Humidity Sensing by Graphitic Carbon Nitride Nanosheet/TiO₂ Nanoparticle/Ti₃C₂T_x Nanosheet Composites for Monitoring Respiration and Evaluating the Waxing of Fruits

Abstract

Relative humidity (RH) is an important physical quantity in industry, agriculture, and medical treatment. However, it is still challenging to exploit high-performance humidity sensors that can meet the detection requirement for responding to both high humidity variation and low humidity variation. In this work, ternary graphitic carbon nitride (g-C 3 N 4 ) nanosheet/TiO 2 nanoparticle/Ti 3 C 2 T x nanosheet composites were synthesized by in situ oxidation and thermal polymerization. The response of the g-C 3 N 4 /TiO 2 /Ti 3 C 2 T x sensor reaches 531 from 11−95% RH, which enhances 4, 11, and 450 times compared with that of TiO 2 , g-C 3 N 4 , and TiO 2 /Ti 3 C 2 T x sensors. Moreover, the ternary g-C 3 N 4 /TiO 2 /Ti 3 C 2 T x sensor demonstrates excellent reproducibility, fast response speed, low hysteresis loop, and good anti-interference ability. The as-fabricated g-C 3 N 4 /TiO 2 /Ti 3 C 2 T x sensor is further utilized in practical applications for human respiration detection and evaluation of waxing of fruits. The test results show that our fabricated sensor is capable of precisely sensing breathing status and distinguishing the waxing of fruits. In addition, our sensor can be used in most application scenarios and accelerate the integration of the Internet of Things (IoT).

Photoacid-Loaded Nanopores of Hollow Mesoporous Organosilica Capsules for Fluorescent Humidity Sensing

“…Besides the performance evaluation under static RHs, we further examined the humidity sensors for human respiration. ,,− We first quantitatively examined the response and recovery time of sensors 1 and 2 with a single breath. As illustrated in Figure a,b, color change response times of sensors 1 and 2 are estimated to be 0.8 and 1.3 s, respectively.…”

“…Fast and robust humidity sensing has wide applications in research, medical, and industrial scenes. − Among the abundant diversity of strategies, the mainstream of reported strategies for humidity sensing is electronic-based sensing. The impedance, , capacitance, voltage, or current signals of a semiconductor can be slightly affected by water vapor in ambient air, which poses fundamental principles of electronic-based humidity sensors. Taking advantage of the ultra-sensitive detection of electronic signals, the electronic-based humidity sensing exhibits excellent sensitivity, fast response, and recovery.…”

Enhancement of Photoactivity of TiO2 for Potential Applications in CO2 Conversion and Water Splitting: A Hybrid Density Functional Theory Study

“…TiO 2 has attracted extensive attention as a promising multifunctional material for the generation of H 2 through water splitting, , degradation of environmental pollutants, lithium battery applications, , biomedical applications including cancer therapy, , photovoltaic applications, − CO 2 conversion, − and sensor applications. − However, due to a wide band gap (3.20 eV for anatase), TiO 2 shows photoactivity only under ultraviolet-light (UV) irradiation, which accounts for a smaller fraction (less than 5%) of solar energy . It is preferable that the band gap of the photocatalyst would be less than 3.0 eV for the effective utilization of sunlight.…”

Effect of Open Metal Sites in Cobalt-Based Bimetallic Metal–Organic Framework Nanoparticles-Coated Quartz Crystal Microbalance (QCM) for Humidity Detection

“…Due to some special needs in the production and life of modern society, humidity is key factor in the manufacture and life of human beings. Real-time monitoring of relative humidity (RH) is an indispensable technique in various fields such as environmental survey, industrial and agricultural production, food preservation, and biomedical science. − Some researchers report that the most suitable environmental humidity for people’s life is between 30% and 55% RH. The risk of bacterial growth will increase when the humidity is too high, which may threaten life.…”