Ga-doped CeO2 solid solutions as promoters for Cu-based catalysts: Enhancing CO2 hydrogenation to methanol via optimized metal–support interaction

The low methanol selectivity of Cu/CeO₂ in CO₂ hydrogenation stems from weak metal–support interaction (MSI) and dominant reverse water gas shift (RWGS) pathways. Ga-doped CeO₂ solid solutions are proposed to enhance MSI and oxygen vacancies, addressing insufficient CO₂ activation and H₂ dissociation in conventional Cu-based catalysts. CuO-CeGaₓOₓ (y = 0–0.3) catalysts were synthesized via co-precipitation. Structural and catalytic properties were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed H₂ reduction (H₂-TPR), temperature-programmed desorption of adsorbed CO₂ (CO₂-TPD), and transmission electron microscopy (TEM). Ga doping (y = 0.2) optimized CeGaOₓ solid solution formation, achieving the highest specific surface area (142 m²/g), and Cu⁰ content (73.4%). At 260°C, CuO-CeGa₀.₂Oₓ showed 12.6% X_CO₂, 57% S_CH₃OH, and STY = 308.8 g_MeOH Kgcat⁻¹ h⁻¹. Enhanced oxygen vacancies and moderate basic sites suppressed RWGS, favouring methanol pathways. Stability tests confirmed 180 h performance retention without structural degradation. Ga doping strengthens MSI via CeGaOₓ solid solutions, promoting oxygen vacancies and Cu⁰ dispersion. This dual optimization enhances CO₂ adsorption, H₂ dissociation, and methanol selectivity while suppressing CO byproducts. The CuO-CeGa₀.₂Oₓ catalyst demonstrates industrial potential, offering a design strategy for high-performance CO₂ hydrogenation catalysts.