Abstract
A demand for functionalization of novel materials and surfaces has accelerated the study of preparation methods for thin films and coatings. Preparation of catalytically active materials such as metal oxides, mixed oxides, zeolites and hydrotalcites in the form of thin films and coatings has led to chemical and physical properties widely different from those of their bulk analogues. Conventional applications of zeolite powders were limited to ion-exchange, sorption and catalysis. However, recent advances in synthesis methods for controlling the catalyst architecture in two and three dimensions have led to discovery of new applications for zeolitic materials. Zeolite thin films and coatings have experienced a high demand arising from their applications in monolith catalysts, catalytic membrane reactors, permeation barriers, anti-reflective surfaces, low dielectric constant materials and sensing. In addition, zeolite thin films have facilitated a better understanding of the relationship between their crystalline structure and functional activity. Such understanding has given a boost to rational design of functional materials for targeted applications. Latest developments in methods of thin film preparation demonstrate the preparation of well-ordered directionally oriented thin films and coatings. This review focuses on conventional and modern synthetic methods used for preparation of catalytically active thin films and coatings. It is evident from the tremendous growth and improvements observed in this research area that catalyst coatings and micro channel reactors will play a very important role in industrial catalysis as well as academic research in the imminent future.