Electroless deposition of zinc oxide for photocatalytic membrane

Photocatalysis technology has the potential to address challenges associated with traditional water treatment methods in removing organic pollutants by employing free electron pairs of photocatalysts under ultraviolet irradiation. Ceramic materials have been widely used for photocatalysis and shown to be an excellent photocatalyst. Among them, one of the most popular ceramic materials for photocatalytic membranes is zinc oxide (ZnO). Electroless deposition (ELD) is one of the methods to deposit this ceramic material on the surface of substrate for the preparation of photocatalytic membrane. There are three major steps in the preparation of ELD: (i) surface preparation, (ii) sensitizing and activation, and (iii) deposition. Surface preparation is carried out to increase surface area and introduce polar functional groups. Sensitizing and activation step is to deposit the palladium layer on the substrate to act as a catalyst for the ELD of the ceramic material. During the deposition process, the concentration of metal salt, concentration of reducing agent and, deposition temperature are important for controlling the properties of prepared ceramic photocatalysts. The variables and concentration of the ELD bath in each fabrication step have a substantial effect on the particle size, deposition density, surface area, crystallinity, and structure of the prepared ceramic photocatalyst, which will subsequently affect its photocatalytic activity. This chapter is to outline the use of ELD to prepare the ZnO membrane, an example of preparing a photocatalytic ceramic membrane as a means to enhance its photocatalytic activity by optimizing the deposition process and deposition parameters to achieve desirable morphology.