New reaction pathway induced by N-deficient conjugated polymer-supported bimetallic oxide quantum dot S-scheme heterojunction for benzyl alcohol oxidation in water

Abstract

The catalytic conversion of aromatic alcohols to their corresponding carbonyls under mild conditions is challenging because of their low selectivity and activity. A 0D/2D based S-scheme heterojunction material with bimetallic oxide quantum dots (NixFe1-xO QD) and nitrogen-deficient conjugated polymers, such as g-C3N4 (NvCN), was designed for the photocatalytic conversion of benzyl alcohols to benzaldehyde/benzoic acid using simulated solar light. The optimized Ni0.5Fe0.5O QD/NvCN (NFO/NvCN) hybrid catalyst exhibited excellent conversion (85%) and selectivity (98%) for photocatalytic oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) in an aqueous medium (88%) and for benzoic acid (BzA) under dilute alkaline conditions (99%). The structure-activity relationship was established using catalytic activity data, surface physicochemical characteristics, optoelectronic characteristics, and scavenging studies. The band alignment of the heterojunction converts the type-I junction into a type-II junction and follows S-scheme charge dynamic pathways through the nitrogen vacancy pathways, which can accelerate the separation and transfer of photogenerated charge carriers. Mechanistic pathways have been proposed based on O–H bond cleavage by electrons and C–H bond cleavage by holes. Hybrid materials based on defect-rich supports and bimetallic oxide-quantum dot interactions are promising catalysts that can compete with the best photocatalysts.