Controlling the up-conversion photoluminescence property of carbon quantum dots (CQDs) by modifying its surface functional groups for enhanced photocatalytic performance of CQDs/BiVO4 under a broad-spectrum irradiation

Synthesis of carbon quantum dots/porous aromatic frameworks (CQDs/PAF-45) composites and their enhanced photocatalytic performance

Modification and functionalization of porous aromatic framework (PAF) materials have emerged as crucial research directions in various fields. In this study, we employed a hydrothermal method to synthesize a carbon quantum dots (CQDs) solution. By loading different amounts of CQDs onto the surface of PAF-45 material through ultrasonic and hydrothermal treatments, we successfully formed CQDs/PAF-45 composite materials. The introduction of CQDs effectively transformed the hydrophobic nature of PAF-45 into a hydrophilic material, thereby overcoming the challenge of achieving efficient contact between PAF catalysts and reactants in aqueous solutions. In the photocatalytic degradation experiments of Rhodamine B (RhB), tetracycline, CQDs/PAF-45 composite materials surpassed that of the pristine PAF-45 material. Notably, the 1 wt% CQDs/PAF-45 composite material exhibited the highest photocatalytic activity, with degradation efficiencies for Rhodamine B, tetracycline, and phenol approximately 1.4 times, 1.5 times and 1.5 times higher than those of the PAF-45 material, respectively.

Construction Strategy and Mechanism of a Novel Wood Preservative with Excellent Antifungal Effects

Wood is a naturally porous material prone to microbial erosion and degradation in outdoor environments. Therefore, the development of an environmentally friendly wood preservative with excellent antibacterial effects and low toxicity is urgently needed. In this study, nitrogen-doped carbon quantum dots (N-CQDs) with excellent antifungal performance and fluorescent properties were synthesized using a one-step hydrothermal method with chitosan quaternary ammonium salt (HACC) as the raw material. The fluorescence characteristics of N-CQD preservatives can help track their position and distribution in wood. The minimum inhibitory concentration (MIC) of N-CQDs is 1.8 mg/mL, which was nearly 22 times lower than that of HACC (40.0 mg/mL) in the PDA medium. The decay resistance test demonstrated that wood treated with N-CQDs showed a considerably reduced decay degree and its mass loss rate decreased from 46 ± 0.5% to 3.8 ± 0.5%. Biological transmission electron microscopy revealed that N-CQDs effectively destroyed fungal cell structures, thereby hindering the growth of Coriolus versicolor. N-CQDs synthesized using the one-step hydrothermal method can be used as an efficient wood preservative that can effectively improve the utilization and service life of wood.

Bi/BiOI/carbon quantum dots nano-sheets with superior photocatalysis

A new photocatalyst of Bi/BiOI/Carbon quantum dots (CQDs) was synthesized via a simple method. Photocatalytic performance of Bi/BiOI/CQDs was evaluated by photodegradation of RhB. Experiment indicated that the introduction of CQDs could improve the photocatalysis activity of BiOI obviously. Moreover, there is a optimum percentage of CQDs. In this photocatalytic system, the enhanced photoactivity was mainly attributed to the heterojunction interface between CQDs and BiOI, as well as the enhanced light harvesting for the appropriate CQDs introduction. The radicals trapping experiments revealed that O2˙-, ˙OH and h+ were the main active species during the photocatalysis process.

Deciphering photocatalytic degradation of methylene blue by surface-tailored nitrogen-doped carbon quantum dots derived from Kraft lignin

Lignin in black liquor can be used to manufacture carbon nanomaterials on a large scale. However, the effect of nitrogen doping on the physicochemical properties and photocatalytic performance of carbon quantum dots (NCQDs) remains to be explored. In this study, NCQDs with different properties were prepared hydrothermally by using kraft lignin as the raw material and EDA as a nitrogen dopant. The amount of EDA added affects the carbonization reaction and surface state of NCQDs. Raman spectroscopy showed that the surface defects increased from 0.74 to 0.84. Photoluminescence spectroscopy (PL) showed that NCQDs had different intensities of fluorescence emission at 300-420 nm and 600-900 nm. Meanwhile, NCQDs can photo-catalytically degrade 96 % of MB under simulated sunlight irradiation within 300 min. After three months of storage, the fluorescence intensity of NCQDs remained above 94 %, showing remarkable fluorescence stability. After four times of recycling, the photo-degradation rate of NCQDs was maintained above 90 %, confirming its outstanding stability. As a result, a clear understanding of the design of carbon-based photo-catalyst fabricated from the waste of the paper-making industry has been gained.