Bismuth-Decorated Honeycomb-like Carbon Nanofibers: An Active Electrocatalyst for the Construction of a Sensitive Nitrite Sensor.

The existence of carcinogenic nitrites in food and the natural environment has attracted much attention. Therefore, it is still urgent and necessary to develop nitrite sensors with higher sensitivity and selectivity and expand their applications in daily life to protect human health and environmental safety. Herein, one-dimensional honeycomb-like carbon nanofibers (HCNFs) were synthesized with electrospun technology, and their specific structure enabled controlled growth and highly dispersed bismuth nanoparticles (Bi NPs) on their surface, which endowed the obtained Bi/HCNFs with excellent electrocatalytic activity towards nitrite oxidation. By modifying Bi/HCNFs on the screen-printed electrode, the constructed Bi/HCNFs electrode (Bi/HCNFs-SPE) can be used for nitrite detection in one drop of solution, and exhibits higher sensitivity (1269.9 µA mM-1 cm-2) in a wide range of 0.1~800 µM with a lower detection limit (19 nM). Impressively, the Bi/HCNFs-SPE has been successfully used for nitrite detection in food and environment samples, and the satisfactory properties and recovery indicate its feasibility for further practical applications.

Biobased mussel-inspired underwater superoleophobic chitosan derived complex hydrogel coated cotton fabric for oil/water separation.

Superhydrophilic and underwater superoleophobic materials exhibit excellent oil/water separation performance but are usually fabricated from nonrenewable and nondegradable feedstocks and thus would cause secondary pollution after use. Herein, we report a fully biobased and mussel-inspired underwater superoleophobic hydrogel coated cotton fabric (CF) prepared by surface coating and subsequent oxidation polymerization of chitosan & dopamine mixtures. The obtained chitosan & polydopamine hydrogel coated CF (CS&PDA/CF) showed superhydrophilicity and underwater superoleophobicity, due to the formed rough surface structure with hydrophilic complex hydrogel. The CS&PDA/CF exhibited excellent oil/water separation performance with separation efficiency higher than 99.5% for various oil/water mixtures. Moreover, the CS&PDA/CF showed excellent resistance against various harsh conditions such as boiling water, ultrasonication, and concentrated salt solution, due to the mussel-inspired strong adhesion stabilized structure and morphology. We believe that the fully biobased and mussel-inspired underwater superoleophobic cotton fabric shows great potential as an eco-friendly and high-efficient oil/water separation material.

Organic carbon dot coating for superhydrophobic aluminum alloy surfaces.

A novel fluorine-free and silicon-free superhydrophobic aluminum alloy (treated-Al) is fabricated by chemical etching using hydrochloric acid and hydrogen peroxide and modified with an organic carbon dot (OCD) coating. The water contact angle (CA) of the treated-Al surface increases with the OCD concentration. When etched aluminum (etched-Al) is modified with 0.5 mg/ml OCDs, a CA of 161.4° is achieved, which indicates good nonwettability. SEM results verify that porous microstructures with cavities are uniformly distributed on the surface of etched-Al, in contrast to the bare aluminum alloy, which forms a primary rough structure. After treatment with 0.5 mg/ml OCDs, a nanoparticle coating is dispersed on the rough structures of treated-Al-0.5, which can trap air and make a water droplet essentially rest on a layer of air. The treated-Al-0.5 material has good self-cleaning properties and can sweep away contaminants at both 20 and 0°C. The Ecorr and Icorr of treated-Al-0.5 are - 0.56 V and 2.82 × 10-6 A/cm2, respectively, which shows good anticorrosion performance.

Construction of a luminescent sensor based on a lanthanide complex for the highly efficient detection of methyl parathion.

A highly sensitive and selective luminescent sensor for the detection of methyl parathion (MP) pesticide was described in this study. The target molecule HL was synthesized by modifying the structure of 4-hydroxybenzlidene imidazolinone (HBI) with nitrogen-containing heterocyclic 1,10-phenanthroline. In the presence of Eu3+, a HL-Eu3+ complex was formed which could emit strong red fluorescence due to the removal of coordinated water molecules and an intramolecular energy transfer from HL to Eu3+. Addition of MP into the strongly fluorescent solution of HL-Eu3+ induced quenching of the complex's fluorescence, and this quenching behavior occurred because of the competition coordination of MP and HL for Eu3+. A calibration curve was developed that related the extent of fluorescence quenching to MP concentration, making the HL-Eu3+ system a sensitive and selective fluorescent sensor for MP. Under the experimental conditions, the detection limit for MP was down to 95 nM based on LOD = 3σ/S. Moreover, the fluorescence assay developed here allowed the detection of MP in two different types of real samples including pond water and pear juice, and satisfactory results demonstrate that this fluorescent sensor based on HL-Eu3+ has potential application in environment and food analysis.