铁、氮掺杂石墨烯/碳黑复合材料的制备及氧还原电催化性能

以高含氮量的2-氨基咪唑为氮源,三氯化铁为铁源,高比表面积的KJ600碳黑为载体,通过水热法制得氨基咪唑聚合物前驱体,再经二次高温热处理,制得石墨烯/碳黑复合材料. 透射电镜表征显示该材料为石墨烯纳米片与碳黑颗粒的复合结构. BET表征表明这是一种多孔结构,具有很高的比表面积（882 m²•g^-1）,这有利于暴露更多活性位点,并促进传质. XRD证实催化剂中存在石墨烯,且石墨烯结构是在第一次热处理过程中形成的. 电化学测试表明,该催化剂在酸性和碱性介质中都具有很高的氧还原电催化活性和低H₂O₂产率,并且在碱性介质中对甲醇小分子的抗毒化性能明显优于商业Pt/C催化剂,展示出在实际燃料电池系统中的应用潜力.     

Catalytic reduction of NO_x by CO on hydro-talcites-derived mixed oxides Co AIM and MgAlM (M = Cr, Mn, Fe, Co, Ni, Cu)

Two series of mixed oxides, CoAlM and MgAlM (M= Cr, Mn, Fe, Co, Ni, Cu) , were prepared by calcining their corresponding hydrotalcite-like compounds (HTLc) . The ratio of Mg: Al: M (or Co: Al: M) was 3:1:1. The catalytic activity of all samples for the reaction of NO CO was investigated. The results showed that the activity of CoAlM was much higher than that of MgAlM. The structure and the property of redox were characterized by XRD and H2-TPR. The results indicated that only MgO phase was observed after calcining MgAlM hydrotalcites, and the transition metals became more stable. The spinel-like phase appeared in all of CoAlM samples after the calcination, and the transition metals were changed to be more active, and easily reduced . The activities of three series of mixed oxides CoAlCu obtained from different preparation methods, different ratio of Co:Al:Cu and at different calcination temperatures, were studied in detail for proposing the mechanism of reaction. The ability of adsorption of NO and CO     

Catalytic reduction of NOx by CO on hydrotalcites-derived mixed oxides CoAlM and MgAlM (M=Cr,Mn, Fe,Co, Ni,Cu)

Two series of mixed oxides, GIAlM and MgAlM (M= G, Mn, Fe, Co, Ni, Cu), were prepared by calcining their corresponding hydrotalcite-like compounds (HTLc). The ratio of Mg: Al: M (or Co: Al: M) was 3:1:1. The catalytic activity of all samples for the reaction of NO + CO was investigated. The results showed that the activity of CoAlM was much higher than that of MgAlM. The structure and the property of redox were characterized by XRD and H₂-TPR. The results indicated that only MgO phase was observed after calcining MgAlM hydrotalcites, and the transition metals became more stable. The spinel-like phase appeared in all of CoAlM samples after the calcination, and the transition metals were changed to be more active, and easily reduced. The activities of three series of mixed oxides CoAlCu obtained from different preparation methods, Different ratio of Co: Al: Cu and at different calcination temperatures. were studied in detail for proposing the mechanism of reaction. The ability of adsorption of NO and CO were investigated respectively for supporting the mechanism.     

Co-M(M=La,Ce, Fe,Mn, Cu,Cr)复合金属氧化物催化分解N2O

通过共沉淀法制备了一系列Co-M(M= La, Ce, Fe, Mn, Cu, Cr)复合金属氧化物及纯Co3O4催化剂, 考察了其催化分解N2O 的活性. 结果表明在研究的系列催化剂中, Co-Ce 复合氧化物催化剂具有最好的催化分解N2O的活性; 其活性与Ce/Co 摩尔比有直接的关系, 当Ce/Co 摩尔比为0.05 时(CoCe0.05 催化剂)催化活性最佳; 当有NO 和O2共存时, 可能在催化剂活性中心上形成表面硝酸盐或亚硝酸盐吸附物种而使其活性受到较大影响. 通过对Co-M 催化剂的XRD、BET、O2-TPD及H2-TPR 等表征结果的分析, 发现作为主要活性位的Co2+的氧化还原能力是影响催化剂活性的主要原因. 这是因为根据反应机理, N2O 的表面分解步骤与Co2+氧化成Co3+的能力相关, 而吸附氧的脱附与Co3+还原成Co2+的能力相关. 在所研究的催化剂中, 添加除CeO2之外的其它过渡金属氧化物时, 催化剂中Co3+/Co2+的氧化还原能力降低, 因此其催化性能降低. 另外, 添加不同过渡金属氧化物也改变了N2O 催化分解反应的速控步骤.     

Reactions of Hydrated Singly Charged First‐Row Transition‐Metal Ions M+(H2O)n (M=V,Cr, Mn,Fe, Co,Ni, Cu,and Zn) toward Nitric Oxide in the Gas Phase

Reactions of M⁺(H₂O)_n (M=V, Cr, Mn, Fe, Co, Ni, Cu, Zn; n≤40) with NO were studied by Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry. Uptake of NO was observed for M=Cr, Fe, Co, Ni, Zn. The number of NO molecules taken up depends on the metal ion. For iron and zinc, NO uptake is followed by elimination of HNO and formation of the hydrated metal hydroxide, with strong size dependence. For manganese, only small HMnOH⁺(H₂O)_n?1 species, which are formed under the influence of room‐temperature black‐body radiation, react with NO. Here NO uptake competes with HNO formation, both being primary reactions. The results illustrate that, in the presence of water, transition‐metal ions are able to undergo quite particular and diverse reactions with NO. HNO is presumably formed through recombination of a proton and ³NO^? for M=Fe, Zn, preferentially for n=15–20. For manganese, the hydride in HMnOH⁺(H₂O)_n?1 is involved in HNO formation, preferentially for n≤4. The strong size dependence of the HNO formation efficiency illustrates that each molecule counts in the reactions of small ionic water clusters.