Adsorption enhanced catalytic degradation of airborne formaldehyde in bifunctional composite materials

Abstract

Formaldehyde (HCHO) is one of the well-known carcinogenic VOCs in indoor, which poses a serious threat to the environment and human health. Bifunctional composite materials (BFCMs) have great application prospects in the field of HCHO removal due to their impressive adsorption-promoted catalytic synergies and good catalytic stability. However, the urgency of efficient degradation of HCHO at near room temperature poses many challenges to the design of BFCMs, especially the design of components in BFCMs, such as support components (SCs) and catalytic components (CCs). In addition, the influences of multiple components in BFCMs on the degradation of HCHO are highly complex, especially the component synergies and the adsorption-promoted catalysis mechanism. To understand these effects and improve the degradation efficiency of HCHO, we firstly discuss the encouraging research outcomes in recent years, encompassing the design, preparation, and multilevel synergies in BFCMs (such as adsorption-catalytic synergies, heterogeneous synergies within SCs or CCs, structural synergies, mass and heat transfer synergies). Subsequently, we concentrate on analysing the impacts of support component factors (such as types, crystal phases, particle sizes, morphologies, specific surface areas, and acidity) and catalytic component factors (such as shapes, morphologies, particle sizes, metal chemistry states, and loading capacities) on the HCHO removal performances. Finally, the degradation mechanism of HCHO and the catalytic stability of BFCMs are concluded.