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[Display omitted] • Decreasing Ce/Zr molar ratio improves the thermal stability and catalytic activity. • Increasing Ce/Zr molar ratio within 0.89 ∼ 1.44 clearly inhibits the growth of Pt particles. • The main factor affecting catalyst activity is the valence state of Pt. The synthesis of Pt-supported catalysts with high stability faces an enormous challenge, especially for applications in high-temperature environments. Here we attempt to improve the catalytic activity and thermal stability of Pt-supported catalyst via modulating Ce/Zr molar ratio. The crystalline structure, texture and metal dispersion of the Pt/Ce x Zr 1-x samples were studied by XRD, Raman, XPS, HRTEM and H 2 -TPR. The results indicate that decreasing Ce/Zr molar ratio can improve the thermal stability, the reducibility of surface lattice oxygen of the catalyst, and enhance the oxygen vacancy content. On the contrary, a higher Ce/Zr molar ratio facilitates the interaction between Pt and CeO 2 and inhibits the growth of Pt particles thereby maintaining high Pt dispersion. The Pt/Ce x Zr 1-x catalysts with Ce/Zr molar ratio of ∼1.0 might exhibited the best overall catalytic performance within long-term use. The effect of the valence state of Pt on catalytic activity is greater than that of the Pt dispersion. Our findings contribute to a depth understanding of Pt/CeZr catalysts and provide insights into the design of more efficient and durable catalysts for automotive exhaust purification. [ABSTRACT FROM AUTHOR]

Development of high performance room temperature sensors remains a grand challenge for high demand of practical application. Metal oxide semiconductors (MOSs) have many advantages over others due to their easy functionalization, high surface area, and low cost. However, they typically need a high work temperature during sensing process. Here, p-type sensing layer is reported, consisting of pore-rich dumbbell-like Co 3 O 4 particles (DP-Co 3 O 4 ) with intrinsic high catalytic activity. The gas sensor (GS) based DP-Co 3 O 4 catalyst exhibits ultrahigh NH 3 sensing activity along with excellent stability over other structure based NH 3 GSs in room temperature work environment. In addition, the unique structure of DP-Co 3 O 4 with pore-rich and high catalytic activity endows fast gas diffusion rate and high sensitivity at room temperature. Taken together, the findings in this work highlight the merit of integrating highly active materials in p-type materials, offering a framework to develop high-sensitivity room temperature sensing platforms. [ABSTRACT FROM AUTHOR]

Abstract: Cu–Zn/ZnO nanocomposites with a novel core-shell structure have been prepared by a surface precipitation process in aqueous solution. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy are employed to analyze the structure and morphology of the present products. The influence of the annealing temperature on the core-shell structure of the nanocomposites is investigated, and a possible growth model is proposed. Furthermore, the gas sensors based on the Cu–Zn/ZnO nanocomposites are fabricated and tested, which exhibits high sensitivity and fast response to CO. The best results are obtained for the sensor based on the film annealed at 350°C, which shows that the sensitivity is about 6.3 when the sensor is exposed to 100ppm CO at the operating temperature of 240°C. The possible sensing mechanism of the Cu–Zn/ZnO sensing film has also been discussed. [Copyright &y& Elsevier]

In this work, core-shell WO 3 -SnO 2 (CS-WS) nanofibers (NFs) have been successfully synthesized via a coaxial electrospinning approach. The structure and morphology characteristics of the resultant products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS). To investigate the sensing mechanism of the CS-WS NFs, sensors based on SnO 2 NFs, WO 3 NFs, and SnO 2 -WO 3 composite NFs were fabricated respectively, and their gas sensing properties were investigated by using CO, ethanol, toluene, acetone, and ammonia as the test gas. The results indicated that the CS-WS NFs exhibited a good response to ethanol (5.09 at 10 ppm) and short response/recovery time (18.5 s and 282 s) compared with the other test gases. The enhanced ethanol sensing properties of CS-WS NFs compared with those of SnO 2 NFs were closely associated with the CS structure and its derivative effect due to the different work function of SnO 2 and WO 3 . The approach proposed in this study may contribute to the realization of more sensitive metal oxide semiconductor (MOS) core-shell heterostructure sensors. [ABSTRACT FROM AUTHOR]

Abstract: K2CO3-SBA-15 with different K2CO3 content was prepared by thermal dispersion. The structures of resultant powders were characterized by XRD, N2 adsorption and IR. The humidity sensing properties of the powders were also investigated. Compared with pure SBA-15, K2CO3-SBA-15 shows improved humidity sensing properties and the introducing level of K2CO3 has a great influence on the humid sensitivity of K2CO3-SBA-15 composites. The optimal mixing ratio was K2CO3-SBA-15 (0.8g/g), which exhibited excellent linearity in the whole range of 11–95%RH, a resistance variation of about five orders of magnitude, and a rapid response time and recovery time about 15 and 50s, respectively. The mechanism of the humidity sensitive properties was also discussed. [Copyright &y& Elsevier]