Enhanced visible light photocatalytic non-oxygen coupling of amines to imines integrated with hydrogen production over Ni/CdS nanoparticles

Abstract

This work presents an efficient strategy for visible light-driven imine production through a photocatalytic non-oxygen coupling reaction of diverse amines dramatically boosted by hydrogen evolution over noble metal-free Ni/CdS nanoparticles. Thanks to the integrating effect, close to 100% conversion of benzylamine (75.2 h⁻¹ turnover frequency), 97% selectivity for imine with 21.4 mmol g⁻¹ h⁻¹ hydrogen evolution rate (λ > 420 nm) and 11.2% apparent quantum yield (450 nm, 10 mg catalyst) have been achieved at room temperature and ambient pressure. In comparison with the use of common sacrificial agents like TEOA or Na₂S/Na₂SO₃, by the coupling of amines to imines, the H₂ evolution rate increases by two orders of magnitude. The aforementioned integrating strategy has been extended to diverse amines, and an outstanding photocatalytic performance for H₂ and imine production was obtained. Besides, the catalyst can be recycled several times without evident activity loss, suggesting a bright prospect for sustainable chemistry and solar utilization. This new discovery may open a new horizon for efficiently boosting solar hydrogen evolution and simultaneously clean producing diverse high value-added fine chemicals under mild conditions.