Sensitive and facile photoelectrochemical and colorimetric dual-mode analysis of H2S based on MOF-derived TiO2/C@Au@Cu(II) nanodisk

Abstract

Considering the severe toxicity and potential harm of hydrogen sulfide (H₂S) released during agricultural and industrial activities, the development of sensitive and reliable method to measure H₂S is worthwhile for environmental monitoring and human health. Here, the Cu(II) ions were introduced into MIL-125-derived TiO₂/C@Au nanodisk (denoted as TiO₂/C@Au@Cu(II)) and worked as the recognition elements. The H₂S could react with Cu(II) ions to generate CuS, resulting in a reduction in photocurrent and an augment in absorption. Based on this, a sensitive and facile photoelectrochemical (PEC) and colorimetric dual-mode sensing platform was designed for H₂S detection. In PEC mode, the steric hindrance of CuS obstructed the transport of photoexcited charge carriers and the diffusion of electron acceptor/donor between the electrode and electrolyte solution. Thereby, a quenching of the photocurrent signal was observed. For colorimetry, using the peroxidase-mimicking activity of CuS, the color reaction of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the presence of H₂O₂ was triggered, causing an obvious absorbance response of colorimetric solution. Noticeably, the dual-mode detection exhibited a wide linear scope of 1 – 5 × 10⁵ nM for H₂S, achieving detection limits of 0.33 and 0.41 nM, respectively. Furthermore, this method presented numerous merits, containing high specificity, remarkable reliability, simplicity, cost-effectiveness and time-efficiency, highlighting its application prospects in environmental analysis and human safety.