Pd@Pt Core-Shell Nanocrystal-Decorated ZnO Nanosheets for ppt-Level NO2 Detection.

Bimetallic nanocrystals (NCs) have obtained significant attention due to their unique advantages of the intrinsic properties of individual metals and synergistic enhancements resulting from the electronic coupling between two constituent metals. In this work, Pd@Pt core-shell NCs were prepared through a facile one-pot solution-phase method, which had excellent dispersion and uniform size. Concurrently, ZnO nanosheets were prepared via a hydrothermal method. To explore their potential in nitrogen dioxide (NO2) gas sensing applications, sensitive materials based on ZnO nanosheets with varying mass percentages of Pd@Pt NCs were generated through an impregnation process. The sensor based on 0.3 wt % Pd@Pt-ZnO exhibited remarkable performance, demonstrating a substantial response (Rg/Ra = 60.3) to 50 ppb of NO2 at a low operating temperature of 80 °C. Notably, this sensor reached an outstanding low detection limit of 300 ppt. The enhancement in gas sensing capabilities can be attributed to the sensitization and synergistic effects imparted by the exceptional catalytic activity of Pd@Pt NCs, which significantly promoted the reaction. This research introduces a novel approach for the utilization of core-shell structured bimetallic nanocrystals as modifiers in metal-oxide-semiconductor (MOS) materials for NO2 detection.

The DNA controllable peroxidase mimetic activity of MoS2 nanosheets for constructing a robust colorimetric biosensor.

The low activity of nanozymes, which work as an alternative to natural enzymes, limits their applications in the fabrication of biosensors, drawing increasing attention aimed at improving their catalytic capacity. In this work, the peroxidase-like activity of MoS2 nanosheets (NSs) was dramatically enhanced through DNA modification, and was 4.3-times higher than that of bare MoS2 NSs. Such an enhancement of catalytic activity was mainly ascribed to the increased affinity of the DNA/MoS2 NSs toward the substrate, TMB, further accelerating electron transfer from TMB to H2O2. On the basis of DNA-tuned MoS2 NS nanozyme activity, a colorimetric sensing platform was developed for the facile detection of carcinoembryonic antigen (CEA) in a sensitive manner. Interestingly, a convenient, affordable, and instrument-free portable test kit was fabricated to visually monitor CEA via rooting the aptamer/MoS2 NS system into an agarose hydrogel. Importantly, our work illuminates the feasibility of using DNA to enhance the catalysis of nanozymes and their application potential in the label-free, portable, and visual detection of aptamer-targeted biomolecules.

Au39Rh61 Alloy Nanocrystal-Decorated W18O49 for Enhanced Detection of n-Butanol.

Here, AuxRh1-x alloy nanocrystals (NCs) were used to decorate W18O49 for enhanced detection of n-butanol vapor. Monodisperse AuxRh1-x alloy NCs with a tunable composition and urchinlike W18O49 were synthesized by a simple solvothermal method. AuxRh1-x alloy NCs were loaded onto the W18O49 surface by the impregnation method. A series of material characterization methods were employed to characterize the structure and morphology of as-synthesized materials. The performance of AuxRh1-x-W18O49-based sensors to n-butanol was investigated. The results demonstrated that the Au39Rh61-W18O49-based sensor had the highest response, short response time, good selectivity, excellent repeatability, and stability to n-butanol. The gas sensing mechanism was supposed, the excellent catalytic capability of the AuxRh1-x alloy NCs were believed to be a major factor in enhancing the detection of n-butanol.

Preparation of silver-loaded titanium dioxide hedgehog-like architecture composed of hundreds of nanorods and its fast response to xylene.

Hedgehog-like titanium dioxide (TiO2) architectures composed of hundreds of one-dimensional (1D) nanorods and silver (Ag) loaded TiO2 with different amounts (0.2 at%, 0.5 at% and 1 at%) were successfully prepared by facile hydrothermal process and simple isometric impregnation route. The high electron mobility of 1D nanorods on the surface of TiO2 and the high porosity of Ag loaded hedgehog-like TiO2 architectures enable the sensor with fast responsive and recovered properties. TiO2 loaded with 0.5 at% Ag exhibited the highest response to xylene with low response/recovery time at the operating temperature of 375 °C. In addition, the sensitivity and selectivity of the TiO2 sensor were enhanced markedly with Ag loading.