Catalytic oxidation and deionization of nitrite and nitrate ions using mesoporous carbon-supported nano-flaky cobalt and nickel oxyhydroxides.

The composite electrode of NiCo oxide supported by porous carbon was synthesized for nitrite oxidation and nitrate electro-sorption. The crystal structure and chemical state of the Co and Ni oxyhydroxides which were precipitated on loofah-derived activated carbon (AC) using hypochlorite were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and BET surface area. The voltammetry showed that the redox couple of Co(II)/Co(III) and Ni(II)/Ni(III) as the mediator catalytically transferred the electrons of NO2-/NO3-; the Ni site had a relatively high transfer coefficient and diffusive current, while the Co site was better in the capacitive removal of the nitrite and nitrate compounds. A batch electrolysis of nitrite ions was operated under constant anodic potential mode (0 to + 1.5 V vs. Ag/AgCl) to assess the performance of the composite electrodes. The adsorption capacity of NiCo/AC (Ni = 5% and Co = 5% on AC by weight) was 23.5 mg-N g-1, which was twice that of AC substrate (7.5 mg-N g-1), based on a multilayer adsorption model. The steady-state kinetics of the consecutive reaction were derived to determine the rate steps of the electrochemical oxidation of NO2- and adsorption of NO3-.

Oxygen-vacancy-rich BiOCl materials with ultrahigh photocatalytic efficiency by etching bismuth glass.

Bismuth oxychloride (BiOCl) is a promising photocatalyst material for water purification to remove organic pollutants. However, BiOCl materials can only degrade pollutants under ultraviolet-light owing to their wide band gap. Herein, we propose a simple synthesis route based on Bi2O3-B2O3-ZnO-SrO-Na2O (BBZSN) glass to fabricate 3D hierarchical-structured BiOCl materials with rich oxygen vacancies (OVs), which were introduced from BBZSN glass and inhibited the recombination of electron-hole pairs and adjusted the band structure. The photocatalytic activity of the obtained 3D hierarchical-structured BiOCl photocatalyst was evaluated by the degradation of Rhodamine B (RhB) under ultraviolet light and visible light. The experimental results suggested that the as-fabricated flower-shape BiOCl-NaCl could effectively degrade RhB under ultraviolet light (92.7%/20 min) or visible light (71.4%/20 min, 92.8%/100 min) respectively, which indicates its potential to be applied in environmental remediation.