Photocatalytic oxidation of gas-phase Hg0 by carbon spheres supported visible-light-driven CuO–TiO2

An environmentally friendly visible-light-driven photocatalyst, silver vanadates/SBA-15, was prepared through an incipient wetness impregnation procedure with silver vanadates (SVO) synthesized under a hydrothermal condition without a high-temperature calcination. The addition of mesoporous SBA-15 improves the formation of nanocrystalline silver vanadates. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirms the presence of Brønsted and Lewis acids on the SVO/SBA-15 composites. The results of photoluminescence spectra indicated that the electron-hole recombination rate have been effectively inhibited when SVO was loaded with mesoporous SBA-15. All the composites loaded with various amount of SVO inherit the higher adsorption capacity and larger mineralization yield than those of P-25 (commercial TiO2) and pure SVO. The sample loaded with 51% of SVO (51SVO/SBA-15) with mixed phases of Ag4V2O7and α-Ag3VO4exhibits the best photocatalytic activity. A favorable crystalline phase combined with high intensities of Brønsted and Lewis acids is considered the main cause of the enhanced adsorption capacity and outstanding photoactivity of the SVO/SBA-15 composites.

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Water-Stable Boron-Doped Boron Nitride Photocatalyst for Visible Light-Driven H2 Evolution and CO2 Photoreduction

10.26434/chemrxiv.12333314.v1 ◽

2020 ◽

Author(s):

Ravi Shankar ◽

Daphne Lubert-Perquel ◽

Elan Mistry ◽

Irena Nevjestić ◽

Sandrine Heutz ◽

...

Keyword(s):

Boron Nitride ◽

Visible Light ◽

Gas Phase ◽

Hyperfine Interactions ◽

Quantum Yields ◽

H2 Evolution ◽

Co2 Photoreduction ◽

Boron Doped ◽

Out Of Plane ◽

Visible Light Driven

Developing robust, multifunctional photocatalysts that can facilitate both hydrogen evolution via photoreforming of water and gas phase CO2 photoreduction is highly desirable with the long-term vision of integrated photocatalytic setups. Here, we present a new addition to the boron nitride (BN) photocatalyst material platform, boron-doped boron oxynitride (B-BNO), capable of fulfilling this goal. Detailed EPR studies revealed hyperfine interactions between free charges located on discrete OB3 sites, exhibiting an out-of-plane symmetry, and the nuclei of neighbouring boron atoms. This material resolves two long-standing bottlenecks associated to BN-based materials concomitantly: instability in water and lack of photo activity under visible light. We show that B-BNO maintains prolonged stability in water for at least three straight days and can facilitate both liquid phase H2 evolution and gas phase CO2 photoreduction, using UV-Vis and deep visible irradiation (λ > 550 nm), without any cocatalysts. The evolution rates, apparent quantum yields, and selectivities observed for both reactions with B-BNO exceed those of its porous BNO counterpart, P25 TiO2 and bulk g-C3N4. This work provides scope to expand the BN photocatalyst platform to a wider range of reactions.

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Boron-Doped Boron Nitride Photocatalyst for Visible Light-Driven H2 Evolution and CO2 Photoreduction

10.26434/chemrxiv.12333314.v2 ◽

2020 ◽

Author(s):

Ravi Shankar ◽

Daphne Lubert-Perquel ◽

Elan Mistry ◽

Irena Nevjestić ◽

Sandrine Heutz ◽

...

Keyword(s):

Visible Light ◽

Gas Phase ◽

Hyperfine Interactions ◽

Free Oxygen Radicals ◽

Co Catalysts ◽

Boron Doped ◽

The Family ◽

Visible Light Driven ◽

Band Gap Narrowing

Developing robust, multifunctional photocatalysts that can facilitate both hydrogen evolution via photoreforming of water and gas phase CO2 photoreduction is highly desirable with the long-term vision of integrated photocatalytic setups. Here, we present a step-change in the family of boron oxynitride materials by introducing the first example of a B-doped boron oxynitride (B-BNO). This material resolves an on-going bottleneck associated with BN-based materials, i.e. the lack of photoactivity under visible light. Detailed EPR studies revealed distinct hyperfine interactions between the free oxygen radicals and 3 neighbouring boron nuclei. This confirmed isolated OB3 sites, which contribute to band gap narrowing, as the radical species and origin of paramagnetism in BNO materials. We show that B-BNO can facilitate both liquid phase H2 evolution and gas phase CO2 photoreduction, using UV-Vis and deep visible irradiation (λ > 550 nm), without any co-catalysts. The evolution rates, quantum efficiencies, and selectivities observed for both reactions with B-BNO exceed those of its porous BNO counterpart, P25 TiO2 and bulk g-C3N4.

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