MnCo2O4/activated carbon wheat husk (ACWH) as a novel electrode material for electrochemical capacitors

Supercapacitors are very suitable devices for energy storage in the coming years. Researches on the introduction of efficient, cost-effective, and environmentally friendly electrodes are still ongoing. In this investigation, we used wheat husk, which is an agricultural waste, for the preparation of carbon with excellent specific surface area to be used in supercapacitors' electrodes. Then, the activated carbon wheat husk (ACWH) was hybridized with MnCo2O4.The results of BET analysis showed a specific surface area of 339.04 m2 g−1 for MnCo2O4/ACWH. We achieved the specific capacity of 1392 F/g at a current density of 1 A/g by the addition of MnCo2O4 to the ACWH, while ACWH showed a specific capacity of 564 F/g. Also, the results of EIS analysis showed that the charge transfer resistance for the ACWH electrode decreased from about 22 Ω to 3.8 Ω after adding the MnCo2O4, indicating increased conductivity. Comparative investigations were done on the three-electrode system with ACWH, MnCo2O4, and MnCo2O4/ACWH electrodes. Results indicated that the synergistic effect of the synthesized carbon (with the excellent surface area) along with MnCo2O4 increases the number of active sites and, thus, the specific capacity. Furthermore, using a ACWH improved MnCo2O4 electrode stability so that the synthesized hybrid showed 90.8 % stability after 5000 consecutive cycles.