Hierarchical SnS2/CuInS2 nanosheet heterostructure film decorated with C60 for remarkable photoelectrochemical water splitting.

Rational architectural design and catalyst components are beneficial to improve the photoelectrochemical performance. Herein, hierarchical SnS2/CuInS2 nanosheet heterostructure porous films were fabricated and decorated with C60 to form photocathodes for photoelectrochemical water reduction. Large-size CuInS2 nanosheet film was firstly grown on the transparent conducting glass to form substrate film. Then small-size SnS2 nanosheets were epitaxially grown on the double-side of CuInS2 nanosheets to form uniform hierarchical porous laminar film. The addition of C60 on the surface of SnS2/CuInS2 porous nanosheets effectively increased visible light absorption of composite photocathode. Photoluminescence spectroscopy and impedance spectroscopy analyses indicated that the formation of SnS2/CuInS2 heterojunction and decoration of C60 significantly increased photocurrent density by promoting the electron-hole separation and decreasing the resistance to the transport of charge carriers. The hierarchical SnS2/CuInS2 nanosheet heterostructure porous film containing multiscale nanosheets and pore configurations can enlarge surface area and enhance visible light utilization. These beneficial factors make the optimized C60 decorated SnS2/CuInS2 photocathode exhibit much higher photocathodic current (4.51 mA cm-2 at applied potential -0.45 V vs. RHE) and stability than the individual CuInS2 (2.58 mA cm-2) and SnS2 (1.92 mA cm-2) nanosheet film photocathodes. The study not only reveals the promise of C60 decorated hierarchical SnS2/CuInS2 nanosheet heterostructure porous film photocathodes for efficient solar energy harvesting and conversion, but also provides rational guidelines in designing high-efficiency photoelectrodes from earth abundant and low-cost materials allowing widely practical applications.