Surface Modulation of Co3O4 Yolk-Shell Spheres with Tungsten Doping for Superior Acetone Sensitivity

Efficient mixed-potential acetone sensor with yttria-stabilized zirconia and porous Co3O4 nanofoam sensing electrode for hazardous gas monitoring and breath analysis

For hazardous gas monitoring and non-invasive diagnosis of diabetes using breath analysis, porous foams assembled by Co3O4 nanoparticles were designed as sensing electrode materials to fabricate efficient yttria-stabilized zirconia (YSZ)-based acetone sensors. The sensitivity of the sensors was improved by varying the sintering temperature to regulate the morphology. Compared to other materials sintered at different temperatures, the porous Co3O4 nanofoams sintered at 800 °C exhibited the highest electrochemical catalytic activity during the electrochemical test. The response of the corresponding Co3O4-based sensor to 10 ppm acetone was -77.2 mV and it exhibited fast response and recovery times. Moreover, the fabricated sensor achieved a low detection limit of 0.05 ppm and a high sensitivity of -56 mV/decade in the acetone concentration range of 1-20 ppm. The sensor also exhibited excellent repeatability, acceptable selectivity, good O2/humidity resistance, and long-term stability during continuous measurements for over 30 days. Moreover, the fabricated sensor was used to determine the acetone concentration in the exhaled breaths of patients with diabetic ketosis. The results indicated that it could distinguish between healthy individuals and patients with diabetic ketosis, thereby proving its abilities to diagnose and monitor diabetic ketosis. Based on its excellent sensitivity and exhaled breath measurement results, the developed sensor has broad application prospects.

Self-powered photoelectrochemical aptasensor for fumonisin B1 detection based on a Z-scheme ZnIn2S4/WO3 photoanode

The incidence of esophageal cancer is positively associated with fumonisin contamination. It is necessary to develop methods for the rapid detection of fumonisins. In this work, a self-powered photoelectrochemical aptamer sensor based on ZnIn2S4/WO3 photoanode and Au@W-Co3O4 photocathode is proposed for the sensitive detection of fumonisin B1 (FB1). Among them, under visible light irradiation, the Z-type heterostructure of ZnIn2S4/WO3 acts as a photoanode to improve the electron transfer rate, which contributes to the enhancement of the photocathode signal and lays the foundation for a wider detection range. The Au@W-Co3O4 photocathode as a sensing interface reduces the probability of false positives (comparison of anode sensing platforms). The PEC sensor has a good working performance in the detection range (10 pg/mL-1000 ng/mL) with a detection limit of 2.7 pg/mL (S/N = 3). In addition, the sensor offers good selectivity, stability and excellent recoveries in real sample analysis. This work is expected to play a role in the field of analyzing environmental toxins.

Surface modification of Co3O4 nanosheets through Cd-doping for enhanced CO sensing performance

The detection of hazardous CO gas is an important research content in the domain of the Internet of Things (IoT). Herein, we introduced a facile metal-organic frameworks (MOFs)-templated strategy to synthesize Cd-doped Co3O4 nanosheets (Cd-Co3O4 NSs) aimed at boosting the CO-sensing performance. The synthesized Cd-Co3O4 NSs feature a multihole nanomeshes structure and a large specific surface area (106.579 m2·g-1), which endows the sensing materials with favorable gas diffusion and interaction ability. Furthermore, compared with unadulterated Co3O4, the 2 mol % Cd-doped Co3O4 (2% Cd-Co3O4) sensor exhibits enhanced sensitivity (244%) to 100 ppm CO at 200 °C and a comparatively low experimental limit of detection (0.5 ppm/experimental value). The 2% Cd-Co3O4 NSs show good selectivity, reproducibility, and long-term stability. The improved CO sensitivity signal is probably owing to the stable nanomeshes construction, high surface area, and rich oxygen vacancies caused by cadmium doping. This study presents a facile avenue to promote the sensing performance of p-type metal oxide semiconductors by enhancing the surface activity of Co3O4 combined with morphology control and component regulation.

Mixed Potential Type Acetone Sensor with Ultralow Detection Limit for Diabetic Ketosis Breath Analysis

Breath analysis using gas sensors is an emerging method for disease screening and diagnosis. Since it is closely related to the lipid metabolism and blood ketone concentration of the body, the detection of acetone content in exhaled breath is helpful for the screening and monitoring of diabetes and ketosis. The development of an acetone sensor with high selectivity, stability, and low detection limit has been the research focus for this purpose. Here, we developed a mixed potential type acetone sensor based on Gd2Zr2O7 solid electrolyte and CoSb2O6 sensing electrode. The developed sensor exhibits an extremely low detection limit of 10 ppb, enabling linear detection for acetone in an extremely wide range of 10 ppb-100 ppm. The good results of systematic evaluation on selectivity, repeatability, and stability prove the superior reliability of the sensor, which is a prerequisite for the application in actual breath detection. The ability of the sensor to distinguish healthy people from diabetic ketosis patients was confirmed by using the sensor to detect the breath of healthy people and diabetic patients, proving the feasibility of the sensor in the diagnosis and monitoring of diabetic ketosis.