In-Ti-Cu trimetallic sites mediated CO2 coordination model and enhanced surface frustrated Lewis pairs for controlling the selectivity of photoreduction of CO2

Abstract

The CuTi_xIn_5-xS₈ (TCIS) catalysts were prepared by introducing Ti sites into the hollow tubular CuIn₅S₈ lattice. The catalyst realized the selective change of products from CO to CH₃OH in the photoreduction of CO₂. The selectivity of CO in the photoreduction CO₂ products with CuIn₅S₈ is 81.67 %, and the yield is 7.35μmol.g⁻¹.h⁻¹, while the selectivity of CH₃OH with TCIS-2 is 96.89 %, and the yield is as high as 42.67μmol.g⁻¹.h⁻¹. A series of in situ characterizations and density functional theory (DFT) calculations results show that the excellent activity of TCIS-2 is mainly attributed to the formation of Ti^4+δ-S^2- enhanced surface frustrated Lewis pairs (SFLPS), and the construction of CO₂ coordination model mediated by In^3-δ-Ti^4+δ-Cu^2-δ trimetal sites. In this coordination model the peripheral electrons of In and Cu are transferred to CO₂, while the electrons on CO₂ are transferred to empty orbitals around Ti. In addition, by placing the catalyst on the gas-liquid contact surface for the reaction, it is beneficial to improve the yield and selectivity of methanol. This work not only provides an effective strategy for the trimetallic coordination models, but also provides a new idea for tailoring the selectivity of the CO₂ photoreduction.