Multifunctional Nanocomposites for Coupled Photovoltaic and Electrochemical Energy Storage Devices

In the pursuit of next-generation energy systems, we report a novel multifunctional nanocomposite engineered for simultaneous solar energy harvesting and electrochemical storage within a unified architecture. The hybrid material comprising reduced graphene oxide (rGO), titanium dioxide (TiO₂), and polyaniline (PANI) was synthesized via a dual-step method integrating hydrothermal treatment with in-situ oxidative polymerization. This design enables synergistic interactions between the photoactive TiO₂, conductive rGO network, and pseudocapacitive PANI, offering high photoconductivity and redox reactivity within a single matrix. Comprehensive characterization through SEM, XRD, FTIR, UV-Vis spectroscopy, and electrochemical impedance spectroscopy confirms the formation of an interpenetrated nanostructure with favorable band alignment and efficient charge transport. The nanocomposite delivered a solar-to-capacitive conversion with a maximum photovoltage of 0.86 V under AM 1.5G conditions and a specific capacitance of 421 F/g at 1 A/g. Remarkably, the device exhibited self-charging behavior under light exposure and retained 91.3% capacity over 1,000 cycles. This research introduces a unique platform that bridges energy conversion and storage in a scalable, low-cost configuration. Unlike conventional bifunctional systems, our architecture operates through a photo-coupled electron–ion transfer mechanism that synchronizes solar absorption with real-time electrochemical energy retention. The approach paves the way for autonomous, off-grid microsystems, wearable power modules, and compact solar-storage devices. Our results establish a new benchmark for integrated nanomaterial systems, grounded in practical experimentation, advanced material synthesis, and device-level innovation.