Electrochemical CO2 Reduction to Fuels Using Pt/CNT Catalysts Synthesized in Supercritical Medium

Abstract

The electrochemical reduction of CO2 in the gas phase has been carried out in a solid polymer electrolyte type cell (25 cm2 geometric area) in continuous operation mode using carbon nanotube-supported platinum catalysts (Pt/CNT). The main novelty of this work relies on the use of supercritical media (supercritical CO2) for Pt deposition on CNT. Supercritical synthesis has allowed obtaining small Pt nanoparticles divided into two modal distributions (for 3–4 nm and 8–9 nm, respectively) with a high deposition efficiency (about 80%). The main reaction products of the electrocatalytic conversion of CO2 have been formic acid (59–89%), methane (2–33%), CO (3–11%), methanol (0–1.9%), and small amounts of acetone, isopropanol, and methyl acetate. The CO2 conversion rate multiplies almost by four when increasing current density, although selectivity barely changes. Lower temperature promotes further reduction of CO2 to methane (33% of selectivity) to the detriment of formic acid and CO. However, increases of temp...