Rational design of nickel cobalt phosphate-sensitized tungsten-doped titania nanotubes (NiCoP@WTNT) for efficient light-assisted energy storage in flexible photo-supercapacitors

Developing efficient and low-cost systems for simultaneous solar energy harvesting and storage remains a critical challenge in next-generation energy technologies. Herein, we report a flexible photo-supercapacitor based on nickel–cobalt phosphate (NiCoP)-sensitized tungsten-doped titania nanotube arrays (NCP@WTNT) as a dual-function photoelectrode. The heterostructure combines enhanced light absorption, improved charge transport, and abundant redox-active sites, leading to enhanced photo-assisted energy storage. The optimized electrode exhibits a 4.1-fold increase in areal specific capacitance under illumination, from 9.20 to 37.54 mF cm −2 , demonstrating its effective photoresponse. Flexible devices fabricated from this material show rapid self-charging behavior, stable cycling performance, and good mechanical stability under different bending conditions. In addition, photocharging without an external bias and stable electrochemical performance under illumination demonstrate the feasibility of integrating solar energy harvesting and storage within a single device. By coupling bimetallic phosphate chemistry with tungsten-doped titania nanotube architectures, this work provides an effective strategy for improving the performance of flexible photo-supercapacitors. The results demonstrate the potential of the NCP@WTNT architecture as a cost-effective platform for integrated solar energy conversion and storage, offering opportunities for self-powered, light-responsive, and flexible energy storage devices for wearable and portable electronics.