Xingming Sun

Retraction of “Few-Layer Antimonene: Large Yield Synthesis, Exact Atomical Structure, and Outstanding Optical Limiting”

The predictions of arsenene and antimonene open a gate to new two-dimensional (2D) materials. In contrast to the severe unstability of black phosphorus in ambient atmosphere, arsenene and antimonene were recently predicted to be of high stability, as well as outstanding physical and chemical properties, such as extremely high mobility, superior thermal conductivity, high refractive index, and directionally optically transparent. Significantly, monolayer and few-layer antimonenes were recently experimentally fabricated by mechanical exfoliation, however the yield was very low and there’s lack of clear characterizations on the atomical structure and potential applications, which are critical and necessary to promote the developments of this field. Here, we report on a high-yield experimental preparation of high quality, few-layer antimonenes via liquid exfoliation, their atomic level structural elucidation, and unexpected but outstanding nonlinear optical limiting properties even better than graphene in the visible and near infrared region (532 nm-2000 nm) and high transmission (more than 80%) when dispersed in solutions or high concentration doped in Ormosil gel glasses, which might lead to many promising applications in nonlinear optical fields such as laser protection. This work demonstrates that Group 15 2D materials beyond BP could be not only a new 2D crystal family with stability in ambient condition, but also of unique properties

In situ bifunctionalized carbon dots with boronic acid and amino groups for ultrasensitive dopamine detection

In this paper, in situ bifunctionalized carbon dots (B-N-CDs) with boronic acid and amino groups were prepared by a simple hydrothermal method using 3-aminophenylboronic acid as the sole precursor. The high quantum yield of B-N-CDs is as high as 67%, leading to fluorescence emission observed even under daylight excitation. The B-N-CDs exhibited obvious fluorescence enhancement to trace dopamine in the range of 1 pM to 1 μM with a detection limit of 0.1 pM (S/N = 3), which is two orders of magnitude more sensitive than that of present fluorescent sensors. The excellent sensing performance is based on the interaction of two functional groups with DA. This dopamine probe owned advantages of high sensitivity, superior selectivity, good reproducibility and simplicity. Moreover, the analytical reliability of this dopamine sensor was demonstrated in human serum samples.

C96H30 tailored single-layer and single-crystalline graphene quantum dots

By controllable synthesis of a carbon precursor and with a suitable preparation routine, a series of single-layer and single-crystalline graphene quantum dots (GQDs) with uniform size distribution were prepared from C96H30. It was found that the absorption, photoluminescence (PL) and two-photon photoluminescence (TPPL) show a high size-dependent effect with a redshift that occurs as the size grows. Two-photon absorption (TPA) properties of GQDs were measured at 800 nm under a femtosecond pulse laser. Two-photon bioimaging of HeLa cells was carried out to determine TPA properties. Most significantly, the as-prepared GQDs showed potential in a practical application in two-photon cell bioimaging due to their high contrast TPPL. In addition, the superior nonlinear absorption, stable TPPL and excellent solubility were beneficial to the optical limiting (OL) properties.

Broadband optical limiting of a novel twisted tetrathiafulvalene incorporated donor–acceptor material and its Ormosil gel glasses

To accomplish broadband optical limiting with high visible-light region (ca. 400–700 nm) transmittance, as well as to satisfy the requirement of practical applications, a novel molecule, TTF-Pt(bzimb), has been rationally designed and synthesized by connecting an excellent electron donating tetrathiafulvalene and a Pt(II)-incorporated electron withdrawing Pt(bzimb) with a C–C triple bond. Chlorine substituted Cl-Pt(bzimb) was presented for comparison. As expected, the theoretical calculation results clearly demonstrate that TTF-Pt(bzimb) exhibits a twisted conformation with a dihedral angle of 50° at the C–C triple bond. The intramolecular charge transfer existing between the donor and the acceptor is well evidenced by a series of experimental results such as UV-vis spectra, fluorescence spectra, and CV. Benefiting from a unique conformation, TTF-Pt(bzimb) and its doped Ormosil gel glasses in a methyltriethoxysilane matrix exhibit broadband (532 and 1064 nm) optical limiting behaviour with high visible-light transmittance. Furthermore, TTF-Pt(bzimb) shows more remarkable optical limiting behaviour than the state-of-the-art optical limiting material, C60, under 532 nm. Thus, our results disclose a rational molecular design strategy for the accomplishment of remarkable optical limiting. TTF-Pt(bzimb) and its gel glasses can be considered as promising candidates for the applications of optical limiting and for use in nonlinear optical devices.

Highly Efficient Carbon Dots with Reversibly Switchable Green–Red Emissions for Trichromatic White Light-Emitting Diodes

Carbon dots (CDs) have potentials to be utilized in optoelectronic devices, bioimaging, and photocatalysis. The majority of the current CDs with high quantum yield to date were limited in the blue light emission region. Herein, on the basis of surface electron-state engineering, we report a kind of CDs with reversible switching ability between green and red photoluminescence with a quantum yield (QY) of both up to 80%. Highly efficient green and red solid-state luminescence is realized by doping CDs into a highly transparent matrix of methyltriethoxysilane and 3-triethoxysilylpropylamine to form CDs/gel glasses composites with QYs of 80 and 78%. The CDs/gel glasses show better transmittance in visible light bands and excellent thermal stability. A blue-pumped CDs/gel glasses phosphor-based trichromatic white light-emitting diode (WLED) is realized, whose color rendering index is 92.9. The WLED gets the highest luminous efficiency of 71.75 lm W-1 in CDs-based trichromatic WLEDs. This work opens a door for developing highly efficient green- and red-emissive switching CDs which were used as phosphors for WLEDs and have the tendency for applications in other fields, such as sensing, bioimaging, and photocatalysis.

In situ hydrosilane reduction and preparation of gold nanoparticle–gel glass composites with nonlinear optical properties

Gold nanoparticle (AuNP)–gel glass composites were prepared on a carboxyl organosilicon oligomer by an in situ method using hydrosilane as a reductant. The organosilicon oligomer stabilized AuNPs, and hydrosilane directly bonded to the oligomer after the reducing reaction. The reaction and samples were characterized by FT-IR spectroscopy, UV-vis absorption spectrometry, UV-vis-NIR transmission spectrometry, TEM, EDS, XPS and SEM. Meanwhile, the nonlinear optical limiting properties of the AuNP–gel glass composites were investigated using the Z-scan technique and optical limiting measurements, and these composites exhibited broadband nonlinear optical limiting properties (532 nm and 1064 nm). This new reductant is a promising candidate for in situ preparation without the need for extra stabilizing agents or removal of residue byproducts, and the generated particles exhibited uniform size and distribution, providing a new insight into the preparation of metal–polymer nanocomposites.