Emergent hierarchical porosity by ZIF-8/GO nanocomposite increases oxygen electroreduction activity of Pt nanoparticles

Official URL: https://dx.doi.org/10.1016/j.ijhydene.2021.07.123

Hierarchically porous materials are promising as catalyst supports in fuel cells and batteries as they increase overall mass transfer and active site density. In this work, a hierarchically porous catalyst support for oxygen reduction reaction (ORR) in acidic media has been developed by a bottom-up approach. Graphene oxide (GO) was introduced during synthesis conditions of zeolitic imidazolate framework-8 (ZIF-8) to produce hybrid material of ZIF-8/GO. Successful nanocomposite formation was realized by preserved crystallinity and chemical interaction between species as revealed by X-ray diffraction and Fourier transform infrared spectroscopy. Introduction of GO and pyrolysis of resulting hybrid structure causes emergence of disordered meso/macropores with an accompanying increase in pore volume as revealed by N2 sorption experiments. Pt nanoparticle deposition on pyrolyzed hybrid material by polyol method results in electrocatalyst Pt/NC-1, which shows greatly improved mass activity (182 vs 86 A g−1Pt) and specific activity (467 vs 186 μA g−1Pt) at 0.8 V for ORR against reference electrocatalyst Pt/r-GO and improved specific activity against Pt/C.