At present, the actual mechanism of the photoluminescence （PL） of fluorescent carbon dots （CDs） is still an open debate among researchers. Because of the variety of CDs, it is highly important to summarize the PL ...At present, the actual mechanism of the photoluminescence （PL） of fluorescent carbon dots （CDs） is still an open debate among researchers. Because of the variety of CDs, it is highly important to summarize the PL mechanism for these kinds of carbon materials; doing so can guide the development of effective synthesis routes and novel applications. This review will focus on the PL mechanism of CDs. Three types of fluorescent CDs were involved： graphene quantum dots （GQDs）, carbon nanodots （CNDs）, and polymer dots （PDs）. Four reasonable PL mechanisms have been confirmed： the quantum confinement effect or conjugated 7x-domains, which are determined by the carbon core; the surface state, which is determined by hybridization of the carbon backbone and the connected chemical groups; the molecule state, which is determined solely by the fluorescent molecules connected on the surface or interior of the CDs; and the crosslink- enhanced emission （CEE） effect. To give a thorough summary, the category and synthesis routes, as well as the chemical/physical properties for the CDs, are briefly introduced in advance.展开更多
The simultaneous integration of heteroatom doping and surface plasmon resonance(SPR) modulation on semiconductor photocatalysts could be capable of improving visible light utilization and charge separation, achieving ...The simultaneous integration of heteroatom doping and surface plasmon resonance(SPR) modulation on semiconductor photocatalysts could be capable of improving visible light utilization and charge separation, achieving better solar light conversion and photocatalysis efficiency. For this purpose, we have designed a novel Bi quantum dots(QDs) implanted C-doped BiOCl photocatalyst(C/BOC/B) for NOx removal. The feasibility was firstly evaluated through density functional theory(DFT) calculations methods, which indicates that the enhanced photocatalytic performance could be expected owing to the synergistic effects of doped C heteroatoms and loaded Bi QDs. Then, the C/BOC/B was synthesized via a facile hydrothermal method and exhibited efficient and stable visible light photocatalytic NO removal. The results found that the doped C atoms can serve as electron guides to induce oriented charge transfer from Bi QDs to BiOCl, while the Bi QDs can act as light-capture and electron-donating sites. The reaction pathway and mechanism for NO conversion was unveiled by in situ Fourier-transform infrared spectroscopy combined with DFT calculation. The enhanced adsorption of reactants and intermediates could promote the overall reaction efficiency and selectivity in photocatalytic NO conversion. This work could provide a new perspective on the mechanistic understanding of the synergistic effects toward non-metal doping and SPR effects in semiconductor photocatalysts, and this presented technique could be extended for other semiconductor materials.展开更多
文摘At present, the actual mechanism of the photoluminescence （PL） of fluorescent carbon dots （CDs） is still an open debate among researchers. Because of the variety of CDs, it is highly important to summarize the PL mechanism for these kinds of carbon materials; doing so can guide the development of effective synthesis routes and novel applications. This review will focus on the PL mechanism of CDs. Three types of fluorescent CDs were involved： graphene quantum dots （GQDs）, carbon nanodots （CNDs）, and polymer dots （PDs）. Four reasonable PL mechanisms have been confirmed： the quantum confinement effect or conjugated 7x-domains, which are determined by the carbon core; the surface state, which is determined by hybridization of the carbon backbone and the connected chemical groups; the molecule state, which is determined solely by the fluorescent molecules connected on the surface or interior of the CDs; and the crosslink- enhanced emission （CEE） effect. To give a thorough summary, the category and synthesis routes, as well as the chemical/physical properties for the CDs, are briefly introduced in advance.
文摘The simultaneous integration of heteroatom doping and surface plasmon resonance(SPR) modulation on semiconductor photocatalysts could be capable of improving visible light utilization and charge separation, achieving better solar light conversion and photocatalysis efficiency. For this purpose, we have designed a novel Bi quantum dots(QDs) implanted C-doped BiOCl photocatalyst(C/BOC/B) for NOx removal. The feasibility was firstly evaluated through density functional theory(DFT) calculations methods, which indicates that the enhanced photocatalytic performance could be expected owing to the synergistic effects of doped C heteroatoms and loaded Bi QDs. Then, the C/BOC/B was synthesized via a facile hydrothermal method and exhibited efficient and stable visible light photocatalytic NO removal. The results found that the doped C atoms can serve as electron guides to induce oriented charge transfer from Bi QDs to BiOCl, while the Bi QDs can act as light-capture and electron-donating sites. The reaction pathway and mechanism for NO conversion was unveiled by in situ Fourier-transform infrared spectroscopy combined with DFT calculation. The enhanced adsorption of reactants and intermediates could promote the overall reaction efficiency and selectivity in photocatalytic NO conversion. This work could provide a new perspective on the mechanistic understanding of the synergistic effects toward non-metal doping and SPR effects in semiconductor photocatalysts, and this presented technique could be extended for other semiconductor materials.
