Photochemical eco-friendly synthesis of photothermal and emissive copper nanoclusters in water: towards sustainable nanomaterials

The pursuit of sustainable and environmentally benign approaches to nanomaterial synthesis has gained significant momentum in recent years. Copper is rather cheap and more abundant than gold or silver and small copper nanoclusters (B1 nm) show unique characteristics which makes them extremely attractive for technological applications. Among these endeavours, the development of eco-friendly methods for the synthesis of copper nanoclusters (Cu NCs) in aqueous environments has emerged as a promising avenue. This shift towards green syntheses not only addresses the growing concerns regarding the environmental impact of conventional synthetic routes but also offers a platform for producing Cu NCs with tailored properties for diverse applications. In the present study, we report on a green photochemical approach to synthesising water-dispersible copper nanoclusters capped with monoethanolamine to confine their size. The obtained material was characterized by a large palette of techniques, including UV-vis spectroscopy, fluorescence spectroscopy, electron paramagnetic resonance, X-ray photoelectron spectroscopy, Z-potential analysis, cyclic voltammetry, field-dependent magnetization, scanning transmission electron microscopy and dynamic light scattering. The results unequivocally demonstrate that the Cu NCs are temporally and thermally stable for months, therefore promising for technological uses.