3D Hierarchical ZnIn₂S₄ Nanosheets with Rich Zn Vacancies Boosting Photocatalytic CO₂ Reduction

Abstract

Zinc vacancy (VZn) is successfully introduced into 3D hierarchical ZnIn2S4 (3D‐ZIS). The photo‐electrochemical experiments demonstrate that the charge separation and carrier transfer are more efficient in the 3D‐ZIS with rich VZn. Of note, for the first time, it is found that VZn can decrease the carrier transport activation energy (CTAE), from 1.14 eV for Bulk‐ZIS (Bulk ZnIn2S4) to 0.93 eV for 3D‐ZIS, which may provide a feasible platform for further understanding the mechanism of photocatalytic CO2 reduction. In situ Fourier transform infrared (FT‐IR) results reveal that the presence of rich VZn ensures CO2 chemical activation, promoting single‐electron reduction of CO2 to CO2−. In addition, in situ FT‐IR and CO2 temperature programmed desorption results show that VZn can promote the formation of surface hydroxyl. To the best of current knowledge, there are no reports on the photoreduction of CO2 simply by virtue of 3D‐ZIS with VZn and few literature reports on the photocatalytic reduction of CO2 concerned with CTAE. Additionally, this work finds that surface hydroxyl may play a crucial role in the process of CO2 photoreduction. The work may provide some novel ways to ameliorate solar energy conversion performance and a better understanding of photoreaction mechanisms.

Atomic‐Level Reactive Sites for Semiconductor‐Based Photocatalytic CO2 Reduction

“…He et al synthesised 3D hierarchical ZnIn 2 S 4 nanosheets with rich Zn vacancies, and explored surface adsorption of CO 2 . CO 2 TPD indicated a stronger peak at 242.7 °C than that for bulk ZnIn 2 S 4 .…”

“…This has received therefore significant attention from researchers. Different vacancies are fabricated in crystals including oxygen vacancy, sulphur vacancy, nitrogen vacancy, and some cation vacancies . Some researchers introduce dual vacancies in the same material.…”

Nanostructured Metal Sulfides: Classification, Modification Strategy, and Solar‐Driven CO2 Reduction Application

“…through an in‐situ impedance characterization (Figure 22g) and analysis over hierarchical ZIS microspheres composed of vertically distributed nanoplates. [ 174 ] Up to about 19 times improvement activity for CO 2 reduction to CO (14.6 µmol g −1 h −1 for bulk ZIS to 276.7 µmol g −1 h −1 for ZIS microspheres with rich zinc vacancy) was accomplished under simulated solar irradiation, convincing that abundant zinc vacancy on the surface of ZIS resulted in the reduction of carrier transport activation energy and the large probability of CO 2 to form CO 2 − (Figure 22i). In regard to zinc vacancy, the structural defect caused by the non‐stoichiometric composition were unveiled to have a negative effect on the separation and migration of charge carriers.…”

“…g) The impedance plots of 3D‐ZIS at various temperatures. [ 174 ] Copyright 2019, Wiley‐VCH. h) Proposed mechanism of photocatalytic reaction in the I) absence and II) presence of composites faults.…”

The Active Sites Engineering of Catalysts for CO2 Activation and Conversion

“…Reproduced with permission. [ 96 ] Copyright 2019, Wiley‐VCH. d) DFT‐calculated adsorption energies of CO 2 and H 2 O molecules on the V o ‐doped ZnAl‐LDH system and bulk ZnAl‐LDH.…”