Sm3+ rare-earth doping in non-noble metal oxide –WO3 grown on carbon cloth fibre as a bifunctional electrocatalyst for high-performance water electrolysis

Abstract

Sustainable electrocatalysts which perform the kinetics required for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are held in high esteem. Pristine WO₃ favours the hydrogen evolution reaction in most of its stable phase structures while the incorporation of rare earth elements with higher ionic radii favours both HER and OER kinetics due to the distortions that are created in the parent lattice structure creating many oxygen vacancies. Sm in different molar weight percentages (x = 1, 2, 4 and 5) was incorporated into the WO₃ structure by a facile hydrothermal route. The Sm doped WO₃ electrocatalysts showed affinity towards catalyzing both HER and OER. Sm 4% and Sm 5% doped samples outperformed in the HER and OER showcasing an exceptional Tafel slope value of 69 and 98 mV dec⁻¹ respectively in an acidic environment. Considering the practical accountability for overall water splitting, the respective electrocatalysts were deposited on carbon cloth (CC) which exhibited a superior Tafel slope of 54 and 90 mV dec⁻¹ for initiating the HER and OER respectively. The Sm doped WO₃ electrocatalysts deposited on CC exhibited a high endurance for 12 h with incomparable stability in acidic media. The sophisticated conducting surface of CC along with the interfacial sites and defects consisting of oxygen vacancies proves that rare earth Sm-doped WO₃ is an excellent candidate for overall water splitting.