Iron-doped nickel-cobalt bimetallic phosphide nanowire hybrids for solid-state supercapacitors with excellent electromagnetic interference shielding.

The development of flexible and wearable electronics subjects to the limited energy density and accompanying electromagnetic pollution. With a high theoretical specific capacity, nickel-cobalt bimetallic phosphide (NiCoP) is considered to be potential cathode materials for supercapacitor. However, the pristine NiCoP fails to display excellent electrochemical performance due to its inferior rate performance and cycling stability. Herein, we design Fe doped NiCoP nanowire arrays on carbon cloth (Fe-NiCoP/CC) as the cathode for supercapacitors. The introduced Fe doping enable to increase in the electronic conductivity and enhance the adsorption of OH, supported by the density functional theory (DFT) analysis. As a result, Fe-NiCoP/CC electrode displays a high areal capacity of 3.18 F cm at 1 mA cm, superb rate capability (86.3 % capacity retention at 20 mA cm) and outstanding structure stability, superior to the NiCo/CC, FeNiCo/CC, and NiCoP/CC counterparts. Moreover, the assembled Fe-NiCoP/CC||VN/CNT/CC hybrid supercapacitor (HSC) device delivers a high energy density of 176.9 μWh cm at the power density of 750 μW cm. More importantly, the designed electrodes and assembled HSC device exhibits excellent electromagnetic interference (EMI) shielding performance. This design concept presented in this paper can provide insights into the construction of multifunctional and high-performance flexible electronic devices.