Single-crystal perovskites with excellent photophysical properties are considered to be ideal materials for optoelectronic devices, such as lasers, light-emitting diodes and photodetectors. However, ...the growth of large-scale perovskite single-crystal films (SCFs) with high optical gain by vapor-phase epitaxy remains challenging. Herein, we demonstrated a facile method to fabricate large-scale thin CsPbBr3 SCFs (∼300 nm) on the c-plane sapphire substrate. High temperature is found to be the key parameter to control low reactant concentration and sufficient surface diffusion length for the growth of continuous CsPbBr3 SCFs. Through the comprehensive study of the carrier dynamics, we clarify that the trapped-related exciton recombination has the main effect under low carrier density, while the recombination of excitons and free carriers coexist until free carriers plays the dominate role with increasing carrier density. Furthermore, an extremely low-threshold (∼8 μJ cm–2) amplified spontaneous emission was achieved at room temperature due to the high optical gain up to 1255 cm–1 at a pump power of 20 times threshold (∼20 P th). A microdisk array was prepared using a focused ion beam etching method, and a single-mode laser was achieved on a 3 μm diameter disk with the threshold of 1.6 μJ cm–2. Our experimental results not only present a versatile method to fabricate large-scale SCFs of CsPbBr3 but also supply an arena to boost the optoelectronic applications of CsPbBr3 with high performance.
In this study, three kinds of SnO2 particles were synthesized by hydrothermal treatment with the assistance of three different surfactants of cetyl trimethyl ammonium bromide (CTAB), sodium dodecyl ...benzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS). The synthesized SnO2-CTAB, SnO2-SDBS and SnO2-SDS microparticles were successfully doped into β-PbO2 film of PbO2 electrode through composite electrodeposition technology to obtain PbO2/SnO2-CTAB, PbO2/SnO2-SDBS and PbO2/SnO2-SDS electrodes. Physical characterizations, electrochemical measurements and electrocatalytic oxidation of m-nitrophenol (m-NP) were conducted to explore the electrocatalytic activity of prepared electrodes. The results showed that doping SnO2 was favorable to improve electro-catalytic activity of PbO2 electrode, which was attributed to that the SnO2 particles in β-PbO2 films improved the active sites on the surface, oxygen evolution potential and •OH radicals generation rate of the electrodes. The experimental results also revealed that the PbO2/SnO2-CTAB was most efficient in three PbO2/SnO2 electrodes due to the higher zeta potential, smaller particle size and higher specific surface area of SnO2-CTAB than those of SnO2-SDBS and SnO2-SDS. Besides, the accelerated lifetime test shows that the PbO2/SnO2-CTAB electrode possessed longer service lifetime than PbO2/SnO2-SDBS, PbO2/SnO2-SDS and pristine PbO2 electrodes. Overall, the PbO2/SnO2-CTAB electrode is promising for environmental remediation.
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•Three types of surfactant were used to assist the synthesis of SnO2 particles.•PbO2/SnO2 composite anode was fabricated using composite electrodeposition.•PbO2/SnO2-CTAB showed optimum activity due to its higher OEP and more active sites.
In this work, a three-dimension grapnene-PbO2 (3DG-PbO2) composite anode was prepared using coelectrodeposition technology for electrocatalytic oxidation of perfluorooctane sulfonate (PFOS). The ...effect of 3DG on the surface morphology, structure and electrocatalytic activity of PbO2 electrode was investigated. The results indicated that the 3DG-PbO2-0.08 anode (3DG concentration in electrodeposition solution was 0.08 g L−1) possessed the best electrocatalytic activity due to its stronger ·OH radicals generation capacity, more active sites and smaller charge-transfer resistance. The degradation rate constant of PFOS on 3DG-PbO2-0.08 anode was 2.33 times than that of pure PbO2 anode. Additionally, the by-products formed in electrocatalytic degradation of PFOS were identified and a PFOS degradation pathway was proposed accordingly, which was dominated by the dissociation of –CF2- groups via the attack of ·OH radicals. Finally, the toxicity evolution of degradation solution was examined to evaluate the ecological risk of electrocatalytic oxidation of PFOS by acute toxicity assays to zebrafish embryos.
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•The 3DG-PbO2 composite anode was prepared by coelectrodeposition technology.•The 3DG-PbO2 anode was used for electrochemical degradation of PFOS.•The degradation pathway of PFOS on 3DG-PbO2 anode was proposed.•The toxicity of PFOS degradation process was evaluated using toxic bioassays.
Plasmonic nanolaser holds great potential in breaking down the diffraction limit of conventional optics to the deep sub‐wavelength regime and in ultrafast lasing dynamics. However, plasmonic laser ...devices are constrained in practical applications due to their high cost and high thresholds. All‐inorganic cesium lead halide perovskites are promising solutions for their excellent optical gain properties and high emission efficiency. In this work, high‐quality single‐crystalline CsPbBr3 perovskite nanowires (NWs) are synthesized by chemical vapor deposition method. The plasmonic lasing is achieved from the CsPbBr3 nanowire based plasmonic devices with lasing threshold down to ≈6.5 µJ cm−2 at room temperature. The highly polarized emission parallel to nanowire axis and polarization‐sensitive pump response confirm the plasmonic characteristic in these devices. Furthermore, time‐resolved photoluminescence study suggests that the radiative recombination lifetime of CsPbBr3 NW is shortened by a factor of ≈6.14 due to Purcell effect. The lasing threshold of plasmonic device increases along with the nanowire length, indicating greater potential in small size and integration in plasmonic device than its photonic counterparts. The results not only provide a solution to fabricate low‐cost nanowire based plasmonic lasers, but also advocate the prospect of all‐inorganic perovskite nanowires as promising candidates in plasmonic‐based devices.
Plasmonic nanolaser holds great potential in breaking down the diffraction limit of conventional optics to deep sub‐wavelength regime. Herein, all‐inorganic CsPbBr3 nanowire based plasmonic lasers are demonstrated at room tempearutre with threshold ≈6.5 µJ cm−2. The lasing threshold of plasmonic device increases along with the nanowire length, indicating greater potential in plasmonic integration device than its photonic couterparts.
This study aims at investigating the electrocatalytic oxidation of sodium pentachlorophenate (PCP-Na) using a novel nano-PbO
2
powder anode. The nano-PbO
2
powder (marked as HL-PbO
2
) was prepared ...by a simple hydrolysis process, and hydrothermal treatment was followed to improve the activity of HL-PbO
2
. The HL-PbO
2
treated for 24 h by hydrothermal process (HL/HT-PbO
2
–24) was confirmed to possess higher crystallinity, higher oxygen evolution potential, and more active sites, resulting in stronger OH radical generation capacity and higher electrochemical activity. Compared with conventional electrodeposited PbO
2
(ED-PbO
2
) anode, the HL/HT-PbO
2
-24 anode showed higher PCP-Na degradation rate. Under the same operating conditions, the mineralization current efficiency at HL/HT-PbO
2
-24 was 2.7 times than that at ED-PbO
2
. Five intermediates were detected in PCP-Na degradation solution and possible degradation mechanism of PCP-Na was discussed. In addition, the acute toxicity of PCP-Na degradation solution to zebrafish embryos and the oxidative stress induced in zebrafish embryos/larvae were studied to evaluate the ecological security of electrocatalytic oxidation of PCP-Na.
Lead halide perovskites exhibit good performance in room-temperature exciton–polariton lasers and efficient flow of polariton condensates. Shaping and directing polariton condensates by confining the ...potential is essential for polariton-based optoelectronic devices, which have seldom been explored based on perovskite materials. Here, we investigate the trapping of polaritons in micron-sized CsPbBr3 flakes embedded in a microcavity by varying the negative detuning energy (from −36 to −172 meV) at room temperature. The confinement by the crystal edge results in quantized polariton states both below and above the condensed threshold. As the cavity is more negatively detuned (Δ ≤ −118 meV), the condensed polaritons undergo a transition from the ground state to metastable states with a finite group velocity (∼50 μm/ps at Δ = −118 meV). The metastable polariton condensates can be optically and stably driven between different polariton states by simply changing the pump fluence. The manipulations of the polariton states reveal the effective control of polariton relaxation in quantized polariton states by the underlying exciton–polariton and polariton–polariton scattering. Our findings pave the way for novel polaritonic light sources and integrated polariton devices through the trap engineering of perovskite microcavities.
Wheeled machines, such as agricultural tractors, snowplows, and wheeled mobile robots, usually work on icy or snow-covered roads. Therefore, it is very important to study the driving and slip ...resistance of the tires of these machines. In this paper, we investigate the driving behavior of tires on snow-covered terrain by means of numerical simulations. A high-fidelity snow-covered road model is established, and smoothed particle hydrodynamics (SPH) and the finite element method (FEM) are employed to account for the behaviors of the snow layers and the pavement, respectively. We use the node-to-surface algorithm for the contact interactions between the snow and the pavement. The SPH parameters for the snow are calibrated by means of a triaxial compression experiment. A simplified tire model is established as well, using the FEM, and the effectiveness of the model is demonstrated via comparisons with the experimental data in terms of stiffness. Finally, the tire driving performance on the snow-covered road is simulated, and the influence of the tire surface configuration, external load, inflation pressure, and snowpack compression on the tire traction behaviors is systematically investigated.
Abstract
Biexcitons are a manifestation of many-body excitonic interactions, which are crucial for quantum information and computation in the construction of coherent combinations of quantum states. ...However, due to their small binding energy and low transition efficiency, most biexcitons in conventional semiconductors exist either at cryogenic temperatures or under femto-second pulse laser excitation. Herein, we demonstrated strong biexciton emissions from CsPbBr
3
nanoplatelets with continuous-wave excitation at room temperature by coupling them with a plasmonic nanogap. The exciton occupancy required to generate biexciton was reduced ~10
6
times in the Ag nanowire–Ag film nanogaps. The extremely large enhancement of biexciton emissions was driven by nonlinear Fano resonance between biexcitons and surface plasmon cavity modes. These results provide new pathways to develop high efficiency non-blinking single photon sources of biexciton (with spectral filter for biexciton), entangled light sources, and lasers based on biexciton states.
In present work, SnO2 nanoparticles were synthesized using simple hydrothermal process, and then a novel PbO2/SnO2 electrode was successfully fabricated using obtained SnO2 nanoparticles for ...electrochemical oxidation of 3-chlorophenol (3-CP). The microstructure, element distribution, crystal structure and chemical composition of samples were characterized by the analytical techniques including SEM, EDS, XRD and XPS. The electrochemical performances of electrodes were evaluated using LSV and CV measurements. The ·OH radicals generation capacity of electrodes was determined using terephthalic acid as trapping agent. Moreover, the PbO2/SnO2 electrodes were applied in the electrochemical degradation of 3-CP in aqueous solution. The results show that the doping of SnO2 nanoparticles reduced the grain size of PbO2 crystal and improved the content of Oads on the surface of electrode. In contrast with the pure PbO2 electrode, the PbO2/SnO2-1.0 electrode (the concentration of SnO2 in electroplating solution was 1.0 g/L) exhibited higher oxygen evolution potential, stronger direct oxidation capacity and ·OH radicals generation capacity, and superior electrochemical activity for degradation of 3-CP. The intermediates formed in electrochemical degradation of 3-CP were revealed by HPLC and a plausible degradation pathway was proposed. Furthermore, PbO2/SnO2-1.0 electrode also showed a high reusability for 3-CP degradation.
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•PbO2/SnO2 composite anode was successfully fabricated for electrochemical oxidation.•Electrocatalytic properties of PbO2/SnO2 anode were evaluated.•The degradation intermediates of 3-CP were identified and pathway was elucidated.
Two-dimensional (2D) transition-metal carbides (MXenes) have attracted great interest owing to their unique structures and superior properties compared to those of traditional 2D materials. The ...transformation of 2D MXenes into sub-5-nm quantum sheets (QSs) is urgently required but rarely reported. Herein, the Ti3AlC2 MAX and Ti3C2 MXene QSs with monolayer structures and sub-5-nm lateral sizes are demonstrated. Exceptionally high yields (>15 wt %) are obtained through an all-physical top-down method. The QS dispersions present unique photoluminescence, and the QSs-poly(methyl methacrylate) (PMMA) hybrid thin films demonstrate remarkable nonlinear saturation absorption (NSA). Absolute modulation depths of 30.6 and 49.9% and saturation intensities of 1.16 and 1.25 MW cm–2 (i.e., 116 and 125 nJ cm–2) are achieved for Ti3AlC2 QSs and Ti3C2 QSs, respectively. Such record-high NSA performances of MXene QSs would boost the application of MAX/MXene materials in nonlinear optics.
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