Photoelectrochemical and first-principles investigation on interactions between zinc ion and halide perovskite surface in the aqueous solution

•The experimental photovoltage increases by 0.2 V upon the visible light illumination.•A non-negligible specific capacitance of the Zn2+/perovskite system is produced.•Structural, electronic and optical properties of Zn2+/CH3NH3PbI3 system are revealed.•Zinc ion diffuses efficiently on the halide perovskite surface. Understanding the interactions between the metal ions and the halide perovskite materials in the aqueous solution are critical to realize next-generation energy conversion and storage systems. In this manuscript, we perform photoelectrochemical and first-principles investigations to understand the fundamental interactions between the zinc ions and the CH3NH3PbI3 halide perovskite surfaces in the aqueous environment and evaluate their electronic and optical properties toward the opto-ionic and photo-rechargeable applications. The photovoltage of the CH3NH3PbI3/ZnSO4/Zn system increases by 0.2 V upon the visible light illumination while small yet non-negligible specific capacitance of the aqueous-based Zn2+/perovskite system remains relatively stable in 50 cycles. The first-principles calculations reveal the detailed nanoscopic structural, electronic and optical properties of the Zn2+/CH3NH3PbI3 system, and suggest the efficient surface diffusion of the zinc ion on the halide perovskite surface. The adsorption of one zinc ion on the perovskite surface leads to a Zn…I distance of 2.57 Å. The theoretical capacity of the CH3NH3PbI3 halide perovskite system is 172.9 mAh/g, and the specific capacitance maintains at 14 mF/g in the first few charge-discharge cycles, and slightly decreases to 12.5 mF/g at 40th cycle. Suggestions to engineer the aqueous-based ion/perovskite systems to improve the light-driven photo-rechargeable properties and energy storage performance are provided. The presents study provides a theoretical platform to advance the halide perovskite materials for the ion-based energy applications. [Display omitted]