Electrodeposition synthesis of free-standing metal/carbon felts electrodes for electrocatalytic hydrogenation of levulinic acid

Abstract

Converting levulinic acid (LA) to fuel precursors such as gama-valerolactone (GVL) and valeric acid (VA) via an efficient and low-cost method is of great significance. Herein, a series of free-standing electrodes consisting of metallic metals supported by carbon felts (CFs) were fabricated via a facile electro-deposition process. The resulting M/CFs (M = Pb, Cd, Co, Ni, Cu and Bi) electrodes were evaluated for electrocatalytic hydrogenation (ECH) of LA. The electrocatalytic activity of the electrodes was extensively studied by various electrochemical methods including cyclic voltammetry, linear sweep voltammetry and chronoamperometry measurements. The products of the ECH processes were analyzed by gas chromatography-mass spectrometry. Of all the prepared samples, the Pb/CFs and Cd/CFs electrodes showed superior performance for ECH of LA. The selectivity of VA reached up to 91.7% when the Pb/CFs was used and the conversion of LA reached to 57.2% using the Cd/CFs electrode, rendering them as one of the best electrodes for ECH reported in the literature. The effects of applied potentials on the ECH process were investigated. To further optimize the ECH performance of the Pb/CFs electrodes, several key parameters including deposition time, pH value of the electrolyte and reaction time were studied. When the electrodeposition time was 600 s and the concentration of sulfuric acid in the electrolyte was 0.5 M, the complete transformation of 0.2 M of LA was achieved after 6 h. This study may afford an alternative way to the conversion of LA to GVL or VA.