Designing Tunable Paper-Based Colorimetric Sensor for Precise Detection of Hydrogen Peroxide Vapor

Detection of hydrogen peroxide (H₂O₂) vapor remains a significant challenge for conventional sensing technologies, despite its significance in applications such as the detection of improvised explosive devices (IEDs). Herein, we report a novel, highly sensitive colorimetric sensor system capable of detecting H₂O₂ vapor at concentrations as low as parts-per-billion (ppb). The sensor is based on a cellulose microfibril network, derived from paper towels, which provides a versatile and tunable substrate for the incorporation of Ti-(IV) oxo complexes. These complexes selectively bind to H₂O₂, forming a Ti-(IV)-peroxide coordination complex that induces a prominent chromatic shift from colorless to bright yellow, with an absorption maximum at approximately 400 nm. This complexation-driven color transition exhibits exceptional selectivity for H₂O₂, with no detectable color change in the presence of water, oxygen, common organic solvents, or other chelating agents. The sensor is designed for single-use and is inherently low-cost, providing a simple yet effective approach for H₂O₂ vapor detection. Additionally, the system highlights the potential of cellulose-based nanofibril materials in advancing colorimetric sensing platforms. By reducing the fiber dimensions, the available surface area for interaction with gaseous analytes is significantly enhanced, thus improving the sensitivity and overall performance of the sensor. This work not only demonstrates the feasibility of an efficient paper-based sensor for H₂O₂ vapor detection but also opens avenues for further exploration into nanostructured materials for the development of next-generation sensing technologies.