Abstract: The development of photoelectrochemical (PEC) systems for glycerol valorization and green hydrogen (H2) production is crucial for advancing sustainable energy technologies. In this work, a novel multilayer CaTiO3/WO3/BiVO4 (CWB) heterostructured photoanode was fabricated via automated spray-coating to promote efficient charge separation and enable glycerol photoelectrooxidation, with photogenerated electrons delivered to a dark cathode to drive the hydrogen evolution reaction (HER). The CWB photoanode operated in a filter-press flow cell, facilitating selective glycerol photoelectrooxidation toward valuable C1-C3 compounds, while H2 was simultaneously produced at a platinum plate dark cathode. At a current density of -10 mA cm-2 under visible light illumination, glycerol conversion yielded dihydroxyacetone (DHA), glyceric acid (GEA), and formate (HCOO?) with an overall Faradaic efficiency (FE) of 64%, achieving a DHA production rate of 124 mmol m-2 s-1. Concurrently, H2 was produced at the cathode with a production rate of 549 mmol m-2 s-1, corresponding to an energy consumption (ECon) of 383 kWh kmol-1 and a cathodic energy efficiency (CEE) of 74%. The improved performance is attributed to enhanced charge separation promoted by the multilayer heterostructure, with efficient electron transfer across the WO3/BiVO4 interface and improved charge collection through the CaTiO3 layer. These findings demonstrate that replacing the oxygen evolution reaction (OER) with glycerol photoelectrooxidation in multilayer heterostructured photoanodes enables simultaneous H2 production and generation of value-added chemicals, providing a promising platform for integrated PEC systems.

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