Solid Solution Derived Cu Clusters on Partially Reduced CuCeO2 with Abundant Oxygen Vacancies Enable Efficient Reverse Water Gas Reaction

Abstract

The reverse water gas shift (RWGS) reaction provides a convenient approach to convert CO₂ to CO, which facilitates to achieve the goals of carbon peaking and carbon neutrality. Herein, the Cu/CeO₂ catalyst prepared by a co-precipitation method using a mixture of Na₂CO₃ and NaOH at pH of 10 (sample Cu/CeO₂-10) achieved an intrinsic reaction rate of 428.4 mmol ⋅ g_cat⁻¹ ⋅ h⁻¹ with 100 % CO selectivity at 400 °C and CO₂/H₂ ratio of 1 : 4, which is much higher than Cu/CeO₂ prepared by impregnation and other methods. Various characterizations showed the highest fraction of CuCeO₂ solid solution in the calcined Cu/CeO₂-10, and formed highly dispersed Cu clusters (~2.5 nm) on partially reduced CuCeO₂ solid solution with abundant of oxygen vacancies upon reduction. The Cu and oxygen vacancies facilitates the activation of H₂ and CO₂, respectively, resulting in lowered H₂ and CO₂ reaction orders. As a result, the synergy between the two components enhanced the overall RWGS activity with lowered activation energy. Moreover, the optimal catalyst is very stable in 24 h stability test without detectable agglomeration of Cu clusters.