NO2 is a highly irritating toxic gas that poses risks to respiratory health, and its concentration fluctuations in exhaled breath are associated with respiratory diseases such as asthma. Thus, developing high-performance room-temperature NO2 gas sensors is of great practical significance. In this study, a room-temperature NO2 gas sensor based on few-layer Ti3C2 MXene/WO3 nanoparticles composites was developed. WO3 nanoparticles were synthesized via a one-step hydrothermal method and physically mixed with few-layer Ti3C2 MXene. The crystal structure, surface morphology, and NO2 sensing performance of the composite materials were characterized. The results show that the optimized Ti3C2 MXene/WO3 composites exhibited excellent gas-sensing properties with a response of 8.3 (dR/R-a) to 1 ppm NO2, which is 23 times higher than that of pure WO3 (response of 0.36). Further tests verified that the optimized sensor had excellent repeatability, long-term stability, and good selectivity. This work demonstrates the potential of the WO3/Ti3C2 MXene composite for room-temperature NO2 detection.

NO₂ is a highly irritating toxic gas that poses risks to respiratory health, and its concentration fluctuations in exhaled breath are associated with respiratory diseases such as asthma. Thus, developing high-performance room-temperature NO₂ gas sensors is of great practical significance. In this study, a room-temperature NO₂ gas sensor based on few-layer Ti₃C₂ MXene/WO₃ nanoparticles composites was developed. WO₃ nanoparticles were synthesized via a one-step hydrothermal method and physically mixed with few-layer Ti₃C₂ MXene. The crystal structure, surface morphology, and NO₂ sensing performance of the composite materials were characterized. The results show that the optimized Ti₃C₂ MXene/WO₃ composites exhibited excellent gas-sensing properties with a response of 8.3 (dR/Ra) to 1 ppm NO₂, which is 23 times higher than that of pure WO₃ (response of 0.36). Further tests verified that the optimized sensor had excellent repeatability, long-term stability, and good selectivity. This work demonstrates the potential of the WO₃/Ti₃C₂ MXene composite for room-temperature NO₂ detection.

The Cu-Fe bimetallic composite carbon (CuFeO2@CR) was synthesized by using the waste cation exchange resins as the carbon source to degrade carbamazepine (CBZ) by activating peroxymonulfate (PMS). Results found that 91.3 % of CBZ was degraded under the optimal condition ([PMS] = 0.2 g/L, [CuFeO2@CR] = 0.3 g/L, T = 25degree celsius). CuFeO2@CR could efficiently degrade CBZ at pH 3.03-9.02 and maintain the degradation at 83.6 % in the fifth cycle. The reactive oxygen species (ROS) were SO4 center dot-, center dot OH, and O-1(2) with the relative contribution of 35 %, 29 %, and 36 %, respectively. DFT calculation demonstrated that CuFeO2@CR exhibited a preferential affinity for PMS and greater transfer electrons capacity than CR. Three reaction pathways were proposed in the CuFeO2@CR/PMS system, and the degradation could effectively reduce the toxicity into non-toxic. The continuous flow catalytic experiment indicated the promising application in the treatment of antibiotic wastewater. This work provides guidance and theoretical support for CBZ degradation mechanisms.

The application of competitive immunoassay brings many advantages to the detection of trace biomolecules and has the potential to be applied to urine-based clinical practice. However, this type of detection method has strict requirements for secondary antibody incubation processes and analysis equipment, leading to strong demands for convenient, rapid, and inexpensive detection platforms. In this study, a mechanical competitive immunosensor (MCI) was proposed for the detection of human serum albumin (HSA) based on goat anti-rabbit @Fe2O3 magnetic beads with magnetic sensitization. With the doping of Fe2O3 , the conversion layer of MCI responds more accurately and rapidly to stress. In addition, goat anti-rabbit conjugated with animated Fe2O3 nanoparticles were introduced as secondary antibodies for signal amplification. Under the synergistic effect of the magnetic force of magnetic beads and the stress caused by the specific binding of antigen and antibody, the deformation of the film was amplified, which can effectively change the conductive pathway formed by doped carbon nanotubes, resulting in a larger output electric signal. Through competitive immunoassay for HSA, a limit of detection (LOD) of 68 ng/mL was achieved, which was an order of magnitude lower than direct detection methods. With high reproducibility and stability, MCI demonstrated effectiveness in the detection of HSA at a clinically significant concentration range (0.1- $50 \; \mu $ g/mL). Moreover, MCI showed excellent specificity and selectivity, which held promise to offer an alternative tool for clinical diagnosis of urine HSA levels in nephrotic patients.

In this study, Congo red (CR) was degraded by different particle sizes of zero-valent copper (ZVC) activated persulfate (PS) under mild temperature. The CR removal by 50 nm, 500 nm, 15 μm of ZVC activated PS was 97%, 72%, and 16%, respectively. The co-existence of SO42- and Cl- promoted the degradation of CR, and HCO3- and H2PO4- were detrimental to the degradation. With the reduction of ZVC particle size, the effect of coexisting anions on degradation grew stronger. The high degradation efficiency of 50 nm and 500 nm ZVC was achieved at pH=7.0, while the high degradation of 15 μm ZVC was achieved at pH=3.0. It was more favorable to leach copper ions for activating PS to generate reactive oxygen species (ROS) with the smaller particle size of ZVC. The radical quenching experiment and electron paramagnetic resonance (EPR) analysis indicated that SO4-•, •OH and •O2- existed in the reaction. The mineralization of CR reached 80% and three possible paths were suggested for the degradation. Moreover, the degradation of 50 nm ZVC can still reach 96% in the 5th cycle, indicating promising application potential in dyeing wastewater treatment.

To resource utilization of the spent cation exchange resin, the carbonized resin with Fe doping (Fe3O4@CR) was prepared to activate persulfate (PS) for the degradation of oxytetracycline (OTC). Fe3O4@CR exhibited high catalytic potential for the degradation of OTC with relatively low activation energy (Ea = 28.86 kJ/mol). In the Fe3O4@CR/PS system, 76.4% of the OTC was removed under the conditions ([PS]: 0.15 g/L, [Fe3O4@CR]: 0.3 g/L, T: 25oC). Fe3O 4@CR could work effectively for activating PS to degrade OTC in the pH range of 3.0-7.0. The free radical quenching experiments and electron paramagnetic resonance (EPR) analysis showed that •OH and SO4 •were the main radicals for the degradation of OTC. The conversion between Fe3+ and Fe2+ accelerated the degradation of OTC by generating •OH and SO4 •-. The possible degradation pathways were proposed. The OTC was mineralized to smaller molecules, such as C14H10O3 and C7H11O. This study offers a new perspective on waste resin recycling and water purifi cation.

The conventional mechanical biosensor based on stress and electrical conversion can be an effective method to detect key human biomarkers for clinical diagnosis and early disease prevention. However, the applications of this type of biosensor are greatly limited due to their unsatisfactory sensitivity. In this work, a magneticsensitized (MS) mechanical biosensor based on multi-field coupling was developed for higher sensitivity, giving access to detect human serum albumin (HSA). Via introducing secondary magnetic antibodies labeled with magnetized Fe2O3 nanoparticles to the stress and electrical conversion element of the MS-biosensor, the multifield coupling was realized based on stress, electricity, and magnetism. Under the action of the magnetic field, the magnetic force of the secondary magnetic antibody and the stress of antigen-antibody binding jointly drove and enhanced the deformation of the MS-biosensor, amplifying the electrical signal, and realizing magnetic sensitization. The HSA was detected by the MS-biosensor at a range of 0-80 & mu;g/mL with a limit of detection (LOD) of 0.14 & mu;g/mL, demonstrating the high performance of the MS-biosensor. Moreover, the MS-biosensor showed high selectivity, specificity, and stability, indicating that the magnetic sensitization strategy of the MS-biosensor was significant for the clinical application of mechanical biosensors.

Black Phosphorus (BP) has attracted considerable attention in gas detection fields attributing to layer-dependent direct bandgap, and high carrier mobility. Currently, many researchers use blended polyethyleneimine/ polyethylene-glycol (PEI/PEG) functionalized two-dimensional (2D) material to detect carbon dioxide (CO2). However, the detection rage of CO2 sensor based blended PEI/PEG functionalized 2D materials still need further with widen to realize more application. In this paper, a RT (25 C) CO2 sensor prepared by a One-Pot method based on a PEI/PEG functionalized BP composite material is developed, in which the existence of PEI/PEG onto BP was confirmed by SEM, EDS, etc. The gas-sensing experiment results show that the low limit of detection of PEI/PEG-BP gas sensor is 200 ppm CO2 under air conditions and a high limit of detection of 250,000 ppm CO2 under N2 conditions. Moreover, the PEI/PEG-BP sensor shows high selectivity, and excellent repeatability. The excellent gas-sensing properties of the PEI/PEG-BP sensor can be attributed to the meso-macropores structure, the recognition function of amino groups, and the formation of P-N heterojunction between BP and PEI. The reported results of PEI/PEG-BP sensor can provide a foundation for PEI/PEG functionalized 2D material and understand the sensing mechanism for compositing the 2D materials with polymer semiconductors.