Highly dispersed Au nanoparticles decorated WO3 nanoplatelets: Laser-assisted synthesis and superior performance for detecting ethanol vapor.

Loading of noble metal nanoparticles (NPs) on the surfaces of semiconductor oxides to form a hybrid nanostructure is an effective strategy to improve gas-sensing performance. In this study, WO3 nanoplatelets decorated with Au NPs were prepared by laser ablation in liquids (LAL) with subsequent aging and annealing treatments. Results indicated that Au NPs with an average size of 7.8 ±â€¯2.5 nm were highly dispersed on the surface of WO3 nanoplatelets. As gas-sensing materials, the obtained Au-decorated WO3 nanoplatelets showed lower operating temperature of 320 °C and higher response value of 3.5-fold in detecting ethanol molecules compared with pure WO3 nanoplatelets. Moreover, Au-decorated WO3 nanoplatelets displayed good selectivity toward ethanol compared with other tested vapors and excellent stability within several cycled measurements. These results can be ascribed to the supported Au NPs, which promote the adsorption and dissociation of oxygen species, eventually resulting in accelerated electron depletion on the surface of Au-WO3 hybrids.

Laser-Irradiation-Induced Melting and Reduction Reaction for the Formation of Pt-Based Bimetallic Alloy Particles in Liquids.

Laser melting in liquids (LML) is one of the most effective methods to prepare bimetallic alloys; however, despite being an ongoing focus of research, the process involved in the formation of such species remains ambiguous. In this paper, we prepared two types of Pt-based bimetallic alloys by LML, including Pt-Au alloys and Pt-iron group metal (iM=Fe/Co/Ni) alloys, and investigated the corresponding mechanisms of alloying process. Detailed component and structural characterizations indicate that laser irradiation induced a quite rapid formation process (not exceeding 10 s) of Pt-Au alloy nanospheres, and the crystalline structures of Pt-Au alloys is determined by the monometallic constituents with higher content. For Pt-iM alloys, we provide direct evidence to support the conclusion that FeOx /CoOx /NiOx colloids can be reduced to elementary Fe/Co/Ni particles by ethanol molecules during laser irradiation, which then react with Pt colloids to form Pt-iM sub-microspheres. These results demonstrate that LML provides an optional route to prepare Pt-based bimetallic alloy particles with tunable size, components, and crystalline phase, which should have promising applications in biological and catalysis studies.

A novel reduction approach to fabricate quantum-sized SnO2-conjugated reduced graphene oxide nanocomposites as non-enzymatic glucose sensors.

Quantum-sized SnO2 nanocrystals can be well dispersed on reduced graphene oxide (rGO) nanosheets through a convenient one-pot in situ reduction route without using any other chemical reagent or source. Highly reactive metastable tin oxide (SnO(x)) nanoparticles (NPs) were used as reducing agents and composite precursors derived by the laser ablation in liquid (LAL) technique. Moreover, the growth and phase transition of LAL-induced SnO(x) NPs and graphene oxide (GO) were examined by optical absorption, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and high-resolution transmission electron microscopy. Highly dispersed SnO(x) NPs can also prevent rGO from being restacked into a multilayer structure during GO reduction. Given the good electron transfer ability and unsaturated dangling bonds of rGO, as well as the ample electrocatalytic active sites of quantum-sized SnO2 NPs on unfolded rGO sheets, the fabricated SnO2-rGO nanocomposite exhibited excellent performance in the non-enzymatic electrochemical detection of glucose molecules. The use of LAL-induced reactive NPs for in situ GO reduction is also expected to be a universal and environmentally friendly approach for the formation of various rGO-based nanocomposites.