The role of green redox powder (melanin) to enhance the capacitance of graphene/FeOx based supercapacitors

M.L. Paniagua Chávez, L.A. Garcés Patiño, C. Rodriguez Gonzalez, Rocío Meza Gordillo, A. Martínez Antonio, A. de J. Ruiz Baltazar, J. Oliva

Te invitamos a leer el artículo "The role of green redox powder (melanin) to enhance the capacitance of graphene/FeOx based supercapacitors" publicado en "Journal of the Indian Chemical Society" en el que colaboró el Dr. Agustino Martínez Antonio de Cinvestav Irapuato.

Autores:

M.L. Paniagua Chávez, L.A. Garcés Patiño, C. Rodriguez Gonzalez,  Rocío Meza Gordillo,  A. Martínez Antonio,  A. de J. Ruiz Baltazar,  J. Oliva

Resumen:

In this work, melanin (extracted from Mucuna-pruriens) was mixed with iron oxide (FeOx) nanoparticles to make redox powders. Supercapacitors (SCs) made with electrodes of graphene (G) + melanin produced a capacitance of 252 F/g, which is 74 % higher than that for the SC made only with graphene electrodes (145 F/g). Later, two different concentrations of melanin were mixed with FeOx and the mixtures were deposited on SC electrodes. SCs made with 6.7 % and 16.7 % of melanin produced capacitances of 456.6 F/g and 310 F/g, respectively. Thus, the capacitance incremented 53 % with respect to the SC made only with graphene + melanin. In fact, the capacitance was 23–81 % higher after adding FeOx to the SCs. The best device, containing 6.7 % of melanin, was also heated at 70 °C and its capacitance incremented due to the enhancement of ion conductivity through the electrodes (confirmed by impedance analysis). Such device also maintained a high capacitance retention of 84–88 % after 5000 cycles of charge-discharge or 1000 bending-cycles. Raman and XPS spectroscopies demonstrated a higher presence of oxygen-vacancy defects and Fe3+/Fe2+ species on the SC electrodes made with melanin + FeOx, therefore, those ones were more efficient for the charge storage. Interestingly, the output voltage of SCs was controlled by its temperature, since it oscillated from 0.46 to 0.58 V in the temperate range of 25–70 °C. Hence, the results here indicated that ecofriendly/low-cost materials (melanin + FeOx) can be used to fabricate SCs able to operate at high temperatures.