Assisting the formation of S-doped FeMoO₄ in lieu of an iron oxide/molybdenum sulfide heterostructure: A unique approach towards attaining excellent electrocatalytic water splitting activity

Development of novel type bifunctional electrocatalyst containing Fe, Mo, S and O for overall water splitting is important. Either a bimetallic compound or a heterostructure could be developed utilizing these elements however; the widely utilized hydrothermal reaction would favor the formation of the later one. Herein, a unique triethanolamine-assisted strategy was adopted to facilitate the formation of S-doped FeMoO₄ instead of an iron oxide/molybdenum sulfide heterostructure. Through electrochemical investigation revelaed that the said assistance was crucial in achieving excellent bifunctional electrocatalytic activity. The activity of the optimally doped FeMoO₄ (especially towards oxygen evolution reaction) was superior to most of the recently reported transition-metal-based electrocatalysts. Moreover, it achieved 10 mA cm⁻² for overall water splitting at 1.561 V, which was ∼60 mV lower than that required for the RuO₂–Pt/C couple. A very high Faradaic efficiency (95.88%) and operational robustness was associated with the overall water splitting catalyzed by S-doped FeMoO₄.