Ru-Modulated Pt-Based Catalysts for Electrochemical Oxidation of Dihydroxybenzenes in Direct Liquid Organic Hydrogen Carrier Fuel Cells

Abstract

The rising global energy demand and the imperative to mitigate climate change have accelerated the search for alternative energy carriers. Liquid organic hydrogen carriers (LOHCs) offer a promising solution for hydrogen storage and transport due to their high stability and compatibility with existing infrastructure. However, conventional LOHC-based hydrogen fuel cells rely on high-temperature catalytic dehydrogenation for hydrogen release, adding complexity and limiting their practicality. A direct LOHC fuel cell, which utilizes LOHCs as fuels without requiring separate hydrogen extraction, presents an alternative approach by simplifying system architecture and enhancing safety. Among potential LOHC candidates, phenol-based compounds have garnered interest due to their electrochemical reversibility, enabling direct oxidation at the anode. However, the electrochemical oxidation of dihydroxybenzenes (DHBs), a subclass of phenols, generates phenoxy radicals that undergo electropolymerization, leading to electrode deactivation. To address this challenge, we systematically investigate the oxidation behavior of three DHB isomers—catechol, resorcinol, and hydroquinone—at high concentrations and develop an electrodeposited PtRu alloy catalyst tailored to mitigate polymerization. Our results reveal distinct electrochemical behaviors among the isomers, with significant variations in polymeric film formation on the electrode surface. Notably, Ru incorporation into Pt effectively suppresses polymer formation while enhancing catalytic activity and durability. The optimized PtRu catalyst exhibits improved electrochemical performance and stability, demonstrating its viability as an anode material for direct LOHC fuel cells. These findings underscore the critical role of Ru in enhancing catalytic efficiency and durability, providing valuable insights for the rational design of electrocatalysts for direct LOHC fuel cells.