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Conversion of CO2 into value-added chemicals is regarded as an effective way to reduce carbon emissions and improve the carbon recycling economy. In the process of hydrogenation of CO2 to CH4, nickel (Ni) has been extensively investigated due to its promising activity and easy availability. However, the inferior performance at low temperatures of Ni-based catalysts and the tendency of sintering at high temperatures lead to a rapid decline in activity, which hinders their large-scale applications. In this study, mesoporous silicas with highly ordered mesoporous structures but different pore symmetries and textural properties have been investigated as supports to synthesize Ni-based catalysts modified by La2O3. The effect of mesoporous symmetries and textural properties of the silica support on catalytic performance has been reasonably revealed. The catalysts supported on optimized silica with bicontinuous three-dimensional cubic pore symmetry exhibit considerably enhanced activity and stability in long-term CO2 methanation, which is attributed to the high dispersion of metal particles and the better mass transfer performance of interconnected mesopores in the silica support. [ABSTRACT FROM AUTHOR]

Product selectivity of solar‐driven CO2 reduction and H2O oxidation reactions has been successfully controlled by tuning the spatial distance between Pt/Au bimetallic active sites on different crystal facets of CeO2 catalysts. The replacement depth of Ce atoms by monatomic Pt determines the distance between bimetallic sites, while Au clusters are deposited on the surface. This space configuration creates a favourable microenvironment for the migration of active hydrogen species (*H). The *H is generated via the activation of H2O on monatomic Pt sites and migrate towards Au clusters with a strong capacity for CO2 adsorption. Under concentrated solar irradiation, selectivity of the (100) facet towards CO is 100 %, and the selectivity of the (110) and (111) facets towards CH4 is 33.5 % and 97.6 %, respectively. Notably, the CH4 yield on the (111) facet is as high as 369.4 μmol/g/h, and the solar‐to‐chemical energy efficiency of 0.23 % is 33.8 times higher than that under non‐concentrated solar irradiation. The impacts of high‐density flux photon and thermal effects on carriers and *H migration at the microscale are comprehensively discussed. This study provides a new avenue for tuning the spatial distance between active sites to achieve optimal product selectivity. [ABSTRACT FROM AUTHOR]

The recovery of valuable metals from spent ternary lithium-ion batteries (LIBs) has recently garnered significant attention due to the imperatives of the circular economy and environmental management. While the reclamation of lithium is generally straightforward, the hydrometallurgical methods most frequently employed for leaching and separating the remaining nickel, cobalt, and manganese from spent electrode material often yield secondary liquid and solid wastes. In this study, we present a mechanochemical strategy aimed at repurposing lithium-removed spent ternary LIBs cathode material as a precursor for perovskite oxides through a straightforward and scalable solid-state high-energy ball-milling synthesis. By optimizing the synthesis procedure, we have obtained a perovskite catalyst composed of LaNi0.6Co0.2Mn0.2O3 with a trace amount of phase-separated surface NiO nanocrystals. This catalyst demonstrates outstanding performance in the low-temperature oxidation of CO, exhibiting no degradation in performance over extended periods of service. Notably, it achieves a T50 of 162 °C and a T90 of 197 °C, which compares favorably with previously reported perovskite catalysts prepared via wet synthesis, utilizing fine chemicals as precursors. This approach not only presents a novel method for valorizing spent ternary LIBs but also expands the repertoire of metal precursors available for oxidation catalysts. [ABSTRACT FROM AUTHOR]

H2O dissociation plays a crucial role in solar-driven catalytic CO2 methanation, demanding high temperature even for solar-to-chemical conversion efficiencies <1% with modest product selectivity. Herein, we report an oxygen-vacancy (Vo) rich CeO2 catalyst with single-atom Ni anchored around its surface Vo sites by replacing Ce atoms to promote H2O dissociation and achieve effective photothermal CO2 reduction under concentrated light irradiation. The high photon flux reduces the apparent activation energy for CH4 production and prevents Vo from depletion. The defects coordinated with single-atom Ni, significantly promote the capture of charges and local phonons at the Ni d-impurity orbitals, thereby inducing more effective H2O activation. The catalyst presents a CH4 yield of 192.75 µmol/cm2/h, with a solar-to-chemical efficiency of 1.14% and a selectivity ~100%. The mechanistic insights uncovered in this study should help further the development of H2O-activating catalysts for CO2 reduction and thereby expedite the practical utilization of solar-to-chemical technologies. This work reports a single-atom Ni incorporated CeO2 catalyst that boosts the efficiency of solar CO2 reduction under concentrated light irradiation. [ABSTRACT FROM AUTHOR]