Self-doping of SnO_2−xnanocrystals accompanying abundant oxygen vacancies results in significant enhancement in the gas sensing performance.

Rigid three-dimensional (3D) Ni ₃ S ₄ nanosheet frames assembled from ultrathin nanosheets are synthesized via a facile solvothermal method.

Bimetallic ruthenium–copper nanoparticles embedded in the pore walls of mesoporous carbon were prepared via a template route and evaluated in terms of catalytic properties in D-glucose hydrogenation. The existence of bimetallic entities was supported by Ru L₃-edge and Cu K-edge X-ray absorption results. The hydrogen spillover effect of the bimetallic catalyst on the hydrogenation reaction was evidenced by the results of both hydrogen and carbon monoxide chemisorptions. The bimetallic catalyst displayed a higher catalytic activity than the single-metal catalysts prepared using the same approach, namely ruthenium or copper nanoparticles embedded in the pore walls of mesoporous carbon. This improvement was due to the changes in the geometric and electronic structures of the bimetallic catalyst because of the presence of the second metal.

Spermine assumes a pivotal role in assessing food safety due to its potential to induce a spectrum of diseases upon excessive consumption. However, contemporary spermine detection methodologies, exemplified by high-performance liquid chromatography (HPLC), demand costly instrumentation and the expertise of skilled technicians. To address this challenge, the study introduces a portable fluorescence sensing platform. Ratiometric fluorescent probes were realized through the utilization of CdS quantum dots deeply doped with Ag⁺ (CdS:Ag QDs) and nitrogen-doped carbon quantum dots (N-CQDs). Hydrogen bonds formed between CdS:Ag QDs and spermine result in the formation of the assembly and the decreasing of the fluorescence intensity. In an effort to broaden the applicative scope and streamline deployment processes, fluorescent sensing hydrogels were meticulously engineered, capitalizing on the swelling properties inherent in polyvinyl alcohol (PVA) hydrogels. The systematic delineation of the correlation between 1 − R/B and spermine concentration facilitates the quantitative determination of spermine concentration. The incorporation of this composite construct serves to alleviate environmental influences on the probes, thereby augmenting their precision. The portable fluorescent sensing platform proves pivotal in expeditiously measuring spermine concentration within the fluorescent sensing hydrogel, enabling a quantitative assessment of pork freshness. The utilization of this platform for food freshness evaluation imparts the benefits of convenience, cost-effectiveness, and intuitive operation.

A series of Cu _x O self-assembled mesoporous microspheres (SMMs), with different and controlled morphology (virus-like, urchin-like, spherical), were synthesized by facile liquid phase approach. The morphology of the as-prepared Cu _x O SMMs was evolved from spherical to virus-like shape by controlling the ratio of DI water in solution. It can also realize the transformation from loose assembly to dense assembly by extending the reaction time. These Cu _x O SMMs exhibited good response to NO₂ gas at room temperature, benefiting from their 3D self-assembly structure. Among these the resulting virus-like CuxO SNMMs-based sensor exhibits largely enhanced response to 1 ppm NO₂ gas at room temperature. The enhanced response of the virus-like Cu₂O SMMsbased sensor can be ascribed to the high surface area, hierarchical 3D nanostructures, micropores for effective gas diffusion, the heterojunctions formed between CuO and Cu₂O, and the existence of abundant surface oxygen vacancies.