In situTEM observation of solid-gas reactions

Gas Sensors Based on Chemi-Resistive Hybrid Functional Nanomaterials

Chemi-resistive sensors based on hybrid functional materials are promising candidates for gas sensing with high responsivity, good selectivity, fast response/recovery, great stability/repeatability, room-working temperature, low cost, and easy-to-fabricate, for versatile applications. This progress report reviews the advantages and advances of these sensing structures compared with the single constituent, according to five main sensing forms: manipulating/constructing heterojunctions, catalytic reaction, charge transfer, charge carrier transport, molecular binding/sieving, and their combinations. Promises and challenges of the advances of each form are presented and discussed. Critical thinking and ideas regarding the orientation of the development of hybrid material-based gas sensor in the future are discussed.

Catalytic behavior of noble metal nanoparticles for the hydrogenation and oxidation of multiwalled carbon nanotubes

The catalytic behavior of various noble metal nanoparticles (NPs) supported directly on multiwalled carbon nanotubes (MWCNTs) was observed using environmental transmission electron microscopy (E-TEM). Gasification of the MWCNTs via catalytic hydrogenation or oxidation progressed at ∼450°C in conjunction with certain noble metal NP catalysts at the interface between MWCNTs and the NPs. During such catalytic reactions, the NPs were observed to move rapidly over the MWCNT surfaces. The mobility and wettability of the NPs varied depending on the particular metal NPs employed and the ambient atmosphere. While rhodium NPs exhibited high wettability under both hydrogen and oxygen atmospheres, the wettability of platinum, palladium and iridium NPs on MWCNTs varied with the atmosphere. The metal NPs seemed to have high degrees of crystallinity while their morphologies fluctuated throughout the catalytic reactions.