Fig. 1: The protonation steps and reaction network of CO2 conversion with H2O to C1 products.

During the photothermal catalytic CO2 conversion with H2O, light irradiates H2O molecules to split and provide protons and electrons to reduce CO2. It takes two protons and two electrons to generate CO, six protons and two electrons to generate CH3OH, and eight protons and two electrons to generate CH4.