Few‐Layered WS₂ Nanoplates Confined in Co, N‐Doped Hollow Carbon Nanocages: Abundant WS₂ Edges for Highly Sensitive Gas Sensors

Abstract

Edges of 2D transition metal dichalcogenides (TMDs) are well known as highly reactive sites, thus researchers have attempted to maximize the edge site density of 2D TMDs. In this work, metal-organic framework (MOF) templates are introduced to synthesize few-layered WS 2 nanoplates (a lateral dimension of ≈10 nm) confined in Co, N-doped hollow carbon nanocages (WS 2 _Co-N-HCNCs), for highly sensitive NO 2 gas sensors. WS 2 precursors are assembled in the surface cavity of Co-based zeolite imidazole framework (ZIF-67) and subsequent pyrolysis produced WS 2 _Co-N-HCNCs. During the pyrolysis, the carbonized ZIF-67 are doped by Co and N elements, and the growth of WS 2 is effectively suppressed, creating few-layered WS 2 nanoplates functionalized Co-N-HCNCs. The WS 2 _Co-N-HCNCs exhibit outstanding NO 2 sensing characteristics at room temperature, in terms of response (48.2% to 5 ppm), selectivity, response and recovery speed, and detection limit (100 ppb). These results are attributed to the enhanced adsorption and desorption kinetics of NO 2 on abundant WS 2 edges, confined in the gas permeable HCNCs. This work opens up an efficient way for the facile synthesis of edge abundant few-layered TMDs combined with porous carbon matrix via MOF templating route, for applications relying on highly active sites.

State of the Art in Alcohol Sensing with 2D Materials

“…The ability to prepare these groups of nanosheets in high yield and large scale via various methods, such as mechanical exfoliation [114], electrochemical lithiation [115], liquid exfoliation with sonication [116], and chemical vapour deposition (CVD) growth [117], has led to increasing studies on their hybridisation with other materials to create novel functional composites, aiming to engineer their chemical, physical, and electronic properties and thus achieve good performance for some specific applications. One of the most popular applications of TMDs is using them as photodetectors, gas sensors, moisture sensors, and biosensors [118][119][120][121][122][123][124]. Among members of this family, sulphides and selenides of Mo and W are the most studied with several investigations on tuning their properties through chemical functionalisation or pairing them with other 2D materials, such as graphene, through van der Waal forces to form what is known as 2D heterostructures [124].…”

Sensing Behavior of Two Dimensional Al- and P-Doped WS2 Toward NO, NO2, and SO2: an Ab Initio Study

“…However, pristine 2D WS 2 as a sensitive element has some disadvantages, such as weak adsorption with target gases, which cannot capture the gas molecules effectively [18]. In this case, doping is widely used in 2D materials to adjust the surface properties and binding force between materials and gas molecules and improve the adsorption and sensing capability of gases [19,20]. Of course, different dopants have different effects on the sensing performance.…”

Porous Ion Exchange Polymer Matrix for Ultrasmall Au Nanoparticle-Decorated Carbon Nanotube Chemiresistors

“…The N 1s peaks in XPS analysis show the characteristic peaks of pyridine N at 398.2 eV, imidazole N at 399.5 eV, and imidazole N + at 401.0 eV. 29,30 The XPS spectra of S 2p exhibit the sulfone groups in ITPES with the specific peaks at 168.5 eV for 2p 3/2 and 169.7 eV for 2p 1/2 . 31 Therefore, the XPS spectra of C 1s, N 1s, and S 2p confirm the that P4VP-SWCNT and ITPES are intact as expected, in the samples.…”