Single atom sites as CO scavenger to allow for crude hydrogen usage in PEMFC.

The IrRh@C ZIF-8 catalysts capable of oxidizing H 2 , CO, or a combination of the two is fabricated through the secondary high temperature annealing. Benefiting from the closely located single atom sites to the nanoparticles, CO on the metal nanoparticles could be efficiently removed, thus conferring the catalysts with excellent H 2 oxidation performance in CO presence that has not been possible before. This work opens up a new avenue to conquer the formidable poisoning issue of PEMFCs. [Display omitted] Nanosized Pt catalysts are the catalyst-of-choice for proton exchange membrane fuel cell (PEMFC) anode, but are limited by their extreme sensitivity to CO in parts per million (ppm) level, thereby making the use of ultrapure H 2 a prerequisite to ensure acceptable performance. Herein, we confront the CO poisoning issue by bringing the Ir/Rh single atom sites to synergistically working with their metallic counterparts. In presence of 1000 ppm CO, the catalyst represents not only undisturbed H 2 oxidation reaction (HOR) catalytic behavior in electrochemical cell, but also unparalleled peak power density at 643 mW cm−2 in single cell, 27-fold in mass activity of the best PtRu/C catalysts available. Pre-poisoning experiments and surface-enhanced Raman scattering spectroscopy (SERS) and calculation results in combine suggest the presence of adjacent Ir/Rh single atom sites (SASs) to the nanoparticles (NPs) as the origin for this prominent catalytic behavior. The single sites not only exhibit superb CO oxidation performance by themselves, but can also scavenge the CO adsorbed on approximated NPs via supplying reactive OH* species. We open up a new route here to conquer the formidable CO poisoning issue through single atom and nanoparticle synergistic catalysis, and pave the way towards a more robust PEMFC future. [ABSTRACT FROM AUTHOR]