Abstract
In this study, tiny sized (∼2 nm) copper nanoclusters (Cu NCs) were synthesized with strong optical response, where red/green emitting features were observed using protein/amino acid as surfactant molecules. The photocatalytic water splitting reactions for both ligand-mediated Cu NCs were carried out in a photochemical reactor under solar simulator for 12 h. Interestingly, protein mediated red colour emitting Cu NCs produced stable H2 ∼ 256 mmol g−1 and the solar to hydrogen efficiency (STH) is approximately ∼ 0.5% while comparing with green emitting Cu NCs with 86 mmol g−1 and STH of 0.08%. These interesting results were achieved due to their longer lifetime, strong colloidal stability, high quantum yield and rich surface functionalization features. These were further confirmed through absorption spectroscopy, fluorescence spectroscopy, time-resolved photoluminescence, zeta potential, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy analytical techniques. Thus, these inexpensive Cu NCs could be used as alternate photocatalysts for H2 production than obviating the usage of precious noble metal platinum-based ones.
