Discovery of a Novel High Activity Photocatalyst Material: A Great Step Toward the Realization of Artificial Photosynthesis

Discovery of a Revolutionary Oxidation Property in Silver Phosphate with Quantum Yield of Approximately 90% in Visible Light

2010.06.07

National Institute for Materials Science

The Photocatalytic Materials Center of the National Institute for Materials Science discovered that silver phosphate (Ag3PO4) is a photocatalytic material which displays extremely high oxidizing power under irradiation with visible light.

Abstract

  1. The Photocatalytic Materials Center (Managing Director: Jinhua Ye) of the National Institute for Materials Science (NIMS; President: Sukekatsu Ushioda) discovered that silver phosphate (Ag3PO4) is a photocatalytic material which displays extremely high oxidizing power under irradiation with visible light.
  2. The Photocatalytic Materials Center discovered this revolutionary oxidation property of silver phosphate in an oxygen generation test by decomposition of water and a methylene blue decomposition test. In the oxygen generation test, the efficiency of this substance was far superior to that of other visible light-responsive photocatalysts, and its quantum yield under visible light irradiation showed an astonishing value of approximately 90%. The new silver phosphate photocatalyst also displayed extremely high photooxidation performance in the methylene blue decomposition test.
  3. Because photocatalysts form hydrogen from photolysis of water, this class of substances has attracted attention as a technology for producing clean energy as a substitute for fossil fuels. Furthermore, with certain photocatalysts, it is also possible to decompose and remove harmful substance using only sunlight. Because this function is similar to photosynthesis in plants, it is also called artificial photosynthesis technology.
  4. Titanium dioxide (TiO2) is a representative conventional photocatalyst. However, because TiO2 only reacts under ultraviolet (UV) light and its efficiency is poor, much research and development work has been done on photocatalytic materials which can be used from the UV to the visible light region. These substances are called visible light-responsive photocatalysts.
  5. The silver phosphate photocatalyst discovered by the NIMS group is not limited to use in decomposition and removal of harmful substances. A wide range of other applications is also possible, including use as a thin film electrode material for photoelectrode systems, and by use in combination with an appropriate reducing material, application to the synthesis of fuels/resources by production of hydrogen by water decomposition and reduction of carbon dioxide. High expectations are placed on this new photocatalyst as a turning point toward the realization of artificial photosynthesis systems.
  6. These research results are being published in advance in the online edition of Nature Materials, which is a sister journal of Nature, at 2:00a.m. on June 7 (Monday) Japan time (18:00 on June 6, local time in London).