Gold-diamond Nanocomposites Efficiently Generate Hydrated Electrons upon Absorption of Visible Light

An efficient source of hydrated electrons generated by visible light has the potential to have a major impact on solar homogeneous catalysis. Diamond has the capability of efficiently emitting hydrated electrons, but direct excitation of its band gap is only possible using ultraviolet light (λ < 225 nm). In this work, we demonstrate the efficient absorption of visible light by nanocomposites consisting of detonation nanodiamonds and gold nanoparticles (AuNP@DNDs), which subsequently emit electrons into the aqueous environment in which they are suspended. This has been done by exciting the AuNP@DND with visible laser light and monitoring the appearance and intensity of the transient absorption of hydrated electrons centered at around 720 nm. We suggest that this mechanism is made possible by the plasmonic enhancement of visible absorption by sp2-hybridized islands on the detonation nanodiamonds surface. Optimization of this process could lead to important reakthroughs in solar photocatalysis of energy-intensive reactions such as N2 and CO2 reductions as well as provide a nontoxic source of hydrated electrons for applications in wastewater management and nanomedicine.