Equilibrium photo-thermodynamics enables a sustainable methanol synthesis

Methanol synthesis from greenhouse gas CO₂ and green H₂ is envisioned to be a promising approach for achieving carbon neutrality and sustainability. Although this process is traditionally carried out by thermal heterogeneous catalysis, the methanol production rate and selectivity, however, are limited by thermodynamic constraints. To circumvent this challenge, we discovered that photons could break the limitations of traditional methanol synthesis by shifting the thermodynamic equilibrium to a photo-thermodynamic state. Under light irradiation, about 80% of the photogenerated charge carriers were found to be directed to the methanol synthesis pathway, leading to a 17.5-fold increase in the methanol production rate to 1,757.1 μmol g⁻¹ h⁻¹ and a concomitant boost in selectivity. Overall, this advance emphasizes the advantages provided by light in the synthesis of green methanol and provides new insights into reaction pathway regulation through light intensity and wavelength, know-how which can be expanded to other solar-powered heterogeneous catalytic processes.