A hydrophilic porphyrin-based COF to reduce CO2 and nitrite in situ for photoelectrochemical catalysis synthesis of urea

Porphyrin-based photocatalysts exhibit superior photoelectronic properties, photothermal stability, and structural diversity. A hydrophilic covalent organic framework (COF_PP-DRS) was synthesized by linking aldolized tetrabromophenylporphyrin (PP) with dopamine(DA) and resveratrol(Res) copolymers via Schiff base reactions. It unfolded good CO2 reduction reaction (CO2RR) performance under photoelectrocatalytic (PEC) conditions, achieving a 25% higher catalytic efficiency than PP. This photocatalyst enabled urea (CO(NH2)2) synthesis from CO2 and NO2− while co-producing NH3, HCOOH, and CO. It exhibited broad pH tolerance (pH 4–10). Infrared data revealed that NO2− and CO2 adsorbed on the catalyst surface, formed *NO2 and *OCO intermediates, respectively. Sequential hydrogenation and dehydration steps yielded *NH and *CO, which coupled in situ to form CO(NH2)2. This work present a new COFs material for a green way to photoelectrocatalytic urea synthesis.