A precursor-anchoring strategy to fabricate monolithic Zn, N, O-doped carbon for thermal and photothermal CO2 cycloaddition

Hierarchical three-dimensional (3D) porous architectures are critical for overcoming mass-transfer limitations in catalytic CO 2 conversion, yet their scalable integration with atomically dispersed active sites remains challenging. Herein, we report a facile precursor-anchoring strategy to fabricate monolithic Zn, N, O-codoped porous carbon (ZnNC-900) via carbonization of melamine sponge uniformly coated with a Zn 2+ -polydopamine layer. The melamine sponge provides a continuous 3D macroporous network that facilitates efficient reactant flow, whereas dopamine-mediated chelation generates Zn and N sites along with oxygen functionalities. This unique structure not only enhances the adsorption and activation of both CO 2 and epoxides but also enables a pronounced synergistic photothermal-photocatalytic effect under light irradiation. Under mild conditions of either thermal (80 °C, 0.1 MPa) or room-temperature light irradiation (350 mW/cm 2 ), ZnNC-900 achieves a high yield of >99% within 12 h for CO 2 cycloaddition with epichlorohydrin. Furthermore, the catalyst displays robust stability and broad substrate tolerance, underscoring its practical potential for CO 2 fixation.