It is worth exploring the strategy for selective oxidation of cinnamaldehyde to benzaldehyde to address the insufficiency of natural benzaldehyde supply. We have developed an efficient Fe single-atom catalyst through nitrogen vacancy engineering for photodriven oxidation to generate benzaldehyde. Excitingly, FeSA/g-C3N5 (Nv) can achieve a conversion of 81% and a benzaldehyde selectivity of 89% under an oxygen atmosphere. The introduction of N vacancies guides the Fe-N4 active sites, enabling precise generation of •O2−, thereby serving as the origin of the selectivity. On the contrary, FeSA/g-C3N5 achieves a conversion of 95% and a selectivity of 60% for benzaldehyde. The Fe-N3 active sites mainly produce 1O2, which generate benzaldehyde through another pathway and promote side reactions. The N vacancy-induced transformation of Fe-N3 to Fe-N4 has been characterized by X-ray photoelectron spectroscopy, X-ray absorption fine structure, and electron paramagnetic resonance spectra, and the key intermediates in both reaction pathways have been detected and confirmed. In addition, selective oxidation also demonstrates substrate applicability and cycling stability of FeSA/g-C3N5 (Nv). Overall, this study has achieved the production of natural benzaldehyde under sustainability requirements, providing a demonstration for the selective oxidation of α,β-unsaturated carbonyl compounds to high-value-added products.
Wang et al. (Mon,) studied this question.