Zeolitic Imidazole Framework Sacrificial Template-Assisted Synthesis of NiCoP Nanocages Doped with Multiple Metals for High-Performance Hybrid Supercapacitors

Metal phosphides have great potential for electrochemical energy-storage devices and electrocatalysis. Although monometallic and bimetallic phosphides have been extensively studied, the preparation of more complex metal phosphides remains challenging and it is necessary to further expand the available design space. Herein, we report a universal method to dope various metal cations into NiCoP nanocages (M-NiCoP, M = Al, Cu, Cr, Zn). Interestingly, the method can also be expanded to allow the incorporation of two to four metal dopants simultaneously (AlCu-NiCoP, AlZn-NiCoP, CrZn-NiCoP, AlCrCu-NiCoP, AlCrCuZn-NiCoP). To investigate the effect of incorporating multiple dopants, AlCu-NiCoP was used as the electrode material for supercapacitors, showing enhanced capacity and cycling stability compared to Al-NiCoP, Cu-NiCoP, and NiCoP electrodes. The superior electrochemical performance is attributed to the increased number of active sites, improved ion-diffusion kinetics, and a modulated electronic structure. An aqueous hybrid supercapacitor with AlCu-NiCoP as the positive electrode and activated carbon as the negative electrode was assembled and demonstrated a high energy density of 62.8 Wh kg–1 at a power density of 750 W kg–1 with good cycling stability.