Hierarchical honeycomb-like Pt/NiFe-LDH/rGO nanocomposite with excellent formaldehyde decomposition activity

Formaldehyde (HCHO) is regarded as the most ubiquitous indoor pollutant, which causes severe health symptoms for humans. Catalytic oxidation at ambient temperature has been identified as the most promising technique for indoor HCHO removal. Herein, a hierarchical honeycomb-like nanocomposite of reduced graphene oxide (rGO) and nickel-iron layered double hydroxide (NiFe-LDH) was prepared via a hydrothermal method. After decoration of the NiFe-LDH/rGO with 0.34 wt% of platinum (Pt), the Pt/NiFe-LDH/rGO showed excellent catalytic performance for HCHO degradation at room temperature, which are due basically to the better dispersion of both NiFe-LDH and rGO in the composite. This structural characteristic endows Pt/NiFe-LDH/rGO with larger surface area, thus resulting in plentiful surface active sites and highly dispersed Pt nanoparticles, which are conducive to the activation of both surface oxygen atoms of NiFe-LDH and adsorbed oxygen molecules. Moreover, dioxymethylene and formate were major reaction intermediates, while surface hydroxyl groups and surface active oxygen atoms were the key species involved in the catalytic reaction, which shed light on the HCHO oxidation mechanism. This work demonstrates that introducing graphene materials into hierarchical catalysts can enhance the removal of gaseous HCHO and potentially other indoor pollutants.