Jyoti Yadav, Dipika Sharma, Lakshay Bhardwaj, J. P. Singh
In this study, a Co 3 O 4 /SnS heterojunction was rationally engineered to boost the photoelectrochemical (PEC) water-splitting performance. A two-step procedure was used to fabricate the working electrodes, which entailed the deposition of Co and Sn thin films using electron beam evaporation and the subsequent oxidation and sulfurization using chemical vapor deposition. The PEC response was systematically investigated for bare Co 3 O 4, SnS, and Co 3 O 4 /SnS heterojunctions. In contrast to pristine Co 3 O 4 films, which exhibited a photocurrent density of 0.54 mA cm –2, the Co 3 O 4 /SnS heterojunction attained a significantly higher photocurrent density of 2.02 mA cm –2 at −1.0 V versus Ag/AgCl. The increment in photocurrent density of Co 3 O 4 /SnS electrodes can be attributed to the establishment of a p–p type-II heterojunction between Co 3 O 4 and SnS, facilitating effective charge carrier separation and directional carrier transport at the junction with prolonged absorption of light. Additionally, the electrochemical impedance for Co 3 O 4 and Co 3 O 4 /SnS decreases under illumination with increasing bias, signifying improved interfacial charge transfer due to higher conductivity. Overall, these findings reinforce the pivotal role of the Co 3 O 4 /SnS interface in enhancing interfacial charge kinetics and providing a promising pathway for the rational design of heterostructures in efficient PEC water-splitting systems.