Synthesis of non-planar graphene-wrapped copper nanoparticles with iron(III) oxide decoration for high performance supercapacitors

Abstract The performance of supercapacitors strongly depends on the electrochemical characterizations of electrode materials. Herein, a composite material consisted of iron(III) oxide (Fe₂O₃) and multilayer graphene-wrapped copper nanoparticles (Fe₂O₃/MLG-Cu NPs) is fabricated on a flexible carbon cloth (CC) substrate via two-step synthesis process for supercapacitor application. Where, MLG-Cu NPs are prepared on CC by one-step chemical vapor deposition synthesis approach; thereafter, the Fe₂O₃ is further deposited on the MLG-Cu NPs/CC via successive ionic layer adsorption and reaction method. The related material characterizations of Fe₂O₃/MLG-Cu NPs are well investigated by scanning electron microscopic, high resolution transmission electron microscopy), Raman spectrometer and X-ray photoelectron spectroscopy; the electrochemical behaviors of the pertinent electrodes are studied by cyclic voltammogram, galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy measurements. The flexible electrode with Fe₂O₃/MLG-Cu NPs composites exhibits the best specific capacitance of 1092.6 mF cm⁻² at 1 A g⁻¹, which is much higher than those of electrodes with Fe₂O₃ (863.7 mF cm⁻²), MLG-Cu NPs (257.4 mF cm⁻²), multilayer graphene hollow balls (MLGHBs, 14.4 mF cm⁻²) and Fe₂O₃/MLGHBs (287.2 mF cm⁻²). Fe₂O₃/MLG-Cu NPs electrode also exhibits an excellent GCD durability, and its capacitance remains 88% of its original value after 5000 cycles of the GCD process. Finally, a supercapacitor system consisted of four Fe₂O₃/MLG-Cu NPs/CC electrodes can efficiently power various light-emitting diodes (i.e. red, yellow, green, and blue lights), demonstrating the practical application of Fe₂O₃/MLG-Cu NPs/CC electrode.