Controllable Porous Nanogrids of Chromium Nitride with Strong Metal–Support Interactions for Achieving Stable Oxygen Reduction Reaction

To facilitate the extensive adoption of proton exchange membrane fuel cells (PEMFCs), it is important to address the issues of electrochemical corrosion and weak interaction with platinum (Pt) caused by the carbon support. Herein, a strong metal–support interaction (SMSI) effect was constructed with Pt nanoparticles loaded in porous chromium nitride (CrN) nanogrids (labeled as Pt/CrN). The porous CrN nanogrids are synthesized via a Maillard nitridation method, and better support size was obtained by controlling the average diameter of CrN nanoparticles by adjusting the proportion of precursors in the oxide preparation. Electrochemical tests establish that Pt/CrN is a stable oxygen reduction reaction catalyst with half-wave potential attenuated by only 4.5 mV after accelerated durability tests, which can be a result of the SMSI effect between Pt and CrN. Moreover, CrN was shown to modulate the ionomer distribution in the catalyst layer (CL). Further investigations have revealed that CrN remains stable up to 1.2 V but degrades significantly above 1.4 V. This work not only broadens the spectrum of Pt-based catalyst support options but also provides insights into the engineering of the SMSI effect. This knowledge will benefit the future design of transition metal nitride for PEMFCs and other technologies.