Plasmon-Enhanced Electrochemical Oxidation of Alcohol Molecules

Plasmon-mediated electrocatalysis, i.e., the application of plasmonic nanostructures as electrodes/catalysts or both, has emerged as a promising approach to facilitate electrochemical reactions. We have investigated the electrochemical oxidation of 4-(hydroxymethyl)benzoic acid (4-HMBA) on different metallic working electrodes in alkaline electrolytes, including gold (Au), nickel (Ni), and platinum (Pt) metal. Au shows the lowest onset potential for catalyzing the electrooxidation of 4-HMBA among the three metals in base, whereas Pt does not catalyze the electrooxidation of 4-HMBA under alkaline conditions. The products of electrochemical oxidation of 4-HMBA catalyzed on Au working electrode are 4-carboxybenzaldehyde and terephthalic acid analyzed by high-performance liquid chromatography. The electrodeposited Au nanostructures on indium tin oxide (ITO)-coated glass is further utilized as the working electrode and catalyst for the 4-HMBA electrooxidation by introducing the plasmonic effects of the Au nanostructures. With the broad absorption of the Au nanostructures anchored on the ITO substrate in the visible and near-infrared range, we show that they could enhance the electrochemical oxidation of 4-HMBA under green and red LED light illuminations. The plasmonic effects of the Au nanostructures are proposed to contribute to the enhancement of the reaction and the photothermal effect is excluded based on electrolyte-temperature-dependent measurements. A possible reaction mechanism is proposed for the electrochemical oxidation of 4-HMBA on Au working electrodes in an alkaline electrolyte. Ongoing work focuses on investigating the electrochemical oxidation of electronically unique aromatic substituents of 4-HMBA and the plasmonic effects from the Au nanostructure electrodes in assisting other electrochemical reactions.<br/><br/><b>Reference:</b><br/>J. Chem. Phys. 157, 081101 (2022)