Highly efficient hydroxyethyl radicals-mediated photocatalytic benzimidazole synthesis and hydrogen evolution over defect-engineered Pt/Nb2O5

The hydroxyethyl radical (•CH(CH 3 )OH)-mediated pathway, by avoiding the formation of aldehyde intermediates, constitutes a promising approach for the highly selective photocatalytic synthesis of benzimidazoles from ethanol and o -phenylenediamine. However, inefficient reactant adsorption and activation, as well as severe recombination of photogenerated charge carriers of traditional photocatalysts, impose a fundamental challenge for this reaction pathway. Herein, we construct an oxygen vacancy (V O )-rich Nb 2 O 5 decorated with Pt nanoparticles (NPs), which exhibits the highest photocatalytic activity to date, with production rates of 4.0 mmol g −1 h −1 for 2-methylbenzimidazole and 10.2 mmol g −1 h −1 for H 2 , respectively. The synergistic interaction between V O and Pt NPs markedly promotes the migration and separation of photogenerated charge carriers. The electron-accumulating Pt NPs drive efficient H 2 evolution through proton reduction, while the engineered V O sites enhance ethanol adsorption and selectively activate α-C–H bond cleavage to generate •CH(CH 3 )OH radicals, suppressing the accumulation of N-ethyl-2-methylbenzimidazole by-products inherent to conventional aldehyde-mediated reaction pathways, significantly facilitating the co-production of benzimidazoles and H 2 . This work achieves directional pathway regulation via rational design of semiconductor defects and metal co-catalysts, establishing a radical-mediated strategy for efficient and selective green synthesis of N-heterocyclic compounds.