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The heavy metal lead (Pb) holds significant importance in the manufacturing industry due to its extensive range of applications. However, its high toxicity poses a serious risk to both environment and human health. Consequently, on-site portable analysis methods have been developed to detect Pb2+, which is advantageous for obtaining timely information regarding environmental pollution. In this study, a fungal-like porous CoS (FP CoS) was discovered to selectively recognize, adsorb, and detect Pb2+. FP CoS exhibited rapid kinetics (reducing from 8.56 mg∙L–1to 69 µg∙L–1within 30 min) as well as exceptional adsorption capacity of 88.14 mg∙g−1for Pb2+. Benefiting from the selective enrichment of Pb2+, the peroxidase-like activity of FP CoS nanoenzyme was further enhanced, enabling colorimetric detection of Pb2+with a detection limit of 14 ng∙L–1, surpassing numerous reported materials. When applied to environmental samples spiked with 0–100 μg∙L–1Pb2+, the combination of FP CoS nanosensor and a portable RGB color sensor yielded an impressive recovery percentage of 112 %. Based on these results, the FP CoS nanosensor not only provides a rapid and visually discernible colorimetric approach for trace and ultra-trace Pb2+but also serves as a sensitive sensor for detecting Pb2+in various scenarios.

We report a portable and highly sensitive Hg2+nanosensor, where the CuS nanozyme functions as an Hg2+recognition unit, a Hg2+enrichment/preconcentration carrier, and a signal amplifier/output unit. The as-designed enrichment-detection integration strategy is customizable and endows the sensor with both a wide detection range from 50 ppt to 400 ppb and a high sensitivity with a minimum detectable Hg2+concentration of 50 ppt. In order to make the Hg2+nanosensor portable and cost-effective, a commercial RGB sensor is employed here in conjunction with the Hg2+-dependent colorimetric reaction. More importantly, the as-developed Hg2+nanosensor is feasible for analysis of real samples with satisfactory accuracy (deviation <10%) and reproducibility (recovery ∼82%). Thus, this portable Hg2+nanosensor appears to be a viable solution to meet the actual needs of on-site and real-time mercury contamination analysis and may also pave the way to colorimetric nanosensors for other metal ions.

Recently, flexible transparent conductive films composed of metal nanowires have received significant interest, particularly for flexible electronics. However, the high contact resistance among metal nanowires and the weak bonding effect between metal nanowires and substrates often result in films whose conductivity, adhesion, and flexibility fall short of the stringent requirements demanded by real-world uses. We developed a simple method to fabricate high-performance flexible transparent conductive films via successively spin-coating silver nanowires (AgNWs) and acidic silica sol onto the surface of the substrate. Under the capillary force of ethanol and the etching effect of hydrochloric acid, the adjacent AgNWs are induced to chemically weld in situ to form a stable network. The resulting composite film exhibits a sheet resistance of only 8.5 Ω/sq, marking an impressive 80% decrease compared with the pristine AgNW film. Meanwhile, the silica sol acts as a filler, improving light transmittance while further reinforcing the network structure and firmly bonding it to the substrate. Thus, the delamination of the nanowires under bending motion is effectively inhibited, and the resulting film was endowed with resistance remaining below 15 Ω/sq after 3000 bending and 200 tape peeling. The energy-efficient in situ chemical welding and reinforcement method for nanowires provides an innovative strategy for the batch preparation of flexible transparent conductive films.