A novel electrocatalyst composed of graphene oxide/graphitic carbon nitride and CuFe/N-C@Co nanoparticles-embedded in nitrogen-doped carbon nanotube for oxygen reduction reaction and supercapacitor

The elaborate construction of electrocatalysts plays a key role in the development of high-performance excitation reactions and supercapacitors. This research presents a convenient avenue for the fabrication of CuFe-ZIF@ZIF67-derived carbon framework (CuFe/N-C@Co/N-CNTs), as well as incorporating CuFe-ZIF@ZIF67 with graphitic carbon nitride (CuFe-ZIF@ZIF67@gCN) and graphene oxide (CuFe-ZIF@ZIF67@GO) as novel bifunctional catalysts. After pyrolysis of these composites, CuFe/N-C@Co/N-CNTs, CuFe/N-C@Co/N-CNTs@gCN, and CuFe/N-C@Co/N-CNTs@GO are formed. The physical tests of Raman, XRD, FESEM, TEM, HRTEM, EDX, ICP-OES, XPS, and BET were employed to assess the morphology, structural and electronic properties of samples. In the following, electrochemical tests for ORR and supercapacitor were performed. The performance of the electrocatalysts was explored by a three-electrode cell system in an alkaline medium. The onset potentials of CuFe/N-C@Co/N-CNTs, CuFe/N-C@Co/N-CNTs@gCN, and CuFe/N-C@Co/N-CNTs@GO were calculated to be −0.058, −0.049 and −0.033 vs. Ag/AgCl, respectively, by the Linear Sweep Voltammetry (LSV) measurement. Moreover, the values of electron transfer number were obtained as 3.09, 3.28, and 3.78, demonstrating that the ORR follows a mixed 2e − and 4e − pathways in the first two samples and a dominant 4e − with partial 2e − route in the latter sample. In the following, the nanostructures are employed as electrodes to be assembled in the supercapacitor. According to the Galvanostatic Charge-Discharge (GCD) measurements, the specific capacitance of CuFe/N-C@Co/N-CNTs, CuFe/N-C@Co/N-CNTs@gCN, and CuFe/N-C@Co/N-CNTs@GO at 1 A/g were obtained as 305, 355 and 493 F/g, respectively. In this study, high-performance and low-cost electrocatalysts are fabricated by an easy preparation approach for oxygen reduction catalyst and supercapacitor electrode. The outcomes manifest that the addition of graphene oxide to core-shell CuFe-ZIF@ZIF67 improves the performance of CuFe/N-C@Co/N-CNTs@GO dramatically and exhibits superior performance as an efficient bifunctional electrocatalyst due to the synergistic effects of CuFe/N-C@Co/N-CNTs and graphene oxide. CuFe/N-C@Co/N-CNTs@GO reveals remarkable energy storage capability, abundant porosity, high conductivity, outstanding electron and mass transfer, large surface area, and excellent stability with 94.4 % current retention after 20,000 s. As a result, CuFe/N-C@Co/N-CNTs@GO possesses a desired electrochemical performance in ORR and supercapacitor application. • Novel composites of CuFe/N-C@Co/N-CNTs, CuFe/N-C@Co/N-CNTs@gCN, and CuFe/N-C@Co/N-CNTs@GO were synthesized. • The CuFe/N-C@Co/N-CNTs@GO nanocomposite demonstrated outstanding electrochemical performance in ORR and supercapacitor. • The onset potential of CuFe/N-C@Co/N-CNTs@GO was obtained as −0.033 V vs. Ag/AgCl. • According to the GCD measurements, the specific capacitance at 1 Ag −1 was found to be 493 Fg 1 .