Ruthenium-doped cobalt sulphide electrocatalyst derived from a ruthenium-cobalt Prussian blue analogue (RuCo-PBA) for an enhanced hydrogen evolution reaction (HER).

The designing of efficient electrocatalysts for hydrogen generation is essential for the practical application of water-splitting devices. With numerous electrochemical advantages, transition metal sulphides are regarded as the most promising candidates for catalysing the hydrogen evolution reaction (HER) in acidic media. In the present study, Ru-doped cobalt sulphide nanosheets, termed Co 9 S 8 /Ru@ t ( t = 24 h, 48 h, and 72 h), were obtained by varying the reaction time from 24 h to 72 h from a RuCo-PBA precursor. The role of the time period for the synthesis of Co 9 S 8 /Ru@48h is vital in increasing the number of electroactive sites and optimising the hydrogen adsorption-desorption phenomena leading to an increment in the HER activity. The electrochemical outcomes demonstrate that the optimized Co 9 S 8 /Ru@48h requires a low overpotential of just 94 mV to produce 10 mA cm -2 current density, and also exhibits a lower Tafel slope value of 84 mV dec -1 defining its faster reaction kinetics. The as-synthesized Co 9 S 8 /Ru@48h was stable for up to 20 h of constant electrolysis signifying its outstanding durability. The optimized synthetic approach and impressive electrochemical results make Co 9 S 8 /Ru@48h a suitable alternative to noble-metal-based electrocatalysts for the HER.