Two-in-one template-assisted construction of hollow phosphide nanotubes for electrochemical energy storage

Abstract

In this work, a template-assisted method was used to develop novel Ni₂P@PANI hollow nanotubes as a positive electrode material for supercapacitors using prepared polyaniline (PANI) nanotubes as precursors, and their electrochemical behavior was studied. The results revealed that the Ni₂P@PANI nanotube electrode exhibited an average high specific capacity of 866 C g⁻¹ at 2 A g⁻¹. The experimental data were combined with density functional theory (DFT) calculations to reveal that the strong interaction between PANI and Ni₂P may lead to the formation of novel bonds at their interface and promote the redistribution of charges within the electrode, improving the capacitive properties. The combination of PANI and Ni₂P facilitated the adsorption and desorption of OH⁻, resulting in a rapid Faraday redox reaction at the electrodes. Additionally, a unique Fe₂O₃@PNCT hollow nanotube was fabricated as the negative electrode with the same PANI nanotube precursor. Thus, a “two-in-one” strategy was implemented. The assembled quasi-solid-state asymmetric supercapacitor exhibited a high energy density of 60.6 W h kg⁻¹ at a power density of 852.3 W kg⁻¹ and a high-capacity retention rate of 79.8% after 10 000 cycles.