Colloidal Synthesis of Carbon Dot‐ZnSe Nanoplatelet Van der Waals Heterostructures for Boosting Photocatalytic Generation of Methanol‐Storable Hydrogen

Abstract

Methanol is not only a promising liquid hydrogen carrier but also an important feedstock chemical for chemical synthesis. Catalyst design is vital for enabling the reactions to occur under ambient conditions. This study reports a new class of van der Waals heterojunction photocatalyst, which is synthesized by hot‐injection method, whereby carbon dots (CDs) are grown in situ on ZnSe nanoplatelets (NPLs), i.e., metal chalcogenide quantum wells. The resultant organic‐inorganic hybrid nanoparticles, CD‐NPLs, are able to perform methanol dehydrogenation through CH splitting. The heterostructure has enabled light‐induced charge transfer from the CDs into the NPLs occurring on a sub‐nanosecond timescale, with charges remaining separated across the CD‐NPLs heterostructure for longer than 500 ns. This resulted in significantly heightened H2 production rate of 107 µmole·g−1·h−1 and enhanced photocurrent density up to 34 µA cm−2 at 1 V bias potential. EPR and NMR analyses confirmed the occurrence of α‐CH splitting and CC coupling. The novel CD‐based organic‐inorganic semiconductor heterojunction is poised to enable the discovery of a host of new nano‐hybrid photocatalysts with full tunability in the band structure, charge transfer, and divergent surface chemistry for guiding photoredox pathways and accelerating reaction rates.