Insights into La3+ and Nd3+ doping in CeO2-supported Rh catalysts: Enhancing CO2 hydrogenation and selectivity modulation

• Nd 3+ and La 3+ seamlessly integrate into the CeO 2 lattice, avoiding segregation. • Quantum mechanical calculations reveal that La 3+ diffuses into the bulk, while Nd 3+ localizes near surface oxygen vacancies. • Nd 3+ and La 3+ doping significantly alters catalyst behavior, affecting conversion rates and product selectivity. • Nd 3+ doping boosts methane production, La 3+ increases carbon monoxide formation. • Operando FTIR measurements the formation of Rh-carbonyls species from formate decomposition during the CO2 conversion. Here, we report the impact of incorporating La 3+ and Nd 3+ into Rh/CeO 2 catalysts for CO 2 hydrogenation at atmospheric pressure. The Nd-doped catalyst promotes methane production, while the La-doped favors carbon monoxide generation. Structural characterization techniques confirm the successful incorporation of both cations into the CeO 2 matrix without phase segregation. Notably, Nd 3+ is predominantly located on the CeO 2 surface, whereas La 3+ diffuses throughout the lattice. Quantum mechanical calculations reveal that La ions are mainly situated away from surface oxygen vacancies, while Nd ions are preferentially found near these defects, which aligns with the experimental observations. In situ FTIR analysis shows that CO 2 adsorption is enhanced in the doped catalysts, with adsorption intensity correlating with CO 2 conversion in the order of Rh/Ce < Rh/CeLa < Rh/CeNd. This indicates a direct relationship between catalytic performance and CO 2 adsorption capacity, with the higher surface concentration of Nd contributing to higher CO 2 adsorption compared to La doped catalysts. The presence of Nd facilitates hydrogen spillover, enhancing methane production, whereas La restricts this step, promoting carbon monoxide generation from formate decomposition. Quasi in situ XPS analyses indicate that Rh 0 -CO species in undoped catalysts arise from CO 2 dissociation, while in doped materials, they originate from formate dehydroxylation. Overall, this work offers valuable insights for developing more effective catalysts for CO 2 hydrogenation, enabling controlled selectivity between methane and carbon monoxide.