Synthesis of Fe-Ni(NH۲-BDC)/g-C۳N۴ composite MOF-based as anelectrocatalyst for methanol electrooxidation

Today, the energy crisis and environmental pollution caused by fossil fuels have become a bigchallenge. One of the appropriate solutions to solve this problem is the use of clean energy sources suchas fuel cells, which is a new and environmentally friendly technology. A fuel cell is an electrochemicaldevice that directly converts the chemical energy of fuel into electrical energy. The one-step nature ofthis conversion of chemical energy to electrical energy, compared to the multi- step conversionsinvolving chemical to thermal, mechanical, and electrical processes involved in combustion-based heatengines (۱). Direct methanol fuel cell (DMFCs) is one of the suitable batteries in this field. In general,DMFCs are subsets of proton exchange based fuel cells in which methanol is used as fuel. The mainadvantage of DMFCs is ease of transportation of methanol, because methanol is a liquid with denseenergy and at the same time relatively stable in environmental conditions (۲). Therefore, DMFC isimportant due to its features such as high energy density, easy storage, the possibility of refueling andworking with it at standard temperatures and pressures. In the future, to make these cells more efficientfor methanol oxidation, they are combined with metal-organic frameworks. Metal-organic frameworksare a group of compounds consisting of metal ions or metal clusters that are coordinated with organicligands and form one, two or three-dimensional structures. Also, the conductivity of MOFs can beimproved by combining them with conductive materials such as graphene, graphene oxide (GO),carbon nanotubes (CNTs), reduced graphene oxide (rGO), porous carbon, graphitic carbon nitride (g-C۳N۴) and materials based on improved on heteroatom-doped carbon (۳).In this research, first, the composite based on metal-organic framework Fe-Ni-NH۲BDC/g-C۳N۴ issynthesized as an electrocatalyst. Then, its structural and electrochemical behavior were investigated touse for methanol electrooxidation. The structural and morphological analysis of Fe- Ni-NH۲BDC/g-C۳N۴ was performed using scanning electron microscopy (SEM), which showed the synergistic effectof bimetallic metal-organic framework (MOF) decorated with g-C۳N۴ Conductors improve the catalytic response of MOFs. According to FE-SEM Figure ۱-a obtained from Fe-Ni(NH۲-BDC)/g-C۳N۴ surface, it shows that Fe-Ni(NH۲-BDC)/g-C۳N۴ is well formed. Also, cyclic voltammograms ofFe-Ni(NH۲-BDC)/g-C۳N۴ and carbon paste (CP) electrodes are shown in Figure ۱-b. As can be seen,there is no current density for methanol oxidation in the CPE, but by modifying the CPE body with Fe-Ni(NH۲-BDC)/g-C۳N۴, the methanol oxidation peak appears at a potential of ۱ V with a current densityof ۵۷ mA cm-۲.

کلیدواژه ها:

Metal-organic framework ، Composite ، Methanol ، g-C۳N۴ ، Electrooxidation ، Electrocatalyst