Hierarchical\nSnS₂/CuInS₂ Nanosheet\nHeterostructure Films Decorated with C₆₀ for Remarkable\nPhotoelectrochemical Water Splitting

Abstract

Rational architectural\ndesign and catalyst components are beneficial\nto improve the photoelectrochemical (PEC) performance. Herein, hierarchical\nSnS₂/CuInS₂ nanosheet heterostructure porous\nfilms were fabricated and decorated with C₆₀ to form photocathodes\nfor PEC water reduction. Large-size CuInS₂ nanosheet films\nwere first grown on transparent conducting glass to form substrate\nfilms. Then, small-size SnS₂ nanosheets were epitaxially\ngrown on both sides of the CuInS₂ nanosheets to form uniform\nhierarchical porous laminar films. The addition of C₆₀ on\nthe surface of the SnS₂/CuInS₂ porous nanosheets\neffectively increased visible light absorption of the composite photocathode.\nPhotoluminescence spectroscopy and impedance spectroscopy analyses\nindicated that the formation of a SnS₂/CuInS₂ heterojunction and decoration of C₆₀ significantly increased\nthe photocurrent density by promoting the electron–hole separation\nand decreasing the resistance to the transport of charge carriers.\nThe hierarchical SnS₂/CuInS₂ nanosheet heterostructure\nporous films containing multiscale nanosheets and pore configurations\ncan enlarge the surface area and enhance visible light utilization.\nThese beneficial factors make the optimized C₆₀-decorated\nSnS₂/CuInS₂ photocathode exhibit much higher\nphotocathodic current (4.51 mA cm^–2 at applied potential\n−0.45 V vs reversible hydrogen electrode ) and stability than\nthe individual CuInS₂ (2.58 mA cm^–2)\nand SnS₂ (1.92 mA cm^–2) nanosheet film\nphotocathodes. This study not only reveals the promise of C₆₀-decorated hierarchical SnS₂/CuInS₂ nanosheet\nheterostructure porous film photocathodes for efficient solar energy\nharvesting and conversion but also provides rational guidelines in\ndesigning high-efficiency photoelectrodes from earth-abundant and\nlow-cost materials allowing widely practical applications.