Photoresponsive TiO₂/Graphene Hybrid Electrodes for Dual-Function Supercapacitors with Integrated Environmental Sensing Capabilities

The integration of energy storage and environmental sensing functions into a single device represents a critical step toward the development of autonomous smart systems. In this work, we report the design and fabrication of photoresponsive supercapacitors based on TiO₂/graphene hybrid electrodes that simultaneously deliver enhanced energy storage performance and environmental monitoring capabilities. The nanocomposite electrodes are prepared via a scalable sol-gel and hydrothermal route, followed by mild thermal treatment to optimize interface interactions and photoactivity. Under UV and visible light illumination, the devices exhibit a significant increase in specific capacitance, up to 35% enhancement, due to improved charge separation and interfacial polarization effects. Moreover, the same hybrid materials demonstrate sensitivity to volatile organic compounds (VOCs) and humidity, enabling their use as dual-function components in next-generation smart electronics. The synergistic combination of light-driven capacitive enhancement and real-time environmental response highlights the potential of these hybrid systems for self-powered, multifunctional platforms in wearable and distributed sensor networks.