Titanium dioxide (TiO₂) nanomaterials have garnered extensive scientific interest since 1972 and have been widely used in many areas, such as sustainable energy generation and the removal of environmental pollutants. Although TiO₂ possesses the desired performance in utilizing ultraviolet light, its overall solar activity is still very limited because of a wide bandgap (3.0–3.2 eV) that cannot make use of visible light or light of longer wavelength. This phenomenon is a deficiency for TiO₂ with respect to its potential application in visible light photocatalysis and photoelectrochemical devices, as well as photovoltaics and sensors. The high overpotential, sluggish migration, and rapid recombination of photogenerated electron/hole pairs are crucial factors that restrict further application of TiO₂. Recently, a broad range of research efforts has been devoted to enhancing the optical and electrical properties of TiO₂, resulting in improved photocatalytic activity. This review mainly outlines state-of-the-art modification strategies in optimizing the photocatalytic performance of TiO₂, including the introduction of intrinsic defects and foreign species into the TiO₂ lattice, morphology and crystal facet control, and the development of unique mesocrystal structures. The band structures, electronic properties, and chemical features of the modified TiO₂ nanomaterials are clarified in detail along with details regarding their photocatalytic performance and various applications.

Hollow core–shell NiCo₂S₄@MoS₂ heterostructures were fabricated using zeolitic imidazolate frameworks as templates and exhibited enhanced electrochemical performance for supercapacitors and hydrogen evolution reaction.

The development of a green and sustainable process for electrochemical ammonia synthesis has a significant impact on modern society in terms of agricultural and industrial development, as well as energy reform. The electrocatalytic nitrogen reduction reaction (NRR) has been regarded as a promising strategy and the efficiency of the NRR strongly depends on electrocatalysts with excellent activity, selectivity, and stability. Metal sulfides have been regarded as potential electrocatalysts due to the “accept and back-donate” interaction of metals with N₂. In addition, it has been proposed that both the intrinsic and extrinsic catalytic activity, selectivity and stability of metal sulfides can be improved through defect and interface engineering. In this review, the recent progress on metal sulfides toward the NRR is summarized based on defect and interface engineering. The typical synthetic methods, physicochemical properties, and catalytic performances of the catalysts are outlined to provide insights into the structure–performance relationship of the catalysts. In particular, the origin of the outstanding NRR catalytic activity, selectivity and stability was revealed from both experimental and theoretical perspectives. Furthermore, the remaining challenges and future perspectives are presented with the aim of providing insightful guidance for developing more efficient NRR electrocatalysts.

A gas sensor based on hollow NiFe ₂ O ₄ microspindles delivers unprecedentedly high sensitivity towards acetone vapor as well as good selectivity and cycling stability at a low working temperature.