Preparation and characterization of porous Nb2O5 photocatalysts with CuO, NiO and Pt cocatalyst for hydrogen production by light-induced water splitting

In this study, porous Nb2O5 photocatalyst materials are prepared through thermal oxidation. According to X-ray photoelectron spectroscopy (XPS), at a temperature of 500 °C, an optimum porous Nb2O5 photocatalyst is obtained with an O/Nb ratio close to the theoretical value of 2.5. The X-ray powder diffractometer (XRD) result shows that at the main diffraction angles of 22.63° and 28.33°, crystalline diffraction signals of Nb2O5 appear with corresponding diffraction planes of (001) and (180). When CuO, NiO and Pt catalysts are added to Nb2O5 as the cocatalyst for comparison, the maximum hydrogen production efficiency for a CuO/Nb2O5 photocatalyst is achieved (1405 μmol h−1 g−1). However, when NiO and Pt are added as cocatalysts, the hydrogen production efficiencies are decreased to 800 μmol h−1 g−1 and 510 μmol h−1 g−1, respectively. Through the photoelectrochemical analysis, it finds that the CO signal peak with incomplete oxidation significantly increases as the reaction time increases, thus causing CO to adsorb on the catalyst surface (such as NiO or Pt) leading to catalyst poisoning. This results in reduced catalyst performance and hydrogen production rates.

► The oxidation temperature plays an important role in porous Nb2O5 matrix formation.
► The presence of the Nb2O5 with CuO cocatalyst can promote the H2 production rate.
► CuO cocatalyst can substitute noble metals in photocatalysts for H2 production.
► The use of porous CuO/Nb2O5 photocatalyst can inhibit CO poisoning.
► The porous CuO/Nb2O5 photocatalyst can effectively maintain the catalyst activity.