Amphiphilic Graphene Quantum Dots: Metal-Free Photocatalyst for Hydrogen Evolution via Encapsulation of Organic Thermally Activated Delayed Fluorescence Photosensitizers

Designing a metal-free photocatalyst for the photocatalytic hydrogen evolution reaction (HER) is a very important research goal. Although graphene quantum dots (GQDs) have already been demonstrated as HER photocatalysts, it is necessary to address the poor visible light absorption of GQDs to achieve higher efficiency in the hydrogen evolution reaction (HER) rate. We have synthesized amphiphilic GQD by hexylamine (HA) functionalization through an amide bond formation reaction. We confirmed that HA functionalized GQD (GQD-HA) is amphiphilic and can act as the photocatalyst and templating surfactant at the same time. GQD-HA can form much more stable composite nanoparticles with thermally activated delayed fluorescence (TADF) photosensitizers than bare GQD. Importantly, the HER performance and the stability of the composite systems are remarkably enhanced after HA functionalization. Through electrochemical analyses, it was verified that composite photosensitizer nanoparticles with GQD-HA have efficient charge separation and fast charge transfer properties.

Automated summary

Designing a metal-free photocatalyst for the photocatalytic hydrogen evolution reaction (HER) is important, but the poor visible light absorption of graphene quantum dots (GQDs) limits their efficiency. By functionalizing GQDs with hexylamine (HA) through the amide bond formation reaction, we synthesized amphiphilic GQD-HA that acts as a photocatalyst and templating surfactant. The composite nanoparticles of GQD-HA and thermally activated delayed fluorescence (TADF) photosensitizers show enhanced stability and HER performance due to efficient charge separation and fast charge transfer.