BiVO 4 Photoanodes for TEMPO-Mediated Benzyl Alcohol Oxidation in Organic Media.

The photoelectrochemical production of fuels, exemplified by light-driven water splitting to hydrogen and oxygen, offers a sustainable option to offset dependence on fossil fuels. A low-cost, efficient, and stable photoelectrochemical approach to solar fuels remains elusive but using similar materials and photoelectrodes for chemical production or biomass conversion offers an appealing alternative. This work reports a facile method for fabricating pristine (undoped) BiVO 4 photoanodes to carry out TEMPO-mediated benzyl alcohol oxidation to benzaldehyde in organic media (TEMPO=2,2,6,6-tetramethylpiperidinyl-N-oxyl). The best performing BiVO 4 photoanode studied here gave a faradaic efficiency (FE) of 85±5% for benzaldehyde formation in the presence of TEMPO and pyridine during a 2.5-hour reaction. Compared with direct electrocatalytic conversion under the same conditions, light capture and conversion by the BiVO 4 surface decreased the required applied bias by 46 %. To our knowledge, this is the first report of visible light assisted, TEMPO-mediated benzyl alcohol oxidation using pristine BiVO 4 photoanodes in organic media.