Interstitial nitrogen modified Rh nanocrystals for efficient and CO-resistant alkaline hydrogen oxidation electrocatalysis

Abstract

The preparation of active and CO-tolerant platinum-free electrocatalysts toward the hydrogen oxidation reaction (HOR) under alkaline conditions is significant for the practical development of anion exchange membrane fuel cells. Herein, nitrogen atoms are intercalated into the interstitial void of rhodium (N–Rh/C) nanocrystals, which results in electron-deficient and electron-rich Rh sites simultaneously to coordinate the binding energies of multiple key intermediates, achieving highly active and CO-resistant alkaline HOR. In situ surface-enhanced infrared absorption spectroscopy and density functional theory calculations illustrate that the introduction of interstitial N atoms suppresses the electronic back-donation from Rh 4d to the CO 2π* orbital in electron-deficient sites, thereby weakening the CO adsorption and improving CO resistance. Additionally, the enhanced OH adsorption in electron-rich sites can release more free water into the adjacent gap region, increasing water connectivity and hydrogen-bond networks in the electrical double layer and accelerating alkaline HOR kinetics.