The ability to convert atmospheric CO2 to hydrocarbon and alcohol fuels is an important step towards establishing a close-loop carbon fuel cycle with net zero carbon emission. In their landmark experiment 28 years ago, Y. Hori et al. demonstrated that CO2 could be electrochemically reduced on a copper metal surface to a mixture of small hydrocarbons and alcohols. More recently, T. Jaramillo and co-workers showed that at least 16 C1-C3 products including ketones, alcohols, and carboxylic acids could be obtained from CO2 reduction! Despite these successes, CO2 reduction to fuels remains an industrially unviable process. This is because it is energetically inefficient, unstable and has poor product selectivity.We shall first present an overview of efforts from various workers to design selective and efficient electrocatalysts for reducing CO2. Then, we shall discuss our recent experiments to understand how CO2 can be selectively reduced into specific products such as ethylene. Online electrochemical gas chromatography, cyclic voltammetry and electron microscopy were employed towards this end. The electrolyte in all cases was 0.5 M KHCO3. An electropolished Cu surface or one pulse-deposited with Cu nanoparticles yield poor CH4 or C2H4 selectivity. In contrast, we show that high selectivity for C2H4 formation can be achieved using an electrochemically roughened Cu electrode.  High resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) reveals that the active Cu catalyst has (100) surface facets with step atoms.

Electrocatalysts for the selective and efficient reduction of CO<sub>2</sub>

247th National Meeting (2014)

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Electrocatalysts for the selective and efficient reduction of CO2

Electrocatalysts for the selective and efficient reduction of CO₂