Realizing highly efficient photoelectrochemical performance for vertically aligned 2D ZnIn2S4 array photoanode via controlled facet and phase modulation

Abstract

Exploring semiconductor photoanode with low photocarrier recombination rate and high surface redox reaction rate is eternal pursuit of PEC energy conversion. Herein, intrinsic microstructure regulation strategy substitutes conventional heterostructure establishing to modulate photocarrier dynamics of layered semiconductor photoanode. Firstly, an improved in-situ growth method is designed to construct vertically aligned ZnIn2S4 nanosheet array photoanode with highly exposed surface area and prominent two-dimensional (2D) feature for optimized carrier dynamics at interface with electrolyte. Secondly, controlled phase transition from hexagonal phase ZnIn2S4 (H-ZIS) to rhombohedral phase ZnIn2S4 (R-ZIS) is realized accompanied with evidently enhanced 2D feature via regulating ethanol ratio in precursor solvent, making it highly adjustable to construct two-phase-coexisting 2D photoanode (H@R-ZIS). Introducing R-ZIS to construct homostructure with H-ZIS not merely integrates more advantageous surface activity and photo absorption of R-ZIS, but more importantly realizes highly efficient real space separation of photogenerated electron-hole pairs via directional interfacial photocarrier migration between two phases. The optimum 2D H@R-ZIS achieves excellent PEC performance with photocurrent of 3.1 mA cm−2 at 1.2 VRHE, IPCE reaching 40 % and a record ABPE of 2.65 % at 0.36 VRHE. Such phase and facet modulation strategy will inform microstructure design and optimization of other layered metal sulfide for next-generation photoanodes.