Visible-Light-Enhanced NO₂ Sensing Based on the Hybrid Orthorhombic/Monoclinic-PdSe₂ Nanostructures

Abstract

Palladium diselenide (PdSe2), as a member of two-dimensional dichalcogenides, has a puckered pentagonal structure and tends to exhibit distinct physical properties due to the various polymorphic phases. In contrast to conventionally orthorhombic PdSe2 (O-PdSe2), the fabrication of continuous metastable monoclinic PdSe2 (M-PdSe2) remains a challenge. Here, we report the polymorphic integration of orthorhombic and monoclinic PdSe2 crystals by concisely controlled selenization engineering under Se-sufficient and Se-deficient growth conditions. Thus, the hybrid O-PdSe2/M-PdSe2 (O/M-PdSe2) nanostructures were fabricated for the first time. We found that the O/M-PdSe2 nanostructures may be used as the broadband photodetector with a relatively high responsivity of 211.4 mA W–1, laying the foundation for the expansion of high-performance photoexcited gas sensors operating at room temperature. The O/M-PdSe2 sensor exhibited extremely fast response and recovery times (132/84 s) toward 10 ppm NO2 gas under 405 nm light illumination compared to the dark condition. In addition, according to the optical absorption spectra and ultraviolet photoemission spectroscopy analyses, the energy band alignment at the O/M-PdSe2 interface was determined, and the detailed gas-sensing mechanism was also proposed on this basis. This work realizes the continuous fabrication of the hybrid O/M-PdSe2 nanostructures with promisingly combined photoelectric and gas-electric properties, which may promote the development of high-performance multifunctional nanoelectronic devices to meet the global challenges of energy shortage and environmental protection.

First-Principles Study on the Selective Detection of Toxic Gases by 2D Monolayer PdS2: Insight into Charge Transfer Dynamics and Alignment of Frontier Molecular Orbitals

“…Therefore, the NO 2 , NO, and SO 2 gas molecules can strongly interact with the surfaces of monolayer MoS 2 , PdSe 2 , and graphene due to the comparable energies of the frontier molecular orbitals and band edges. Previous theoretical calculations and experiments confirm that these monolayer materials indeed can serve as promising gas sensors of NO 2 , NO, and SO 2 . ,,,,,, According to this screening criterion, unnecessary calculations can be avoided, and the appropriate adsorption gas molecules and substrate materials can be selected in advance, significantly saving the calculation time and accelerating the screening process.…”

“…Previous theoretical calculations and experiments confirm that these monolayer materials indeed can serve as promising gas sensors of NO 2 , NO, and SO 2 . 5,6,11,25,26,54,55 According to this screening criterion, unnecessary calculations can be avoided, and the appropriate adsorption gas molecules and substrate materials can be selected in advance, significantly saving the calculation time and accelerating the screening process.…”

“…20−24 Recent experiments and calculations have been conducted on monolayer and few-layer PdSe 2 gas sensors, and it has been found that PdSe 2 is a promising sensing material exhibiting sensitive responses toward nitrogen dioxide (NO 2 ) gas and good reusability at room temperature. 5,25,26 Unfortunately, there are no studies to explore whether the monolayer PdS 2 is suitable for gas sensors up to now.…”

“…Unlike most 2D TMDC materials, layered PdS 2 and PdSe 2 consist of Pd 2+ (d 8 ) ions coordinated by four (S 2 ) 2– or (Se 2 ) 2– dimer anions to form square-planar coordination and puckered pentagonal structure . The square-planar coordination in the 2 O phase PdS 2 or PdSe 2 is different from the octahedral (1 T phase) or trigonal prismatic (2 H phase) polyhedron in traditional TMDC materials, which allows it to generate a lot of interesting physicochemical properties. − Recent experiments and calculations have been conducted on monolayer and few-layer PdSe 2 gas sensors, and it has been found that PdSe 2 is a promising sensing material exhibiting sensitive responses toward nitrogen dioxide (NO 2 ) gas and good reusability at room temperature. ,, Unfortunately, there are no studies to explore whether the monolayer PdS 2 is suitable for gas sensors up to now.…”

Adsorption Behaviors of Small Molecules on Two-Dimensional Penta-NiN2 Layers: Implications for NO and NO2 Gas Sensors

“…The difference in the structural and electronic properties of 2D materials may lead to different adsorption strengths, sensitivity, and selectivity of the resulting nano gas sensors. − Choosing specific materials to detect and control target gas molecules can significantly improve the efficiency of the sensors. Previous works have shown that graphene can detect toxic gases, such as CO, NO, NO 2 , and NH 3 molecules. , However, phosphorene has a more significant band gap and electron mobility compared with graphene, which results in a higher affinity for gas molecules. , Its calculated gas adsorption energy and sensor sensitivity are significantly higher than graphene. − Further studies have indicated that the gas selectivities of 2D materials may diversify greatly. − Among graphene, silicene, phosphorene, and MoS 2 , MoS 2 has the highest adsorption intensity for CO molecule, , phosphorene has the most considerable adsorption energy of 0.86 eV for NO molecule, and silicene is the best for detecting NH 3 and NO 2 molecules …”