The synergistic Cu–metal oxide (Cu–MO_x) interface is critical for selective CO₂ hydrogenation to methanol, yet its mechanistic function, the central, long-debated feature of industrial Cu/ZnO/Al₂O₃, remains ambiguous. Using operando transient DRIFTS-SSITKA, we elucidate the roles of M⁺ sites (Zn²⁺, Ga³⁺, and In³⁺) on model Cu─M/SiO₂ catalysts prepared by surface organometallic chemistry (SOMC). X-ray absorption spectroscopy reveals that these promoters restructure from alloys after reduction to cationic species at the interface under reaction conditions. We find the promoter's electronic effect on formate bond strengths provides quantitative descriptors for both activity and selectivity. All catalysts follow a common formate spillover mechanism, with methoxy hydrogenation/desorption as the rate-limiting step. The intrinsic CH₃OH formation rate follows a Sabatier-type volcano with C─O bond strength, while selectivity correlates linearly with C─H bond strength (a proxy for the formate decomposition barrier). Cu─Ga/SiO₂ shows the fastest spillover, suppressing CO formation and yielding the highest selectivity; Cu─Zn/SiO₂ has optimal binding for the highest activity; In³⁺ binds formate too strongly, creating a kinetic trap on the strong-binding side of the volcano. These findings bring mechanistic clarity to the debated Cu─Zn(O) synergy, showing selectivity is governed by a balance of electronic stabilization and spillover dynamics.

On page 452, column 1 (lines 12?23) reads: H2 and CO chemisorption show an uptake of 0.91 molH2 molPd?1 and 0.61 molCO molPd ?1, respectively (Table 1, Supporting Information S6). Considering a 1:1 CO/Pd stoichiometry,32 the dispersion from CO chemisorption (D?CO) equals 61%, in a reasonable agreement with the dispersion from TEM (D?TEM 70%; Supporting Information S9).32 While H2 chemisorption is not effective for a determination of the metal dispersion of Pd nanoparticles due to the formation of a stable bulk hydride with larger particles (2.6 nm),32 a comparison of the H2 uptake and D?CO would correspond to approximately three hydrogen atoms per surface Pd.

The direct conversion of CO₂to CH₃OH represents an appealing strategy for the mitigation of anthropogenic CO₂emissions. Here, we report that small, narrowly distributed alloyed PdGa nanoparticles, prepared via surface organometallic chemistry from silica-supported Ga^IIIisolated sites, selectively catalyze the hydrogenation of CO₂to CH₃OH. At 230 °C and 25 bar, high activity (22.3 mol_MeOHmol_Pd^-1h^-1) and selectivity for CH₃OH/DME (81%) are observed, while the corresponding silica-supported Pd nanoparticles show low activity and selectivity. X-ray absorption spectroscopy (XAS), IR, NMR, and scanning transmission electron microscopy-energy-dispersive X-ray provide evidence for alloying in the as-synthesized material. In situ XAS reveals that there is a dynamic dealloying/realloying process, through Ga redox, while operando diffuse reflectance infrared Fourier transform spectroscopy demonstrates that, while both methoxy and formate species are observed in reaction conditions, the relative concentrations are inversely proportional, as the chemical potential of the gas phase is modulated. High CH₃OH selectivities, across a broad range of conversions, are observed, showing that CO formation is suppressed for this catalyst, in contrast to reported Pd catalysts.

Selective hydrogenation of CO₂ into methanol is a key sustainable technology, where Cu/Al₂O₃ prepared by surface organometallic chemistry displays high activity towards CO₂ hydrogenation compared to Cu/SiO₂, yielding CH₃OH, dimethyl ether (DME), and CO. CH₃OH formation rate increases due to the metal–oxide interface and involves formate intermediates according to advanced spectroscopy and DFT calculations. Al₂O₃ promotes the subsequent conversion of CH₃OH to DME, showing bifunctional catalysis, but also increases the rate of CO formation. The latter takes place 1) directly by activation of CO₂ at the metal–oxide interface, and 2) indirectly by the conversion of formate surface species and CH₃OH to methyl formate, which is further decomposed into CH₃OH and CO. This study shows how Al₂O₃, a Lewis acidic and non-reducible support, can promote CO₂ hydrogenation by enabling multiple competitive reaction pathways on the oxide and metal–oxide interface.