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

Abstract

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.