LAUSR

Abstract Development of facile strategies to directly fabricate the noble-metal-free heterostructure on the conducting substrate and tailoring its electrocatalytic activity are crucial to achieve the superior overall water splitting activity. Herein, a series of MoS2/Fe2O3 heterostructure was directly fabricated on nickel foam substrate by a facile two-step electrodeposition technique. The alteration in duration of the deposition steps regulated the physicochemical properties and water splitting efficiency of the resulting heterostructure. A correlative investigation of Tafel and Nyquist plot revealed that the substrate adsorption–desorption and charge transfer efficiency of the heterostructure varied owing to this alteration. The successful integration of Fe2O3 with MoS2 synergistically enhanced the electrocatalytic activity of the heterostructure and binder-free growth on conducting nickel foam (NF) helped it to achieve higher catalytic current density. The heterostructure obtained through 5 and 6 min long two-step electrodepositions (F5M6), showed superior bifunctional electrocatalytic activity. The symmetric cell constructed with F5M6 electrode outperformed the state-of-the-art RuO2 || Pt/C electrolyzer at higher operating voltage region and was able to achieve a current density of 757 mA cm−2 at 2 V. Moreover, the heterostructure could sustain its overall water splitting proficiency for ~ 30 h at high current density confirming its excellent overall water splitting efficacy. This investigation established the two-step electrodeposition process as an effective electrocatalytic-activity-tailoring strategy.