催化学报 ›› 2021, Vol. 42 ›› Issue (12): 2206-2215.DOI: 10.1016/S1872-2067(20)63766-4

• 论文 • 上一篇    下一篇

甘油氧化的光谱电化学傅里叶变换衰减全反射谱红外光谱薄膜流动池中硼酸镍层厚度的优化

Steffen Cychya, Sebastian Lechlera, Zijian Huanga, Michael Braunb, Ann Cathrin Brixc, Peter Blümlerd, Corina Andronescub, Friederike Schmidd, Wolfgang Schuhmannc, Martin Muhlera,*()   

  1. a波鸿鲁尔大学化学与生物化学系, 工业化学实验室, 波鸿, 德国
    b杜伊斯堡-埃森大学化学学院, 埃森, 德国
    c波鸿鲁尔大学化学与生物化学系, 分析化学-电化学科学中心, 波鸿, 德国
    d美因茨约翰内斯古腾堡大学物理所, 美因茨, 德国
  • 收稿日期:2020-12-23 接受日期:2020-12-23 出版日期:2021-12-18 发布日期:2021-05-06
  • 通讯作者: Martin Muhler

Optimizing the nickel boride layer thickness in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in glycerol oxidation

Steffen Cychya, Sebastian Lechlera, Zijian Huanga, Michael Braunb, Ann Cathrin Brixc, Peter Blümlerd, Corina Andronescub, Friederike Schmidd, Wolfgang Schuhmannc, Martin Muhlera,*()   

  1. aLaboratory of Industrial Chemistry, Department of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44801 Bochum, Germany
    bTechnical Chemistry III and CENIDE, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstr. 7, D-45141, Essen, Germany
    cAnalytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44801 Bochum, Germany
    dInstitute of Physics, Johannes Gutenberg-University Mainz, Staudingerweg 9, D-55128 Mainz, Germany
  • Received:2020-12-23 Accepted:2020-12-23 Online:2021-12-18 Published:2021-05-06
  • Contact: Martin Muhler
  • About author:* E-mail: muhler@techem.rub.de

摘要:

在碱性甘油电氧化反应中, 利用电化学傅里叶变换衰减全反射谱红外光谱法, 研究了薄膜流动池中滴注硼酸镍催化剂负载量对玻碳电极性能的影响. 连续操作的径向流动池包括一个位于内反射元件上方50 µm的钻孔电极, 可实现红外光谱分析. 这是在确定条件下对电催化剂进行简便和可重复筛选的一个适合的方法, 同时还提供了对复杂反应(如甘油氧化)产物选择性的检测. 通过对泵送电解液进行更耗时的定量高效液相色谱分析, 结果表明, 衰减全反射红外光谱法可快速鉴定产物. 在层流条件下, 水中使用0.1 M甘油和1 M KOH, 流速为5 µL min-1时, 甘油转化率较高. 转化率和选择性取决于催化剂的负载量, 负载量又决定了催化剂层的厚度和粗糙度. 由于在更粗糙的膜中停留时间更长有利于再吸附和C-C键断裂, 因此当负载量最高达210 µg cm-2时, 甘油转化率为73%且甲酸选择性接近80%. 当最低负载量为13 µg cm-2时, 甘油转化率达到63%, 甲酸选择性降至60%, 相应地, C2物种(如乙醇酸盐)选择性较高, 为8%. 因此, 只有催化剂负载量较低时才能形成几微米厚度范围内的薄膜, 此时才适合进行优质催化剂的筛选.

关键词: 催化剂层厚度, 电催化剂, 硼化镍, 工况下衰减全反射红外光谱, 高效液相色谱, 流动池, 薄膜, 甘油阳极氧化

Abstract:

The influence of the drop-casted nickel boride catalyst loading on glassy carbon electrodes was investigated in a spectroelectrochemical ATR-FTIR thin-film flow cell applied in alkaline glycerol electrooxidation. The continuously operated radial flow cell consisted of a borehole electrode positioned 50 µm above an internal reflection element enabling operando FTIR spectroscopy. It is identified as a suitable tool for facile and reproducible screening of electrocatalysts under well-defined conditions, additionally providing access to the selectivities in complex reaction networks such as glycerol oxidation. The fast product identification by ATR-IR spectroscopy was validated by the more time-consuming quantitative HPLC analysis of the pumped electrolyte. High degrees of glycerol conversion were achieved under the applied laminar flow conditions using 0.1 M glycerol and 1 M KOH in water and a flow rate of 5 µL min-1. Conversion and selectivity were found to depend on the catalyst loading, which determined the catalyst layer thickness and roughness. The highest loading of 210 µg cm-2 resulted in 73% conversion and a higher formate selectivity of almost 80%, which is ascribed to longer residence times in rougher films favoring readsorption and C-C bond scission. The lowest loading of 13 µg cm-2 was sufficient to reach 63% conversion, a lower formate selectivity of 60%, and, correspondingly, higher selectivities of C2 species such as glycolate amounting to 8%. Thus, only low catalyst loadings resulting in very thin films in the few μm thickness range are suitable for reliable catalyst screening.

Key words: Catalyst layer thicknes, Electrocatalyst, Nickel boride, Operando ATR-IR, High performance liquid chromatography, Flow cell, Thin film, Anodic glycerol oxidation