Zinc–Porphyrin Conjugated Polymer Nanosheets with Accelerated Charge Transfer Dynamics for Selective Photocatalytic CO2 Reduction to CH4

The photocatalytic reduction of CO2 into methane has garnered significant attention; however, the multiple electron and proton processes involved in CO2 reduction often result in low products selectivity. Herein, we present a conjugated polymer photocatalyst (ZnTP-PDA), composed of Zn-porphyrin and pyrazine units, which effectively drives the photoconversion of CO2 to CH4. The nanosheet structure of ZnTP-PDA offers numerous absorption sites and exposes catalytic active centers, thereby enhancing reaction kinetics. Experimental analyses and theoretical calculations demonstrate that the incorporated Zn sites improve CO2 adsorption capability and charge separation efficiency, optimizing both reaction kinetics and thermodynamics, and facilitating the hydrogenation of the key intermediate *CO to generate CH4. Consequently, ZnTP-PDA exhibits an impressive CH4 generation rate of 49.2 μmol h–1 and a selectivity of 90.3% without the use of any photosensitizers, which is approximately 17.6 times higher than that of the pristine TP-PDA under visible light irradiation. This study underscores the beneficial effects of active site engineering on conjugated polymer photocatalysts in tailoring product selectivity during photocatalytic CO2 reduction.