Atomic-Scale CoOx Species in Metal-Organic Frameworks for Oxygen Evolution Reaction
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Citations
Single-atom catalysis for Zinc-air/O2 Batteries, Water Electrolyzers and Fuel Cells applications
Porous Cobalt Oxynitride Nanosheets for Efficient Electrocatalytic Water Oxidation
Single-atom catalysis for zinc-air/O2 batteries, water electrolyzers and fuel cells applications
Scalable Fabrication of Highly Active and Durable Membrane Electrodes toward Water Oxidation.
A Review on the Promising Plasma-Assisted Preparation of Electrocatalysts.
References
Exceptional chemical and thermal stability of zeolitic imidazolate frameworks
Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?
Benchmarking Heterogeneous Electrocatalysts for the Oxygen Evolution Reaction
Single-atom catalysis of CO oxidation using Pt1/FeOx
A perovskite oxide optimized for oxygen evolution catalysis from molecular orbital principles.
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Frequently Asked Questions (15)
Q2. What is the role of O2 plasma in the electrocatalytic process?
O2 plasma is a powerful tool to modify materials for its etching effect, and the metal atom exposed in the O2 atmosphere would be inevitable oxidized.
Q3. What is the role of the pores in ZIF-67?
The abundant pores in ZIF-67 provide channels for O2 plasma to activate the Co ions in MOFs to on-site produce atomic-scale CoOx species, which act as the active sites to catalyze the oxygen evolution reaction with an even better activity than RuO2.
Q4. What was the effect of the plasma treatment on the CoOx species?
During the plasma treatment, the Co-N coordination bonds in the ZIFs were partially broken and the suspended Co species could beeasily reacted with O2 present in the system to obtain CoOx species locally.
Q5. What is the reason why the ZIF-67 was overtreated?
While the RF power reaches up to 300 W, poor OER performance obtained probably due to that the ZIF-67 wasovertreated and the porous structure of ZIF-67 was broken down.
Q6. What is the effect of plasma etching on the Co-N bond?
The destructive effect of plasma etching leads to the break of the Co-N coordination bond and the suspended Co species was rapidly oxidized in the presence of O2 to produce CoOx.
Q7. Why did the surface area of ZIF-67 decrease after plasma treatment?
Thedecrease of surface area after plasma treatment is because the plasma treatment partiallydestroyed the porous structure of ZIF-67 by the etching effect.
Q8. What was the method used for the electrochemical measurement of CoOx-ZIF?
Electrochemical measurement4 mg of CoOx-ZIF was dispersed in 2 mL ethanol followed by ultrasonication for 30 min, 100 μL 5 % Nafion solution was added to the dispersion and ultrasonication for another 30min to obtain the catalytic ink.
Q9. How did the authors fix the ring current?
To study the reaction mechanism of OER, the authors used rotating ring-disk electrode (RRDE) andcollected the ring current by fixing the ring potential at 1.5 V vs. RHE in 1 M KOH solutionat 1600 rpm.
Q10. What is the main absorption peak of CoOx-ZIF?
The main absorption peak (indicated by thevertical bar) of CoOx-ZIF in Figure 3b is enhanced, indicating CoOx-ZIF loses some charges at Co site and thus increases the oxidation state, shifting the absorption peak as well as theabsorption edge to higher energy.
Q11. What is the effect of the O2 plasma treatment on CoOx-ZIF?
After O2 plasma treatment, the Co 2p 3/2 peak of CoOx-ZIF shows a slight broadening and shifting to lower binding energy (Figure S4b).
Q12. What is the effect of oxygen on the co-Ox-ZIF?
Co sites more significantly than nitrogen and therefore giverise to higher unoccupied orbitals at Co sites in CoOx-ZIF (Figure 3b).
Q13. What is the ohm resistance of CoOx-ZIF?
The fitted electrochemical impedance spectroscopy (EIS) indicates that the ohm resistanceof CoOx-ZIF (6.31 Ω) is smaller than that of ZIF-67 (7.60 Ω), which is consistent with the EPR results, indicating the improved conductivity of CoOx-ZIF.
Q14. What are the main problems of OER electrocatalysts?
To solve this problem, many studies have been carried out to develop highly efficient andlow-cost OER electrocatalysts, such as developing transition metal compound and even metal-free materials[4].
Q15. What is the effect of O2 plasma on CoOx-ZIF?
These results confirm that Co-N coordination bonds in ZIF-67 were partially broken and the Co species was oxidized to form CoOx species by O2 plasma.