Review on noble metal-based catalysts for formaldehyde oxidation at room temperature

Formaldehyde (HCHO) is a ubiquitous indoor air pollutant that can cause a variety of adverse health effects; therefore, it is of paramount importance to remove HCHO from indoor air. Catalytic HCHO oxidation at room temperature is the most promising technique for indoor HCHO removal, which entails the development of high-efficiency HCHO oxidation catalysts. In this review, we comprehensively summarize the significant and recent advances in room-temperature HCHO oxidation over noble metal-based catalysts, which contain platinum (Pt), gold (Au), palladium (Pd), silver (Ag), and/or rhodium (Rh) as the essential ingredient. In particular, we focus on the relationship between the chemical and structural properties of the catalysts and their HCHO oxidation performance, as well as the catalytic reaction mechanisms, as revealed by sophisticated in-situ spectroscopic techniques and theoretical calculations. Through the past decade of research efforts, highly efficient HCHO oxidation can be achieved at ambient temperature over well-designed catalysts with minimal noble metal content (e.g.,< 0.1 wt%). A timely review of these significant findings is expected to provide valuable guidance for the design of low-cost yet highly efficient and robust noble metal-based catalysts for practical applications in indoor HCHO removal.