Sustainable energy sources are crucial in the modern world, where conventional fossil fuels contribute towards an alarming percentage of hazardous pollutants in the environment. Hydrogen is a non-polluting fuel and a replenishable energy source, able enough to take the edge of an energy crisis. Noble metal platinum (Pt) has been proved to be the most effective electrocatalyst for hydrogen evolution reaction (HER). However, the high price of Pt limits its applications.

In the development of tungsten-based Plasma Facing Materials/Components (PFMs/PFCs), materials scientists have explored many different, innovative preparation and processing routes to meet the requirement of International Thermonuclear Experimental Reactor (ITER). Tungsten (W) is one of the best candidates for plasma-facing materials in the fusion reactors, owing to its many unique properties. However, some inherent defects such as the embrittlement, high DBTT of tungsten material restrict its application on PFMs and PFCs.

Nitrogen dioxide (NO2) gas sensor at low concentration is important as NO2 is not good to human nervous system and respiratory organs. Tungsten oxide (WO3), a popular n-type semiconductor with a band-gap of 2.6–2.8 eV, has been widely studied as a promising sensing material for determining NO2 gas because it exhibits high sensitivity, low cost of manufacturing and a fast response.

With ever-increasing demands of energy and environmental issues caused by extensive combustion of traditional fossil fuels, the quest for clean and sustainable energy sources as alternatives has attracted extensive research interest. Hydrogen seems to be a promising alternate due to its nontoxicity, ideal combustion efficiency and high gravimetric energy density. Among many accepted ways of hydrogen generation, photoelectrochemical (PEC) water splitting has been widely regarded as an appealing solution.