In the efforts to achieve sustainability in photocatalysis, nonmetal-based catalysts such as graphitic carbon nitride (CN) are getting more attention due to their catalytic activity towards photosynthesis. Microporous organic polymers (MOPs) are also studied due to their gas separation properties 126 and potential photocatalytic properties, for example, CO2 photoreduction. Kung et al. reported a covalently linked graphitic carbon nitridemelamine-resorcinol-formaldehyde (MRF) microsphere polymers, which possesses photocatalytic properties for CO2 reduction to methanol. This material has efficient charge separation due to its covalent C-N bond between CN and MRF, which results in higher photocatalytic properties than CN and MRF alone by 21 and 10 times respectively.