Development of a rGO-BiVO₄ Heterojunction Humidity Sensor with Boosted Performance

Abstract

Humidity sensors with good repeatability, low hysteresis, and low-power consumption are increasingly important for environmental monitoring and industrial control applications. Herein, an impedance-type humidity sensor under low working voltage (5 mV) utilizing a rGO-BiVO4 nanocomposite is demonstrated. The rGO-BiVO4 humidity sensor exhibits superior sensing performances, including good repeatability, negligible hysteresis (0.47%), fast response and recovery time, low power consumption, good stability, and anti-interference ability. The ultraviolet–visible absorption spectrum reveals that the narrow band gap of the rGO-BiVO4 nanocomposite is conductive to the electron transfer. The complex impedance spectra and the energy band structure analysis further suggest that the boosted humidity performance results from the formation of a heterojunction and the decrease of the heterojunction barrier height. The facile fabrication route, enhanced sensing performance, and excellent device reliability make the rGO-BiVO4 sensor highly attractive for high-end humidity sensing applications.

Evaluation of the Humidification Effect of Street Trees Based on All-Inorganic Lead-Free K2CuBr3 Humidity Sensors

“…As the RH level exceeds 75%, upturned tails signifying Warburg impedance ( Z w ) emerge at a low frequency. Warburg impedance essentially refers to the impedance at the interfaces of the K 2 CuBr 3 sensing film and the Ag–Pd electrode caused by the diffusion process of carriers . The EC model, as shown in Figure d, is further updated as the newly added Warburg impedance connected in series with the aforementioned parallel circuit.…”

Multifunctional Flexible Humidity Sensor Systems Towards Noncontact Wearable Electronics

“…Copyright 2016 Elsevier. ( g ) Schematic diagram of the sensing mechanism [ 80 ]. Copyright 2021 ACS Publications.…”

“…The impedance-frequency testing as a function of RH shows that the frequency from 1 Hz to 1 kHz has almost no effect on the sensor output. However, the impedance tends to dramatically decrease when the frequency is over 100 kHz [ 80 ]. Overall, to apply the impedance-type humidity sensors for practical monitoring, it is of high importance to find the optimal operation frequency.…”

“…Similar to metal sulfides, metal oxides-based nanomaterials also exhibit hydrophilic property for sensitive humidity sensors [ 105 ]. Owing to the relatively narrow bandgap nature, metal-oxides nanomaterials with excellent electronic properties are mainly applied for resistive or impedance-type flexible humidity sensors [ 80 , 106 ]. Until now, various metal oxides including TiO 2 , ZnO, CuO, SnO 2 , MoO 3 , and HNb 3 O 8 have been applied as the active materials in response to humidity changes [ 46 , 50 , 75 , 107 – 109 ].…”

Humidity Sensing by Graphitic Carbon Nitride Nanosheet/TiO2 Nanoparticle/Ti3C2Tx Nanosheet Composites for Monitoring Respiration and Evaluating the Waxing of Fruits

“…To enhance the humidity sensing response and detection range, as well as reduce the response time, two-dimensional (2D) materials have gained the attention of researchers due to their large specific surface area and adjustable surface properties, exhibiting great potential for humidity sensing. − MXenes are a kind of transition metal carbides and carbonitrides which are synthesized by etching the A layers from the MAX phases. These are called MAX phases because of their chemical composition: M n +1 AX n , where M represents the transition metal, A is the element belonging to the IIIA or IVA groups, X is C or N, and n = 1, 2, and 3. , Among numerous MXenes, Ti 3 C 2 T x is a typical MXene with extensive and in-depth research.…”