坑洞缺陷限域的金属亚纳米簇用于异相催化
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摘要
金属(氧化物)亚纳米簇是工业催化中一类重要的催化剂~[1]。纳米簇暴露大量特殊活性位点而具有广阔应用前景,然而在催化过程中其容易偏析长大导致失活~[2]。我们报道了一种稳定纳米簇的策略,并通过温和的一锅水热法合成了CeO_2表面坑洞缺陷限域CuO纳米簇的杂化结构。透射电子显微镜表征显示氧化铈纳米颗粒表面密集分布小于5 nm的坑洞,CuO纳米簇限域在坑洞内。我们通过富氢环境下优先氧化CO测试所制备的复合结构催化剂,并与传统的CuO纳米颗粒负载CeO_2和Cu掺杂CeO_2催化剂作对比。研究表明这种结构的催化剂可以在120℃到200℃的宽温度窗口内近乎完全除去CO杂质,并且适合高温潮湿环境下长时间运行,而同组分的对照催化剂在同样条件下无法实现氢气流中完全氧化CO。这种合成策略有望扩展到其他材料体系,譬如CeO_2限域的Au,Pt纳米簇等催化剂。
Metal(oxide) cluster catalysts are critical in industry due to their efficient exposing of active sites.However,the catalyst would be inactive that caused by segregation and growth of metal clusters.We report a mild one-pot hydrothermal method to synthesize a catalyst with CuO clusters confining in pit-type defects of CeO_2.The performance of as-prepared catalyst was determined by preferential CO oxidation in H_2-rich streams(PROX),which is an important process in proton exchange membrane fuel cells.Compared with traditional CuO nanoparticles supported CeO_2 and Cu-doped CeO_2 samples,the confined catalyst exhibited nearly completely CO oxidation in the temperature range from 120 ℃ to 200 ℃,and showed long-time stability at high temperatures in humid PROX conditions.The strategy of confining metal(oxide) sub-nanoclusters in the pit-type defects of CeO_2 is expected to synthesize other systems,such as confined Pt,Au,to construct new types of synergistic catalysts.
引文
[1]Zhang,H.;Watanabe,T.;Okumura,M.;Haruta,M.;Toshima,N.Nat.Mater.2012,11,49-52.
    [2]Delannoy,L.;Giorgio,S.;Mattei,J.G.;Henry,C.R.;El Kolli,N.;Méthivier,C.;Louis,C.Chem Cat Chem 2013,5,2707-2716.

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