Quasi-ZIF-67 for Boosted Oxygen Evolution Reaction Catalytic Activity via a Low Temperature Calcination

Abstract

Exposing catalytically active metal sites in metal–organic frameworks with maintained porosity could accelerate electron transfer, leading to improved performances in electrochemical energy storage and conversion. Here, we report a series of quasi-ZIF-67 obtained from low temperature calcination of ZIF-67 for electrocatalytic oxygen evolution reaction (OER) and reveal the nanostructural structure via the spherical aberration-corrected transmission electron microscopy. The quasi-ZIF-67-350 not only possesses a large Brunauer–Emmett–Teller surface area of 2038.2 m2·g–1 but also presents an extremely low charge-transfer resistance of 15.0 Ω. In catalyzing the OER process, quasi-ZIF-67-350 displays a low overpotential of 286 mV at 10 mA cm–2 in the electrolyte of 1.0 M KOH. The acquired quasi-ZIF-67 demonstrates a high catalytic activity in OER, and the controlled calcination strategy undoubtedly paves a way in synthesizing low-cost and efficient electrocatalysts.

Synthesis and Optimization of Zeolitic Imidazolate Frameworks for the Oxygen Evolution Reaction

“… [27] An enhanced OER activity of these ZIF‐67/CB samples is also observed in 1.0 m KOH electrolyte (inset of Figure 3 d and Figure S13 in the Supporting Information). Now, the overpotential is reduced to about 320 mV to deliver 10 mA cm −2 , which is better than or comparable to many of the modified ZIF‐67‐based hybrid nanostructures of nanosheets, oxides, hydroxides, and carbon‐based heterostructures as well as the reference Ir/C (300–343 mV) [8–11, 13, 15, 17, 26, 41] . In addition, it is very interesting to see an emerging oxygen reduction reaction (ORR) activity in the ZIF‐67/CB samples (Figure S14 in the Supporting Information).…”

“…For example, the MOF‐derived nanostructures, often in the forms of nanosheets, oxides, hydroxides/oxyhydroxides, and metal/metal oxide embedded carbons, obtained by high‐temperature thermolysis routes, have shown a great promise for electrocatalysis reactions, such as the oxygen reduction, oxygen evolution, and hydrogen evolution reactions (ORR, OER, and HER, respectively) [8–14] . Here, it is worth noting that the thermolysis process of MOFs involves severe decomposition of the organic ligand and mass loss [2, 6, 15] . For instance, as low as 10–20 wt % of porous carbon is produced from MOF‐5 or MOF‐74 (Zn) [16] .…”

“…To utilize MOFs more efficiently and to avoid issues related to reproducibility (in terms of controlling the composition, functionality, heterogeneity, porosity, and nanophase) and mass production, it is highly desirable to avoid extensive modification of MOFs. For these reasons, recent works have focused on mild post‐synthesis modification or even direct utilization of MOFs/ZIFs [10, 12, 15, 17–19] …”

A Tunable Amorphous Heteronuclear Iron and Cobalt Imidazolate Framework Analogue for Efficient Oxygen Evolution Reactions

“…Upon introduction of Fe 3 + , the crystalline structure peaks disappeared suggesting the conversion of the crystalline ZIF-67 into an amorphous random network with a large number of surface defects and more exposed metal active sites. [34] Although no XRD peaks were observed for aMOFs, the FTIR spectra demonstrated that the structure of organic linkers was preserved. [35] The characteristic absorption bands around 3310 cm À 1 (Figure 1a) originate from -OH stretching vibrational modes, indicating strong hydrogen-bonding between water molecules and the surface of MOF architecture.…”

A Non-enzymatic Electrochemical Sensor for Glucose Detection Based on Ag@TiO2@ Metal-Organic Framework (ZIF-67) Nanocomposite

“…However, they lack good electrical conductivity. In order to use ZIF-67 in electrochemical applications, several strategies are introduced by researchers such as encapsulating active guests and adding conductive coating (Zhu et al, 2020).…”