## 1 Introduction  
Carbon quantum dots (CQDs) are a unique kind of zero-dimensional fluorescent carbon nanomaterials with high fluorescence intensity, excellent water solubility, biocompatibility [1], adjustable surface functionality, and excellent photostability [2, 3]. CQDs can be used as an auxiliary material to enhance the performance of other materials. Theirfluorescence properties not only enable efficient bioimaging and cell labeling, but also significantly improve the material's performance by combining it with other materials. For example, in Fe\({}_{3}\)O\({}_{4}\)@mSiO\({}_{2}\) composite, carbon dots are fluorescently labeled to achieve mitochondrial targeted imaging and long-term imaging [4]. In CDs@Mat-PANI, carbon dots enhance the magnetic and photoluminescence properties by electron transfer mechanism [5]. Furthermore, the fluorescence properties of CQDs can be affected by heavy metal ions, demonstrating considerable potential for detecting metal ions in water [6]. Fe (III) detection and measuring sensors are used in a wide range of environments, including environmental monitoring [7], biomedical [8], industrial testing [9], and food safety [10]. The CQDs based fluorescence sensor can detect not only Fe\({}^{3+}\), but also other metal ions, such as AA (ascorbic acid), and this sensor shows a good linear relationship and low detection limits in both water samples and human serum [11]. These sensors are widely used in water pollution monitoring and environmental protection because of their high sensitivity and fast response time. Regarding the requirement for particular alterations to carbon quantum dots and their enhanced fluorescence characteristics, as well as factors concerning experimental settings, safety, and cost-efficiency, hydrothermal synthesis has become the primary technique for CQDs preparation. A diversity of materials can function as precursors for the hydrothermal synthesis of carbon quantum dots, including glucose [12], citric acid [13], chitosan [14], coconut shells [15], banana peels [16], sugarcane [17], etc. Despite the hydrothermal method's reputation for generating high-quality CQDs, there remain few reports that produce a significant quantity of these materials. Researchers initially extracted cellulose from bamboo waste using diluted hydrochloric acid, thereafter, introducing 2,4-diaminobenzenesulfonic acid to lignin for carbonization. This technique concurrently provides nitrogen and sulfur elements on the surface of nitrogen-doped carbon quantum dots (N-CQDs). The N-CQDs generated using this approach demonstrate proficient fluorescence detection skills for Fe (III), attaining a detection limit of 0.15 umol/L [18]. Nonetheless, the yield of CQDs in that investigation was below 0.3 g, leading to a diminished overall mass yield owing to a substantial quantity of unutilized precursors. Presently, numerous research efforts on fluorescence intensity, spectrum attributes, and application have been reported, with comparatively minimal attention given to the mass yield of CQDs. [PERSON] et al. oxidized cellulose precursors with nitric acid and integrated nitrogen elements to simultaneously enhance the quality and mass yield of CQDs, increasing the total mass production of N-CQDs from 2.9 wt% to 16.1 wt% [19]. Certain researchers initially exposed glucose and other biomass to hydrothermal carbonization at 200 \({}^{\circ}\)C and then treated the resulting solid biochar with diluted sodium hydroxide and hydrogen peroxide at ambient temperature; this procedure increased the mass production of CQDs from 0.62 wt% to 43.8 wt% [20]. This discovery suggests significant potential for improving the mass yield of carbon-based precursors but requires the neutralization of Na+ with hydrochloric acid, followed by extended dialysis for its elimination. [PERSON] et al. employed commercially available activated carbon as a precursor to synthesize CQDs using a weak base (H\({}_{2}\)O\({}_{2}\)), which does not produce by-products; nonetheless, their yield was restricted to milligram quantities [21].