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

The photocatalytic reduction of CO 2 into methane has garnered significant attention; however, the multiple electron and proton processes involved in CO 2 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 CO 2 to CH 4 . 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 CO 2 adsorption capability and charge separation efficiency, optimizing both reaction kinetics and thermodynamics, and facilitating the hydrogenation of the key intermediate *CO to generate CH 4 . Consequently, ZnTP-PDA exhibits an impressive CH 4 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 CO 2 reduction.