Photoredox-Promoted Co-Production of Dihydroisoquinoline and H 2 O 2 over Defective Zn 3 In 2 S 6

One of the most sustainable and promising approaches for hydrogen peroxide (H O ) production in a low-cost and environment-friendly way is photosynthesis, which, however, suffers from poor carrier utilization and low H O productivity. The addition of proton donors such as isopropanol or ethanol can increase H O production, which, unfortunately, will inevitably elevate the entire cost while wasting the oxidizing power of holes (h ). Herein, the tetrahydroisoquinolines (THIQs) is employed as a distinctive proton donor for the thermodynamically feasible and selective semi-dehydrogenation reaction to highly valuable dihydroisoquinolines (DHIQs), and meanwhile, to couple with and promote H O generation in one photoredox reaction under the photocatalysis by dual-functional Zn In S photocatalyst. Surprisingly, the suitably defective Zn In S offers an excellent and near-stoichiometric co-production performance of H O and DHIQs at unprecedentedly high rates of 66.4 and 62.1 mmol h g under visible light (λ ≥ 400 nm), respectively, which outperforms all the previously available reports even though sacrificial agents were employed in those reports. Additionally, photocatalytic redox reaction mechanism demonstrates that H O can be generated through multiple pathways, highlighting the synergistic effect among ROS (·O and O ), h and proton donor, which has been ignored in previous studies.