A nickel gallium oxide chlorophyll mimic for green methanol synthesis.

Abstract

Light-driven methanol synthesis from CO₂ provides a sustainable fuel source and approach to carbon neutralization. Mimicking natural photosynthesis could improve gas-solid photocatalytic efficiency, but it remains highly challenging due to the absence of well-organized mass and charge transfer networks in artificial materials. Herein, we report a chlorophyll-mimicking, nano-pigment nickel gallium oxide, which facilitates discrete light/dark reactions and proton-mediated charge transfer for efficient photocatalytic hydrogenation of CO₂ to methanol. This nano-pigment features surface frustrated Lewis pairs, enabling heterolytic hydrogen splitting into H^- and H⁺. The H^- acts analogously to nicotinamide adenine dinucleotide phosphate in natural photosynthesis, with Ni(II)/Ni(III) and OH(-I) respectively serving as conduits for ion transport of H^- and H⁺ to the Ni site, where they subsequently react with CO₂, mimicking natural carbon fixation. This approach establishes a chlorophyll-mimetic structure for photocatalytic stepwise CO₂ hydrogenation, achieving 3.0% quantum efficiency, 3.20 mmol·h^-1·g^-1 methanol activity, and 79.6% selectivity.