You are welcome to attend Yue Niu's MASc oral exam, in which they will discuss their research of Cobalt-hexamine (HMT) metal-organic framework-derived bifunctional electrocatalyst for oxygen reduction and evolution reactions, which promises implmentation advantages for rechargeable Zinc-air batteries.
With the high requirement of increasing people’s living standards and building a more sustainable society, electrochemical energy storage devices with large energy density, high power density, and long term durability are greatly needed to mitigate the consumption of fossil fuels. Among all those well-known energy storage systems, zinc-air batteries are one of the most appealing candidates due to sufficient and inexpensive resources applied, promising energy density, as well as the high reduction potential of zinc.
However, Zn-air batteries always suffer from relatively high overpotential, which is predominantly originated from the sluggish kinetics of oxygen electrocatalytic reactions. Enormous efforts have been devoted to the development of active bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER).
Although noble-metal catalysts, such as platinum, iridium, and their alloys have been proved to own outstanding electrochemical performances for oxygen electrocatalysis, their insufficient catalytic bifunctionality, rarity and high cost hinder the commercial utilization. As a result, the design and synthesis of cost-effective, robust and highly stable bifunctional electrocatalysts to replace noble metal catalysts for zinc-air batteries are greatly desirable to realize the commercialization of Zn-air batteries. In recent years, the metal-organic frameworks (MOFs) are burgeoning as attractive precursors for the fabrication of transition-metal-based bifunctional oxygen electrocatalysts with controllable nanostructures due to the structural and compositional advantages of the MOF.
Herein, a layered Co-hexamine coordination framework is prepared and used as an efficient precursor to synthesize high-performance ORR/OER bifunctional electrocatalyst featured with cobalt oxide and cobalt phosphide heterostructured structure (denoted as CoO/CoxP). This design not only generates a high surface area to expose more active sites but also guarantees the excellent bifunctionality by integrating the cobalt phosphide and cobalt oxide, which are specifically active to OER and ORR, respectively. Moreover, the synergistic effects of these nanoparticles, as well as the superior structural features, can further boost the catalytic activities. As a result, CoO/CoxP outperforms the state-of-art non-noble metal catalysts and the noble metal benchmark with a half-wave potential of 0.86 V for ORR and a low potential of 1.60 V to generate a current density of 10 mA cm-2 for OER. The promising bifunctional catalytic activity thus makes it highly promising to be implemented in rechargeable Zinc-air battery.
Supervisor: Professor Zhongwei Chen
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Waterloo, ON N2L 3G1