In-vacancy engineered plate-like In(OH)3 for effective photocatalytic reduction of CO2 with H2O vapor

Abstract

In this work, a series of In(OH)3 with abundant indium vacancies were synthesized by hydrothermal method using mixed solvent of ethylenediamine(En) and water for photocatalytic reduction of CO2 with H2O vapor. The morphology, particle size, crystallinity, pore structure, and vacancy concentration of photocatalysts were successfully regulated by adjusting the ratio of En and water in mixed solvent, which were characterized by XRD, FT-IR, TG-DTA, SEM, HRTEM, UV–vis DRS, PL spectra, XPS, and EPR. Moreover, the effect of En/water ratio on the adsorption capacity to CO2 and photo-electrical properties of In(OH)3 were further investigated by in-situ FTIR, PL spectra, UV–vis DRS, CV, and EIS. In(OH)3 prepared in mixed solution exhibited much higher photocatalytic activity for CO2 reduction with H2O vapor compared to that prepared with water only solvent. The enhanced photocatalytic performance can be attributed to the special morphology, smaller particle size, larger BET surface area, and especially generated indium vacancies creating defect energy levels in the bandgap, which improved visible light absorption, carrier separation, and CO2 chemisorption. This work paves the way to enable a non-visible-light response material with high visible-light photocatalytic activity by regulating vacancy concentration via a facile method.