Design of p–p heterojunctions based on CuO decorated WS₂ nanosheets for sensitive NH₃ gas sensing at room temperature

Abstract

Tungsten disulfide (WS 2 ) nanosheets (NSs) have become a promising room-temperature gas sensor candidate due to their inherent high surface-to-volume ratio, tunable electrical properties, and high on-state current density. For further practical applications of WS 2 -based gas sensors, it is still necessary to overcome the insensitive response and incomplete recovery at room temperature. In this work, we controllably synthesized high-performance ammonia (NH 3 ) gas sensor based on CuO decorated WS 2 NSs. The optimized p-p WS 2 /CuO heterojunctions improve the surface catalytic effect, thereby enhancing the gas-sensing performance. The pure WS 2 NSs-based gas sensors showed a low response and an incomplete recovery in the case of NH 3 sensing. After the functionalization of CuO nanoparticles, the WS 2 /CuO heterostructurebased gas sensor exhibits an improved response value of 40.5% to 5 ppm NH 3 and full recoverability without any external assistance. Density functional theory calculations illustrate that the adsorption of CuO for NH 3 is much superior to WS 2 . The p-p heterojunctions strategy demonstrated in this work has great potential in the design of sensitive materials for gas sensors, and provides useful guidance for enhancing the room-temperature sensitivity and recoverability.

Nanoscale Heterostructured Materials Based on Metal Oxides for a Chemiresistive Gas Sensor

“…Typically, TMDs do not require any surface functionalization unlike graphene, which is chemically inert in nature, and they have higher gas adsorption capacity. They have layer dependent band gaps and high specific surface area, which makes them suitable candidates for gas sensing applications. − However, the intrinsic shortcomings of pure TMDs nanomaterials like high response time/incomplete recovery and cross selectivity limit their practical application. − Alternative strategies to improve their performance by designing semiconductor heterostructure that are constructed by integrating TMDs with metal oxides have been proposed by many authors with properties which are difficult to achieve in a single system. − Previously, Lee et al presented a comprehensive review on TMDs and metal oxide hybrids for gas sensing applications and their collaborative benefit in terms of geometric, electronic, and chemical effects . Although recent achievements in TMDs have promoted increasing research interest in hybrid nanostructures for sensing applications, significant research effort is necessary to unfold many uncertainties for real life applications.…”

Mesoporous WS2/MoO3 Hybrids for High-Performance Trace Ammonia Detection

“…38 These peaks moved toward lower binding energy, 2c). 29,43 Oxygen vacancy played a vital role in the performance improvement because they endowed film surfaces with more active sites. 29 However, MoO 3 showed a major O L peak (530.6 eV), two minor peaks of O V (531.7 eV) and O A (532.8 eV).…”

Oxygen Adsorption and Desorption Kinetics in CuO Nanowire Bundle Networks: Implications for MOx-Based Gas Sensors

“…Multiple works corresponding to CuO nanowires synthesized by different techniques and operated at temperatures between 160 and 325 °C were demonstrated as potential gas sensors for 500 ppb H 2 S, H 2 , , 10–30 ppm butanol, and 1–30 ppm CO . CuO has also been combined with other materials to enhance the gas-sensing properties, either to form an n–p heterostructure, for example, with MoS 2 of Al-doped ZnO for NH 3 sensing, , or a p–p heterostructure, for example, with Cu 2 O for NO 2 sensing, with NiO for glycol sensing, or with WS 2 for NH 3 sensing …”

“…18 Multiple works corresponding to CuO nanowires synthesized by different techniques and operated at temperatures between 160 and 325 °C were demonstrated as potential gas sensors for 500 ppb H 2 S, 19 H 2 , 16,20 10−30 ppm butanol, 13 and 1−30 ppm CO. 21 CuO has also been combined with other materials to enhance the gassensing properties, either to form an n−p heterostructure, for example, with MoS 2 of Al-doped ZnO for NH 3 sensing, 22,23 or a p−p heterostructure, for example, with Cu 2 O for NO 2 sensing, 24 with NiO for glycol sensing, 25 or with WS 2 for NH 3 sensing. 26 In the development of gas sensors, the sensor response and recovery times are important criteria for practical applications. 27 This is more specifically the case for conductometric gas sensors based on MOx, which are known for presenting responses significantly slower (typically on the order of minutes) than their optical counterparts (on the order of seconds).…”