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Determining the correlation between the size of a single quantum dot (QD) and its photoluminescence (PL) properties is a challenging task. In the study, we determine the size of each QD by measuring its absorption cross section, which allows for accurate investigation of size-dependent PL blinking mechanisms and volume scaling of the biexciton Auger recombination at the single-particle level. A significant correlation between the blinking mechanism and QD size is observed under low excitation conditions. When the QD size is smaller than their Bohr diameter, single CsPbI3 perovskite QDs tend to exhibit BC-blinking, whereas they tend to exhibit Auger-blinking when the QD size exceeds their Bohr diameter. In addition, by extracting bright-state photons from the PL intensity trajectories, the effects of QD charging and surface defects on the biexcitons are effectively reduced. This allows for a more accurate measurement of the volume scaling of biexciton Auger recombination in weakly confined CsPbI3 perovskite QDs at the single-dot level, revealing a superlinear volume scaling (τXX,Auger ∝ σ1.96). [ABSTRACT FROM AUTHOR]

The Zeeman-split spin states of a single quantum dot can be used together with its optical trion transitions to form a spin–photon interface between a stationary (the spin) and a flying (the photon) quantum bit. In addition to long coherence times of the spin state itself, the limiting decoherence mechanisms of the trion states are of central importance. Here, we investigate in time-resolved resonance fluorescence the electron spin and trion dynamics in a single self-assembled quantum dot in an applied magnetic field of up to B = 10 T. The quantum dot is only weakly coupled to an electron reservoir with tunneling rates of about 1 ms − 1 . Using this sample structure, we can measure, in addition to the spin-flip rate of the electron and the spin-flip Raman rate of the trion transition, the Auger recombination process that scatters an Auger electron into the conduction band. The Auger effect destroys the radiative trion transition and leaves the quantum dot empty until an electron tunnels from the reservoir into the dot. The combination of an Auger recombination event with subsequent electron tunneling from the reservoir can flip the electron spin and thus constitutes another mechanism that limits the spin lifetime. [ABSTRACT FROM AUTHOR]

[Display omitted] • In 2 O 3 quantum dots were successfully loaded on g-C 3 N 4 by pre-forming In–N bonds. • High-temperature oxidation can improve the oxygen adsorption capacity of g-C 3 N 4. • S-scheme transfer exhibits excellent photoelectric conversion efficiency. • Hydroperoxide C β intermediate was an important intermediate in lignin β–O–4 bond cleavage reaction. The graphitic carbon nitride (g-C 3 N 4) photocatalysis has emerged as a clean method for cleaving lignin-linked bonds due to its mild and sunlight-driven reaction conditions. The fast electron–hole pair complex of g-C 3 N 4 constrains its degradation efficiency, making the heterojunction construction a popular solution. The conventional methods of preparing g-C 3 N 4 heterojunctions by physical mixing destroy π-conjugations in g-C 3 N 4 , reducing the adsorption of lignin containing benzene rings. In this study, a novel indium oxide (In 2 O 3) quantum dot–g-C 3 N 4 0D/2D heterojunction was prepared through the high-temperature oxidation of pre-prepared indium-doped g-C 3 N 4. The introduction of In 2 O 3 at the quantum dot level minimizes the interference with lignin adsorption capacity. The strong combination of the two (In 2 O 3 and g-C 3 N 4) increases the intersection interface area, promoting the S-scheme transfer route of the photogenerated electrons. Consequently, this enhances the photoelectric conversion efficiency and carrier lifetime of the heterojunction, and inhibits the rapid recombination of photogenerated electron–hole pairs in g-C 3 N 4. The proposed heterojunction was 3 times more efficient than g-C 3 N 4 alone for selective cleavage of lignin β–O–4 bonds after 2 h of sunlight irradiation. Combined with inhibitor experiments and gas chromatography–mass spectrometry analysis, this paper defines the reactive oxides and proposes a cleavage pathway for the lignin β–O–4 bonds in In 2 O 3 –g-C 3 N 4 heterojunction system. [ABSTRACT FROM AUTHOR]

The achievement of size uniformity and monodispersity in perovskite quantum dots (QDs) requires the implementation of precise temperature control and the establishment of optimal reaction conditions. Nevertheless, the accurate control of a range of reaction variables represents a considerable challenge. This study addresses the aforementioned challenge by employing manganese (Mn) doping to achieve size uniformity in CsPbBr3 perovskite QDs without the necessity for the precise control of the reaction conditions. By optimizing the Mn:Pb ratio, it is possible to successfully dope CsPbBr3 QDs with the appropriate concentrations of Mn²⁺ and achieve a uniform size distribution. The spectroscopic measurements on single QDs indicate that the appropriate Mn²⁺ concentrations can result in a narrower spectral linewidth, a longer photoluminescence (PL) lifetime, and a reduced biexciton Auger recombination rate, thus positively affecting the PL properties. This study not only simplifies the size control of perovskite QDs but also demonstrates the potential of Mn-doped CsPbBr3 QDs for narrow-linewidth light-emitting diode applications. [ABSTRACT FROM AUTHOR]

Lead halide perovskite quantum dots (PeQDs) generally show slow hot carrier (HC) cooling because of the retarded relaxation of longitudinal optical (LO) phonons induced by hot phonon bottleneck effect. Although the feature is beneficial for designing photovoltaic devices beyond Schottky–Queisser limitation by manipulating HC excess energy, it would be hostile toward light‐emitting applications where fast HC cooling is preferred. Herein, a Ni2+ doping strategy is reported to effectively boost HC cooling in CsPbI3 PeQDs and inhibit Auger recombination, giving rise to near unity photoluminescent quantum yield (PLQY) for the Ni: CsPbI3 sample. Femtosecond transient (fs‐TA) absorption, temperature‐dependent PL spectra and theoretical calculations evidence that Ni2+ doping results in the enhancement of electron‐LO phonon coupling, the introduction of extra energy states at band edges, the increasement of effective carrier mass, and the modification of phonon dispersion spectra as well as density of states (DOS) of LO phonon modes. These synergistic roles ensure efficient Klemens decay within Ni: CsPbI3, which facilitates fast decay of hot phonons and break hot phonon bottleneck. These findings provide a valid route to tackle HC dynamics and pave a way for PeQDs‐based efficient light‐emitting applications. [ABSTRACT FROM AUTHOR]

Lead halide perovskite quantum dots (LHP QDs) emerge as versatile photonic sources in electroluminescence and laser devices. Their applications in optoelectronic devices are hindered by surface distortion and ligand stripping during the purification process. In addition, the device performance roll‐off suffers from the ultrafast non‐radiative Auger recombination (AR). To address these issues, herein, CsPbBr3 QDs are prepared with sizes ranging from 6.5 to 9.2 nm and the universal surface repairing strategy is proved to efficiently increase the biexciton lifetime and quantum yield up to 1.4 and 3 times, respectively. The strategy provides a PbBrx rich surface and strong binding didodecyldimethylammonium bromide (DDAB) ligands to achieve near‐unity photoluminescence efficiency, which significantly improves their stability against anti‐solvents and aging in ambient conditions. A single‐mode laser device is realized by self‐assembling the QDs into superlattice as optical microcavity, with low threshold of 9.45 µJ cm−2, quality factor of 2187 and ultrafast lifetime of 3.22 ps. The superlattice laser is demonstrated as an optical encoder with large coding bandwidth of 0.133 THz. This work proposes new insight into the non‐radiative AR process in these single‐component CsPbBr3 QDs, and will pave the way for optoelectronic devices working in intense conditions. [ABSTRACT FROM AUTHOR]

Blue light‐emitting CdSe@ZnS/ZnS quantum dot (QD) nanoparticles (NPs) were synthesized and their photophysical properties in both solution and film phases were investigated. The morphological properties of films prepared by different coating methods i. e. single layer coating from low to high concentrations of QD solutions and layer‐by‐layer (multilayer) coating within constant low QD solution concentration, were also examined in detail. Varying the concentration (1–10 mg/mL) and the number of layers (from 1–16) did not essentially affect the photophysical properties of QD films, although it resulted in a direct increment in QD film thickness. The concentration and layer‐dependent films were used as an emissive layer (EML) in QD light‐emitting diodes (QLEDs). Although the "6 mg/ml−1 Layer" QD EML‐based device exhibited relatively high device efficiency compared to the "1 mg/ml−10 Layers" based one at working voltage region, it had ~2‐fold higher efficiency roll‐off at high voltage region. The performance differences for both devices with the same QD EML thickness were attributed to the morphological variations for the QD layer in terms of surface roughness, void density, aggregates/clusters, and trap sites that were directly related to the charge injection balance and Auger recombination. [ABSTRACT FROM AUTHOR]

TThe object of research is the donor-acceptor compound, organic and hybrid heterostructures based on it. The paper is focused on a comprehensive approach to solving the problem of the efficiency of light-emitting devices, finding new technological and design solutions for the use of organic compounds as multifunctional materials for various types of light-emitting devices. The paper presents the multifunctional application of a planar 2D molecule as an emission layer for typical and inverted types of light-emitting heterostructures, as well as a matrix for a host-guest system using inorganic quantum dots. The developed light-emitting structures are characterized by external quantum efficiency typical for fluorescent devices, but good stability over the entire length of the consumption voltage. QLED brightness is 1600 cd·m-2 and EQE 1.4 %, which are good parameters for use in display technology. Organic LEDs based on planar molecules are promising candidates for use in modern lighting systems. A separate advantage of these light-emitting structures is the multifunctionality of using one compound for different types of light-emitting structures, including inverted heterostructures. Special attention is paid to the technological and design implementation of invert structures, since their geometry allows direct connection to the back board of the n-channel transistor on the substrate. In addition, organic LEDs have low energy consumption and are environmentally friendly due to the absence of toxic substances in their architecture, which creates the prerequisites for saving energy resources and reducing the industrial burden on the environment. [ABSTRACT FROM AUTHOR]

Light Emitting Diodes (LEDs) are the key to new generation displays. New semiconductor electron-hole recombination layer is the key to high-performance LEDs. Although all-inorganic quantum dot (QD) materials have the advantages of wide color gamut and narrow emission peaks, they face issues of toxicity of heavy metal ions and stability of QDs, the synthesis method is highly polluting and difficult to achieve industrial production. Thereby, lead-free all-inorganic phosphor with narrow FWHM needs to be explored. A new synthesis method is required to be investigated. All-inorganic Mn2+ bromide (Cs3MnBr5) is easy to synthesize and has low toxicity and superior luminescent properties. However, most synthesis methods rely on liquid-phase reaction systems and cannot achieve highly efficient synthesis. High-energy ball milling is an efficient method and has enormous potential for industrial production. In this paper, this method is used to synthesize Cs3MnBr5, and then Cs/Mn ratio, ball milling time, and ligand usage are studied. Furthermore, a new phase transformation of all-inorganic Mn2+ bromide is discovered, and the mechanism of high-energy ball milling is interpreted combining with phase transformation process. This article brings a new method to synthesis of all-inorganic Mn2+ bromide, explains the mechanism of ball milling, and expands the phase transformation of all-inorganic Mn2+ bromide. [ABSTRACT FROM AUTHOR]

Mixed-dimensional composite structures using zero-dimensional (0D) quantum dots (QDs) and two-dimensional (2D) transition metal dichalcogenides (TMDs) materials are expected to attract great interest in optoelectronics due to the potential to generate new optical properties. Here, we report on the unique optical characteristics of a devices with mixed dimensional vertically stacked structures based on tungsten diselenide (WSe2)/CdSeS QDs monolayer/molybdenum disulfide (MoS2) (2D/0D/2D). Specifically, it exhibits an ambipolar photoresponse characteristic, with a negative photoresponse observed in the 400–600 nm wavelength range and a positive photoresponse appeared at 700 nm wavelength. It resulted in the high negative responsivity of up to 52.22 mA·W−1 under 400 nm, which is 163 times higher than that of the photodetector without CdSeS QDs. We also demonstrated the negative photoresponse, which could be due to increased carrier collision probability and non-radiative recombination. Device modeling and simulation reveal that Auger recombination among the types of non-radiative recombination is the main cause of negative photocurrent generation. Consequently, we discovered ambipolar photoresponse near a specific wavelength corresponding to the energy of quantum dots. Our study revealed interesting phenomenon in the mixed low-dimensional stacked structure and paved the way to exploit it for the development of innovative photodetection materials as well as for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Bi 2 S 3 , Bi 2 MoO 6 and TiO 2 composite photoanodes were fabricated using three different preparation routes to improve its photoelectrochemical (PEC) stability. The microstructure of three photoanodes are distinct significantly according to the results of XRD, SEM and TEM. The ordered TiO 2 nanorod arrays (NRAs) and thinner Bi 2 MoO 6 sheet crystals in flower-ball structure facilitate carrier transport and suppresses electron-hole recombination efficiently. The results of PEC tests indicate that the photoanode with Bi 2 MoO 6 sheet crystals in flower-ball structure and TiO 2 NRAs shows significant enhancement in PEC performance stability due to its ordered microstructure facilitating carrier transport and transfer and also good adherence of photoanode layer on FTO glass substrate. This photoanode in Bi 2 S 3 quantum dots/Bi 2 MoO 6 @TiO 2 NRAs structure exhibits satisfactory properties, achieving a PEC stability of 86.41% after 48 h. [Display omitted] • Three photoanodes were fabricated in various preparation routes. • PEC performance of three photoanodes were analyzed based on their different Microstructure. • The PEC stability of Bi 2 S 3 QDs/Bi 2 MoO 6 @TiO 2 NRAs photoanode is up to 86.41% after 48 h. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid materials have emerged as a class of novel materials over the last two decades, as they combine functional organic components and inorganic building blocks into unique materials through various chemical or physical interactions. In the present work, the importance of the use of ethylenediamine in sulfided materials applied to photocatalytic processes in the H2 production is demonstrated. The ZnS/ZnO heterojunction was prepared by the solvothermal synthesis in the presence and absence of ethylenediamine. The photocatalytic behavior showed that the addition of ethylenediamine increases the photocatalytic efficiency up to eight times compared to the photocatalyst without the organic agent. The materials were characterized by X-ray diffraction, scanning electron microscopy, infrared and UV–visible spectroscopies of solids, N2 adsorption–desorption isotherms, X-ray photoelectron spectroscopy, and photoelectrochemical characterization. The ethylenediamine plays a double role: to stabilize the cubic phase of zinc sulfide and to act as a promoter molecule of charge transfer on the surface of ZnS/ZnO/en heterojunction, slowing down the rate of recombination of the electron–hole pair, which is reflected in a decrease in the resistance to transfer of charge carriers, improving the H2 production rate until 1564 µmol h−1 g−1. [ABSTRACT FROM AUTHOR]

The features of photoluminescence (PL) of hybrid nanostructures based on InP/InAsP/InP nanowires array with deposited colloidal CdSe/ZnS-trioctylphosphine oxide quantum dots at increasing pump power have been studied. Pumping was carried out by 10 ps laser pulses duration with 1 MHz repetition rate at 532 nm wavelength in the quasi-resonant region of QDs absorption. It has been established, that PL maximum of the nanostructure shifts hypsochromically with increasing of laser power, revealing a gradual dominance of the bands of its components. This PL manifestation is explained by the cascade filling of excited excitonic states, accompanied by the Auger recombination processes and light quenching. The role of free carriers absorption and energy exchange between excitonic states at high pump intensities is noted, as well as a sharp PL duration reduction associated with an increase of stimulated processes in absorption. [ABSTRACT FROM AUTHOR]

Multi-exciton generation by multi-photon absorption under low-energy photons can be thought a reasonable method to reduce the risk of optical damage, especially in photoelectric quantum dot (QD) devices. The lifetime of the multi-exciton state plays a key role in the utilization of photon-induced carriers, which depends on the dynamics of the exciton generation process in materials. In this paper, the exciton generation dynamics of the photon absorption under low-frequency light in CdSe QDs are successfully detected and studied by the temporal resolution transient absorption (TA) spectroscopy method. Since the cooling time of hot excitons extends while the rate of auger recombination is accelerated when incident energy is increased, the filling time of defect states is irregular, and exciton generation experiences a transition from single-photon absorption to multi-photon absorption. This result shows how to change the excitation. Optical parameters can prolong the lifetime of excitons, thus fully extracting excitons and improving the photoelectric conversion efficiency of QD optoelectronic devices, which provides theoretical and experimental support for the development of QD optoelectronic devices. [ABSTRACT FROM AUTHOR]

We report on the spin and occupation noise of a single, positively charged (InGa)As quantum dot emitting photons in the telecommunication C-band. The spin noise spectroscopy measurements are carried out at a temperature of 4.2 K in dependence on intensity and detuning in the regime beyond thermal equilibrium. The spin noise spectra yield in combination with an elaborate theoretical model the hole-spin relaxation time of the positively charged quantum dot and the Auger recombination and the electron-spin relaxation time of the trion state. The extracted Auger recombination time of this quantum dot emitting at 1.55 μ m is comparable to the typical Auger recombination times on the order of a few μ s measured in traditionally grown InAs/GaAs quantum dots emitting at around 900 nm. [ABSTRACT FROM AUTHOR]

The document titled "Advanced Inorganic Semiconductor Materials" is a summary of a special issue that explores current research and ideas in the field of inorganic semiconductors. The issue includes nine articles and two topical reviews that cover various topics, such as 2D materials, quantum dots, avalanche photodiodes, and perovskites. Each article delves into different aspects of these materials, including their optical, mechanical, and electronic properties, as well as their potential applications in optoelectronic devices. The findings presented in the articles contribute to the understanding and development of advanced inorganic semiconductor materials for various applications. The document expresses gratitude to the contributors and reviewers for their valuable contributions to the special issue. [Extracted from the article]

Carbon quantum dots (CQDs) have emerged as prominent contenders in the realm of luminescent nanomaterials over the past decade owing to their tunable optical properties, robust photostability, versatile surface functionalization and doping potential, low toxicity, and straightforward synthesis utilizing environmentally friendly precursors. In this review, we commence with a concise introduction, presenting both top‐down and bottom‐up strategies for the eco‐friendly synthesis of CQDs. Subsequently, we delve into a comprehensive examination of CQDs' structure and optical characteristics, encompassing their ultraviolet–visible absorption properties, surface confinement effects, and surface state emissions contributing to room‐temperature photoluminescence (PL). This review proceeds to elucidate recent advancements in modification strategies for CQDs, specifically focusing on surface oxidation, passivation, and the incorporation of heteroatoms. These strategies serve to afford control over the physicochemical properties, facilitating the enhancement of PL through the decoration of highly visible‐responsive CQDs. This enhancement is achieved by suppressing the nonradiative recombination of electron‐hole pairs, enabling red/blue shifts in CQDs for the generation of a full‐color emission spectrum, and regulating the band‐gap and surface states to broaden the photoabsorption range. Finally, we offer an overview of the most recent developments in the applications of fluorescent CQDs, emphasizing their utility in biomedicine, fluorescent sensors, lighting, and displays, as well as photocatalysis. [ABSTRACT FROM AUTHOR]

In quantum dot sensitized solar cells (QDSSCs), the photoanode provides a stable support for the quantum dots, and promotes the production of photogenerated electrons and the transfer to external circuit. Therefore, it is very important to search for excellent photoanodes for the commercial application of QDSSCs. In this paper, a core–shell ZnO@TiO2 hexagonal prism heterogeneous structure was prepared by a two-step hydrothermal method. The ZnO@TiO2 heterogeneous structure not only has a unique 1D hexagonal prism morphology, but also can effectively inhibit the electron–hole recombination and has a greater light response and higher collection efficiency while speeding up the electron transmission rate. By adjusting the concentration of the TiO2 source, the best photoanode material Zn@Ti-2 was explored, and it showed excellent cell performance: Jsc = 25.4 mA cm−2, Voc = 0.71 V, PCE = 8.5%, and FF = 0.49. Compared with a single ZnO photoanode, the PCE value is increased by 25%. EIS, Tafel polarization and transient photocurrent responses confirm that the Zn@Ti-2 photoanode has higher catalytic activity and stability. Therefore, Zn@Ti-2 may be a promising photoanode material for QDSSCs. [ABSTRACT FROM AUTHOR]

Electron transfer (ET) process is considered a substantial factor in influencing the photoelectric conversion efficiency of optoelectronic devices. While pressure has demonstrated effective tune ET, a comprehensive investigation into the mechanisms for both restraining and promoting ET remains elusive. Herein, we have performed measurements using in situ high-pressure steady-state photoluminescence (PL), Raman scattering spectra, and femtosecond transient absorption (fs-TA) spectroscopy on InP/ZnS quantum dot–anthraquinone (InP/ZnS QD-AQ) complexes. The experimental results have demonstrated that the pressure-suppressed ET process in the InP/ZnS QD-AQ complexes arises from both the aggregation-induced emission (AIE) effect of AQ in toluene and the quantum confinement effect of the InP/ZnS QDs. The reduction in the distance between InP/ZnS QD and AQ under pressure emerges as a key factor that promotes the ET process in the InP/ZnS QD-AQ complexes. Furthermore, we observed that the pressure not only enhances the ET process but also suppresses the auger recombination process in liquid phase I of toluene, consequently leading to an enhancement in the photoelectric conversion efficiency. This study contributes to understanding the mechanism of the ultrafast dynamic processes in the pressure-induced QD-receptor complexes, and it has great potential for preparing efficient and stable optoelectronic devices. [ABSTRACT FROM AUTHOR]

In this study, the structural and optical properties as well as the photocatalytic performance of Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles were investigated. These nanoparticles were prepared using the co-precipitation method by applying different calcination temperatures (773, 823, 873, 923, and 973 K). The X-ray diffraction analysis confirmed the presence of the cubic spinel ferrite phase without secondary phases. As the calcination temperature increased from 773 to 973 K, the crystallite and particle sizes of Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles increased from 12.84 to 20.19 nm and from 19.13 to 43.83 nm, respectively. Among the prepared samples, Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles calcined at 873 K revealed the highest value of band gap energy along with the lowest values of Urbach energy, refractive index, and optical and static dielectric constant. Additionally, the prepared samples were applied as photocatalysts for the degradation of aniline under ultraviolet irradiation. Improved photocatalytic performance was revealed by Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles calcined at 873 K. This was attributed to the slowest recombination rate of the electron–hole pairs as revealed from PL analysis. To further improve the photodegradation rate, the degradation reaction was studied by varying the catalyst amount, aniline concentration, pH mediums, and reaction temperatures. Increasing the pH and temperature boosted the degradation rate. Finally, the degradation reaction was carried out by incorporating Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles calcined at 873 K with different weight % of carbon quantum dots. The results revealed enhanced photocatalytic activity with k = 30 × 10−4 min−1 was achieved after combining 10 weight % of carbon quantum dots with Ni0.33Cu0.33Zn0.33Fe2O4 nanoparticles. [ABSTRACT FROM AUTHOR]

Since hole trapping agents do not persist in the marine environment, it is more practical to test metal protection in 3.5 wt% NaCl solution so that the photocathodic protection (PCP) technique can be effectively applied in an actual marine environment. In this paper, Bi quantum dots (QDs) and ZIF-8 nanoparticles (NPs) were successfully deposited on TiO2 by hydrothermal and impregnation methods. The PCP performances of ZIF-8/Bi/TiO2 composites in the marine environment without hole trapping agents were evaluated, and compared with the performances of pure TiO2, Bi/TiO2 and ZIF-8/TiO2. The electrochemical impedance spectrum (EIS) fitting results demonstrate that the R ct value of the ZIF-8/Bi/TiO2 composite coupled with 316 stainless steel (SS) decreased from 7678 Ω cm2 to 519.3 Ω cm2 in 3.5 wt% NaCl solution, which is a decrease of about 14.8-fold compared with TiO2 under the same conditions. This indicates that the deposition of Bi QDs and ZIF-8 NPs on TiO2 nanotubes can improve the electron transport efficiency, which in turn slows down the rate of corrosion of 316 SS and significantly improves the PCP performance. This is not only attributable to the Schottky junction and heterojunction structures formed by Bi QDs and ZIF-8 NPs with TiO2, but also to the surface plasmon resonance effect of Bi QDs and the N–Ti–O bond structure formed between ZIF-8 and TiO2, leading to a lower electron–hole recombination efficiency and a higher electron transfer efficiency. [ABSTRACT FROM AUTHOR]

In pursuit of exploring functional applications of coal, this study ultrasound-assisted hydrogen peroxide was used to transform cheap coal into environmentally friendly and high-value coal-based carbon quantum dots (CQDs). These CQDs are then harnessed to synergistically assist the photocatalytic water splitting for hydrogen evolution, in collaboration with CoMoO 4 (CM) and g-C 3 N 4 (CN). The results indicated that the novel composite photocatalyst, CMCN-11/8%SCQDs, exhibited high hydrogen evolution activity, reaching a maximum hydrogen production rate of 4916.63 μmol g−1 h−1 at pH 9. At a wavelength of 420 nm, the apparent quantum efficiency (AQE) was 1.78%. The conduction and valence band positions of CM were determined to be −1.03 eV and 1.65 eV, respectively, while those of CN were −0.83 eV and 1.72 eV, suggesting the formation of an S-type heterojunction between CM and CN. The significant role of SCQDs in enhancing the photocatalytic hydrogen evolution was extensively investigated, demonstrating that the synergistic effect between SCQDs, CM, and CN could enhance the hydrogen evolution activity. SCQDs exhibited excellent electron transfer capabilities, serving as bridges for electron transport, functioning both as electron acceptors and donors, effectively impeding the rapid recombination of electron-hole pairs and enhancing their separation efficiency. This study provides crucial insights into the utilization of coal-based CQDs for photocatalytic water splitting, offering an economically viable and sustainable option for the functional application of coal and opening new avenues for the rational design of efficient and cost-effective photocatalysts. • Eploys ultrasonication-assisted hydrogen peroxide to convert coal into high-value coal-based carbon quantum dots (CQDs). • The hydrogen evolution rate of CMCN-11/8%SCQDs was as high as 4916.63 μmol g−1 h−1. • SCQDs act as pivotal bridges for electron transport, dualistically functioning as electron acceptors and donors. [ABSTRACT FROM AUTHOR]

A Z-scheme heterojunction CuWO4/N-CQD/g-C3N4 (CWO/N-CQD/CN) was constructed using Euphorbia neriifolia leaf derived N-CQDs (nitrogen-doped carbon quantum dots) as an electron mediator. Among the nanocomposites prepared with different ratios of CWO and N-CQD/CN, the 0.2-CWO/N-CQD/CN nanocomposite exhibits excellent photocatalytic degradation efficiency for rhodamine B (RhB) up to 97.8% under visible light irradiation as compared to the binary CWO/CN and N-CQD/CN composites. The reduced photoluminescence intensity and higher lifetime reveal the formation of a heterojunction between the nanoparticles, thereby lowering the recombination of electron–hole pairs. Reactive oxygen species scavenging assays have established that hydroxyl radicals (˙OH), holes (h+) and singlet oxygen (1O2) are the primary reactive species in RhB dye degradation. A Z-scheme photocatalytic mechanism was suggested based on the DFT calculations and band structure of CWO/N-CQD/CN. The effect of various parameters like pH, catalyst amount, H2O2 concentration, and dye content was also examined in RhB degradation. Moreover, the Z-scheme photocatalyst possesses good recyclability up to the fourth cycle. Using the LC-MS approach, the degradation of RhB into smaller organic moieties was also observed. Hence, this study provides a unique perspective on developing an effective Z-scheme photocatalyst that has practical utility in environmental remediation. [ABSTRACT FROM AUTHOR]

Understanding high‐order biexciton dynamics is important for the use of semiconductor quantum dots (QDs) in optoelectronic devices. The core–shell structure can be used to modulate biexciton dynamics by varying the shell thickness and core–shell energy band alignment. In this study, the biexciton dynamics in an unconventional case in which each QD is encapsulated by a submonolayer shell are demonstrated. The result of a transient absorption spectroscopic study shows that InP/ZnS core/shell QDs with submonolayer shell coverage exhibit a prolonged Auger lifetime. However, the QD size dependence of the Auger recombination time features two constant distinct stages instead of the typical monotonic volume scaling law in conventional QDs. It is attributed to the tradeoff between the enlarged QD size and quantum‐well confinement for the Auger processes. However, the abrupt change between the two stages is due to the change in the shell coverage. This study provides a reference for the application of core–shell QDs in optoelectronic devices in which full coverage of the shell is not achieved. [ABSTRACT FROM AUTHOR]

The role of quantum dot (QD) decoration in the hole transport buffer layer and the photoactive medium on the photovoltaic parameters of thin film organic solar cells (TFOSCs) was investigated. A cadmium–tellurium-based QD was synthesized successfully and embedded in two of the functional layers of a TFOSC to improve its overall power conversion efficiency. The experimentally determined optimum concentration of the QD was maintained in the interfacial layer to investigate the effect of QD concentration in the active layer. The observed increased short-circuit current density (Jsc) and open circuit voltage (Voc) are attributable to the enhanced energy level tuning, broadened optical absorption, and charge transport process facilitated by the integration of QDs inside the media. Moreover, an improved device efficiency was obtained when the solvent additive was introduced into the bulk heterojunction photoactive layer films to facilitate QD dispersion and increase the interpenetrating network of the active layer blend that reduces the occurrence of trap sites, which, in turn, limits the Auger recombination rates. The QD-doped TFOSCs catalyzed with solvent additives displayed an enhanced overall photovoltaic parameter, which is quite appreciable in comparison with that of the pristine devices. [ABSTRACT FROM AUTHOR]

Making reliable gas sensors that function at low temperatures is important for safely detecting hydrogen gas. This work proposes sensitising reduced graphene oxide (rGO) nanosheet encapsulated TiO 2 nano-spheres (TiO 2 -NS) with highly sensitive Pd receptors (rGPT-NS). It demonstrates for the first time, hydrogen gas sensing of rGPT-NS under 490 nm visible light conditions at low operating temperatures (25–35 °C) using a low voltage bias (0.1 V). The method suppresses of the electron-hole recombination and creating interfacial nano-Schottky junctions (i.e., heterojunctions) to enhance sensing performances. As a result, chemiresistive based highly responsive, selective, stable, environmentally friendly, and energy-efficient rGPT-NS are synthesised via sol-gel and hydrothermal methods. The fabricated sensing material exhibits high responses of 100.23%, 100.28% and 100.36% with rapid response/recovery (19 s/62 s, 12 s/57 s and 11 s/53 s) towards 500 ppm hydrogen at 25 °C, 30 °C and 35 °C, respectively under 0.1 V and 490 nm visible light. In this work, we have developed a semiconductor gas sensor by sensitising reduced graphene oxide (rGO) nanosheet encapsulated TiO 2 nano-spheres (NS) with highly sensitive Pd receptors (rGPT NS) via sol-gel and hydrothermal methods. The developed sensor shows promising hydrogen sensing properties at low temperatures (25–35 °C) under 490 nm blue light (visible light) conditions and low voltage bias (0.1 V). [Display omitted] • Novel rGO nanosheet encapsulated Pd quantum-sized dots deposited TiO 2 nano-spheres (rGPT) for hydrogen sensing are developed. • The sensor operates at low temperatures (25–35 °C) under visible light conditions and low input voltage bias (0.1 V). • The sensor exhibits high response with fast response/recovery, selectivity and excellent repeatability. • The sensor can detect different hydrogen concentrations from 50 ppm to 2250 ppm in less than 30 s. [ABSTRACT FROM AUTHOR]

Colloidal semiconductor nanocrystals (NCs) have attracted a great deal of attention in recent decades. The quantum efficiency of many optoelectronic processes based on these nanomaterials, however, declines with increasing optical or electrical excitation intensity. This issue is caused by Auger recombination of multiple excitons, which converts the NC energy into excess heat, whereby reducing the efficiency and lifespan of NC-based devices, including lasers, photodetectors, X-ray scintillators, and high-brightness LEDs. Recently, semiconductor quantum shells (QSs) have emerged as a viable nanoscale architecture for the suppression of Auger decay. The spherical-shell geometry of these nanostructures leads to a significant reduction of Auger decay rates, while exhibiting a near unity photoluminescence quantum yield. Here, we compare the optoelectronic properties of quantum shells against other low-dimensional semiconductors and discuss their emerging opportunities in solid-state lighting and energy-harvesting applications. [ABSTRACT FROM AUTHOR]

MAPbBr3 quantum dots in SiO2 mesopores (∼ 4. 4 nm) were prepared by the spin-coating method, and their luminescence and nonlinear optical properties were studied by time-resolved photoluminescence (TRPL) and Z-scan techniques. The results showed that the absorption and photoluminescence peaks are at 464 nm and 476 nm, respectively. The TRPL spectroscopy showed two relaxation processes, a short lifetime (1.04 ns) and a long lifetime (4.49 ns), attributed to the trap–capture recombination and the electron–hole radiative recombination, respectively. Two-photon absorption (TPA) coefficient was 529 cm/GW at 800 nm. The nonlinear signal changed from TPA to saturable absorption with increase in light intensity. [ABSTRACT FROM AUTHOR]

Inorganic quantum dots (QDs) are introduced into organometallic dye sensitized solar cells (DSSCs) to further improve the photoelectric conversion efficiency (PCE) of DSSCs. AgBiS2 quantum dots were prepared through depositing alternately via the successive ion layer absorption reaction (SILAR) route on TiO2 porous film, which then was sensitized with N719 dye. The introduction of AgBiS2 QDs can enhance the efficient charge transfer, inhibiting the electron-hole recombination and improving the electron injection efficiency of carrier injecting into TiO2 layer. According to the analysis results of electrochemical impedance spectroscopy (EIS) and current density-voltage (J-V) curve, the introduction of AgBiS2 QDs can effectively improve the photovoltaic performance, and under one-sun irradiation, the optimum cell sample possessed the short-circuit current density of 14.87 mA·cm− 2, open-circuit voltage of 0.78 V, and PCE of 5.19% that is 68% greater than that of bare DSSCs. [ABSTRACT FROM AUTHOR]

TiO2-based materials are important photocatalysts but the rapid recombination of photoexcited electron–hole pairs, and the wide band gap both limit their photocatalytic activities. In this work, p-type phosphorus-doped graphene quantum dots (P-GQDs, 5~20 nm) were combined with n-type TiO2 nanoparticles (20~50 nm) and n-type silver iodide (AgI, 100~200 nm) by a facile sonication and precipitation process to yield a novel ternary photocatalyst TiO2/P-GQDs/AgI with n-p-n heterojunctions. The morphologies, structures, optical properties, and chemical environments of photocatalysts were all studied. The resulting ternary photocatalyst exhibited enhanced visible photocatalytic activity toward the degradation of methyl orange (MO), estimated to 70.4-fold that of pure TiO2. By contrast, the photocatalytic activities of TiO2/GQDs with an n-n heterojunction, TiO2/P-GQDs with a p-n heterojunction, and TiO2/GQDs/AgI (30%) with an n-n-n heterojunction showed 4.4-fold, 5.3-fold, and 14.2-fold higher than those of TiO2. The electrochemical and optical measurements revealed that the enhanced photocatalytic activity was linked to promoted charge carrier separation by n-p-n heterojunctions coupled with the increased absorption in the visible region. Overall, the new band structure connected in series p-n heterojunctions looks promising as a highly efficient photodegradation system for future use in decontamination of polluted water. [ABSTRACT FROM AUTHOR]

Circulating tumor cells (CTCs) are the important biomarker for cancer diagnosis and individualized treatment. However, due to the extreme rarity of CTCs (only 1–10 CTCs are found in every milliliter of peripheral blood) high sensitivity and selectivity are urgently needed for CTC detection. Here, a sandwich PEC cytosensor for the ultrasensitive detection of CTCs was developed using the photoactive material Au NP/-Fe2O3 and core-shell CdSe@CdS QD sensitizer. In the proposed protocol, the CdSe@CdS QD/Au NP/α-Fe2O3-sensitized structure with cascade band-edge levels could evidently promote the photoelectric conversion efficiency due to suitable light absorption and efficient electron-hole pair recombination inhibition. Additionally, a dendritic aptamer-DNA concatemer was constructed for highly efficient capture of MCF-7 cells carrying CdSe@CdS QDs, a sensitive material. The linear range of this proposed signal-on PEC sensing method was 300 cell mL−1 to 6 × 105 cell mL−1 with a detection limit of 3 cell mL−1, and it demonstrated an ultrasensitive response to CTCs. Furthermore, this PEC sensor enabled accurate detection of CTCs in serum samples. Hence, a promising strategy for CTC detection in clinical diagnosis was developed based on CdSe@CdS QD–sensitized Au NP/α-Fe2O3-based PEC cytosensor with dendritic aptamer-DNA concatemer. [ABSTRACT FROM AUTHOR]

A composite of TiO2 quantum dots (TiO2QDs) and TiO2 nanoparticles (TiO2NPs) was successfully deposited on glass beads (GBs), with a very low content of TiO2 (<0.3 wt%), by a rapid, simple, inexpensive, and scalable synthesis method. The TiO2QDs-TiO2NPs/GBs catalyst possesses an extremely high photocatalytic performance under simulated solar irradiation, with the complete degradation of the aqueous solutions of methylene blue in 60 minutes of photodegradation. There were no changes in the catalytic activity after six times of recycling. The superior performance of the catalyst should be attributed to the role of the synergistic effect between TiO2NPs and TiO2QDs to prevent the accumulation of TiO2 nanoparticles during the oxidation reaction, to improve the absorption in the visible region, to enhance the immigration of photogenerated electrons and holes in interfaces of two materials in the TiO2QDs-TiO2NPs composite, which leads to a reduced charge recombination rate, and to generate midgap states and suppress the recombination of electron-hole pairs. [ABSTRACT FROM AUTHOR]

Colloid quantum dots (CQDs) are recognized as an ideal material for applications in next-generation optoelectronic devices, owing to their unique structures, outstanding optical properties, and low-cost preparation processes. However, monodisperse CQDs cannot meet the requirements of stability and collective properties for device applications. Therefore, it is urgent to build stable 3D multiparticle systems with collective physical and optical properties, which is still a great challenge for nanoscience. Herein, we developed a modified microemulsion template method to synthesize quantum dot supraparticles (QD-SPs) with regular shapes and a high packing density, which is an excellent research platform for ultrafast optical properties of composite systems. The redshift of the steady-state fluorescence spectra of QD-SPs compared to CQD solutions indicates that fluorescence resonance energy transfer (FRET) occurred between the CQDs. Moreover, we investigated the dynamic processes of energy transfer in QD-SPs by time-resolved ultrafast fluorescence spectroscopy. The dynamic redshift and lifetime changes of the spectra further verified the existence of rapid energy transfer between CQDs with different exciton energies. In addition, compared with CQD solutions, the steady-state fluorescence lifetime of SPs increased and the fluorescence intensity decreased slowly with increasing temperature, which indicates that the SP structure suppressed the Auger recombination of CQDs. Our results provide a practical approach to enhance the coupling and luminescence stability of CQDs, which may enable new physical phenomena and improve the performance of optoelectronic devices. [ABSTRACT FROM AUTHOR]

TiO₂ semiconductors exhibit a low catalytic activity level under visible light because of their large band gap and fast recombination of electron–hole pairs. This paper reports the simple fabrication of a 0D/2D heterojunction photocatalyst by anchoring TiO₂ quantum dots (QDs) on graphite-like C₃N₄ (g-C₃N₄) nanosheets (NSs); the photocatalyst is denoted as TiO₂ QDs@g-C₃N₄. The nanocomposite was characterized via analytical instruments, such as powder X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, t orange (MO) under solar light were compared. The TiO₂ QDs@g-C₃N₄ photocatalyst exhibited 95.57% MO degradation efficiency and ~3.3-fold and 5.7-fold higher activity level than those of TiO₂ QDs and g-C₃N₄ NSs, respectively. Zero-dimensional/two-dimensional heterojunction formation with a staggered electronic structure leads to the efficient separation of photogenerated charge carriers via a Z-scheme pathway, which significantly accelerates photocatalysis under solar light. This study provides a facile synthetic method for the rational design of 0D/2D heterojunction nanocomposites with enhanced solar-driven catalytic activity. [ABSTRACT FROM AUTHOR]

Auger nonradiative recombination dominates decay of multicarrier states in high quality colloidal quantum dots (QDs) and thus is critical for many of their optical and optoelectronic applications. Controlling interface-potential smoothness and wavefunction delocalization are proposed as two main strategies for Auger engineering in core/shell QDs. Here, a series of CdSe-based core/shell QDs with nearly ideal optical quality of their single-exciton states are developed and applied for studying biexciton quantum yields and Auger nonradiative recombination rates. Comparative experiments find that the interface-potential smoothness has little influence on biexciton quantum yield and Auger rates of these core/shell QDs with the same CdS outer shells. In contrast, with a fixed total size of the series of QDs, the decreasing hole wavefunction delocalization can increase the Auger rates of positive trions by ∼400%. A mild decrease in electron wavefunction delocalization among the series of QDs results in a small increase in the Auger rates of negative trions (∼50%). Smoothing the core/shell interface can indeed affect the Auger rates, but this is by the way of altering wavefunction delocalization. These findings highlight the importance of control of wavefunction delocalization among the strategies of Auger engineering and provide guidelines for rational design QDs for applications. [ABSTRACT FROM AUTHOR]

In photocatalytic splitting water for hydrogen evolution, narrow light response range and fast electron-hole recombination of g-C 3 N 4 (CN) limit its photocatalytic activity. In this article, the N, S co-doped carbon dots (NSCDs) with up-converted property were loaded on CN nanosheets by thermal polymerization to obtain NSCDs/CN composite catalyst. Characterization, electrochemical researches and hydrogen evolution tests suggest that the photocatalytic activity of CN is greatly promoted by the introduction of NSCDs. Under visible and near-infrared irradiation, the hydrogen evolution rate is 5033.1 μmol g−1 h−1 of NSCDs-5/CN, which is 8.3 times higher than that of CN. The performance improvement is mainly attributed to the increased specific surface area, elevated hydrophilic surface, increased light absorption and suppressed carrier recombination of CN after the introduction of NSCDs. This work unveils the mechanism of the hydrogen evolution activity improvement in NSCDs-5/CN, and also offers a new prospect in the design of high-performance CN-based photocatalysts. [Display omitted] • A novel NSCDs-5/CN photocatalyst was constructed for efficient photocatalytic HER. • Coupling of NSCDs with CN nanosheets further improved carrier separation. • H 2 production efficiency is improved by about 8.3 times under Vis-NIR light. • Improved performance may be attributed to the synergistic effect of NSCDs and CN. [ABSTRACT FROM AUTHOR]

Colloidal quantum dots (CQDs) have emerged as promising candidates for solution‐processed optical gain materials. Despite the substantial progress made with Cd or Pb‐contained CQDs, lasing from the environmentally friendly CQDs remains underexplored. Here, the highly emissive ZnSeTe/ZnSe/ZnS and ZnSe/ZnS CQDs is developed. The optical gain and lasing action from such Te‐alloyed and intrinsic ZnSe/ZnS CQDs across the blue spectral region is achieved. Te‐alloyed ZnSe core manifests a quasitype‐II band alignment with the ZnSe intermediate layer, favorable for suppressing the Auger recombination and also lasing wavelength tuning. The transient absorption spectroscopy reveals evidence of a blue optical gain with a threshold of one exciton per dot and a lifetime of 171 ps in the alloyed CQDs. Under a quasicontinuous‐wave pumping, lasing is observed from the blue CQDs in Fabry–Pérot cavities with a lower threshold fluence of 12.5 µJ cm−2 as compared with the traditional counterparts with heavy metals. The demonstration of heavy‐metal‐free CQD lasing opens up new opportunities in the application of CQDs as efficient and environmental‐friendly gain media. [ABSTRACT FROM AUTHOR]

This paper revealed the changes in physical properties, morphology and photocatalytic activity of samples in each stage of the synthesis of during the NCD/CuBDC. Nitrogen-containing Carbon quantum dots, abbreviated as NCD, was used to modify CuBDC, a copper-based metal–organic framework. CuBDC and NCD/CuBDC samples were successfully prepared by an ultrasonic-assisted, solvothermal method from Copper (II) oxide. SEM images demonstrated that the morphology of the materials changed from agglomerating nanospheres to stacked layers. NCD/CuBDC had a greater surface area (23.4 m2 g−1) and pore size (58.39 nm) than CuBDC (18.1 m2 g−1; 29.29 nm) in terms of porous characteristics. NCD/CuBDC was more visible-light-sensitive, with an estimated band gap energy of roughly 2.67 eV. Furthermore, introducing NCDs into MOF structure boosted the material's photoactivity and impeded electron–hole recombination, as evidenced by the increased MB degradation efficiency. The optimal sample was 280-NCD/CuBDC, with the ability to completely process MB within 90 min, while CuO and pristine CuBDC can only degrade around 20% of MB concentration. Additionally, the 280-NCD/CuBDC could be reused five times continuously. The main contributors to the degradation of MB were hydroxyl radicals and photogenerated holes. The formation of 280-NCD/CuBDC catalyst had been suggested based on the results of XRD, FTIR, UV–vis DRS, and SEM images. In the future, the NCD/CuBDC material will be further studied and applied to treat some other types of pollutant compounds present in wastewater such as heavy metals, antibiotics or pesticides. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting for hydrogen production is one of the key pathways to achieving a zero-carbon economy. Cd 0.8 Mn 0.2 S has significant potential for photocatalytic hydrogen evolution, but it faces serious challenges due to the recombination of photogenerated charge carriers. To address this issue, we successfully coupled Co 3 O 4 QDs onto Cd 0.8 Mn 0.2 S nanorods via ultrasonic self-assembly, constructing a S-scheme heterojunction to reduce charge carrier recombination rates. In this configuration, Co 3 O 4 QDs serves as the electron donor, while Cd 0.8 Mn 0.2 S act as the electron acceptor. The Cd 0.8 Mn 0.2 S/Co 3 O 4 QDs structure creates a closely spaced interface, providing the shortest possible path for electron transfer. Under 10 W white light irradiation, the Cd 0.8 Mn 0.2 S/Co 3 O 4 QDs composite photocatalyst exhibited remarkable hydrogen evolution activity, achieving a hydrogen production rate of 33.39 mmol⋅g⁻¹⋅h⁻¹. This S-scheme heterojunction strategy lays the foundation for the structural design of highly active visible-light photocatalysts. • The S-scheme heterojunction effectively suppresses the recombination of photogenerated electron-hole pairs. • The hydrogen evolution performance of Cd₀.₈Mn₀.₂S/Co₃O₄ quantum dots is 6.6 times higher than that of Cd₀.₈Mn₀.₂S. • Density functional theory (DFT) calculations provide the foundation for understanding the reaction mechanisms of highly active photocatalysts. [ABSTRACT FROM AUTHOR]

In the fabrication of Quantum dot sensitized solar cells (QDSSCs), it is important to fabricate a photoanode with a high ability to trap photons as well as transfer photogenerated electrons. TiO 2 inverse opal (TIO) photonic crystals with their organized porous structures, besides their chemical nature, have unique optical features such as the slow-photon effect, photon localization, and photonic bandgap (PBG). Herein, to improve the efficiency of QDSSCs, gold, silver, and silver/gold core-shell (Ag@Au) plasmonic nanoparticles (nps) are loaded on TIO. The plasmonic nanoparticle-decorated inverse opal improves the light scattering process and provides direct charge transfer tunnels, which can effectively prevent the recombination of electron-hole pairs. In this work, fabricated QDSSCs with TIO (double-layer)/ZnS/CdS/CdSe/ZnSe/ZnS photoanode, and a 6 μm total thickness of the TIO multilayer, has an open circuit voltage (V oc) of 0.745 V and short-circuit current density (J SC) of 16.22 mA/cm2. The obtained results are higher than the common anatase TiO 2 (TiO 2 -A)/ rutile TiO 2 (TiO 2 -R)/QD photoanode. Also, the TIO (double-layer)/Ag@Au/QDs photoanode exhibits J SC= 20.3283 mA/cm2, V oc = 0.75 V, and a power conversion efficiency (PCE) of ƞ=10.79 %. [Display omitted] • A single-layer TiO 2 inverse opal was prepared and used in the photoanode of QDSSCs. • Substituting the single-layer TiO 2 inverse opal with a double-layer one enhanced the QDSSCs efficiency from 4.36 to 7.96 %. • The double-layer TiO 2 inverse opal was decorated with plasmonic nanoparticles (Au, Ag, and Ag@Au nps). • The interfacial ZnS layer on the double-layer TiO 2 inverse opal improves the QDs deposition and harvests more photons. • For the optimized photoanode, ƞ, V OC , and J SC of 10.79 %, 0.75 V, and 20.3283 mA/cm2 were achieved, respectively. [ABSTRACT FROM AUTHOR]

• Synthesized Cu/Ag-Cu doped ZnS QDs via co-precipitation. • 99% Crystal Violet degradation in 100 min under sunlight. • XRD, TEM, XPS confirm structure and properties of QDs. • QDs show stable, reusable photocatalytic performance. • Hemolytic assays suggest QDs are safe for use. In this study, silver (Ag) and copper (Cu) dual-doped zinc sulfide (ZnS) photocatalysts were synthesized using the coprecipitation method and tested for their efficiency in degrading dyes such as Acid Orange, Auramine O, Methylene Blue, Methyl Orange, Rhodamine B, and Crystal Violet under sunlight. X-ray diffraction (XRD) confirmed a cubic structure with high phase purity, and Ag doping reduced the crystalline size. Transmission electron microscopy (TEM) revealed crumpled quantum dots (QDs), while ultraviolet–visible (UV–Vis) spectroscopy showed bandgaps of 3.73, 3.71, and 3.63 eV for Cu, (Cu, 1 % Ag), and (Cu, 2 % Ag)-doped ZnS QDs, respectively. The inclusion of Ag reduced the bandgap, enhancing photocatalytic performance. The degradation efficiencies were 93.09 %, 99.49 %, and 99.95 % for Cu, (Cu, 1 % Ag), and (Cu, 2 % Ag)-doped ZnS QDs, respectively, after 180 min. Dual doping significantly improved performance over Cu-doped QDs, with a rate constant of 49.99 × 10−3 min−1 and an R2 value of 0.9374. Ag ions further enhanced activity by reducing electron-hole recombination. Additionally, polyvinyl alcohol (PVA)-embedded ZCA3 QDs demonstrated high reusability over five cycles. The study also investigated the effects of dosage, dye variation, and hemolytic activity. [ABSTRACT FROM AUTHOR]

This presentation introduces an integrated photocatalyst/adsorbent system, achieved through immobilization and encapsulation of the TiO 2 doped with CQDs (carbon quantum dots) nanocomposite within the calcium alginate (CaAlg) matrix. The nanoparticles and nanocomposites were analyzed using various techniques, including FE-SEM, EDX, TEM, XRD, PL, FT-IR, BET, and UV–vis DRS, to determine their structure and properties. The TiO 2 /CQDs/Alg nanocomposite hydrogel considerably influenced the adsorption and photocatalytic degradation of methylene blue (MB) as a dye pollutant. The adsorption studies were conducted to assess parameters such as adsorption capacity, kinetic behavior, and adsorption isotherms. The outcomes revealed a high adsorption capacity (44.13 mg/g at 90 min) and indicated that the pseudo-second-order kinetic model was highly suitable for describing the adsorption behavior of MB. Moreover, the Freundlich isotherm exhibited better fitting capabilities compared to the Langmuir isotherm. CQDs not only facilitated the transfer of photoelectrons from the TiO 2 surface, preventing recombination of electron-hole pairs but also enhanced visible light absorption by the upconversion photoluminescence. The TiO 2 /CQDs/Alg displayed excellent photodegradation performance (97 %) of MB compared with TiO 2 and TiO 2 /CQDs under visible light due to the abundance of active sites for MB adsorption and photocatalytic reactions. The TiO 2 /CQDs/Alg hydrogel exhibited excellent reusability in degrading MB for up to five consecutive cycles and showed significant swelling behavior across a broad pH range, reflecting the hydrogel's exceptional stability. The use of charge carrier scavengers indicated that O 2 ˙−radicals were the primary surface species involved in the photodegradation of MB. • An integrated photocatalyst/adsorbent system developed by immobilizing TiO 2 /CQDs nanocomposite within Alginate biopolymer. • TiO 2 /CQDs/Alg nanocomposite hydrogel demonstrated significant MB adsorption capacity (44.13 mg/g at 90 min). • Visible light-induced photocatalytic degradation of MB achieved 97 % efficiency. • The observed efficacy could be attributed to creating a porous structure and increased accessibility of active sites for pollutant adsorption. • O 2 ˙− radicals as primary surface species drove the photocatalytic degradation process. [ABSTRACT FROM AUTHOR]

InGaAs/GaAs surface quantum dot (SQD) heterostructures have long been viewed as having great potential for realizing environmental gas detection devices. The research has recently been steered into discovering ways to inject carriers into the available SQD energy states to facilitate readable devices. In the present research, carrier injection from buried QDs (BQDs) to SQDs was controlled by changing the interlayer coupling. Photoluminescence (PL) measurements show that, by increasing the stacking period of BQDs, the carrier collection efficiency and subsequently the luminescence intensity for SQDs can be effectively improved. A rate equation simulation of the carrier recombination process is used to quantitatively describe the luminescent quantum efficiency (I QE) for the SQDs, indicating an increase with additional BQD layers due to an increase in carrier injection. The PL spectra along with the rate equation simulations further indicated that for these SQD hybrid structures nonradiative recombination dominates, with Auger recombination becoming significant at high excitation intensities. These results may help to understand the carrier dynamics in coupled SQDs hybrid structures. In addition, they provide a path to manipulating the properties of InGaAs SQDs for the development of gas sensors. • Architecture carrier injection heterostructures for InGaAs surface quantum dots (SQDs). • Modified rate equation model is used to quantitatively describe carrier recombination of SQDs. • Nonradiative recombination dominates for these SQD hybrid structures, with Auger recombination becoming significant at high excitation intensities. • The PL measurement provides an in-depth assessment of the InGaAs SQDs heterostructures. [ABSTRACT FROM AUTHOR]

• A ternary bond Z-scheme BiVO 4 /MOF-808/CN/CQD (BMC-CQD) photocatalyst was successfully synthesized. • CQD increased the electron transfer rate in the BMC-CQD photocatalyst. • Deep DBT desulfurization of 99.5 % was achieved using the BMC-CQD photocatalyst. • BMC-CQD increased the reaction rate 10.69, 2.13, 8.7 times compared to BiVO 4 , MOF-808, CN. Photocatalytic oxidative desulfurization technology enabling the facile oxidation of these compounds to sulfones, deep desulfurization, operation at ambient temperature and pressure, and minimal energy consumption. This study introduces a novel photocatalyst, BiVO 4 /MOF-808/CN integrated with carbon quantum dots (BMC-CQD), designed for the oxidative desulfurization of dibenzothiophene (DBT) under visible light irradiation. Novel approach was undertaken by integrating the photocatalyst BiVO 4 , g-C 3 N 4 with MOF-808 and carbon quantum dots to enhance the interaction between semiconductors. This innovative photocatalyst addresses several limitations associated with MOF-808, including enhanced visible light absorption (2.21–2.60 eV), reduced electron-hole recombination, rapid charge transfer, high surface area (1370 m2/g), large pore volume (0.908 cm3/g). Under optimized conditions of a catalyst dosage of 1.5 g/L, a reaction temperature of 50 °C, an O/S molar ratio of 6, and an initial DBT concentration of 500 mg/L, the 10 %BMC-CQD photocatalyst achieved an impressive 99.5 % DBT removal efficiency in just 25 min. Incorporating CQD into the BMC framework significantly amplifies the removal rate of the DBT by 10.69, 2.13 and 8.7 times compared to the BiVO 4 , MOF-808 and CN, respectively. The radical trapping experiments have shown that the •OH and •O 2 − radicals play a key role in the DBT removal process. [Display omitted] [ABSTRACT FROM AUTHOR]

CQDs (carbon quantum dots) have attracted a lot of attention in the field of photocatalysis due to its absorption of visible light, up-conversion luminescence, rich free groups on the surface and low cost. CQDs doped semiconductor can improve the photocatalytic reaction rate by the following three points: (1) adjust the band structure of photocatalyst; (2) facilitate the absorption of more visible light; (3) facilitate electron transfer and inhibits electron-hole recombination. In this review, the mechanism (photosensitizer, electron acceptor, up-conversion luminescence, etc.) and applications (photocatalytic degradation of organic pollutants, reduction of heavy metals, etc.) of CQDs in the field of photocatalysis are briefly introduced. Finally, the factors affecting the photocatalytic activity were summarized in order to adjust the reaction conditions and show high catalytic activity. It is hoped that this review can provide insights and inspiration for the development of CQDs in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of organic pollutants is considered an ideal method to solve the global environmental pollution problem. In this method, photocatalytic materials are regarded as the key factor. As an n‐type photocatalytic material, graphitic carbon nitride (g‐C3N4) has attracted much attention due to its suitable bandgap, nontoxicity, and high photostability. However, g‐C3N4 still has defects such as insufficient visible light absorption, low specific surface area, and easy recombination of photogenerated electron–hole pairs, which lead to the poor photocatalytic performance of g‐C3N4. Herein, to solve the above problems, thiourea, lemon juice, and tin chloride pentahydrate are used as precursors, while carbon quantum dots (CQDs) are used as electron mediators, and the third phase SnS2 is introduced by a hydrothermal and ultrasonic composite method. SnS2/CQDs/g‐C3N4 composites with Z‐type heterojunction are successfully prepared. The results show that the SnS2/CQDs/g‐C3N4 has a 2D0D2D structure, which effectively inhibits the recombination of photogenerated electron–hole pairs, making the material have better photocatalytic degradation activity for Rhodamine B (RhB). When the mass ratio of SnS2 is 15%, the photocatalytic degradation efficiency of RhB by the composite reaches the best, which is 87.8%. After four cycles, the photocatalytic degradation efficiency of the 15% SnS2/CQDs/g‐C3N4 composite still remains at 82.9%. [ABSTRACT FROM AUTHOR]

The excellent performance of InP/ZnSe/ZnS core/shell/shell quantum dots (CSS-QDs) in light-emitting diodes benefits from the introduction of a ZnSe midshell. Understanding the changes of ultrafast carrier dynamics caused by the ZnSe midshell is important for their optoelectronic applications. Herein, we have compared the ultrafast carrier dynamics in CSS-QDs and InP/ZnS core/shell QDs (CS-QDs) using femtosecond transient absorption spectroscopy. The results show that the ZnSe midshell intensifies the electron delocalization and prolongs the in-band relaxation time of electrons from 238 fs to 350 fs, and that of holes from hundreds of femtoseconds to 1.6 ps. We also found that the trapping time caused by deep defects increased from 25.6 ps to 76 ps, and there were significantly reduced defect emissions in CSS-QDs. Moreover, the ZnSe midshell leads to a significantly increased density of higher-energy hole states above the valence band-edge, which may reduce the probability of Auger recombination caused by the positive trion. This work enhances our understanding of the excellent performance of the CSS-QDs applied to light-emitting diodes, and is likely to be helpful for the further optimization and design of optoelectronic devices based on the CSS-QDs. [ABSTRACT FROM AUTHOR]

Solution‐processed light‐emitting diodes (LEDs) show great potential for low‐cost fabrication of large‐area display panels, but the efficient perovskite LEDs (PeLEDs) cannot be achieved by all solution process, because the perovskite emitter is easily destroyed by subsequent solution. In particular, the solution‐processed PeLEDs with blue emission wavelength in 460–470 nm (pure‐blue, meeting Rec. 2020 standards) still is inferior. Here, highly efficient and stable pure‐blue PeLEDs are achieved by all solution process based on colloidal perovskite quantum dots and difunctional ZnO (D‐ZnO) nanocrystals. The D‐ZnO nanocrystals are obtained by a ligand strategy of phenethylammonium bromide, which not only repairs the perovskite surface destroyed by the solvent of the D‐ZnO solution, but also enables the balanced charge injection to suppress Auger recombination. The PeLED presented pure‐blue emitting at 470 nm wavelength, a maximum luminance of 11 100 cd m‐2, and external quantum efficiency of 8.7% (record efficiency for pure‐blue emission). The device also showed a continuous operation half‐lifetime of 35 h at luminance of 100 cd m‐2. [ABSTRACT FROM AUTHOR]

Herein, an innovative graphitic carbon nitride (g-C 3 N 4) based nanocomposite with nickel oxide (NiO) is modified with carbon quantum dots (CQDs) to fabricate CQD/NiO/g-C 3 N 4 ternary composites. The effect of various concentrations of CQDs is investigated for photo electrochemical (PEC) water splitting and photocatalytic degradation of methyl orange (MO). XRD pattern of CQDs/NiO/g-C 3 N 4 composite showed the distinctive peaks of g-C 3 N 4 and NiO. The reduction of band-gap values from 2.62 to 1.8 eV in UV–Visible spectra of nanocomposites confirmed an improvement toward red shift. The existence of required functional groups and successful fabrication of nanosheets of g-C 3 N 4 and its nanocomposites are confirmed by FTIR. PL confirms the decrease in electron-hole recombination in binary and ternary composites. CQDs/NiO/g-C 3 N 4 (4.0 mL) showed enhanced PEC activity and photocatalytic performance in visible light exposure. CQDs/NiO/g-C 3 N 4 (4.0 mL) showed an obvious enhancement in current density of ∼ -19 mAcm−2 at potential 0.39 V during hydrogen evolution reaction (HER) and high current density of ∼ 15 mAcm−2 at 1.42 V in oxygen evolution reaction (OER) than all others. The highest degradation rate of MO by CQDs/NiO/g-C 3 N 4 (4.0 mL) was noted due to availability of plenty of active sites and conductive channels provided by CQDs. Incorporated CQDs in samples affect the overall water splitting response and photocatalytic activity by acting as electron conduction bridge for the quick electron transfer from the composite materials to reaction sites on its surface. This combination is active for efficient PEC water splitting and photo degradation purposes. [Display omitted] • CQDs/NiO/g-C 3 N 4 is developed as a new combination for PEC and photocatalysis. • CQDs affect by acting as electron conduction bridge for the quick electron transfer. • Incorporated CQDs effect the overall water splitting response even at lower potentials. • Charge transport in active layers of CQDs/NiO/g-C 3 N 4 is due to interactive excitons. • Improved charge separation in CQDs/NiO/g-C 3 N 4 effects overall performance. [ABSTRACT FROM AUTHOR]