N, Ru Codoped Pellet Drum Bundle-Like Sb2S3: An Efficient Hydrogen Evolution Reaction and Hydrogen Oxidation Reaction Electrocatalyst in Alkaline Medium.

Though investigations have been made on several metal chalcogenides in hydrogen evolution reactions (HERs) and hydrogen oxidation reactions (HORs), antimony sulfide (Sb2S3) has not generated much attention. In this direction, the present work reports on the synthesis of N, Ru codoped pellet drum bundle-like antimony sulfide (Sb2S3) via a simple reflux method. Subsequent HER and HOR electrocatalytic investigations in 1 M KOH revealed their suitability as an efficient and inexpensive alternative to platinum, as is evident from the overpotential (72 mV at a current density of 10 mA cm-2), Tafel slope (193 mV/decade), exchange current density (1.42 mA/cm2), and breakdown potential at ∼0.6 V vs RHE, respectively. Such remarkable HER and HOR performance of N, Ru codoped Sb2S3 could be ascribed to the presence of relatively larger active sites compared to Sb2S3 and N-doped Sb2S3 individually due to synergistic effects arising from N and Ru dopants. Further, N, Ru codoped Sb2S3 demonstrated high intrinsic catalytic activity as indicated by its turnover frequency (2.03 s-1) and current loss, corresponding to 35% after 10 h of continuous amperometric i-t operation. Alternatively, such excellent catalytic performance of N, Ru codoped Sb2S3 arises due to geometric lattice defects with surface oxygen vacancy, and the availability of abundant edges and its pellet drum-like morphology also cannot be overruled.