Study on the structure vs activity of designed non-precious metal electrocatalysts for CO2 conversion

The rising level of carbon dioxide (CO2), mainly a consequence of human activities, it is leading to devastating consequences to our environment and has raised concerns to the public opinion. To face this issue, governments are working to reduce the level of CO2 emissions, whilst the scientific community is focusing to implement the electro-chemical conversion of the emitted CO2 (CO2RR) as source of added value chemicals. Due to the high stability of the CO2 molecule, to make its conversion practical, the process requires a suitable electro-catalyst. With the aim to understand the mechanism toward specific CO2RR product and thus increase selectivity, in this contribution, we have explored copper nanoparticles (Cu NPs), as one of the most promising catalyst for CO2 conversion, and investigated the reactivity as a function of selected experimental parameters. The results were rationalized via theoretical investigation, also discussed in the paper, to understand the mechanism behind their activity but, most importantly, to relate structure to selectivity. The Cu NPs, prepared via an unconventional sol-gel process, were shown to be pure, with homogeneous size and morphology, and were tested toward CO2RRs showing a total FE above 90%. The higher FE toward the production of C2H4 (up to 33% at an applied potential of -1.0 V) is one of the highest FE reported so far for Cu, without using expensive support. The final products were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM).