Increasing\nAccessible Active Site Density of Non-Precious\nMetal Oxygen Reduction Reaction Catalysts through Ionic Liquid Modification

Abstract

Non-precious metal\ncatalysts show great promise to replace the\nstate-of-the-art Pt-based catalysts for catalyzing the oxygen reduction\nreaction (ORR), while their catalytic activity still needs to be greatly\nimproved before their broad-based application. Here, we report a facile\napproach to improving the performance of zeolitic imidazolate framework-derived\ncarbon (ZDC) toward the ORR by incorporating a small amount of ionic\nliquid (IL). The IL would preferentially fill the micropores of ZDC\nand greatly enhance the utilization of the active sites within the\nmicropores, which are initially not accessible due to insufficient\nsurface wetting. It is also disclosed that the ORR activity in terms\nof kinetic current at 0.85 V depends on the loading amount of the\nIL, and the maximum activity is obtained at a mass ratio of IL to\nZDC at 1.2. The optimum stems from the counterbalance between the\nenhanced utilization of the active sites within the micropores and\nthe retarded diffusion of the reactants within the IL phase due to\nits high viscosity.