Water competitive adsorption and limited reaction sites on the micro-scale sensing area of micro-electro-mechanical system (MEMS) sensors are two bottleneck problems that restrict the detection of trace indoor polluted gases, leading to drifting and weak signals. To address this, a “duet-insurance” sensing strategy is proposed to protect and amplify the sensing signal. For the first-level protection, the well-designed double-layer structure consisting of Janus TpMa covalent organic framework (COF)/Eu-doped α-Fe 2 O 3 can resist diffusion of water molecules and facilitate the electron transfer from formaldehyde (CH 2 O) to sensing layers, benefiting from the outer hydrophobic character of Janus TpMa and the strong CH 2 O adsorption capacity of Eu-doped Fe 2 O 3 . For the second-level amplification, the unique variable temperature excitation facilitates the deep penetration of CH 2 O into the active sites across COF layers, enabling signal amplification through thermally actuated carrier modulation. The sensor demonstrates high sensing ability to the CH 2 O, with an ultra-low limit of detection of 794 ppt. Leveraging the novel sensing strategy, a multi-functional, visual sensing system is designed to identify multi-indoor pollution gases by feature signal encoding and color mapping, showcasing the promising potential for MEMS sensors based on Janus TpMa COF/Eu-doped α-Fe 2 O 3 materials.
The photocatalytic technique is an attractive strategy to activate persulfate for generating free radicals in the wastewater purification process. Herein, CdS nanoparticles with unique optical properties were employed to decorate the COF-based photocatalyst (denoted as TpMA) containing C3N4 active units via a feasible method. Interestingly, TpMA decorated with CdS nanoparticles exhibited enhanced optical absorbability and a small charge transfer resistance. Benefitting from the close interfacial connections between CdS nanoparticles and TpMA, the recombination of photogenerated electrons and holes could be effectively inhibited. As expected, the obtained CdS@TpMA composites displayed excellent photocatalytic activity, which could activate persulfate to produce SO4−˙ and ˙OH under visible light irradiation. In comparison with pristine CdS nanoparticles and TpMA, the 25% CdS@TpMA composite presented the best photocatalytic degradation ability, and 97.6% of diclofenac sodium, 95.2% of tetracycline and 93.8% of ibuprofen could be effectively removed within 70 min. The corresponding TOC removal efficiencies were more than 60%. More significantly, the 25% CdS@TpMA composite displayed great performance and structural stabilities. Furthermore, a possible photocatalytic mechanism was also proposed. In short, the current work not only provides a promising candidate for degrading drug residues, but also offers some novel viewpoints for further research.
Poly(dimethylsiloxane) (PDMS) coatings are considered to be environmentally friendly antifouling coatings. However, the presence of hydrophobic surfaces can enhance the adhesion rate of proteins, bacteria and microalgae, posing a challenge for biofouling removal. In this study, hydrophilic polymer chains were synthesised from methyl methacrylate (MMA), Poly(ethylene glycol) methyl ether methacrylate (PEG-MA) and 3-(trimethoxysilyl) propyl methacrylate (TPMA). The crosslinking reaction between TPMA and PDMS results in the formation of a silicone-based amphiphilic co-network with surface reconstruction properties. The hydrophilic and hydrophobic domains are covalently bonded by condensation reactions, while the hydrophilic polymers migrate under water to induce surface reconstruction and form hydrogen bonds with water molecules to form a dense hydrated layer. This design effectively mitigates the adhesion of proteins, bacteria, algae and other marine organisms to the coating. The antifouling performance of the coatings was evaluated by assessing their adhesion rates to proteins (BSA-FITC), bacteria (B. subtilisandP. ruthenica) and algae (P. tricornutum). The results show that the amphiphilic co-network coating (e.g., P-AM-15) exhibits excellent antifouling properties against protein, bacterial and microalgal fouling. Furthermore, an overall assessment of its antifouling performance and stability was conducted in the East China Sea from 16 May to 12 September 2023, which showed that this silicon-based amphiphilic co-network coating remained intact with almost no marine organisms adhering to it. This study provides a novel approach for the development of high-performance silicone-based antifouling coatings.
危险品化学品经营许可证（带存储）