Volatile organic compounds (VOCs) are toxic and recognized as one of the major contributors to air pollution. The development of efficient processes to reduce their emissions is highly required. Complete catalytic oxidation is a promising way to convert VOCs, especially with low concentration, into harmless CO₂ and water. This reaction is highly desirable to proceed at low temperature for the consideration of safety, energy savings, low cost and environmental friendliness. Great efforts have been devoted to develop efficient catalysts in order to reduce the temperature of catalytic oxidation of VOCs. The present review highlights recent important progress in the development of supported noble metal and metal oxide catalysts in this field. We examined several typical metals that are widely adopted as essential components for catalytic oxidation of VOCs and explored the effect of some important influencing factors such as the properties of metal and support, dispersion, particle size and morphology of metals. The specific mechanism that leads to superior catalytic activity towards low temperature VOC oxidation was discussed too.

Due to the anthropogenic pollution, especially the environmental crisis caused by air pollutants, the development of air pollutant degradation photocatalyst has become one of the major directions to the crisis relief. Among them, titania (titanium dioxide, TiO2) family materials were extensively studied in the past two decades due to their strong activity in the photocatalytic reactions. However, TiO2 had a drawback of large bandgap which limited its applications, several modification techniques were hence developed to enhance its catalytic activity and light sensitivity. In recent years, other metal oxide based materials have been developed as replacements for TiO2 photocatalysts. In this review, background information and developments from pure TiO2 to chemically modified TiO2-based materials as photocatalysts were discussed in detail, which covered their basic properties and their role in the air pollutant removal. It also proposes to solve the shortcomings of TiO2 by developing other metal oxide-based materials and predict the future development of TiO2 materials in future environmental applications.