title: X-ray Photochemistry of Prussian Blue Cellulosic Materials: Evidence for a Substrate-Mediated Redox Process.
abstract: Beside its promising applications in the design of multifunctional materials, batteries and biosensors, the pigment Prussian blue is still studied in heritage science because of its capricious fading behavior due to a complex light-induced redox mechanism. We studied model heritage materials composed of Prussian blue embedded into a cellulosic fiber substrate by means of X-ray absorption near-edge spectroscopy. Significant X-ray radiation damage was observed and characterized. X-ray radiation induced first a reduction of Prussian blue, in a similar way to what visible light does, followed by a complete degradation of the pigment and the formation of iron(III) oxyhydroxide. We took advantage of this X-ray photochemistry to investigate in depth the redox behavior of Prussian blue. We could particularly demonstrate that the rate, extent, and quality of Prussian blue photoreduction can be tuned by modifying the pH and alkali cation content of the cellulosic substrate. The present study represents a step further in the understanding of Prussian blue heritage materials from an electrochemical viewpoint and provides evidence of substrate-mediated photochemistry applicable to a wider class of Prussian blue composite materials.
authors.affiliation: †Bern University of Applied Sciences, HKB, Fellerstrasse 11, 3027 Bern, Switzerland.
authors.forename: Claire
authors.initials: C
authors.lastname: Gervais
authors.affiliation: ‡Centre de Recherche sur la Conservation (CRC, USR 3224), Sorbonne Universités, Muséum National d'Histoire Naturelle, Ministère de la Culture et de la Communication, CNRS, CP21, 36 rue Geoffroy-Saint-Hilaire, 75005 Paris, France.|§IPANEMA (CNRS, MCC, USR 3461), Saint-Aubin BP 48, 91192 Gif-sur-Yvette, France.
authors.forename: Marie-Angélique
authors.initials: MA
authors.lastname: Languille
authors.affiliation: †Bern University of Applied Sciences, HKB, Fellerstrasse 11, 3027 Bern, Switzerland.
authors.forename: Giulia
authors.initials: G
authors.lastname: Moretti
authors.affiliation: ∥DiffAbs Beamline at Synchrotron SOLEIL, Saint-Aubin BP 48, 91192 Gif-sur-Yvette, France.
authors.forename: Solenn
authors.initials: S
authors.lastname: Réguer