Lanthanum-mediated enhancement of nickel nanoparticles for efficient CO2 methanation.

• High surface area catalyst prepared by a simple ammonia evaporation method. • La doping improves strong MSI and Ni dispersion. • La doping enhances CO 2 adsorption and decreases CO 2 adsorption energy. • Compelling low-temperature CO 2 methanation performance and stability. • Reaction intermediates include formate and CO* in low-temperature CO 2 methanation. The investigation into CO 2 conversion technologies has gained momentum due to escalating concerns about climate change and the pressing need for sustainable energy sources. While Ni-based catalysts have shown promise in CO 2 methanation, they often exhibit moderate activity. In this study, we sought to address this limitation by incorporating La into Ni nanoparticles supported on SiO 2 using the ammonia evaporation method. The La-doped Ni/SiO 2 catalyst demonstrated a significant improvement in CO 2 conversion, achieving a competitive 71.1 % compared to the 40.2 % observed with the Ni/SiO 2 catalyst at 275 °C. This improvement is evident in the high space–time yield of methane (STY CH4) at 227.3 mmol/(g·h) and a turnover frequency of (TOF CO2) at 0.36 s−1. The incorporation of La species modifies the electronic properties of Ni through electron transfer from Ni to La, resulting in a Ni-La interaction effect. Temperature-programmed reduction and desorption, probed by H 2 and CO 2 , reveal enhanced hydrogen atom spillover and stronger CO 2 adsorption capacity on the La-doped Ni-based catalyst. Density functional theory (DFT) calculations unraveled the underlying mechanisms of La-mediated enhancement, elucidating lower adsorption for CO 2 energy barrier and facilitated activation of C O bonds on the La-doped Ni-based catalyst. In-situ DRIFTS results indicated that, despite both catalysts following a CO pathway, La-doped Ni/SiO 2 possessed more accessible active sites for CO 2 methanation, whereas Ni/SiO 2 shows higher occupancy of active sites by adsorbed CO and formate species. [ABSTRACT FROM AUTHOR]