Intrinsic Charge Polarization in Bi19 S27 Cl3 Nano Roads Promotes Selective C-C Coupling Reaction During Photoreduction of CO2 to Ethanol.

Obtaining multicarbon products via CO2 photoreduction is a major catalytic challenge involving multielectron mediated C-C bond formation. Complex design of multicomponent interfaces that are exploited to achieve this chemical transformation, often leads to untraceable deleterious changes in the interfacial chemical environment affecting CO2 conversion efficiency and product selectivity. Alternatively, robust metal centres having asymmetric charge distribution can effectuate C-C coupling reaction through the stabilization of intermediates, for desired product selectivity. However, generating inherent charge distribution in a single component catalyst is a difficult material design challenge. Here, we present a novel photocatalyst, Bi19 S27 Cl3 , which selectively converts CO2 to a C2 product, ethanol, in high yield under visible light irradiation. Structural analysis through Transmission Electron Microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy reveal the presence of charge polarized bismuth centres in Bi19 S27 Cl3 , which is well complemented by DFT calculation. The intrinsic electric field induced by charge polarized bismuth centres renders better separation efficiency of photogenerated electron-hole pair. Furthermore, charge polarized centres yield better adsorption of CO* intermediate and accelerate the rate determining C-C coupling step through the formation of OCCOH intermediate. Formation of these intermediates was experimentally mapped by in-situ FTIR spectroscopy and further confirmed by theoretical calculation. This article is protected by copyright. All rights reserved.