Exploring a Ni–N₄ Active Site‐Based Conjugated Microporous Polymer Z‐Scheme Heterojunction Through Covalent Bonding for Visible Light‐Driven Photocatalytic CO₂ Conversion in Pure Water

Abstract Designing photocatalysts with efficient charge transport and abundant active sites for photocatalytic CO₂ reduction in pure water is considered a potential approach. Herein, a nickel‐phthalocyanine containing Ni–N₄ active sites‐based conjugated microporous polymer (NiPc‐CMP), offering highly dispersed metal active sites, satisfactory CO₂ adsorption capability, and excellent light harvesting properties, is engineered as a photocatalyst. By virtue of the covalently bonded bridge, an atomic‐scale interface between the NiPc‐CMP/Bi₂WO₆ Z‐scheme heterojunction with strong chemical interactions is obtained. The interface creates directional charge transport highways and retains a high redox potential, thereby enhancing the photoexcited charge carrier separation and photocatalytic efficiency. Consequently, the optimal NiPc‐CMP/Bi₂WO₆ (NCB‐3) achieves efficient photocatalytic CO₂ reduction performance in pure water under visible‐light irradiation without any sacrificial agent or photosensitizer, affording a CO generation rate of 325.9 µmol g⁻¹ with CO selectivity of 93% in 8 h, outperforming those of Bi₂WO₆ and NiPc‐CMP, individually. Experimental and theoretical calculations reveal the promotion of interfacial photoinduced electron separation and the role of Ni–N₄ active sites in photocatalytic reactions. This study presents a high‐performance CMP‐based Z‐scheme heterojunction with an effective interfacial charge‐transfer route and rich metal active sites for photocatalytic CO₂ conversion.