Multicolor emissive carbon dots (CDs) have potential applications in many fields such as photoelectric display, light-emitting devices, and bioimaging. Such CDs by heteroatom doping of nitrogen elements assisted with various solvents has achieved recently, yet generally low efficiency in red-light region. Herein, we developed a facile route to synthesize multicolor-emissive CDs governed by a solvothermal method of tetrahydrofuran solvent. The maximum emission locates at 432, 510, and 584 nm with the absolute FL QYs up to 21.1%, 11.0%, and 55.4% for selected B-CDs, G-CDs, and YG-CDs, respectively. By means of the analysis on their PL spectra, fluorescence lifetimes , and microstructures, the different graphitic degrees and surface states formed under the participation of S and N elements in as-prepared CDs determine the fluorescent color, and large sp 2 -conjugated domains within the YR-CDs is closely related to high QY. They, likewise, endow the YR-CDs with high sensitivity for ion detections of Ag + and Fe 3+ , which was further illustrated to have different quenching mechanisms each other due to the affinity interaction with different surface groups of the CDs. High PL QYs of these CDs emission are beneficial to application in solid lighting, phosphors dried by these CDs solutions were mixed with PVP water solution to fabricate CDs/PVP films. The films exhibited stable fluorescence, and three phosphors were also mixed together in proportion to obtain white-light film with a CIE coordinates of (0.34, 0.34), which demonstrates that these CDs are potentially fluorescent nanomaterial in the solid-state lighting field.
In this work, sulfur/nitrogen modified reduced graphene oxide (S/N-rGO) was employed as both electron shuttle and support to fabricate Fe-Mn bimetallic organic framework@S/N-rGO hybrids (BOF@S/N-rGO) via a facile two-step solvothermal route. Compared with the transition metal ions (Fe 2+ /Mn 2+ ), the classical metal oxide catalyst (Fe 2 O 3 and Fe 3 O 4 ) and nano zero-valent iron (nZVI), BOF@S/N-rGO catalyst can more effectively activate peroxydisulfate (PDS) with ultra-low concentration (0.05 mM) to degrade sulfamethazine (SMT). Quenching experiments, electron paramagnetic resonance (EPR) measurement and linear sweep voltammetry (LSV) showed that the activation pathways of PDS between the two catalysts were different. In BOF@N-rGO+PDS system, the degradation of SMT was mainly attributed to the oxidation of radicals including SO 4 •− and •OH, especially SO 4 •− . However, in BOF@S-rGO+PDS system, in addition to the radical pathway, there are also non-radical pathways, namely 1 O 2 and direct electron transfer . Furthermore, the applicability of BOF@S/N-rGO used in the PDS-mediated advanced oxidation processes (AOPs) was systematically investigated in terms of the effects of operating parameters and coexisting substance (anions and humic acid (HA)), the degradation of other pollutants, as well as the stability and reusability of the catalyst. This study proved that BOF@S/N-rGO was a promising activator of PDS with ultra-low concentration for the degradation of SMT.
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