Morphology Matters: Tuning the Product Distribution of CO2 Electroreduction on Oxide-Derived Cu Foam Catalysts

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• 作者：Abhijit Dutta ; Motiar Rahaman ; Nicola C. Luedi ; Miklos Mohos ; Peter Broekmann
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：June 3, 2016
• 年：2016
• 卷：6
• 期：6
• 页码：3804-3814
• 全文大小：712K
• 年卷期：0
• ISSN：2155-5435

文摘

Mesoporous Cu foams formed by a template-assisted electrodeposition process have been identified as CO<sub>2sub> electrocatalysts that are highly selective toward C2 product formation (C<sub>2sub>H<sub>4sub> and C<sub>2sub>H<sub>6sub>) with C2 efficiencies (FE<sub>C2sub>) reaching 55%. The partial current of C2 product formation was found to be higher than that of the (parasitic) hydrogen evolution reaction (HER) at any potential studied (−0.4 to −1.0 vs the reversible hydrogen electrode). Moreover, formate production could largely be suppressed at any applied potential down to efficiencies (FE<sub>formatesub>) of ≤6%. A key point of the Cu foam catalyst activation is the in operando reduction of a Cu<sub>2sub>O phase, thereby creating a large abundance of surface sites active for C–C coupling. The cuprous oxide phase has been formed after the Cu electrodeposition step by exposing the large-surface area catalyst to air at room temperature. The superior selectivity of the Cu foam catalyst studied herein originates from a combination of two effects, the availability of specific surface sites for C–C coupling [dominant (100) surface texture] and the temporal trapping of gaseous intermediates (in particular CO and C<sub>2sub>H<sub>4sub>) inside the mesoporous catalyst material during CO<sub>2sub> electrolysis. A systematic CO<sub>2sub> electrolysis study reveals a strong dependence of the C2 efficiencies on the particular surface pore size of the mesoporous Cu catalysts with a maximal FE<sub>C2sub> between 50 and 100 μm pore diameters.