Hydrogen peroxide-induced growth of hierarchical Ni₃S₂ nanorod/sheet arrays for high performance supercapacitors

The rational design and simple synthesis of high performance electrodes are important aspects of energy storage fields. However, it is difficult to determine a facile preparation method to obtain hierarchical Ni₃S₂ nanorod/sheet arrays. Herein, hydrogen peroxide-induced growth by the hydrothermal method is used to fabricate the hierarchical Ni₃S₂ nanorod/sheet arrays on nickel foam substrates. Hydrogen peroxide can accelerate the hydrolysis of Na₂S₂O₃ to release sulfur ions and then induce formation of the hierarchical nanorod/sheet. The one-dimensional nanorod skeleton acting as high-speed electron transfer channels can support the nanosheets. The two-dimensional nanosheets can provide abundant active edge sites and protect the backbone from electrochemical corrosion. The hierarchical structure integrates the advantages of sufficient active sites, effective protection and high-speed electron transfer. The electrode based on the Ni₃S₂ nanorod/sheet delivers a high specific capacitance of 6.87 F cm^-2 at 2 mV s^-1 (6.24 F cm^-2 at 5 mA cm^-2) and long cycling stability (85.7% capacitance retention at 15 mA cm^-2 after 3000 cycles). The asymmetric supercapacitor gains a high energy density of 1.16 mWh cm^-3 at 15.00 W cm^-3. The hierarchical Ni₃S₂ nanorod/sheet arrays are expected to be candidates for the electrodes of practical supercapacitors.