In situ preparation of a PHI/SnS2 heterojunction photoanode towards photoelectrochemical applications

Abstract

Polymeric carbon nitride (PCN), as a novel organic photocatalyst, has demonstrated promising application potential in photoelectrochemistry due to its unique physicochemical properties. However, its narrow light absorption range and poor charge separation have severely hindered its practical application. In this study, a crystalline 2D heptazine-based carbon nitride (poly(heptazine imide)) and tin disulfide (PHI/SnS₂) heterojunction is constructed in situ on a conductive substrate (FTO) by a combination of electrochemical deposition and chemical vapor deposition to solve the above limitations of PCN. The experimental results show that the formation of the heterojunction significantly broadens the light absorption spectrum and enhances the charge separation efficiency, thereby improving the photoelectrochemical performance. Under a bias voltage of 1.23 V vs. RHE, the photocurrent density of the PHI/SnS₂ photoanode reaches ca. 880 μA cm⁻², approximately 29 times higher than that of pure PCN. The incident photon-to-current conversion efficiency (IPCE) of PHI/SnS₂ at a wavelength of 380 nm reaches 41.5%. This work represents an important advancement in the rational design and synthesis of CN-based photoanodes with high photoelectrochemical performance.