Synergistic Functionality of Dopants and Defects in Co‐Phthalocyanine/B‐CN Z‐Scheme Photocatalysts for Promoting Photocatalytic CO2 Reduction Reactions

The realization of solar‐light‐driven CO2 reduction reactions (CO2 RR) is essential for the commercial development of renewable energy modules and the reduction of global CO2 emissions. Combining experimental measurements and theoretical calculations, to introduce boron dopants and nitrogen defects in graphitic carbon nitride (g‐C3N4), sodium borohydride is simply calcined with the mixture of g‐C3N4 (CN), followed by the introduction of ultrathin Co phthalocyanine through phosphate groups. By strengthening H‐bonding interactions, the resultant CoPc/P‐BNDCN nanocomposite showed excellent photocatalytic CO2 reduction activity, releasing 197.76 and 130.32 µmol h−1 g−1 CO and CH4, respectively, and conveying an unprecedented 10‐26‐time improvement under visible‐light irradiation. The substantial tuning is performed towards the conduction and valance band locations by B‐dopants and N‐defects to modulate the band structure for significantly accelerated CO2 RR. Through the use of ultrathin metal phthalocyanine assemblies that have a lot of single‐atom sites, this work demonstrates a sustainable approach for achieving effective photocatalytic CO2 activation. More importantly, the excellent photoactivity is attributed to the fast charge separation via Z‐scheme transfer mechanism formed by the universally facile strategy of dimension‐matched ultrathin (≈4 nm) metal phthalocyanine‐assisted nanocomposites. The BNDCN material has remarkably improved photocatalytic CO2 RR activity due to its CB and VB positions being expertly modulated to create ideal band structures for CO2 RR driving force and visible light absorption. The material's designed electronic architecture includes abundant unsaturated sites and strong interlayer CN interaction, which result in efficient electron excitation and accelerated charge transfer kinetics.