Cu-Zn bimetallic-doped cobalt-based spinel catalysts for photothermal CO2 reduction: synergistic effects and defect engineering

Photothermal catalytic CO 2 hydrogenation via the reverse water–gas shift (RWGS) reaction enables sustainable CO production under mild conditions. However, the advancement of this promising technology is critically dependent on the development of high-performance catalysts, which continues to pose a key challenge in the field. Herein, a series of Cu x Zn 1-x Co 2 O 4 spinel catalysts with full solar spectrum absorption were synthesized via co-precipitation to synergize photothermal energy for efficient CO 2 conversion. The Cu/Zn co-doping strategy not only enhanced light absorption but also introduced abundant oxygen vacancies, fostering the formation of frustrated Lewis pairs (FLPs) that destabilize CO 2 ′s linear configuration and weaken C=O bonds. The optimized Cu 0.5 Zn 0.5 Co 2 O 4 catalyst demonstrated exceptional performance, achieving a CO 2 conversion rate of 418.7 mmol·g cat −1 ·h −1 with 93.1 % CO selectivity at 350 °C under light irradiation, alongside stable operation for more than 10 hours. The experimental characterization combined with theoretical calculation reveal that Cu 0.5 Zn 0.5 Co 2 O 4 possesses abundant oxygen vacancies, predominantly localized at the Zn tetrahedral sites. These structural defects play a crucial role in generating more active FLP sites, which in turn leads to significantly improved CO 2 activation efficiency. In-situ diffuse reflectance infrared Fourier transform spectroscopy ( in-situ DRIFTS) investigation elucidates key intermediates and the catalytic mechanism. This work provides a strategy for designing efficient non-precious metal photothermal catalysts through bimetallic doping and defect engineering to enhance CO 2 utilization.