PNNL

Abstract

Direct formic acid fuel cells (DFAFCs) are a durable, lightweight and well-developed energy technology that operate with low temperatures, high-energy conversion efficiency and lower pollutant production and therefore may substitute for conventional batteries in portable electronics in the future.[ref] DFAFCs typically consist of two electrodes installed around a polyelectrolytic membrane (PEM) and produce electricity by formic acid (HCOOH) through the anode and passing oxygen (O2) through the cathode. In idealized high-energy efficiency conditions, anodic catalysts completely oxidize HCOOH to produce protons (H+), electrons (e-) and carbon dioxide (CO2). The protons pass across the PEM, whereas the e- pass across an external circuit for work and back to the cathodic catalysts where they react with O2 and H+ from the PEM to produce water. For nearly 65 years, a default monometallic material for executing the electrocatalytic steps in DMFCs has been platinum (Pt).1-3 The high cost of Pt, its slow rate for conducting the oxygen reduction reaction (ORR) and its susceptibility to poisoning are major barriers to the widespread commercialization of DFAFCs.4 Many of these barriers can be overcome by installing nanoscale Pt and multimetallic Pt-containing catalysts at the anode and cathodes.5,6 Pt-based nanoparticles (NPs) not only have a high surface area-to-volume ratio that maximizes access to surface Pt atoms but also exhibit catalytic activities in excess of that predicted based on miniaturization of bulk properties due to beneficial quantum size effects.