Nanocage confined nitrogen-rich MOF-derived Co/CoN heterostructure for overall water splitting

Abstract

Of great significance is the study towards replacing precious metal electrocatalysts with transition metal electrocatalysts for the electrocatalytic hydrogen evolution from water, regarding clean energy utilization. The precise design and engineering of catalysts at the nanoscale, with a focus on their structural and functional attributes, have garnered significant attention and research interest as pivotal approaches to optimizing their catalytic performance. Among those strategies, fabricating transition metals and their corresponding nitrides has lately gained extensive attentions for electrocatalytic water decomposition, because of their adjustable distribution of electrons. In this study, ZIF-67@MAT-6 precursor was formed by coating ZIF-67 with triazole ligand (MAT-6) based on ligand exchange strategy, followed by confining Co/CoN heterostructure nanoparticles in nitrogen-doped carbon nanocages upon heat treatment under nitrogen flow. The resulting electrocatalyst exhibited outstanding electrocatalytic performance for hydrogen and oxygen evolution reactions in alkaline media, with overpotentials of 115 mV and 290 mV to reach 10 mA·cm−2 in 1 M KOH electrolyte, respectively. In addition, the electrocatalyst showed great durability with only 2.16 % current decay during 24 h potentiostatic electrolysis for water decomposition. The density functional theory (DFT) theoretically supported that the accelerated interfacial charge transfer and promoted electrical conductivity were responsible for the remarkable electrocatalytic performance, caused by the synergic effect between the heterogeneous Co and CoN.