Reaction-driven GO conductive network reconstruction for enhanced sensitivity and selectivity of room-temperature TiO2 gas sensors

Mild UV in-situ assembly synthesizes GO@TiO 2 with Ti–O–C bonds. • Sensor exhibits a response of 25.93–50 ppm ethanol under UV at 25℃. • GO@TiO 2 response shows nonlinear growth with concentration. • Reaction-driven reconducted network boosts sensitivity, selectivity and stability. The development of the Internet of Things (IoT) has created an urgent need for room‑temperature gas sensors that combine high sensitivity, selectivity, and stability, which existing gas-sensing materials still struggle to deliver. Herein, the GO@TiO 2 composite is constructed via photocatalytic in situ assembly, wherein TiO 2 nanosheets are anchored onto graphene oxide (GO) with strong Ti–O–C covalent bonds formed at the interface. Under UV illumination at 25℃, the GO@TiO 2 sensor exhibits a response of 25.93 toward 50 ppm ethanol—a 14.4-fold enhancement over pristine TiO 2 (1.80)—along with excellent selectivity against various interfering gases. Moreover, the response exhibits a nonlinear surge with increasing gas concentration. The reaction-driven conductive network reconstruction mechanism is innovatively proposed: electrons generated from the ethanol oxidation reaction are injected into GO across the Ti–O–C interface, progressively restoring the conductive network and thereby switching the dominant conduction pathway from TiO 2 to the repaired GO. This work provides an innovative strategy for room-temperature gas sensing through the construction of the dynamically tunable conductive network to achieve signal amplification. Download: Download high-res image (221KB) Download: Download full-size image The GO@TiO 2 composite with covalent Ti–O–C bonds are designed for room-temperature ethanol sensing via photocatalytic in-situ assembly. Under UV illumination, the gas sensing reaction injects electrons into GO across the Ti–O–C bonds, driving reconstruction of the GO conductive network from a high‑resistance oxidized state to a conductive reduced state and leading to a sharp drop in resistance. This reaction‑driven network reconstruction triggers a superlinear response, endowing the sensor with high sensitivity (response of 25.93–50 ppm ethanol), selectivity, and stability.