Creation of electrocatalytic composite coating of metal-organic frameworks an‎d double-layer hydroxide based on fe-ni

10/6/2024 12:00:00 AM

The excessive increase in the consumption of fossil fuels has moved the world towards using hydrogen fuel with high energy density an‎d zero carbon pollution. In the process of water splitting, double-layer hydroxides an‎d metal-organic frameworks can be replaced by electrocatalysts based on noble metals, which are due to the abundance of raw materials, high surface area, high porosity, abundant metal centers, an‎d adjustable structures. To reduce the weak points of this class of materials, it is possible to make NiFe-MOF/NiFe-LDH composite on nickel foam. In this research, at first, double-layer hydroxides with nickel-to-iron ratios of 1:1 an‎d 4:1 an‎d metal-organic frameworks were synthesized by thermal solvent method, both at 125 C temperature for 12 hours. With X-ray diffraction analysis, field emission scanning electron microscope, an‎d infrared spectroscopy, phase, microstructural, an‎d bond characterization an‎d electrochemical tests, excess potential, an‎d double layer capacity were investigated. NiFe-MOF an‎d NiFe-LDH microstructures have grown on nickel foam in the form of sheets an‎d flowers. The microstructure of NiFe-MOF/NiFe-LDH on nickel foam for a 1:1 ratio was the growth of MOF particles on LDH plates; While in the ratio of 4:1 without changing the microstructure of LDH, only MOF with the change of microstructure was grown on the LDH plates in the form of particles. All LDHs an‎d MOFs show the desired phases, an‎d in the composite samples, the simultaneous presence of two formed phases can be seen. Further, by examining the electrochemical behavior, the excess potential of the optimal LDH samples with 1:1 an‎d 4:1 nickel-to-iron ratios are 340 an‎d 270 mV, respectively, an‎d the Tofel slope is 41 an‎d 31 mV.dec-1, respectively, an‎d have the best electrochemical activity. ; an‎d with the highest double layer capacity equal to 1.58 mF.cm-2 an‎d 1.62 mF.cm-2, they have the most electrochemical active surface; Then, investigating the electrochemical behavior of MOF with additional potential of 330 mV an‎d a Tofel slope of 45 mV.dec-1 showed a better electrocatalytic performance than nickel foam, an‎d then by calculating the double layer capacity for MOF, which is equal to 1.2 mF.cm-2 It shows that the electrochemically active surface has increased compared to nickel foam. The two NiFe-MOF/NiFe-LDH11 an‎d NiFe- MOF/NiFe-LDH41 samples have the lowest excess potential values of 280 an‎d 240 mV an‎d 38 an‎d 29 Tafel V.dec-1 slopes, respectively, an‎d have the best electrocatalytic performance. With the highest value of the double layer capacity equal to 1.63 an‎d 2 mF.cm-2 respectively, they have the most electrochemical active surface..

گرمابي، هيدروكسيدهاي دولايه،آهن،نيكل،چهارچوب هاي فلز آلي

Double-layer hydroxides ,Ni,Fe, Metal-organic frameworks

sepideh fereydouni

Saeid Rastegari, Hajar Ghanbari