Dictating Reaction Pathways using Organic-Inorganic Hybrid Electrodes

Abstract

Future society requires efficient clean energy conversion and storage technologies. Fuel cell is one of these technologies that converts chemical energy from fuels directly into electrical energy to power electrochemical devices. In fuel cells, the cathodic oxygen reduction reaction (ORR) limits the overall performance of a polymer electrolyte membrane fuel cell. This limitation originates from the sluggish reaction kinetics of O2. At present, Pt or Pt-alloys are used as state-of-the-art catalysts to overcome the sluggish ORR kinetics. However, the prohibitive cost of Pt prevented the widespread adoption of fuel cell technology. Alternatively, cheap non-precious metal (NPM) catalysts are developed to replace Pt. Yet, these NPM materials usually generate H2O2 as a side product that damage fuel cell components such as the membrane, leading to catastrophic failure. Therefore, controlling the selectivity of NPM catalysts to generate H2O as the only product is important. Here, we describe our efforts toward designing an organic-inorganic hybrid bilayer membrane (HBM, Fig. 1) nanoplatform to improve the activity and selectivity of an NPM ORR catalyst [1]. This new electrochemical platform offers a unique opportunity to modulate the thermodynamics and kinetics of proton and electron transfer steps independently and systematically, thereby unravelling the mechanistic details into the factors that dictate the activity and selectivity of the NPM ORR catalyst at the molecular level [2]. HBM results show that the ORR pathways can be altered by regulating the proton and electron transport rates simultaneously, leading to the suppression of the 2e– pathway and the complete elimination of H2O2 as a deleterious side product. These unique insights will lead to high-performing and durable fuel cells Our team hopes to engage in collaborative research projects with peers specialized in in situ spectroscopy, proton-coupled electron transfer (PCET) theory, biophysical modelling, biomedical engineering, analytical sensors, flexible electronics, and other applications. We hope our HBM platform will provide prospects for interdisciplinary discussions that will enable innovations and breakthroughs in the future. This research is funded by the Croucher Foundation.