[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

The production of hydrogen from water using a catalyst and solar energy is an ideal future energy source, independent of fossil reserves. For an economical use of water and solar energy, catalysts that are sufficiently efficient, stable, inexpensive and capable of harvesting light are required. Here, we show that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor. Contrary to other conducting polymer semiconductors, carbon nitride is chemically and thermally stable and does not rely on complicated device manufacturing. The results represent an important first step towards photosynthesis in general where artificial conjugated polymer semiconductors can be used as energy transducers.

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A metal-free polymeric photocatalyst for hydrogen production from water under visible light

This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent Many oxides consisting of metal cations with d0 and d10 configurations, metal (oxy)sulfide and metal (oxy)nitride photocatalysts have been reported, especially during the latest decade The fruitful photocatalyst library gives important information on factors affecting photocatalytic performances and design of new materials Photocatalytic water splitting and H2 evolution using abundant compounds as electron donors are expected to contribute to construction of a clean and simple system for solar hydrogen production, and a solution of global energy and environmental issues in the future (361 references)

Heterogeneous photocatalyst materials for water splitting

Energy harvested directly from sunlight offers a desirable approach toward fulfilling, with minimal environmental impact, the need for clean energy. Solar energy is a decentralized and inexhaustible natural resource, with the magnitude of the available solar power striking the earth’s surface at any one instant equal to 130 million 500 MW power plants.1 However, several important goals need to be met to fully utilize solar energy for the global energy demand. First, the means for solar energy conversion, storage, and distribution should be environmentally benign, i.e. protecting ecosystems instead of steadily weakening them. The next important goal is to provide a stable, constant energy flux. Due to the daily and seasonal variability in renewable energy sources such as sunlight, energy harvested from the sun needs to be efficiently converted into chemical fuel that can be stored, transported, and used upon demand. The biggest challenge is whether or not these goals can be met in a costeffective way on the terawatt scale.2

http://pubs.acs.org/doi/pdf/10.1021/cr1002326

Solar Water Splitting Cells

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

Although Zn-based binary semiconductors such as ZnO and ZnS are photocatalytically unstable toward water oxidation, we found that mixed-anionization successfully addressed this issue. This report shows that an oxysulfide SrZn2S2O functions as a photocatalyst to reduce and oxidize water under band-gap irradiation without noticeable decomposition of the material.

A zinc-based oxysulfide photocatalyst SrZn2S2O capable of reducing and oxidizing water.

An oxyfluoride, Pb2Ti4O9F2, was examined as an electrode material for water splitting, and the electrochemical band edge potentials were compared with those of an analogous oxide, Bi2Ti4O11. Pb2Ti4...

Oxyfluoride Pb2Ti4O9F2 as a Stable Anode Material for Photoelectrochemical Water Oxidation

https://hal-univ-rennes1.archives-ouvertes.fr/hal-02895318/document

Selective CO2 reduction into formate using Ln–Ta oxynitrides combined with a binuclear Ru(II) complex under visible light

Tungsten-modified barium tantalum oxynitride is a new visible-light photocatalyst for water oxidation In the present work, novel barium tantalum strontium tungsten oxynitride solid solutions, (BaTaO2N)1-x(SrWO2N)x, with a cubic Pm3[combining macron]m perovskite-type structure (x = 001 and 002) have been prepared by heating oxide precursors under an ammonia flow These (BaTaO2N)1-x(SrWO2N)x catalysts exhibited photocatalytic water oxidation activity under visible light irradiation The crystal structure, electron-density distribution, and optical properties of (BaTaO2N)1-x(SrWO2N)x (x = 0, 001, and 002) have been studied using synchrotron X-ray powder diffraction, Rietveld analysis, the maximum-entropy method (MEM), and UV-Vis reflectance measurements The lattice parameters of (BaTaO2N)1-x(SrWO2N)x decreased linearly with increasing SrWO2N content x The minimum electron density (MED) at the (Ta,W)-(O,N) bond, determined by the MEM analysis of (BaTaO2N)1-x(SrWO2N)x, increased with x, as supported by DFT-based calculations These results indicate the formation of (BaTaO2N)1-x(SrWO2N)x solid solutions and enhanced covalent bonding due to the stronger W-N bond The MED of the (Ta,W)-(O,N) bond was higher than that of (Ba,Sr)-(O,N), indicating that the (Ta,W)-(O,N) bond is more covalent The presence of nitrogen in (BaTaO2N)1-x(SrWO2N)x was confirmed by the occupancy factor refined using neutron diffraction data and by the weight gain observed by thermogravimetric analysis in air UV-Vis reflectance spectra and DFT calculations indicated that (BaTaO2N)1-x(SrWO2N)x contains W5+ cations with a [Xe] 4f14 5d1 electron configuration and exhibits a more n-type semiconducting character compared with BaTaO2N, which could improve the photocatalytic water oxidation activity under visible-light irradiation

Kazuhiko Maeda

Papers

A zinc-based oxysulfide photocatalyst SrZn2S2O capable of reducing and oxidizing water.

Oxyfluoride Pb2Ti4O9F2 as a Stable Anode Material for Photoelectrochemical Water Oxidation

Selective CO2 reduction into formate using Ln–Ta oxynitrides combined with a binuclear Ru(II) complex under visible light

Structures, electron density and characterization of novel photocatalysts, (BaTaO2N)1−x(SrWO2N)x solid solutions

Preparation of Pt‐Intercalated KCa2Nb3O10 Nanosheets and Their Photocatalytic Activity for Overall Water Splitting