient photocatalytic hydrogen evolution (PHE) is highly desirable for addressing the global energy crisis and environmental problems. Although much attention has been given to electron-hole separation, ridding photocatalysts of poor efficiency remains challenging. Here, a two-electron catalytic reaction is developed by utilizing the distinct trion behavior of ReS and the efficient reduction of two H (2H + 2e → H ) is realized. Due to the monolayer-like structure of the catalyst, the free electrons in ReS can be captured by the tightly bound excitons to form trions consisting of two electrons and one hole. These trions can migrate to the surface and participate in the two-electron reaction at the abundant active sites. As expected, such a two-electron catalytic reaction endows ReS with a PHE rate of 13 mmol g h under visible light irradiation. Meanwhile, this reaction allows the typically poor PHE efficiency of pure transition metal dichalcogenides to be overcome. The proposed two-electron catalytic reaction provides a new approach to the design of photocatalysts for PHE.

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SrTiO3 as semiconducting photocatalyst has been extensively investigated due to its band edges meeting the thermodynamic requirements for water splitting, but a few attention has been concentrated on its application in the NH3 synthesis via N2 photofixation process. Herein, Fe‐doped SrTiO3 (FexSr1–xTiO3) products (0 ≤ x ≤ 0.20) were synthesized via a hydrothermal process followed by calcination at 700 °C. All FexSr1–xTiO3 products (0.03 ≤ x ≤ 0.20) deliver an enhanced N2 fixation ability, and FexSr1–xTiO3 (x = 0.10) achieves the best NH3 production activity of 30.1 µmol g–1 h–1, which is 3.2‐hold higher than that of SrTiO3 alone. Once the x value is higher than 0.10, FexSr1–xTiO3 will transform into composites containing Fe‐doped SrTiO3 and α‐Fe2O3, which acts as charge recombination sites, thus causes a decreased N2 fixation activity. Further investigations demonstrate that the surface Fe3+‐doped sites can not only chemisorb and activate N2 molecules, but also promote the interfacial electron transfer from Fe‐doped SrTiO3 to N2 molecules, and thus significantly improve the N2 fixation ability. The present Fe‐doped SrTiO3 products exhibit characteristic features such as stable and efficient N2 fixation ability as well as simultaneous realization of N2 reduction and H2O oxidation without co‐catalyst, which are of significance in artificial photosynthesis with H2O as electron and proton sources.

A novel composite electrode containing brookite TiO 2 quasi nanocubes and anatase TiO 2 sea urchin-like microspheres is fabricated for improving the dye-sensitized solar cell's performance. The brookite nanocubes have a mean size of $50 nm, and the anatase microspheres with $3 mm diameter display hierarchical structures composed of secondary TiO 2 nanoribbons and nanoparticles. An optimal efficiency of 7.09% is obtained from the solar cell fabricated with a composite TiO 2 electrode containing 30 wt% nanocubes and 70 wt% microspheres, with 81% or 30% improvement in the efficiency as compared to the single nanocube or microsphere film-based cell. Those brookite nanocubes in the microsphere film can fill the interspaces of the hierarchical microspheres, which can not only enhance the dye-loading, but also reduce the charge recombination. All these lead to a higher voltage and current, leading to the improved performance of the anatase TiO 2 film-based solar cell.