Mesoporous and Encapsulated In₂O₃/Ti₃C₂T_x Schottky Heterojunctions for Rapid and ppb-Level NO₂ Detection at Room Temperature

Abstract

Rapid and ultrasensitive detection of toxic gases at room temperature is highly desired in health protection but presents grand challenges in the sensing materials reported so far. Here, we present a gas sensor based on novel zero dimensional (0D)/two dimensional (2D) indium oxide (In 2 O 3 )/titanium carbide (Ti 3 C 2 T x ) Schottky heterostructures with a high surface area and rich oxygen vacancies for parts per billion (ppb) level nitrogen dioxide (NO 2 ) detection at room temperature. The In 2 O 3 /Ti 3 C 2 T x gas sensor exhibits a fast response time (4 s), good response (193.45% to 250 ppb NO 2 ), high selectivity, and excellent cycling stability. The rich surface oxygen vacancies play the role of active sites for the adsorption of NO 2 molecules, and the Schottky junctions effectively adjust the charge-transfer behavior through the conduction tunnel in the sensing material. Furthermore, In 2 O 3 nanoparticles almost fully cover the Ti 3 C 2 T x nanosheets which can avoid the oxidation of Ti 3 C 2 T x , thus contributing to the good cycling stability of the sensing materials. This work sheds light on the sensing mechanism of heterojunction nanostructures and provides an efficient pathway to construct high-performance gas sensors through the rational design of active sites.

P–N Heterojunction formation: Metal Sulfide@Metal Oxide Chemiresistor for ppb H2S Detection from Exhaled Breath and Food Spoilage at Flexible Room Temperature

“…X-ray diffraction analysis was conducted on pure In 2 O 3 nanofibers (NFs), pure MoS 2 nanosheets, and the In 2 O 3 @MoS 2 -2 nanofiber. In Figure , the diffraction peaks of In 2 O 3 point to the cubic phase In 2 O 3 (PDF#06-0416), with 2θ values of 30.58, 35.466, 51.037, and 60.67° corresponding to the (222), (400), (440), and (622) crystal planes, respectively . The diffraction peaks of MoS 2 are located at 2θ values of 33.02, 38.370, and 58.31°, corresponding to the hexagonal phase MoS 2 (PDF#17-0744) crystal planes of (101), (104), and (110) .…”