Selective C2 electrochemical synthesis from methane on modified alumina supporting single atom catalysts

Abstract

The production of C2 compounds in an aqueous solution by efficient and selective electro-conversion of methane is a challenge and of great significance topic. Here, enhanced catalysts, with tunable electrocatalytic activities with time, for direct and selective oxidation of methane to C2 products (i.e., acetic acid and ethanol) at ambient temperature were prepared by exploiting Rh and Cu single atoms dispersed on NH4BF4 modified Al2O3 nanoparticles exhibiting a large amount of Brønsted acid sites. Brønsted acid sites play a pivotal role in the final formation allowing the direct CO insertion into reaction intermediates. A high acetic acid production, over the Rh-based electrocatalyst, of 33.57 μmol/hcm2 after only 40 min of reaction was obtained. On the other hand, a selective ethanol production rate of 37.14 μmol/hcm2 after 120 min of reaction was achieved over the Cu-based catalyst, thanks to the tendency vs acetyl species formation over copper single atoms. Catalysts activity was kept stable for at least 120 min, at 2 V, and ambient temperature. The comparative analysis with the literature results highlights the high efficiency of our catalysts in selectively promoting acetic acid and ethanol productions with high yields, and stability. A novel way, exploiting single-atoms dispersed on suitable supports, for the production of performing surfaces, was provided.