Engineering Catalytic Interfaces in Cu^δ+/CeO₂-TiO₂ Photocatalysts for Synergistically Boosting CO₂ Reduction to Ethylene

Abstract

Photocatalytic CO2 conversion into a high-value-added C2 product is a highly challenging task because of insufficient electron deliverability and sluggish C–C coupling kinetics. Engineering catalytic interfaces in photocatalysts provides a promising approach to manipulate photoinduced charge carriers and create multiple catalytic sites for boosting the generation of C2 product from CO2 reduction. Herein, a Cuδ+/CeO2-TiO2 photocatalyst that contains atomically dispersed Cuδ+ sites anchored on the CeO2-TiO2 heterostructures consisting of highly dispersed CeO2 nanoparticles on porous TiO2 is designedly constructed by the pyrolytic transformation of a Cu2+-Ce3+/MIL-125-NH2 precursor. In the designed photocatalyst, TiO2 acts as a light-harvesting material for generating electron–hole pairs that are efficiently separated by CeO2-TiO2 interfaces, and the Cu–Ce dual active sites synergistically facilitate the generation and dimerization of *CO intermediates, thus lowering the energy barrier of C–C coupling. As a consequence, the Cuδ+/CeO2-TiO2 photocatalyst exhibits a production rate of 4.51 μmol–1·gcat –1·h–1 and 73.9% selectivity in terms of electron utilization for CO2 to C2H4 conversion under simulated sunlight, with H2O as hydrogen source and hole scavenger. The photocatalytic mechanism is revealed by operando spectroscopic methods as well as theoretical calculations. This study displays the rational construction of heterogeneous photocatalysts for boosting CO2 conversion and emphasizes the synergistic effect of multiple active sites in enhancing the selectivity of C2 product.

Selective Photocatalytic Oxidation of Methane to Oxygenates over Cu–W–TiO2 with Significant Carrier Traps

“…The number of oxygen vacancies increased obviously after metal doping, especially for Cu–W–TiO 2 . Low-temperature electron paramagnetic resonance (EPR) was performed to determine the surface oxygen vacancies and Ti 3+ state (Figure b), and the strongest EPR signal of oxygen vacancies was found at g = 1.991 for Cu–W–TiO 2 . Additionally, the EPR signal intensity of Ti 3+ species characterized by two special peaks at the g -values of 1.98 and 2.00 was positively correlated with the oxygen vacancy concentration based on XPS results.…”

Photocatalytic CO2conversion: from C1 products to multi-carbon oxygenates

“…For instance, a Cu δ + /CeO 2 –TiO 2 photocatalyst containing atomically dispersed Cu δ + sites that were anchored on a CeO 2 –TiO 2 heterostructure was constructed by the pyrolytic transformation of Cu 2+ –Ce 3+ /MIL-125-NH 2 precursors. 47 Under simulated sunlight irradiation, this photocatalyst exhibited a production rate of 4.51 μmol g −1 h −1 and 73.9% selectivity in terms of electron utilization for conversion of CO 2 to C 2 H 4 on bimetallic Cu–Ce reactive sites (Fig. 3d).…”

“…(d) Photocatalytic CO 2 reduction to ethylene over Cu δ+ /CeO 2 -TiO 2 . 47 Copyright 2022, American Chemical Society. (e) Schematic illustration of the photocatalytic CO 2 conversion to acetone over ZDC/Ts catalysts.…”

“…9e and f ). 47 The function of TiO 2 in this system was considered as a light-harvesting material for generating electron-hole pairs, which were then efficiently separated by the formed interfaces between CeO 2 and TiO 2 . The Cu-Ce dual active sites in CeO 2 /TiO 2 interface synergistically facilitated the generation and dimerization of *CO intermediates, benefiting the lower energy barrier of C-C coupling.…”

“…(e) FT-EXAFS spectra and (f) wavelet-transform (WT)-EXAFS for the k 3 -weighted Cu K-edge. 47 Copyright 2022, American Chemical Society. (g) The schematic illustration of Zn-O-Ge sites for boosting CO 2 reduction to CH 3 COOH.…”