Nanotechnology is used in sectors of science and technology such as energy, medicine and drugs, nanobiotechnology, nanodevices, optical engineering, cosmetics, bioengineering, nano fabrics, and in the defense sector because of its large surface-area-to-volume ratio. Nanomaterials are classified based upon their origin and structure. The classifications which depend upon the origin are natural nanomaterials, artificial nanomaterials, zero-dimensional, one-dimensional, twodimensional, and three dimensional. Structural classification nanomaterials are classified into four types: carbon-based, metal-based, dendrimers, and composites. Size distribution is the most important information in dealing with nanomaterials. With decrease in size there is increase in portion of surface atoms. Ultrasound causes high-energy chemistry that is accomplished through the process of acoustic cavitation. Ultrasound is used as an important source for the initiation or enhancement of catalytic reactions, in both homogeneous and heterogeneous systems. Ultrasound technology is already into the research field providing nanomaterials or being implicated in decoration procedures of catalyst supports for energy applications and material production. Ultrasound (US) is largely used to accelerate chemical reactions (especially organic syntheses) and in degradation and hydrolysis reactions. US has been only sparingly used to assist analytical reactions despite the proven high potential of this form of energy for their acceleration. Nanomaterials have large surface-area-to-volume ratio that differs in orders of magnitude greater from the macroscopic materials. The size and structure of the nanomaterials depend upon factors such as surfactant additives, reactant concentrations, temperature, solvent conditions on the time of synthesis, and salt. In order to develop reproducible synthesis of nanomaterials, characterization of nanomaterials is found to be important. Characterization refers to the study of composition, structure, and other properties such as physical, chemical, electrical, and magnetic. Many techniques are available for the characterization of nanomaterials, but a degree of uncertainty is seen in each technique. photocatalytic process is environmental friendly, inexpensive and save process for air disinfection, nanomaterial as catalyst under the suitable wavelength of light in photocatalytic process produce reactive oxygen species which react with air pollutant and decomposed them.