| HCHO is one of the indoor volatile organic pollutants(VOCs).Prolonged exposure to HCHO gas can seriously harm human health.Therefore,it is imperative to develop efficient catalysts for indoor HCHO removing.Supported platinum(Pt)catalysts consist of Pt nanoparticles(NPs)has recently triggered extraordinary interest for HCHO degradation because of their effectiveness at room temperature that save energy and also shows excellent performance.In this paper,the activity and stability of low temperature HCHO oxidation of Pt-based catalyst were studied.The main contents of this article are as follows.(1)Catalytic oxidation of HCHO on Pt supported SrBi2Ta2O9(SBT)catalystThe high level of dispersion of Pt NPs on SBT was prepared by photoreduction process for sequential degrading formaldehyde(HCHO)to carbon dioxide gas(CO2(g))at room temperature.The actual percentage of Pt on prepared samples were 0.44%,0.9%,1.5%and 1.63%,respectively.The catalyst activity test suggested that the 1.5%-Pt/SBT catalyst(the actual percentage of Pt were 1.5%)showed the best performance for catalytic oxidation of HCHO.Then,the 1.5%-Pt/SBT sample was calcined in air.The XPS characterization showed that the Pt NPs in un-calcinated sample were composed of Pt0 and Pt4+,and observed partial transformation of Pt0 atoms to Pt2+ ions after calcination treatment.HRTEM images showed that the average particle size of Pt NPs on the samples before and after calcination was about 2 nm.The catalyst activity test suggested that the 1.5%-Pt/SBT-400 catalyst(calcinated at 400?)showed the best performance of catalytic oxidation for HCHO.The conversion of HCHO to CO2(g)were monitored by in situ Fourier transform infrared spectroscopy,which showed first conversion of HCHO to CO32-ions onto Pt0 active sites and subsequently the conversion of CO32-ions to CO2(g)by neighboring Pt2+ species of the catalyst.The later process by Pt2+species do not allow CO32-poisoning of the catalyst.Pt0 and Pt2+drive different reaction steps respectively in the reaction process and therefore achieve the tandem catalysis mechanism.The 1.5%-Pt/SBT-400 prepared in this paper was a kind of tandem catalyst.The enhanced activity of the prepared tandem catalyst to oxidize HCHO was maintained continuously for 680 min.Comparatively,the catalyst without Pt2+showed the activity only for 40 min.Additionally,the tandem catalyst presented in this paper has better performance than Pt/titanium dioxide(TiO2)catalyst to degrade HCHO.Overall,the tandem catalyst may be applied to degrade organic pollutants efficiently.(2)Catalytic oxidation of HCHO on Bi3+-(OH)3-Pt interfaces It is concluded that the metal-metal hydroxide interface exhibit higher catalytic activity than the traditional metal-substrate interface in the catalytic reaction.Therefore,the preparation of the metal-metal hydroxide interface with higher activity is of great importance for the development of HCHO catalyst.Here,we synthesized BiOH-Pt-SBT catalyst with high activity metal-metal hydroxide interface(Bi3+-(OH)3-Pt interface)for catalytic oxidation of formaldehyde.The conversion of HCHO to CO2(g)were monitored by in situ Fourier transform infrared spectroscopy,which showed that the Bi3+-(OH)3-Pt interface in BiOH-Pt-SBT catalyst had highly efficient oxygen activation capability.The highly efficient oxygen activation capability of BiOH-Pt-SBT catalyst significantly improved the performance for catalytic oxidation of HCHO,as well as the stability.The Pt/SBT interface in Pt-SBT catalyst drives HCHO?HCOO-?CO32-?CO2 pathway.The synthesis of metal-metal hydroxide interface in BiOH-Pt-SBT catalyst changed the path of formaldehyde oxidation reaction.The Bi3+-(OH)3-Pt interface drives HCHO?HCOO-?CO?CO2 pathway.Moreover,the synthesis of metal-metal hydroxide interface is also successfully applied to Au-based and Ag-based noble metal catalysts.Therefore,the preparing of metal-metal hydroxide interface on nobe-metal catalyst to improve the catalytic activity for HCHO oxidation is of great significance. |
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