PEDOT-Doped Transition Metal Phosphide/Sulfide on Silicon Nanowire Arrays for Supercapacitor and Electrocatalysis Applications

Transition metal sulfides (TMSs) and phosphides (TMPs) have emerged as promising candidates for electrochemical energy storage and conversion systems (EESCSs) due to their unique physicochemical properties. However, pristine TMSs or TMPs often experience significant volume changes and sluggish reaction kinetics during electrochemical processes. These challenges can be effectively addressed by fabricating TMS- or TMP-based composites. Considering their compatibility and the potential for seamless integration with existing silicon-based devices, three-dimensional (3D) silicon frameworks with large specific surface areas are particularly attractive for applications in EESCSs. Herein, hierarchical double active shells composed of PEDOT-doped nickel–cobalt phosphide (NCP) and nickel–cobalt sulfide (NCS) were electrodeposited around nickel-decorated silicon nanowires (SiNWs), forming the NSi/NCP-E/NCS-E electrode. The resulting electrode exhibits exceptional specific capacitance (1760 F/g at 1 A/g) and outstanding rate capability (837 F/g at 100 A/g). The corresponding hybrid NSi/NCP-E/NCS-E//AC supercapacitor achieves an exceptional energy density of 163 Wh/kg. Impressively, the NSi/NCP-E/NCS-E electrode requires low overpotentials of 129 mV for HER (10 mA/cm2) and 423 mV for OER (50 mA/cm2), highlighting its bifunctional catalytic performance. These results highlight the potential of 3D silicon frameworks combining conductive polymer-doped metal chalcogenides for developing high-performance, cost-effective EESCS materials.