Achieving photocatalytic water oxidation on LaNbON2 under visible light irradiation

LaNbON 2 has narrow bandgap and wide visible-light absorption band, yet no photocatalytic water oxidation on LaNbON 2 has been reported. By a post-annealing treatment in Ar, anion vacancies were brought into LaNbON 2 as shown by EPR spectroscopy. These could act as donors in the semiconductor. And consequently the oxidative power of holes was enhanced as indicated by the difference between fermi level and valence band maximum ( E F - E VBM ) evaluated from valence band XPS . The annealed LaNbON 2 photocatalyst acquired water oxidation ability for the first time, which was improved by combining CoO x as cocatalyst . Annealed LaNbON 2 derived from La 3 NbO 7 had smaller particle size, higher concentration of anion vacancies, bigger E F - E VBM and better performance for photocatalytic oxygen evolution reaction than LaNbON 2 derived from LaNbO 4 .