Photocatalytic degradation, as an emerging method to control environmental pollution, is considered one of the most promising environmental purification technologies. As Tibet is a region with some of the strongest solar radiation in China and even in the world, it is extremely rich in solar energy resources, which is ideal for applying photocatalytic technology to its ecological environment protection and governance. In this study, Na₂Ti₃O₇ nanobelts were prepared via a hydrothermal method and converted to TiO₂∙xH₂O ion exchange, which was followed by high-temperature calcination to prepare TiO₂(B) nanobelts (“B” in TiO₂(B) means “Bronze phase”). A simple in situ method was used to generate Ag₃PO₄ particles on the surface of the TiO₂ nanobelts to construct a Ag₃PO₄/TiO₂(B) heterojunction composite photocatalyst. By generating Ag₃PO₄ nanoparticles on the surface of the TiO₂(B) nanobelts to construct heterojunctions, the light absorption range of the photocatalyst was successfully extended from UV (ultraviolet) to the visible region. Furthermore, the recombination of photogenerated electron–hole pairs in the catalyst was inhibited by the construction of the heterojunctions, thus greatly enhancing its light quantum efficiency. Therefore, the prepared Ag₃PO₄/TiO₂(B) heterojunction composite photocatalyst greatly outperformed the TiO₂(B) nanobelt in terms of photocatalytic degradation.

Electrolysis of water to produce hydrogen is crucial for developing sustainable clean energy and protecting the environment. However, because of the multi-electron transfer in the oxygen evolution reaction (OER) process, the kinetics of the reaction is seriously hindered. To address this issue, we designed and synthesized hollow CoP/FeP₄ heterostructural nanorods interwoven by carbon nanotubes (CoP/FeP₄@CNT) via a hydrothermal reaction and a phosphorization process. The CoP/FeP₄@CNT hybrid catalyst delivers prominent OER electrochemical performances: it displays a substantially smaller Tafel slope of 48.0 mV dec⁻¹ and a lower overpotential of 301 mV at 10 mA cm⁻², compared with an RuO₂ commercial catalyst; it also shows good stability over 20 h. The outstanding OER property is mainly attributed to the synergistic coupling between its unique CNT-interwoven hollow nanorod structure and the CoP/FeP₄ heterojunction, which can not only guarantee high conductivity and rich active sites, but also greatly facilitate the electron transfer, ion diffusion, and O₂ gas release and significantly enhance its electrocatalytic activity. This work offers a facile method to develop transition metal-based phosphide heterostructure electrocatalysts with a unique hierarchical nanostructure for high performance water oxidation.

Photocatalytic degradation is one of the most promising emerging technologies for environmental pollution control. However, the preparation of efficient, low-cost photocatalysts still faces many challenges. TiO₂ is a widely available and inexpensive photocatalyst material, but improving its catalytic degradation performance has posed a significant challenge due to its shortcomings, such as the easy recombination of its photogenerated electron–hole pairs and its difficulty in absorbing visible light. The construction of homogeneous heterojunctions is an effective means to enhance the photocatalytic performances of photocatalysts. In this study, a TiO₂(B)/TiO₂(A) homogeneous heterojunction composite photocatalyst (with B and A denoting bronze and anatase phases, respectively) was successfully constructed in situ. Although the construction of homogeneous heterojunctions did not improve the light absorption performance of the material, its photocatalytic degradation performance was substantially enhanced. This was due to the suppression of the recombination of photogenerated electron–hole pairs and the enhancement of the carrier mobility. The photocatalytic ability of the TiO₂(B)/TiO₂(A) homogeneous heterojunction composite photocatalyst was up to three times higher than that of raw TiO₂ (pure anatase TiO₂).

Research has demonstrated that the formation of composites of titanium dioxide (TiO₂) with silver phosphate (Ag₃PO₄) through the construction of heterojunctions can expand its light absorption range and suppress the recombination of photogenerated electron–hole pairs, thereby improving the photocatalytic performance. However, this method offers only limited performance improvements, and the composite photocatalysts are costly due to the expensive Ag₃PO₄. In this study, Ti₃C₂ MXene, which has good hydrophilicity and excellent electrical conductivity, is first used to form Schottky junction composites with bronze TiO₂ (TiO₂(B)) via electrostatic self-assembly. Then, Ag₃PO₄ quantum dots were further formed on the surface of the TiO₂(B)/Ti₃C₂ MXene by in situ self-growth, and Ag₃PO₄ formed heterojunctions and Schottky junctions with TiO₂(B) and Ti₃C₂ MXene, respectively. Finally, a ternary composite photocatalyst TiO₂(B)/Ti₃C₂ MXene/Ag₃PO₄ was jointly constructed by these functional junctions. Under the synergistic effect of these functional junctions, the mobility and fast separation performance of photogenerated electron–hole pairs of the composite photocatalyst were significantly improved, the recombination of photogenerated electron–hole pairs was effectively suppressed, and the light absorption performance was enhanced. As a result, the composite photocatalyst exhibited excellent photocatalytic performances.

Hydrogen is regarded to be one of the most promising renewable and clean energy sources. Finding a highly efficient and cost-effective catalyst to generate hydrogen via water splitting has become a research hotspot. Two-dimensional materials with exotic structural and electronic properties have been considered as economical alternatives. In this work, 2D SnSe films with high quality of crystallinity were grown on a mica substrate via molecular beam epitaxy. The electronic property of the prepared SnSe thin films can be easily and accurately tuned in situ by three orders of magnitude through the controllable compensation of Sn atoms. The prepared film normally exhibited p-type conduction due to the deficiency of Sn in the film during its growth. First-principle calculations explained that Sn vacancies can introduce additional reactive sites for the hydrogen evolution reaction (HER) and enhance the HER performance by accelerating electron migration and promoting continuous hydrogen generation, which was mirrored by the reduced Gibbs free energy by a factor of 2.3 as compared with the pure SnSe film. The results pave the way for synthesized 2D SnSe thin films in the applications of hydrogen production.