Synthesis, analysis and characterization of alpha-Fe2O3 nanoparticles and their applications in supercapacitors

The development of iron-based supercapacitors has been gaining more attention in the field of energy storage applications due to their non-toxicity, abundance and low cost. In this paper, single phase hematite nanoparticles were synthesized by high temperature thermal decomposition method and directly served as electrochemical supercapacitor electrode material. Structural study (XRD) revealed the single-phase hematite nanoparticles formation with trigonal alpha-Fe2O3 structure. Morphological study (SEM) confirms silkworm chrysalis shape like morphology by many interconnected nanoparticles of the average size of 30 nm. The electrochemical study indicates that the synthesized hematite electrode material can maintain good farad capacitance at 100 mV/s and it shows a specific capacitance of 149.3 F/g at a current density of 1 A/g with the maximum energy and power densities of 4.20 Wh/Kg and 224.90 W/Kg, respectively. Equivalent series resistance and charge transfer resistance of alpha-Fe2O3 electrode material are 1.079 Ω and 9.055 Ω, respectively. This is attributed to the alpha-Fe2O3 nanostructure, which can provide a large contact area between electrode and electrolyte for ionic reaction and transport. The material can still retain 43.8% of the initial specific capacitance after 5000 cycles. The investigation results show that the hematite nanoparticle-based electrode material holds great potential in electrochemical supercapacitors and provides a certain reference in the direction of global energy needs.