Research Progress on the Effects of Cu-Based Catalysts on CO₂ Hydrogenation to Methanol

CO₂ hydrogenation to methanol is an important route for reducing carbon emissions and utilizing hydrogen energy, and multiple catalytic systems have been developed. Among them, Cu-based catalysts remain an important class because of their low cost and substantial research foundation. This review focuses on structural regulation of Cu-based catalysts and discusses the effects of Cu particle size, the Cu⁰/Cu⁺ ratio, metal–support interfaces, oxygen vacancies, spinel supports, and alloying on reaction performance. The function of Cu-based catalysts is attributed mainly to multisite cooperation. Cu⁰ primarily supplies hydrogen species, whereas Cu⁺ and oxide interfaces more readily stabilize oxygenated intermediates. Excessive pursuit of Cu dispersion or defect concentration is not advisable. A more rational direction is to maintain moderate CO₂ adsorption, stable adjacent Cu⁰/Cu⁺ structures, and low interfacial deactivation during the reaction.