Micellar Nanoreactors Enabled Site‐Selective Decoration of Pt Nanoparticles Functionalized Mesoporous SiO₂/WO_3‐x Composites for Improved CO Sensing

Abstract

Site‐selective and partial decoration of supported metal nanoparticles (NPs) with transition metal oxides (e.g., FeOx) can remarkably improve its catalytic performance and maintain the functions of the carrier. However, it is challenging to selectively deposit transition metal oxides on the metal NPs embedded in the mesopores of supporting matrix through conventional deposition method. Herein, a restricted in situ site‐selective modification strategy utilizing poly(ethylene oxide)‐block‐polystyrene (PEO‐b‐PS) micellar nanoreactors is proposed to overcome such an obstacle. The PEO shell of PEO‐b‐PS micelles interacts with the hydrolyzed tungsten salts and silica precursors, while the hydrophobic organoplatinum complex and ferrocene are confined in the hydrophobic PS core. The thermal treatment leads to mesoporous SiO2/WO3‐x framework, and meanwhile FeOx nanolayers are in situ partially deposited on the supported Pt NPs due to the strong metal‐support interaction between FeOx and Pt. The selective modification of Pt NPs with FeOx makes the Pt NPs present an electron‐deficient state, which promotes the mobility of CO and activates the oxidation of CO. Therefore, mesoporous SiO2/WO3‐x‐FeOx/Pt based gas sensors show a high sensitivity (31 ± 2 in 50 ppm of CO), excellent selectivity, and fast response time (3.6 s to 25 ppm) to CO gas at low operating temperature (66 °C, 74% relative humidity).

Theoretical Validation of Non-Noble Cu Sites Integrated on SnO2 Nanoflowers for Enhanced Gas Sensing of Ethanethiol at Room Temperature

“…The influence of specific surface area on gas-sensing characteristics is widely acknowledged, with pronounced effects observed in 1D and layered nanomaterials . Nevertheless, it is crucial to recognize the involvement of additional structural factors in shaping the gas-sensing properties of three-dimensional (3D) sensing materials, such as the pivotal role played by the thickness of the pore wall. , For example, mesoporous materials find extensive use in gas sensing, where the enhancement of performance is significantly influenced by Knudsen diffusion and interfacial catalysis. , Consequently, it is speculated that the diffusion path of EtSH, both on the surface and within the sensing material, plays a significant role in influencing the performance of the sensor. The increase in the concentration of non-noble Cu sites engenders an amplification in the specific surface area of SnO 2 nanoflowers.…”

Microflowers Composed of VO2 Nanoflakes for Selective Detection of Acetone and Ammonia

“…For gas sensors, unique performances like good sensitivity, specific selectivity, and fast response/recovery are highly desired. In recent decades, metal oxide semiconductors (MOS; e.g., TiO 2 , SnO 2 , ZnO, WO 3 , and In 2 O 3 − ) have been widely used in gas sensors due to their low price and good sensitivity to a broad range of gases. However, they typically operate at high temperatures and show a poor gas selectivity.…”

A Novel Molten Salt Mediated Synthesis of Mesoporous Metal Oxides with High Crystallization

“…The typical synthesis of mesoporous metal oxides usually includes two main steps: the formation of mesostructure using a metal precursor and template (hard-template or soft-template) and the subsequent high-temperature crystallization as well as template removal. − The hard-template method, similar to nanocasting, starts with infiltrating precursors into ordered mesoporous carbon or mesoporous silica (MCM-41, KIT-6, SBA-15) and then etching off the template to obtain the inverse mesostructure . Gu et al synthesized mesoporous ZrO 2 as a hard template, in which the surface-modified functional groups help to enhance the interaction between the template and the precursor.…”