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Porous and hollow nanostructures functionalized with nanoscopic catalysts have attracted considerable interest in a wide range of applications depending on surface reactions. In this study, we present an efficient and versatile synthetic strategy of porous metal oxide hollow frameworks (HFs) decorated with noble metal nanoparticles (NPs). The key lies in the use of porous and bicontinuous polystyrene- block -poly(4-vinylpyridine) (PS- b -P4VP) microparticles as templates, which feature pores on the order of several hundred nanometers in size. Homogeneous Pt loading on the surface of the porous microparticles is achieved through the preferential adsorption of Pt precursors onto the P4VP block via electrostatic interactions. Subsequent SnO 2 thin film deposition and calcination ultimately yield honeycomb-like SnO 2 HFs with macropores and uniform distribution of Pt NPs. The Pt NP-loaded SnO 2 HFs exhibit exceptional formaldehyde (HCHO) sensing capabilities, characterized by remarkable sensitivity (31.4 at 5 ppm), rapid response time (4.7 s at 5 ppm), ultra-low detection limit of 10 ppb, and remarkable cross-selectivity. These outstanding features result from their high surface area, gas permeability within porous hollow structures, and well-dispersed Pt NPs, which catalytically activate the sensor. Our study provides great promise for advancing surface catalytic reactions due to their exceptional surface area and gas permeability, paving the way for future applications. [Display omitted] • We present an innovative synthetic strategy for the fabrication of Pt/SnO 2 hollow frameworks. • The key is the use of Pt-functionalized porous block copolymer microparticles as a sacrificial template. • The Pt/SnO 2 HFs demonstrate remarkable sensitivity (31.4 at 5 ppm), rapid response time (4.7 s at 5 ppm). • Our nanoscopic catalyst-loaded porous metal oxide hollow frameworks serve as a versatile catalytic platform. [ABSTRACT FROM AUTHOR]

Chemical sensors have been essential components in recent years due to the gathering attention in environmental monitoring and healthcare. In this review, the authors comprehensively highlight recent progresses on the 1D chemiresistive-type sensors based on semiconductor metal oxides (SMOs) and optical-type sensors, which are prepared by electrospinning technique. In the part of chemiresistive-type sensors, diverse synthesis techniques for 1D SMO nanofibrous structure are presented with controlled microstructure and surface morphology. In addition, unique functionalization routes of emerging nanocatalysts encapsulated by bio-inspired templates are described for the next generation catalyst on the 1D SMO nanofibers (NFs). For the optical-type sensors, new classes of 1D NFs employing specific absorption and emission properties are introduced. In particular, diverse 1D NF-based colorimetric and fluorescence sensors as well as Raman and surface-enhanced Raman scattering sensors are covered in the view point of material preparation and optical sensing properties. Finally, the authors prospect future research directions to overcome current limitations and challenges to achieve high performance chemical sensors. [ABSTRACT FROM AUTHOR]

Front Cover: The feature describes two different types of chemical sensors, i.e., chemiresistive type sensors and optical sensors. For the chemiresistive type sensors, electrical signals are modulated during the reaction with chemical gas species. On the other hand, distinctive color changes are occurred in the case of optical sensors after the reaction with chemical analytes. The feature is designed for the review paper about one‐dimensional nanofibrous sensing structures for chemiresistive type sensors and optical sensors. This is reported by Seon‐Jin Choi, Luana Persano, Andrea Camposeo, Ji‐Soo Jang, Won‐Tae Koo, Sang‐Joon Kim, Hee‐Jin Cho, Il‐Doo Kim and Dario Pisignano, in article number 1600569. [ABSTRACT FROM AUTHOR]

Electrospun WO 3 nanofibers (NFs) with hierarchically interconnected porosity (HP_WO 3 NFs) are designed by using dual sacrificial templates including zero-dimensional (0D) polystyrene (PS) colloids and one-dimensional (1D) multi-walled carbon nanotubes (MWCNTs). Multi-dimensionally interconnected pore-loaded structures offer much enhanced surface area and abundant gas penetration pathway into the inner sensing layers, which are essential requirements for effective gas adsorption-desorption reactions, fast gas diffusion, and high gas response. Moreover, such porous WO 3 NFs are homogeneously decorated by Pt nanoparticles (Apo-Pt) encapsulated in a protein nanocage, i.e., apoferritin, which enables uniform catalyst sensitization in interior and exterior of highly gas accessible NFs. The HP_WO 3 NFs sensitized by Apo-Pt (Apo-Pt@HP_WO 3 NFs) exhibited highly selective and sensitive acetone response (R air /R gas  = 10.80 ± 0.06 @ 1 ppm) under high humidity atmosphere (90% RH). To investigate the potential suitability as exhaled breath analyzers, we tested three sensor arrays consisting of mesoporous WO 3 NFs templated by MWCNTs (MP_WO 3 NFs), HP_WO 3 NFs, and Apo-Pt@HP_WO 3 NFs. The result revealed that targeted acetone molecules were clearly classified against six different interfering molecules (H 2 S, C 7 H 8 , C 2 H 5 OH, CO, NH 3 and CH 4 ) through principle component analysis (PCA), confirming excellent acetone selectivity of the designed sensor arrays. [ABSTRACT FROM AUTHOR]