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

Abstract

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 halfwave 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.

Potent Noble Metal–Nickel Oxide Interaction: A Strategy for Improved Oxygen Reduction Reaction via Engineering the Electronic Structure

“…Furthermore, the kinetics of the ORR was greatly enhanced by increasing the oxygen partial pressure and temperature. − The approach of strong interaction between precious metals and metal oxides has been widely used as a potential method for surface and interface engineering for increasing the catalytic activity and robustness of the ORR. Strong metal–support interaction, the original notion, is the basis of this promising technique. , The metal–support interaction will modulate the local electronic structure of noble metals, specifically the d-band center, which is correlated with the number of unpaired electrons in the metal. This modulation aims to optimize the adsorption energy of oxygen species, thereby enhancing the kinetics of the ORR reaction and resulting in increased ORR activity. , However, stability problems that arose in carbon-based noble metal catalysts would be significantly reduced, thanks to the special qualities of metal oxide, such as strong corrosion resistance, especially in the acidic environment. − …”