Efficient Electrochemical Reduction of CO₂ to Formic Acid

Fossil fuels comprise more than 80% of global energy sources because of their availability, versatility, and high energy density. However, their continued use at this level is accompanied by an unchecked accumulation of atmospheric CO₂. An attractive alternative is to develop a scalable synthesis of carbon-containing products (formic acid, methane, methanol, and ethanol) using renewable energy, H₂O, and CO₂ at room temperature and atmospheric pressure. An efficient catalyst must mediate multiple electron and proton transfers to CO₂ for the reduction of CO₂ in the presence of H₂O, and selectively produce one of many possible products. Researchers over the past three decades have identified several materials (e.g., semiconducting metal oxides) that are capable of reducing CO₂ electrochemically in aqueous solutions, but none are efficient and stable enough for practical use due to the large overpotential (>0.7 V) required for CO₂ reduction to outcompete H₂O reduction. The energy level of the conduction band of semiconducting materials such as Cu₂O or CuO cannot contain the sufficient reduction potential of CO₂ to formic acid (HCOOH). In this regard, we are going to present our recent progress on the efficient CO₂ reduction to formic acid by using bipolar WO₃/Cu-CuO nanowires hybrid electrodes with low overpotential.