WO3-based materials for photoelectrocatalytic glycerol upgrading into glyceraldehyde: Unravelling the synergistic photo- and electro-catalytic effects

The photoelectrocatalytic (PEC) glycerol oxidation has emerged as a promising technology for the simultaneous valorization of this biomass waste and hydrogen production. Herein, we report the enhancement of the photocatalytic (PC) activity and stability of a monoclinic WO3 catalyst, by means of an external bias, for the selective generation of value-added C3 products under near-neutral conditions. Glyceraldehyde and dihydroxyacetone production were increased up to 4.5 and 11.5 times, respectively, while maintaining a liquid selectivity of these C3s above 87% and a stable faradaic efficiency above 50% of the additional holes generated, in a wide potential range (0.5–2.0 V vs. RHE). Indeed, the photo- and electro-catalytic contributing effects are unravelled for the first time herein. The photoelectrocatalytic mechanisms on WO3 and WO3/TiO2 are discussed, as well as the key role of the sub-stoichiometric WO3−x content and the oxygen vacancies, which confer advantageous properties for the selective PEC valorization of glycerol. [Display omitted] •WO3−x photoanodes selectively valorize glycerol at ambient and neutral conditions.•Glyceraldehyde/DHA production is boosted by PEC with selectivity up to 87%.•The PEC mechanism at the electrolyte/reactant/electrode interface is unraveled.•Above 50% of potential-driven holes are employed for targeted C3 s at 0.3–1.5 V.•WO3−x has promising properties for sustainable solar-to-chemical energy conversion.