A novel CaTiO₃/WO₃/BiVO₄ heterostructured photoanode for simultaneous glycerol valorization and hydrogen evolution

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 μmol m⁻² s⁻¹. Concurrently, H₂ was produced at the cathode with a production rate of 549 μmol m⁻² s⁻¹, corresponding to an energy consumption (E_Con) 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.