Hydrogen production by photoelectrochemical water splitting using WO3 nanostructures anodized in tartaric acid for the catalytic transformation of levulinic acid into γ-valerolactone

Green hydrogen was produced by photoelectrochemical water splitting to carry out the hydrogenation reaction of levulinic acid using a ruthenium catalyst under mild conditions (atmospheric pressure and only 30 °C). For the hydrogen production, novel WO3 nanosheets were synthesized by electrochemical anodization under hydrodynamic conditions using different concentrations of tartaric acid. The samples were morphologically characterized by Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy techniques. The electrochemical behavior was studied by Electrochemical Impedance Spectroscopy analysis, Mott-Schottky diagrams and water splitting tests. From the analyses performed, it was determined that the nanostructures synthesized with intermediate concentrations of tartaric acid had an optimum behavior for hydrogen production. In fact, using the optimal WO3 photocatalyst (anodized with 0.1 M of tartaric acid) together with the ruthenium catalyst supported on alumina a γ-valerolactone yield of 72.1 % was achieved at only 30 °C and atmospheric pressure after 8 h.