A novel detection method for sulfur content in ship fuel based on metal-doped tin oxide quantum dots as fluorescent sensor

The International Maritime Organization (IMO) issues compulsory regulations that require fuel sulfur content (FSC) less than 0.50% (m/m) to reduce sulfur dioxide emission from ships. However, current FSC detection suffers from low efficiency and high cost. In this work, a novel method for FSC detection is developed based on semiconductor quantum dots (QDs). The adsorption properties of primary functional groups -SH, -COOH, -NH2, -OH, and -CN of organic compounds in fuel on pristine and metal-doped tin oxide (SnO2) QDs are simulated by density functional theory (DFT) calculations. Ni dopant is selected after screening adsorption of organics on metal-doped SnO2. The fluorescent sensor is designed by nickel-doped SnO2 (Ni-SnO2) QDs for the FSC detection. The detection range and limit of detection are 0.429-0.97% m/m and 0.065% m/m, respectively. Furthermore, the sensing mechanism is discussed and the quenching of fluorescence emission of Ni-SnO2 QDs is ascribed to the photoinduced electron transfer. This work provides a novel technique based on Ni-doped SnO2 QDs for actual fast-responsive, highly-selective, reliably-repeatable, low-cost FSC detection, which can meet the detection requirements of FSC below 0.10% m/m in the emission control areas (ECAs).