Constructing porous aluminum borate/polymeric carbon nitride for efficient carbon dioxide capture and photocatalytic conversion.

Photocatalytic CO2 reduction technology is a current research hotspot in negative carbon technologies, yet it faces bottlenecks such as insufficient CO2 capture capacity of catalysts and low separation efficiency of photogenerated carriers. This study aims to construct a photocatalyst integrating efficient CO2 capture and photocatalytic conversion by leveraging the adsorption capacity of porous aluminum borate and the superior photocatalytic capability of carbon nitride. Porous aluminoborate frameworks (PKU) was synthesized via a solid-state reaction and interfacially coupled with polymeric carbon nitride (PCN) prepared through ammonium formate-urea calcination to fabricate the adsorption-catalysis bifunctional composite catalyst PKU/PCN. Characterization results revealed that PKU exhibits a rod-like stacking structure, PCN displays a thin-sheet morphology, and the composite PKU/PCN features a nanorod-inserted nanosheet architecture with uniform elemental distribution. While the crystal structures and structural characteristics of individual components remained unaltered, the average pore size significantly increased. Photoelectrochemical tests and in situ characterizations demonstrated that the introduction of PKU markedly enhanced the local CO2 concentration on the PCN surface, facilitating the generation and enrichment of key intermediates (*COOH and *CHO) and accelerating the CO2 reduction process. The composite catalyst achieved CO and CH4 production rates of 40.43 and 25.02 μmol·g-1·h-1, respectively, corresponding to 2-fold and 1.5-fold improvements over pristine PCN, while exhibiting excellent stability. This work provides new insights for designing CO2 reduction materials with integrated high-efficiency adsorption and catalytic functionalities.