Performance and Mechanism of a Commercial Cu/ZnO/Al ₂ O ₃ Catalyst for the Gas–Solid Photothermal Catalytic Reverse Water–Gas Shift Reaction

Photothermal catalysis has gained significant attention as a research hotspot area in recent years. Cu/ZnO/Al2O3, an important industrial catalyst for the water–gas shift reaction and methanol synthesis, has been extensively studied for decades. Considering the localized surface plasmon resonance characteristic inherent to Cu species within this catalyst, it is anticipated to display favorable photothermal catalytic performance. However, no relevant experimental reports have been published to date. Herein, we investigated a commercial Cu/ZnO/Al2O3 catalyst for the photothermal CO2 hydrogenation reaction. Unexpectedly, and yet reasonably, the catalyst achieved 100% CO selectivity with a CO production rate of 471.4 mmol gcat–1 h–1 under 1.5 W cm–2 light irradiation, which is 3.2 times higher than that obtained in the dark at the same catalyst surface temperature of 342.9 °C. The enhanced performance can be attributed to the synergistic effect of Cu and Zn that promotes photothermal conversion, facilitates the separation of photogenerated carriers, accelerates reactant activation, and thus drives the reaction forward. In situ/operando spectroscopies confirm that the RWGS reaction over Cu/ZnO/Al2O3 follows a redox mechanism, in which Cu species act as the active sites for CO2 conversion, with the redox transformation being Cu2+ ↔ Cu0/Cu+. This study provides a comprehensive evaluation of the photothermal CO2 hydrogenation performance of a commercial Cu/ZnO/Al2O3 catalyst, offering valuable mechanistic insights into the photothermal CO2 hydrogenation process within the Cu/Zn/Al systems.