Catalytic vs electrocatalytic CO2 reduction to added-value products

The increase of CO2 concentration in the atmosphere after industrial revolution plays a critical role in global climate crisis, which can be mitigated by exploiting CO2 as a raw material to synthesize high added-value products [1]. The electrochemical (EC) reduction of CO2 is a sustainable and technologically interesting process for the production of chemicals or fuels using renewable electricity sources [2]. The main challenge is to find a suitable electrocatalyst (with a high selectivity, stability and activity) to establish this technology at an industrial level. We are investigating for this EC process nanostructured Cu-based catalysts that are active for the thermocatalytic (TC) CO2 reduction reaction (CO2RR) to CH3OH. A commercial Cu-Zn-Al-based material was tested for these two processes for comparison purposes. The TC CO2RR in H2 atmosphere (25 bars and 250 oC) leads to a methanol selectivity of 50% and CO as side-product, while the EC CO2RR (at ambient conditions) yields different alcohols and other C-based products (C1 to C3) with an overall faradaic efficiency of  70%. The chemical-physical properties of the catalyst were studied before and after both experiments by several characterization techniques (e.g. X-rays diffraction, X-ray Photoelectron Spectroscopy, Field-Emission Electron Microscopy, among others) to understand the role of the modification of the catalyst components during operation in the final selectivity and activity. These results demonstrated that there are synergies between the TC and the EC processes that can be exploited to develop new electrocatalysts compositions for producing useful liquid products (e.g. alcohols) from CO2. In addition, from our primary data we perform a Life Cycle Assessment (LCA) for comparing the TC and EC processes from the environmental and energy consumption viewpoints, demonstrating that the EC CO2RR technology is a more promising approach than the TC one to reduce the impact of global warming, with additional energetic advantages.