The electrochemical CO₂ reduction reaction (CO2RR) has become a promising path forward to a carbon neutral energy cycle by combining carbon capture with hydrocarbon production, especially if excess power from regenerative resources such as wind and solar is available and used. The key obstacle for deployment of the one-step electrochemical CO2RR technology is the development of low-cost electrocatalysts that facilitate energy-efficient production of hydrocarbons from CO₂ with high selectivity and long-term stability. Here, copper has emerged as the most promising catalyst for the formation of hydrocarbons at ambient pressures and temperatures.

We have developed a unique expertise in the synthesis of nanoporous metal catalysts including nanoporous Cu (npCu) made from CuMn and CuZn alloys, Cu nanocube surface functionalizations and Cu-oxide/Cu nanowire forests (Fig. 1). Preliminary CO2RR tests of these materials have confirmed that oxidized npCu electrodes have a significantly increased transient reactivity towards the electrochemical reduction of CO₂. We will discuss results using a novel electrochemical cell geometry that is designed to take full advantage of the high surface area of the catalyst.

Fig. 1: (a) NpCu prepared by dealloying CuZn alloys; (b) Cu nanocube surface functionalization of npCu; (c) Cu-oxide nanowires grown on Cu foam formed by annealing in air (1h @ 500C).

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344