可控CO吸附决定CO2电还原产生乙烯和甲烷

武汉大学高等研究院阴国印教授课题组和湖北工程学院生物医学材料工业技术研究所朱磊教授课题组合作报道了镍/铜双金属协同催化的非活化末端烯烃的1,n-芳硅化反应(n=2-5),以题为“Synergistic Ni/Cu catalyzed migratoryarylsilylation of terminal olefins”在线发表于Science Bulletin。钾离

在所有的CO₂电还原产物中，甲烷(CH₄)和乙烯(C₂H₄)是两种典型且有价值的烃类产物，它们通过同一CO中间体的加氢(C1)和二聚(C2)反应而形成。理论研究表明，CO中间体的吸附构型和吸附强度决定了反应途径。然而，实验上控制催化剂上CO中间体的吸附构型是一个挑战，因此烃类产物选择性仍然很低。本文合成了两种表面环境可控的铜纳米粒子作为模型催化剂。在相同的还原条件下，所得的催化剂对CH₄(83%)和C₂H₄(93%)具有极高的碳选择性。扫描、透射电子显微镜和X射线吸收谱表征显示，两种催化剂分别具有低配位Cu⁰位点和局部Cu⁰/Cu⁺位点。CO程序升温脱附、原位衰减全反射傅里叶变换红外光谱和密度泛函理论研究表明，低配位Cu⁰位点上桥式吸附的CO倾向于加氢反应产生CH₄，而Cu⁰/Cu⁺位点上桥式吸附和线性吸附的CO倾向于共聚产生C₂H₄。本文的发现为设计具有可控CO吸附构型的高烃类产物选择性催化剂开辟了一条新途径，以题为“Controllable CO adsorption determines ethylene and methane productions from CO₂ electroreduction”发表于Science Bulletin。

图文速览

Fig. 1. Morphologycharacterizations. (a), (b) TEM images of the MP-Cu and EP-Cu catalysts. Insetsshow a uniform particle size of ~15 nm for both catalysts. (c), (d) STEM imagesof a representative catalyst particle of EP-Cu and MP-Cu, revealing the Cu⁰ phase with abundant step sites in MP-Cu while abundant local Cu⁰/Cu⁺sites in EP-Cu.

Fig. 2.  XAS characterizationsof the MP-Cu and EP-Cu. (a) Cu K-edge XANES spectraof MP-Cu versus time, showing the valence states of Cu from initial 2+ to thestabilized 0. (b) Linear combination fit results of MP-Cu XANES at the CuK-edge acquired in 90 mins using Cu, Cu₂O and CuO NPs as standards(Fitting range: 8970 to 9030 eV). (c) Cu K-edge XANES spectraof EP-Cu versus time, showing the valence states of Cu from initial 2+ to thestabilized positively charged Cu. (d) Linear combination fit results of EP-Cu XANESat the Cu K-edge acquired in 90 mins using Cu, Cu₂O and CuO NPs asstandards (Fitting range: 8970 to 9030 eV).

Fig. 3.  CO₂RR performance of MP-Cu and EP-Cu. (a) FE distribution of reduction products on MP-Cuand (b) carbon selectivity distribution comparing to all carbon containingproducts of MP-Cu at optimized potential. (c) FE distribution of reductionproducts on MP-Cu and (d) carbon selectivity distribution comparing to allcarbon containing products of MP-Cu at optimized potential. (e) FE distributionof reduction products on MP-Cu versus applied potential. (f) FE distribution ofreduction products on EP-Cu versus applied potential.

Fig. 4. CO adsorption studies of EP-Cu and MP-Cu. (a) CO TPDresults of EP-Cu, MP-Cu and the catalysts support carbon paper (CP), showingonly CO_B on MP-Cu while both CO_L and CO_B onEP-Cu. (b) In-situ ATR-FTIR study of MP-Cu versus applied potential, representingonly CO_B on MP-Cu. (c) In-situ ATR-FTIR study of EP-Cu versusapplied potential, revealing both CO_L and CO_B on EP-Cu.(d) Optimized CO adsorption configuration andrelative vibration frequency on step site (bridge, left side) and on oxidizedsite (linear, right side) after removing the beneath Cu to show the sub-surfaceoxygen from DFT results (side views). (e) Illustration of differentCO adsorption configurations towards either hydrogenation or dimerization reactionpathways.

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Haipeng Bai, Tao Cheng, Shangyu Li, Zhenyu Zhou, Hao Yang, Jun Li, Miao Xie, Jinyu Ye, Yujin Ji, Youyong Li, Zhiyou Zhou, Shigang Sun, Bo Zhang*, Huisheng Peng*. Controllable CO adsorption determines ethylene and methane productions from CO₂ electroreduction. Science Bulletin, 2021, 66(1): 62-68

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