Selective Electrochemical Decarboxylation of n-Octanoic Acid to Hydrocarbons on Pt Nanocrystals

Electrocatalytic synthesis of valuable biofuels and chemicals from biomass-derived acids is a promising approach, but selectively producing deoxygenated hydrocarbons is still a great challenge. In this work, we investigated selective electrochemical decarboxylation of n-octanoic acid to produce hydrocarbons (n-tetradecane, n-heptane, and n-heptene) in a single electrolytic cell at room temperature. Pt nanoparticles with different morphologies (nanospheres, nanoflowers, and nanothorns) and further Pt nanothorns with different plane distributions on carbon fiber paper (CFP) were fabricated by a controllable electrodeposition method. The results proved that the Pt(311) plane has the best selectivity and intrinsic activity for decarboxylation products, especially for Kolbe hydrocarbons. The Pt(110) plane shows a similar intrinsic activity as the Pt(311) planes. High selectivity (75%), yield (35%), and Faraday efficiency (34%) for hydrocarbons were achieved over the Pt nanothorn (Pt-NT), which were approximately 1.6, 2.3, and 3.3 times that of Pt nanoflowers, Pt nanospheres, and Pt/C, respectively. The high electrocatalytic activity of Pt nanothorns was attributed to its high electrochemically active surface area (ECSA) and enhanced intrinsic activity derived from the high level of Pt(311) and Pt(110) planes.