Boosting photothermal reverse water gas shift reaction performance by creating oxygen vacancies in Ni/MgO catalysts

The conversion of CO 2 to CO via the reverse water-gas shift (RWGS) reaction is crucial for CO 2 hydrogenation. However, conventional thermal catalysis relies heavily on fossil fuels and fails to achieve carbon neutrality. Photothermal catalysis offers a promising alternative pathway for efficient CO 2 conversion. Yet, enhancing CO 2 adsorption and activation for high activity and selectivity remains a challenge in RWGS reactions. In this article, a series of Ni supported catalysts (Ni/MgO -x , where x  = 1.2, 2.4, and 3.6) with abundant oxygen vacancies (Ovs) were prepared using a simple combustion method with magnesium acetate (Mg(CH 3 COO) 2 ) and urea as precursors. The results indicate that Ni/MgO -x catalysts with higher Ovs concentrations exhibit enhanced efficiency compared to Ni/MgO catalysts. The optimized catalyst achieved a high CO yield rate (12 mmol g −1  h −1 ), which was 36 times greater than that of the control catalyst under 1 W cm −1 lamp irradiation at 300 °C. Detailed characterization and density functional theory (DFT) results revealed an HCOO* reaction pathway and demonstrated the role of excess Ovs in CO 2 adsorption, activation, and reduction of the RWGS reaction activation energy. This research explores novel approaches for RWGS based on MgO supports for efficient CO 2 adsorption and activation, coupled with low-temperature synergistic photothermal effects.