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

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 photo -anode. 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 in-tegrates 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 photo -current 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.

Automated summary

Exploring semiconductor photoanodes with optimized carrier dynamics has always been an important goal in the field of photoelectrochemical energy conversion. In this study, by regulating the microstructure of layered semiconductor photoanodes, a vertically aligned ZnIn2S4 nanosheet array photoanode with highly exposed surface area and a two-phase coexisting 2D photoanode (H@R-ZIS) were successfully constructed. The H@R-ZIS photoanode exhibited excellent PEC performance, including high photocurrent, high IPCE, and a record ABPE, indicating the significance of phase and facet modulation strategy in designing and optimizing next-generation photoanodes.