X-ray-induced reduction of Au ions in an aqueous solution in the presence of support materials andin situtime-resolved XANES measurements

Abstract

Synchrotron X-ray-induced reduction of Au ions in an aqueous solution with or without support materials is reported. To clarify the process of radiationinduced reduction of metal ions in aqueous solutions in the presence of carbon particles as support materials, in situ time-resolved XANES measurements of Au ions were performed under synchrotron X-ray irradiation. XANES spectra were obtained only when hydrophobic carbon particles were added to the precursor solution containing Au ions. Changes in the shape of the XANES spectra indicated a rapid reduction from ionic to metallic Au in the precursor solution owing to synchrotron X-ray irradiation. In addition, the effects of the wettability of the carbon particles on the deposited Au metallic spots were examined. The deposited Au metallic spots were different depending on the relationship of surface charges between metal precursors and support materials. Moreover, a Au film was obtained as a by-product only when hydrophilic carbon particles were added to the precursor solution containing the Au ions.

Radiation-Assisted Formation of Metal Nanoparticles in Molten Salts

“…With their strong reducing capacity, the solvated electrons reduce the Au 3+ cation first to a low-valence (Au 2+ /Au + ) state before ultimately reducing it to the zerovalent metallic state. While several examples of X-ray induced nanoparticle formation in aqueous solutions , and ionic liquids are known, , there are no reports, to the best of our knowledge, of X-ray-assisted production of zerovalent metals in molten salts.…”

Microwave-assisted synthesis of water-soluble, fluorescent gold nanoclusters capped with small organic molecules and a revealing fluorescence and X-ray absorption study

“…Furthermore, a significant photoreduction of gold can be excluded because of the relatively low photon flux of the beamlines used for DELTA. 14 Moreover, the spectra of the Au I references, Au(PPh 3 )Cl and Au(tht)Cl (tht = tetrahydrothiophene), are different with respect to the white-line intensities and the post edge structures, most obviously seen in the feature at about 11.970 keV. The edge and white-line energies for Au 2 O 3 and NaAuCl 4 are similar to that of Au metal, while those of the other substances are located at substantially larger photon energies.…”

Unexpected effects in non crystalline materials exposed to X-ray radiation

“…In biological materials a reduction of metal centres in proteins has also been observed [55,56] and, although the reports on X-ray induced reduction in both materials science and biology are rare, these examples are by no means unique [57][58][59][60]. Oxidation is also reported [61].…”