Hydrogen fuel could play a key role in future sustainable energy systems as demand for energy is globally increasing. Moreover, an environment friendly energy resources are in urgent need to replace the current fossil fuel energy systems. Among the available energy sources, hydrogen possesses significantly high energy density compared to conventional fossil fuels and hence emerges as one of the ideal replacements to fossil fuels.

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.

Tungsten (W) alloy are widely applied in many engineering applications including radiation shields, counterweight balance, electrical contacts, damping devices, and kinetic energy penetrators. The wide applications benefit from its high melting point, good thermal stability, high strength, and high radiation absorption capacity. However, tungsten alloy suffers from low temperature brittleness and unexpected growth characteristics in recrystallization.

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.