title: Oxygen vacancies and intense luminescence in manganese loaded Zno microflowers for visible light water splitting.
abstract: ZnO nanorods and Mn/ZnO microflowers with nano-sized petals exhibit singly ionized oxygen vacancies, V. This is strongly supported by a green photoluminescence emission at 2.22 eV and an EPR g value of 1.953, both of which are suppressed greatly after annealing in an oxygen atmosphere. A strong red emission observed during exposure to X-rays reveals the presence of F(+) centres as a consequence of the V. Mn/ZnO displayed enhanced H2 generation with visible light exposure, when compared to pure ZnO and annealed Mn/ZnO in the visible region, which directly correlated with the oxygen vacancy concentration. There is an interesting correlation between the intensities of the EPR lines at the g-value of 1.953 due to the oxygen vacancies, the intensity of light emitted from the exposure to X-rays, the intensity of the photoluminescence due to oxygen vacancies and the quantity of H2 produced by the photocatalytic effect when comparing the three different nanomaterials, viz. pure ZnO, Mn/ZnO before and after annealing, all having been made exactly by the same methodologies.
authors.affiliation: Department of Chemistry, Indian Institute of Technology-Madras, Chennai-60036, India. ptm@iitm.ac.in.
authors.forename: Balaji
authors.initials: B
authors.lastname: Sambandam
authors.forename: Robin Jude Vimal
authors.initials: RJ
authors.lastname: Michael
authors.forename: Periakaruppan T
authors.initials: PT
authors.lastname: Manoharan