Controlling the Crystal Phase Structure of WO₃ Nanosheet-Based Hierarchical Spheres for Enhanced Gas Sensing Performance

Abstract

The pursuit of high performance is the eternal theme in gas sensor research. Because of the complexity of the response and recovery processes, the selective detection, high response, rapid response, and recovery remain challenging in the atmospheric environment. In this paper, WO3 hierarchical spheres (WO3 HS) with different crystalline phase ratios are successfully synthesized to evaluate the relationship between the phase structure and gas-sensitive properties. The as-prepared WO3-2 HS samples achieve superior gas sensing characteristics including high response (S = 24.2) and fast response and recovery speed (1 and 19 s) to 100 ppm acetone at 300 °C. The superior acetone sensing performance probably originates from the regulation of the phase ratios of nanosheet-based WO3. With the decrease of orthorhombic phase and the increase of monoclinic phase, the specificity detection to acetone is increased significantly. The reasons for such a huge selectivity change are discussed in detail. From the perspective of reaction kinetics, we also compare the contributions of specific surface area and crystalline phase impacting the gas sensing performance.

In Situ Synthesis of Mixed-Phase WO3 on Nitrogen-Doped Graphene with Enhanced Photoelectric Properties

“…Compared to WO 3 (0.35 × 10 –4 A/cm 2 ), WO 3 /rGO (0.78 × 10 –4 A/cm 2 ), and WO 3 /N-rGO (2.04 × 10 –4 A/cm 2 ) exhibit stronger photocurrent, which is considered as the strategy of integrating WO 3 with rGO and N-rGO. Graphene can rapidly transfer photogenerated carriers to external circuits due to its high electrical conductivity. , In addition, the photocurrent of WO 3 /N-rGO is 2.6 times as high as that of WO 3 /rGO due to the formation of phase junction between monoclinic WO 3 and orthorhombic WO 3 , − and the doping of N. , The phase junction effectively promotes the separation of electron–hole pairs, while the nitrogen doping lowers the Schottky junction barrier of WO 3 /N-rGO and facilitates the transfer of electrons from WO 3 to N-rGO . The rise–decay dynamics of transient photocurrent measurement provide direct information on trapping, recombination, and charge transport .…”

Innovations in WO3 gas sensors: Nanostructure engineering, functionalization, and future perspectives

“…The bandgaphas implications for electrical conductivity, optical absorption, photocatalysis, and photoactivation effects [ 11 ]. For gas sensing, smaller bandgaps can enable room temperature activation but may impact selectivity [ 12 ]. Larger bandgaps improve stability but increase the operating temperature.…”

Review on Porosity Control in Nanostructured Semiconducting Metal Oxides and Its Influence on Chemiresistive Gas Sensing

“…In recent years, there has been a growing interest in the synthesis and application of chemiresistive materials such as semiconducting metal oxides (SMOs), − metals, , transition-metal dichalcogenides, − metal–organic frameworks, graphite, graphene, , black phosphorus, , MXenes, and their composites − for gas-sensing applications. Among them, SMOs have been widely used as gas-sensing layers due to their superior gas sensitivity at elevated temperatures. − In particular, nanostructured materials have been actively investigated in the gas sensor .…”