Engineering Ag3PO4/SnS2 heterojunction composite: A promising electrocatalyst for hydrogen evolution reaction in acidic medium

A Ag3PO4/SnS2 heterojunction composite electrocatalyst was fabricated using combined facile liquid exfoliation and hydrothermal technique by varying the concentration of SnS2 in Ag3PO4. Tin disulfide (SnS2) is a transition metal dichalcogenide that is a promising non-precious catalyst for hydrogen evolution reaction (HER) application. However, the practical application of this material is limited due to its poor electrical conductivity, to overcome this limitation it is made as a composite with Ag3PO4 as a n-type semiconductor which function by absorbing visible light with its suitable bandgap. The HER is evaluated through the three-electrode electrochemical set-up, where the catalyst coated on carbon cloth serves as a working electrode along with Ag/AgCl and platinum wire as reference and counter electrode respectively. The electrocatalyst is considered as best when it has certain criteria including lesser value of overpotential implying low current requirement to produce hydrogen. The catalyst should obey the following criteria like low resistance, high conductive nature, smaller exchange current density and has large surface area to actively participate in the electrochemical reaction. Apparently Ag3PO4/5 wt% of SnS2 is found to be the best performing composite as evidenced from the experimental data. This work may be useful for heterojunction composite catalyst for the practical application in electrochemical water splitting.