Prussian blue as a co-catalyst for enhanced Cr() photocatalytic reduction promoted by titania-based nanoparticles and aerogels

• Published in: New journal of chemistry 2021-06, Vol.45 (23), p.1217-1231
• Main Authors: Ferreira-Neto, Elias Paiva, Ullah, Sajjad, Perissinotto, Amanda Pasquoto, de Vicente, Fábio S, Ribeiro, Sidney José Lima, Worsley, Marcus Andre, Rodrigues-Filho, Ubirajara Pereira
• Format: Article
• Language: English
• Subjects: Aerogels; Catalysts; Catalytic activity; Chromium; Drinking water; Heavy metals; Hexavalent chromium; Low concentrations; Nanomaterials; Nanoparticles; Photocatalysis; Photocatalysts; Pigments; Reagents; Silicon dioxide; Titanium dioxide
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d1nj01141c

Hexavalent chromium (Cr( vi )) is an noxious and highly toxic heavy metal that presents a serious threat to human health if present even in low concentrations in drinking water. Photocatalytic reduction of Cr( vi ) to its less toxic Cr( iii ) state is a potential strategy to combat Cr( vi ) pollution, but the efficiency of the process is low, especially in the absence of hole scavenger organic reagents. To address this issue and prepare efficient photocatalysts for Cr( vi ) removal from water, in this study, we explored Prussian blue (PB) as a co-catalyst for improving the photoreduction performance of different high surface area TiO 2 -based materials (titania or silica-titania nanoparticles and aerogels). The photocatalyst nanomaterials were surface-modified with nanocrystalline PB using the photodeposition route. The PB layer acts as an effective electron acceptor/mediator between the semiconductor photocatalyst and Cr( vi ) species. All the PB-modified photocatalysts exhibit higher photocatalytic activity (up to 9 times faster) as compared to the unmodified photocatalysts towards reduction of Cr( vi ). Importantly, the PB-modified photocatalysts exhibited high photocatalytic performance (98-99% reduction in 40 min for pH = 5.6 and in 10 min for pH = 3) without addition of organic reagents. The simple approach reported herein can be followed to prepare new PB-photocatalyst systems with improved photocatalytic performance towards Cr( vi ) reduction and other target applications. A nanostructured Prussian blue layer deposited on titania-based materials acts as an efficient electron acceptor/mediator greatly enhancing Cr( vi ) photocatalytic reduction.