Solid-state Chemical Synthesis Of Co₃O₄ Nanomaterials And CO Catalytic Oxidation Properties

CO is a toxic and detrimental air pollutant.It not only affects human beings but also vegetation and environment,which has been paid more attention recently.Various technologies have been developed to remove the toxic CO.Among of them,catalytic oxidation technology of CO is an effective and desired way that can make a toxic CO convert to innoxious CO2.Spinel structure Co₃O₄ nanomaterials owing to its low-cost,high stability and outstanding properties are emerging as attractive materials.Particularly,Co₃O₄ nanomaterials with high catalytic activity are able to achieve similar effects as noble metal for CO oxidation,which is considered as a substitute for precious metals catalysts.In this article,we adopted a facile solid-state chemical method to synthesize Co₃O₄ nanomaterials and the catalytic activity for CO oxidation of Co₃O₄ nanomaterials was investigated in normal feed gas or mormal feed gas with moisture.Additionally,the surface modification of Co₃O₄-rods with transition metal ions was performed in order to further enhancing the catalytic performance towards low-temperature.?1?Co₃O₄ nanomaterials with different morphologies were synthesized by a facile solid-state chemical method.The structure and morphology of Co₃O₄ nanomaterials were characterized by various characterization techniques.The influence of different reactants and reaction conditions on the structure and morphology was investigated to obtain the grow mechanism of Co₃O₄ nanomaterials in solid-state chemical reaction.Then the catalytic activity of as-prepared Co₃O₄ samples for CO oxidation was evaluated in normal feed gas.The results showed that Co₃O₄ nanomaterials with different shape have different catalytic activity for CO oxidation.Among them,Co₃O₄-rods exhibited the highest catalytic activity for CO oxidation,which can be attributed to more active sites(oxygen defects and Co³⁺)on Co₃O₄-rods surface.Additionally,Co₃O₄-rods also exhibited excellent durablility?without pretreatment?in normal feed gas and even in the presence of moisture.?2?Transition metal doped Co₃O₄-rods were synthesized by a facile solid-state chemical strategy.The structure and morphology were characterized by various characterization techniques.The catalytic activity of transition metal doped Co₃O₄-rods for CO oxidation was evaluated in normal feed gas.Additionally,the influence of different doping amount and calcination temperature on catalytic activity of catalysts was also investigated.The results showed that the low temperature catalytic activity and the thermal stability for CO oxidation was improved after vanadium???doped into Co₃O₄-rods.This can be attributed to Co³⁺contents increased and the formation of more active defects by introducing vanadium into metal oxide lattice.?3?Co₃O₄ nanomaterials were prepared via a facile solid-state chemical reaction between Co?NO3?2 and NaHCO3.The influence of reaction conditions on their catalytic performance were also investigated.Bi³⁺ was induced to Co₃O₄ nanomaterials lattice in order to further enhancing the low temperature catalytic activity.The performance test results show that the incorporation of Bi³⁺ into Co₃O₄ nanomaterials lattice can greatly enhance the low-temperature catalytic activity of Co₃O₄ nanomaterials for CO oxidation.Especially,3% Bi-doped Co₃O₄ nanomaterials exhibited the highest catalytic activity for CO oxidation and could completely convert CO to CO2 at 50 oC.The improvement of catalytic activity can be attributed to more Co³⁺ formed and the mobility of lattice oxygen after Bi³⁺ doped into Co₃O₄ lattice.