Hierarchically hexagon-like NiCoP/Co(PO3)2 composites supported on Ni foam as multifunction electrodes for supercapacitors and overall water splitting

Designing multifunctional materials with special morphology, high specific surface area structure and environmentally friendly is still crucial for energy conversion and storage application. Transition metal phosphide has been regarded as a promising and competitive candidate owing to its multiple merits such as earth-abundant, enriched redox-active sites and superior stability. In this study, the hierarchically hexagon-like NiCoP/Co(PO3)2 composites supported on Ni foam (NF@NiCoP/Co(PO3)2) were prepared by a hydrothermal reaction, followed by a phosphorization treatment. The obtained NF@NiCoP/Co(PO3)2 composites offer short ion diffusion distance, numerous reaction active sites and fast electron conduction rate, which enhancing the performance of supercapacitors and electrocatalysis. When used as a supercapacitor electrode, the as-synthesized electrode material exhibits high specific capacity (2.33 mAh cm-2 at a 4 mA cm-2), excellent rate capacity (84%, 4 mA cm-2 to 25 mA cm-2) and good long-term cycling stability (retained 80.3% over 5000 cycles). The asymmetric supercapacitor device (NF@NiCoP/Co(PO3)2//AC ACS) achieve a high energy density of 46.86 Wh kg-1 at a power density of 1.6 kW kg- 1. Furthermore, the NF@NiCoP/Co(PO3)2 nanostructure also demonstrated the superior electrocatalytic performances toward overall water splitting. A low cell voltage of 1.69 V can be achieved at current densities of 50 mA cm-2 (eta 50 = 1.69 V). The results show that NF@NiCoP nanomaterials are promising multifunctional materials for supercapacitor and overall water splitting applications.

Automated summary

In this study, hexagon-like NiCoP/Co(PO3)2 composites supported on Ni foam were prepared and exhibited exceptional performance in supercapacitors and electrocatalysis. The obtained composites offer short ion diffusion distance, numerous reaction active sites and fast electron conduction rate, enhancing the overall performance. The materials also showed promising results in terms of specific capacity, rate capacity, long-term cycling stability, energy density, and electrocatalytic performance for overall water splitting applications.