Plasmonic photocatalyst Ag@AgCl, in which Ag nanoparticles are deposited on the surfaces of AgCl particles (SEM image depicted), was prepared by treating Ag2MoO4 with HCl to form AgCl powder and then reducing some Ag+ ions in the surface region of the AgCl particles to Ag0. This photocatalyst is highly efficient, for example in the degradation of organic dyes, and stable under visible light.

The efforts to produce photocatalysts operating efficiently under visible light have led to a number of plasmonic photocatalysts, in which noble metal nanoparticles are deposited on the surface of polar semiconductor or insulator particles. In the metal-semiconductor composite photocatalysts, the noble metal nanoparticles act as a major component for harvesting visible light due to their surface plasmon resonance while the metal-semiconductor interface efficiently separates the photogenerated electrons and holes. In this article, we survey various plasmonic photocatalysts that have been prepared and characterized in recent years.

Der plasmonische Photokatalysator Ag@AgCl, in dem sich Ag‐Nanopartikel auf der Oberfläche von AgCl‐Partikeln befinden (siehe SEM‐Bild), wurde hergestellt, indem Ag2MoO4 mit HCl zu AgCl‐Pulver umgesetzt und anschließend einige Ag+‐Ionen im Oberflächenbereich der AgCl‐Partikel zu Ag0 reduziert wurden. Dieser Photokatalysator ist beispielsweise beim Abbau organischer Farbstoffe hoch effizient und wird durch sichtbares Licht nicht zerstört.

A new composite photocatalyst Ag/AgBr/WO(3).H(2)O was synthesized by reacting Ag(8)W(4)O(16) with HBr and then reducing some Ag(+) ions in the surface region of AgBr particles to Ag nanoparticles via the light-induced chemical reduction. Ag nanoparticles are formed from AgBr by the light-induced chemical reduction reaction. The Ag/AgBr particles are on the surface of WO(3).H(2)O and have irregular shapes with sizes varying between 63 and 442 nm. WO(3).H(2)O appears as flakes about 31 nm thick and 157-474 nm wide. The as-grown Ag/AgBr/WO(3).H(2)O sample shows strong absorption in the visible region because of the plasmon resonance of Ag nanoparticles in Ag/AgBr/WO(3).H(2)O. The ability of this compound to destroy E. coli and oxidize methylic orange under visible light was compared with those of other reference photocatalysts. Ag/AgBr/WO(3).H(2)O is a highly efficient photocatalyst under visible light. The Ag/AgBr/WO(3).H(2)O samples recovered from repeated photooxidation experiments are almost identical to the as-prepared samples, proving the stability of Ag/AgBr/WO(3).H(2)O sample.

The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion-exchange process between the silver bromide and potassium iodide, then by reducing some Ag(+) ions in the surface region of Ag(Br,I) particles to Ag(0) species. Ag nanoparticles are formed from Ag(Br,I) by the light-induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83 nm to 1 mum. The as-grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce Cr(VI) under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I).