In this work, a highly efficient and rapid method for simultaneously removing cationic dyes from aqueous solutions was developed by using monodispersed mesoporous silica nanoparticles (MSNs) as the adsorbents. The MSNs were prepared by a facile one-pot method and characterized by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and Brunauer-Emmett-Teller. Experimental results demonstrated that the as-prepared MSNs possessed a large specific surface area (about 585 m2/g), uniform particle size (about 30 nm), large pore volume (1.175 cm3/g), and narrow pore size distribution (1.68 nm). The materials showed highly efficient and rapid adsorption properties for cationic dyes including rhodamine B, methylene blue, methyl violet, malachite green, and basic fuchsin. Under the optimized conditions, the maximum adsorption capacities for the above mentioned cationic dyes were in the range of 14.70 mg/g to 34.23 mg/g, which could be achieved within 2 to 6 min. The probable adsorption mechanism of MSNs for adsorption of cationic dyes is proposed. It could be considered that the adsorption is mainly controlled by electrostatic interactions and hydrogen bonding between the cationic dyes and MSNs. As a low-cost, biocompatible, and environmentally friendly material, MSNs have a potential application in wastewater treatment for removing some environmental cationic contaminants.

This work reports a simple and sensitive sensing protocol for the quantitative monitoring of telomerase activity based on target-responsive release of cargo from wrapping DNA-capped mesoporous silica nanoparticles (MSNs) by coupling with a portable personal glucometer (PGM).

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Recent studies in 2D transition-metal-dichalcogenides (TMDs) for electrocatalytic applications have mainly concentrated on MoS2, while the catalytic properties of the majority of TMDs with other metal compositions remain uncovered. This...

Inspired by the recent experimental advance in the fabrication of a new type of two-dimensional (2D) material, MoSi 2 N 4 and WSi 2 N 4 , in this work we performed density functional theory (DFT) calculations to explore the electrocatalytic feature of the new MA 2 Z 4 family in oxygen reduction reaction (ORR). Through different combinations of the M, A, and Z elements (M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W; A = Si or Ge; Z = N, P, or As), we predicted about 42 MA 2 Z 4 compounds that share the same structural framework as MoSi 2 N 4 /WSi 2 N 4 are dynamically stable. Most of them prefer the four-electron (4e − ) mechanism to produce H 2 O, and their ORR activity follows a general trend as MGe 2 As 4 > MSi 2 As 4 > MSi 2 N 4 > MSi 2 P 4 > MGe 2 P 4 ≈ MGe 2 N 4 . Among them, four of them (VGe 2 As 4 , CrGe 2 As 4 , VSi 2 As 4 , and NbSi 2 As 4 ) are screened out to be highly promising electrocatalysts with small overpotential around 0.5−0.6 V. The topmost surface As acts as the active site, and the p-band center of the As atom is found to show correlation with the adsorption strength of the critical intermediate. In particular, CrGe 2 As 4 exhibits outstandingly high ORR activity with ultralow overpotential (0.49 V) comparable to the Pt-based catalysts. The metallic conductivity and the moderate adsorption and orbital hybridization between As and O* intermediate are responsible for the exceptional activity. Our investigations verify the promising catalytic performance of the emerging 2D MA 2 Z 4 , which would stimulate the future efforts in their synthesis and electrocatalytic applications in oxygen reduction and other advanced applications.