Two-in-One Ni²⁺-Doped CsPbBr₃ Nanocrystals Enabling Acceptorless Photocatalytic Dehydrogenation of Diaryl Hydrazines

Direct utilization of solar energy by semiconductor nanocrystals for chemical transformations via photocatalysis has recently drawn a great deal of attention. While most photocatalytic reactions are mediated through photoredox events, the ultimate reaction scalability relies on the use of sacrificial agents. The imbalanced population of photogenerated electrons and holes often leads to catalyst degradation through photocorrosion. To circumvent this, we designed Ni²⁺-doped CsPbBr₃ nanoplatelets (NPls) as a "redox-neutral" photocatalyst, where both oxidative and reductive cycles occur in one photocatalyst. We showed that surface Ni²⁺ ions can act as an "electron shuttle" to reduce protons, generating clean-energy H₂ gas, while the photogenerated holes can be used to oxidize diaryl hydrazines to afford valuable azobenzenes and derivatives. Compared with previous photocatalytic demonstrations, our catalysts show excellent reaction yields with a wide substrate scope, unity atomic efficiency, and enhanced stability and recyclability.