Oxidation of copper nanoparticles in water: mechanistic insights revealed by oxygen uptake and spectroscopic methods

Abstract

Oxidation of aqueous ∼8 nm unprotected copper nanoparticles takes place under air in approximately 2 hours at 30 °C to give Cu(2+) as a final product through an intermediate Cu(+) species. At 5 °C the process is about 5 times slower; similarly, vitamin C, which plays a sacrificial role, also slows down the oxidation, while CuNP catalyses the oxidation. In this work, we present a detailed analysis of the oxidation mechanism of colloidal CuNP inferred through spectroscopic methods (UV-visible and EPR) combined with oxygen uptake measurements, with emphasis on factors affecting the oxidative process.

Deciphering Ligands’ Interaction with Cu and Cu2O Nanocrystal Surfaces by NMR Solution Tools

“…The copper oxide crystals are dissolved in the acidic medium and Cu II complexes are formed. [30] This latter point is confirmed by the observation of the size reduction of the NPs after long oxidation time (two days; Figure S12 in the Supporting Information). In addition, after elimination of the solvent, the resulting powder presents an EPR signal in agreement with a paramagnetic inorganic material displaying g k and g ?…”

Biosynthesis of copper nanoparticles and its effect on actively dividing cells of mitosis in Allium cepa

“…The control spectra were observed with the absence of particular absorbance peak, while, two absorbance peaks, a sharp peak at 578 nm and a weak peak at 349 nm were recorded for copper nanoparticle suspension. The absorbance peak recorded at 578 nm specific to CuNPs can be attributed to surface plasmon resonance phenomenon which indicates formation of CuNPs . It is now a well‐established fact that UV‐visible absorbance characteristics possess strong relationships with size and shape of nanoparticles .…”

Copper nanoparticle heterogeneous catalytic ‘click’ cycloaddition confirmed by single-molecule spectroscopy

“…Copper nanoparticles (CuNP) are being explored as click catalysts in the hope of improving reusability and efficiency compared to their solution counterparts [13][14][15][16][17][18][19][20][21] . Despite recent proof-of-concept examples of CuNP-catalysed click reactions, few investigate the catalytic activity of CuNP, and generally it is difficult, if not impossible, to establish if the true catalyst is the CuNP, copper ions leaching from it 22 , or if the CuNP acts as a reductant converting Cu(II) to Cu(I).…”