Fabrication Of Nickel Foam-based Metallic Oxides For Catalytic Formaldehyde Oxidation At Room Temperature

Nowadays,people tend to use more decorate materials and furniture to make their home more comfortable and artistic.However,what cannot be ignored is that gaseous formaldehyde?HCHO?is emitted mainly from such decorate materials and furniture.HCHO is one of the indoor air pollutants,which will do great harm to human health.Recently,many works have reported that people spend much of their time indoor that contains even low concentration of gaseous HCHO will feel uncomfortable and even suffer cancer.Hence,it is highly desired to seek for efficient methods to remove indoor HCHO.Among all of the indoor HCHO remove stratergies,room-temperature catalytic HCHO oxidation has been attracting worldwide attentions and become a promising method.However,the catalysts reported recently are synthesized in powder form.For practical application,extra treatment processes are needed,which may inhibit HCHO oxidation activities.To solve the problem,herein,sponge-like nickel foam was used as substrate,accompanied by facile synthesis process,to prepare two kinds of nickel foam-based practical and excellent catalysts for room-temperature HCHO oxidation.?1?In this work,flexible nickel?Ni?foam coated with Pt/NiO nanoflake catalysts were prepared through fast chemical bath deposition,which exhibited enhanced activity for HCHO removal at room temperature.In contrast,no HCHO oxidation activity was observed for control samples without loading platinum?Pt?or coating nickel?II?oxide?NiO?nanoflakes.By optimizing the deposition duration,almost 90%HCHO removal efficiency was achieved within 1 h over the sample with 1 h deposition time.The deposition of NiO nanoflakes over Ni foam not only forms hierarchical structure facilitating the reactions kinetically,but also provides sufficient oxygen vacancies promoting Pt deposition and consequent HCHO oxidation.The HCHO oxidation activity of the catalysts positively correlated with Pt dispersion and with the proportion of oxygen-deficient NiO,as determined by hydrogen temperature programmed reduction.Moreover,the mechanism of room-temperature HCHO catalytic oxidation over as-prepared catalysts was investigated by in-situ diffuse reflectance infrared Fourier transform spectra,which identified formate and dioxymethylene as the main reaction intermediate.Compared with powder-like catalysts,the Ni foam-supported Pt/NiO catalysts are of great flexibility and machinability,holding great promise for actual application.?2?The nickel foam coated with Pt/MnO₂/Ni?OH?₂?Pt/MnNi@NF?composite catalyst was prepared via the facile one-step hydrothermal method and then traditional impregnation approach.And the catalyst exhibited improved performance of room temperature HCHO oxidation due to synergestic effect of the three components and nickel foam substrate.OH groups of Ni?OH?₂ were helpful for the adsorption of molecular HCHO,while Pt nanoparticles facilitated the formation of active oxygen species.Besides,oxygen vacancies on the surface of MnO₂ were beneficial to migration of active oxygen species.Herein,nickel foam served as substrate,which contributed to the formation of thinner nanosheets with lager lateral size and smaller grain size,thus exposing more active sites and improving the homogeneous dispersion of Pt nanoparticles.Therefore,HCHO catalytic oxidation activity of Pt/MnNi@NF was remarkably enhanced.What is more,nickel foam was also used as Ni source during preparation,in which Ni reacted with KMnO₄ to form MnO₂-Ni?OH?₂ hybrid nanosheets,which tightly bonded with the Ni foam substrate and could not be inhaled by users,thus holding great promise for application in daily life.