The Preparation Of MOFs/C Based Catalysts And Their Performances For Oxygen Reduction And Evolution Reactions

It is an important significance thing to improve the performance of the chargeable Li-air battery, that developing the bifunctional catalyst which has high performance and low cost for ORR and OER. Recently, Metal Organic Frameworks (MOFs) got most attention in electro-catalysis because it's high specific surface area, adjustable pore structure and easy functional. In this article, we composite the MOFs and carbon materials, get the complex catalyst MOFs/C. Then, we obtain MOFs/C-based derivative catalyst by calcination. Finally, we calculate the ORR and OER performance about these catalyst in alkaline electrolyte.We make Co-OBA in-situ growth on the surface of XC-72 by hydrothermal method, get the composite Co-OBA/XC-72. The composite not only stay the needle-like structure but also has better electro conductibility and thermostable. Hence, the composite has superior ORR/OER catalytic activity. In 0.1 M KOH electrolyte, the ORR initial voltage and the current density in-0.4 V of catalyst is -0.162 V and 6.35 mA·cm-2, respectively. The OER current density in 0.8 V is 12.10 mA·cm-2.We achieve Co-ZIF-4 by hydrothermal method and mix with CNTs, then take the mixture calcined in N2 to obtain the composite catalyst. The composite catalyst which electro catalytic activity increase at first then decreases with the rise of calcination temperature keep the unique structure of ZIF. In these catalysts, the best is Z-CT-800 which initial voltage, half-wave voltage and current density in -0.8 V about ORR is 0.111 V,-0.176 V and 5.47 mA·cm-2, respectively, potential in 10 mA·cm-2 and current density in 0.8 V about OER is 0.71 V and 104.14 mA·cm-2.We achieve ZIF-67 by hydrothermal method and mix with GO, then take the mixture calcined in N2 and O2 successively to obtain composite catalyst GO@Co3O4@Co. The electro catalytic activity of the composite catalyst increase at first then decreases with the rise of calcination temperature in O2. In these catalysts, the catalyst which calcination temperature in O2 is 200 shows the best catalytic activity in alkaline approaching to commercial Pt/C. The half wave voltage about ORR and the potential in 10 mA·cm-2 about OER of the optimal catalyst are -0.111 V and 0.734 V, respectively.