The development of two-dimensional (2D) inorganic materials-based quantum dots (QDs) is still in its infancy but is triggering immense enthusiasm due to their high chemical stability, good aqueous dispersibility, excellent optical property, good biocompatibility and easy functionalization. This review covers almost all the extant 2D-QDs based on graphene, phosphorene, silicene, carbides, nitrides, transition metal dichalcogenide, transition metal oxides and MXenes, etc. Their categories, synthetic routes, properties, functionalization and applications are critically highlighted. In the application section, special emphasis is placed on the progress in bioimaging, cancer therapy, fluorescent sensing and optoelectronics. Meanwhile, the latest advances in 2D QDs-based catalysis and energy since 2015 are addressed. Moreover, 2D nanoclusters, in particular 2D-QDs, are also included. This review provides guidance for 2D-QDs studies to meet the increasing demands in the many diverse applications.

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Carbon quantum dots (CQDs) are attracting tremendous interest owing to their low toxicity, water dispersibility, biocompatibility, optical properties and wide applicability. Herein, CQDs with an average diameter of (4.0 ± 0.2) nm and high crystallinity were produced simply from the electrochemical oxidation of a graphite electrode in alkaline alcohols. The as-formed CQDs dispersion was colourless but the dispersion gradually changed to bright yellow when stored in ambient conditions. Based on UV-Vis absorption, fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM), this colour change appeared to be due to oxygenation of surface species over time. Furthermore, the CQDs were used in specific and sensitive detection of ferric ion (Fe(3+)) with broad linear ranges of 10-200 μM with a low limit of detection of 1.8 μM (S/N = 3). The application of the CQDs for Fe(3+) detection in tap water was demonstrated and the possible mechanism was also discussed. Finally, based on their good characteristics of low cytotoxicity and excellent biocompatibility, the CQDs were successfully applied to cell imaging.

Graphene has been regarded as a promising candidate for a new generation of transparent electrodes (TEs) due to its prominent characteristics including high optical transmittance, exceptional electronic transport, outstanding mechanical strength, and environmental stability. Comprehensive and critical insights into the latest advances in graphene-based TEs (GTEs) since, but not limited to 2013, are provided, with an emphasis on fabrication, modification, and versatile applications. Several emerging application areas not previously summarized, including electrochromic devices, supercapacitors, electrochemical and electrochemiluminescent sensors, are discussed in detail. The challenges and prospects in these fields are also addressed.

such as layered transition metal dichalcogenides (TMDs), [2] hexagonal boron nitride (h-BN), [3] metal halides, [4] and black phosphorus, [5] which opened up a new horizon for a novel class of low-dimensional systems with superior properties for applications in optoelectronics, [6] energy conversion, [7] and catalysis. [8] Among these, h-BN nanosheet has its peculiar and fascinating properties such as good electrical insulation, [9] high-temperature stability, [10] high mechanical strength, [11] large thermal conductivity, [12] low toxicity and chemical stability, [13] leading to a variety of potential applications as both structural and electronic materials. [14] With further reducing the size of the layered BN sheets to less than 10 nm, 0D BN quantum dots (BNQDs) with excellent fluorescence properties and good dispersibility can be endowed due to the quantum confinement, edge effects, and defect centers. [13][14][15] Combining with the intrinsic properties of BN, BNQDs were supposed to be promising agents in biological and optoelectronic applications. [15b] However, compared with the widely studied 2D BN nanosheet, [9][10][11]16] BNQDs were much less reported than expected. [13][14][15] First, further exploration is required for the preparation of desired BNQDs products. BNQDs were initially prepared via high intensity ultrasound and subsequent refluxing. [14a] Allwood et al. have also successfully fabricated monolayer BNQDs via three steps of potassium-intercalation, deintercalation, and disintegration of BN edges, but only low quantum yield (QY) of 2.5% was achieved. [15a] Recently, sonication-solvothermal strategy was found to be a facile and universal method for the generation of BNQDs with relatively high QY of 8.6% or 19.5%. [13,15b] Although the filling factor of the autoclave, synthesis temperature and reaction time in the solvothermal process have been investigated, [13] little attention has been paid to how different solvents affect the properties of the BNQDs, which is usually an important parameter to influence the optical properties and QYs of the zero-dimensional QDs. [17] Second, besides the most frequently studied PL properties, electrochemiluminescence (ECL) is also an interesting characteristic Exploration of novel optical features, generation mechanisms, and versatile applicability of boron nitride quantum dots (BNQDs) is still in nascent stage. Herein, BNQDs are prepared using liquid exfoliation-solvothermal treatment of bulk BN in three different solvents. The photoluminescence of BNQDs is blue in ethanol (or N,N-dimethylformamide (DMF)) and green in N-methyl-2-pyrrolidone (NMP) under the same UV-irradiation, respectively.The quantum yields (QYs) and average lateral sizes of the BNQDs are 12.6% and 4.1 ± 0.2 nm, 16.4%, and 2.8 ± 0.3 nm, as well as 21.3% and 2.0 ± 0.2 nm in solvents of ethanol, DMF, NMP, respectively. The distinct sizes, QYs, and optical properties of the BNQDs are found to depend on the polarity of these solvents. Different BNQDs can be chosen on-demand for versatile...

A generic screening approach was performed to investigate the binding of various potential ligands to proteins in order to investigate how proteins interact with ions and the complete surrounding solution. This also allows to study binding behavior and its regulation and protein functionality in general in a native environment. The ACE technique affords an excellent precision by applying appropriate rinsing procedures using a pressure of 2.5 bar and a continuous flow concept. Confidence intervals were estimated to proof significance of the interactions. This enables to investigate smaller yet important interactions, which were not possible with less precise techniques before. The influence of various ions on ovalbumin, β-lactoglobulin, and BSA were screened by comparing the mobility ratios of the free protein and the influenced one. The analysis was performed using the metal ions Ba(2) +, Ca(2) +, Cu(2) +, Mg(2) +, Mn(2) +, Ni(2) +, the pharmaceutical cations ephedrine hydrochloride, ethambutol dihydrochloride, pilocarpine hydrochloride and pirenzepine dihydrochloride, and various anions, in particular phosphate, acetate, succinate, glutamate, and salicylate. For the anion influence study, myoglobin was also included to the screened proteins. The influence of these ions on the proteins was well diversified. The interactions could be distinguished with a fast and precise screening method since 90% of all mobility ratios had a RSD% below 2% and 79% had a RSD% lower than 1%. Hence, for more than 75% of the protein-ligand pairs significant interactions are observed with a very small confidence interval due to the very excellent precision of these used method.