Fraunhofer Institute for Surface Engineering and Thin Films IST
Fraunhofer Institute for Surface Engineering and Thin Films IST

Photo and electrochemical processes

Photocatalysis

Photocatalytic coatings - preparation of the coating plant.
© Ronald Frommann
Photocatalytic coatings - preparation of the coating plant.

Photocatalytically active coatings are used to give self-cleaning properties to surfaces, clean air and water, or kill bacteria, algae and fungi. Organic contaminants are degraded to H2O and CO2 by irradiation with light of a suitable wavelength, usually UV light. In principle, the photocatalysis dispenses with additional chemical substances and is therefore one of the most environmentally friendly and sustainable technologies.

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Electroplating

Galvanic deposition on filigree 3D printed structures.
© Fraunhofer IST, Falko Oldenburg
Galvanic deposition on filigree 3D printed structures.

Electroplating is the electrochemical precipitation of metallic coatings on objects. These objects are usually made of metal, but plastics are increasingly being coated as well. Galvanising takes place in a watery solution containing the ions of the metal being deposited (electrolyte). An electric voltage is applied between the work piece being coated (cathode) and a counter electrode (anode). This reduces the ions to the elementary metal on the work piece. Corrosion protection is the leading field of application (zinc and zinc alloys), followed by decorative coatings (chrome) and tribological functions (hard chrome, chemical nickel). Measured by the coated surface, electroplating is one of the leading surface engineering methods.

Diamond electrodes

Water purification by means of diamond electrodes.
© Fraunhofer IST, Falko Oldenburg
Degradation of blue textile dye using diamond electrodes. left: before water purification, right: after water purification by means of diamond electrodes.

Diamond electrodes for the water treatment

By coating technical substrates with conductive diamond layers, a new electrode material with outstanding properties was developed at the Fraunhofer IST: the diamond electrode.

Diamond electrodes are very chemically stable and have the widest known electrochemical window for the electrolysis of water. Oxidizing agents such as ozone, hydrogen peroxide and even hydroxyl radicals can be efficiently formed on diamond anodes, the oxidizing power of which is used for highly efficient electrochemical processes for treating water without additional chemicals.

 

Diamond electrodes for electrochemical synthesis

In addition to water purification, diamond electrodes are also used for the most modern and highly efficient electrochemical syntheses at the Fraunhofer IST.

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