Edge‐Enriched Mo₂TiC₂T_x/MoS₂ Heterostructure with Coupling Interface for Selective NO₂ Monitoring

Abstract

Endowed with rich terminal groups, good electrical conductivity, and controllable structure, transition metal carbides/nitrides (MXenes) have attracted extensive attention for potential application in gas sensor, but long-standing challenges of the MXenes (titanium carbide as the representative) are their limited selectivity and sensitivity. Herein, a high-active double transition-metal titanium molybdenum carbide (Mo 2 TiC 2 T x ) with superstrong surface adsorption (−3.12 eV) for NO 2 gas molecule is proposed, and it is further coupled with molybdenum disulfide (MoS 2 ) by interface modulation to construct an edgeenriched heterostructure. Due to the synergistic effect of strong adsorption, rich adsorption sites, and coupling interface of Mo 2 TiC 2 T x /MoS 2 composite, the as-fabricated Mo 2 TiC 2 T x /MoS 2 gas sensor exhibits an outstanding response toward NO 2 with high selectivity against various interference gases, which is well supported by density functional theory calculations. Meanwhile, the sensor exhibits a sensitivity of 7.36% ppm −1 , detection limit of 2.5 ppb, and reversibility at room temperature. A portable, wireless NO 2 monitoring system is demonstrated for gas leakage searching and dangerous warning based on Mo 2 TiC 2 T x /MoS 2 gas sensor. This work facilitates the gas sensing application of MXenes, and provides an avenue for the development of wireless sensing system in environmental monitoring and safety assurance.

Single-step growth of p-type 1D Se/2D GeSexOy heterostructures for optoelectronic NO2 gas sensing at room temperature

“…A depletion layer at the interface between the GeSe x O y nanosheet and Se belt is formed, in which the width of the depletion region ( W ) can be calculated by following eqn (1)–(3). 74–76 Here, ε is the static dielectric constant; Δ V is the built-in potential difference between the GeSe x O y nanosheet and Se belt; N is the carrier concentration; q is the charge carried by the carrier. The specific values of each parameter are as follows: ε Se = 0.54 × 10 −10 F m −1 , 76 ε GeSe x O y = 1.35 × 10 −10 F m −1 , 77 N Se = 1 × 10 14 cm −3 , 78 N GeSe x O y = 1.93 × 10 15 cm −3 ; 79 Ф Se = 5.16 eV, Ф GeSe x O y = 4.82 eV, and q = 1.6 × 10 −19 C. As a result, the calculated depletion layer width of GeSe x O y and Se is around 1.2 nm and 14.4 nm, respectively.…”

“…A depletion layer at the interface between the GeSe x O y nanosheet and Se belt is formed, in which the width of the depletion region (W) can be calculated by following eqn (1)-(3). [74][75][76]…”

Black Phosphorus Nanosheet/Tin Oxide Quantum Dot Heterostructures for Highly Sensitive and Selective Trace Hydrogen Sulfide Sensing

“…Alternatively, two-dimensional (2D) layered nanomaterials, such as graphene and transitional metal dichalcogenides, were leveraged to construct heterojunctions with the SnO 2 material by virtue of their admirable advantages of large surface area, excellent electrical conductivity, and versatile layer-dependent properties . Moreover, 2D nanomaterials could serve as platforms to produce mixed-dimensional heterostructures. , For instance, Viet et al synthesized composites of 2D/1D molybdenum disulfide (MoS 2 ) nanoflakes/SnO 2 nanofibers for SO 2 detection, and compared to pure SnO 2 , these composites significantly lowered the OT and augmented the response. Song et al realized improved H 2 S sensing based on heterojunctions of 2D/1D graphene oxide (GO) nanosheets/SnO 2 nanowires .…”

Computational Screening of Ti3C2TX MXene by Controlling the Functionalized Catalyst for NH3 Gas Sensor

“…[16] It is well known that the key step of heterogeneous catalytic reactions is the adsorption and activation between the gas molecules and the functionalized surface catalysts of sensing materials. [17,18] An effective method to understand the interaction of gas molecules with sensing materials at the atomic level is the first principles of density-functional theory (DFT) [19][20][21] . Most of the first principles calculation reports focus on the discussion between Ti 3 C 2 T x (T X = O) and NH 3 or other gases.…”