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Electrocatalytic water splitting, as a sustainable, pollution-free and convenient method of hydrogen production, has attracted the attention of researchers. However, due to the high reaction barrier and slow four-electron transfer process, it is necessary to develop and design efficient electrocatalysts to promote electron transfer and improve reaction kinetics. Tungsten oxide-based nanomaterials have received extensive attention due to their great potential in energy-related and environmental catalysis. To maximize the catalytic efficiency of catalysts in practical applications, it is essential to further understand the structure–property relationship of tungsten oxide-based nanomaterials by controlling the surface/interface structure. In this review, recent methods to enhance the catalytic activities of tungsten oxide-based nanomaterials are reviewed, which are classified into four strategies: morphology regulation, phase control, defect engineering, and heterostructure construction. The structure–property relationship of tungsten oxide-based nanomaterials affected by various strategies is discussed with examples. Finally, the development prospects and challenges in tungsten oxide-based nanomaterials are discussed in the conclusion. We believe that this review provides guidance for researchers to develop more promising electrocatalysts for water splitting. [ABSTRACT FROM AUTHOR]

• Interface controlled Au-NiS x heterostructures were prepared by solvothermal method. • The presence of Au improves the HER properties of NiS x. • Electron transfer along the interface mainly determines the catalytic properties. Nickel sulfides (NiS x) as promising catalysts for hydrogen evolution reaction (HER) have attracted much interest. However, the HER catalytic activities of NiS x reported are relatively low for their poor electrical conductivity. The HER catalytic performance of NiS x is expected to be further enhanced by increasing their electronic conductivity. Constructing heterostructures consisting of noble metal and semiconductor has been proven to be an efficient method to promote their physicochemical performances benefitting from synergistic effects along the metal-semiconductor interface. Here, Au-NiS x heterostructures including core@shell, yolk-shell, and oligomer-like structures have been designed and synthesized by different solvothermal methods. A formation mechanism involving the Kirkendall effect has been proposed for the yolk-shell structure with an empty space around the Au core rather than the seeded grown core@shell structure. Catalytic performance measurements indicate that the Au@NiS x core@shell nanoparticles (NPs) exhibit superior HER catalytic property to Au-NiS x yolk-shell, oligomer-like structures, and "pure" NiS x NPs, resulting from the electron transfer between Au and NiS x interfaces. The overpotentials of Au-NiS x NPs with core@shell and yolk-shell nanostructures are 253 mV and 263 mV at 10 mA/cm2, respectively, which are lower than those of oligomer-like Au-NiS x (283 mV) and pure NiS x (321 mV) NPs. The Tafel slope of Au@NiS x core@shell structure (43.7 mV/dec) is also the lowest. These results demonstrate that the core@shell NPs possess the best HER performances, followed by their yolk-shell and oligomer-like counterparts. These findings confirm that the physicochemical performances of the metal-semiconductor heterostructures can be efficiently optimized by adjusting the electron transfer through the interface structure control. [ABSTRACT FROM AUTHOR]