Adhesion properties of inorganic binders for the immobilization of photocatalytic ZnO and [formula omitted] nanopowders

Abstract

Sodiumsilicate, potassiumsilicate and zinc phosphate were tried as inorganic binders to immobilize photocatalyst nanopowders. These binding materials are commercially available except the zinc phosphate which was synthesized by the reaction of ZnO powders and phosphoric acid. These binders were used to immobilize the ZnO and TiO 2 (P-25, Degussa) nanopowders on the glass substrates. The ZnO nanopowders were synthesized by the solution combustion method (SCM) which was developed by the authors. After immobilization, scratch test and ultrasonic vibration test were carried out to examine the mechanical properties of the binders. The zinc phosphate which immobilized SCM ZnO nanopowders showed the best adhesion properties such as highest cohesive force ( 1.7 – 4.3 times higher) with the SCM ZnO nanopowders and highest adhesive force (4.1–37.5 times higher) with the glass substrate. The zinc phosphate also immobilized the SCM ZnO nanopowders twice more than other combinations of the binders and photocatalysts. It made 92% of SCM ZnO nanopowders remained after ultrasonic vibration of 10 min. These abnormally good adhesion properties are probably due to the chemical reaction rather than physical binding between the zinc phosphate and the SCM ZnO nanopowders.