Noble metal

About: Noble metal is a research topic. Over the lifetime, 15113 publications have been published within this topic receiving 337947 citations.

The incorporation of noble metal nanoparticles into host matrix thin films: synthesis, characterisation and applications

Abstract: This feature article focuses on the synthesis of noble metal nanoparticles and how these particles can be incorporated into thin films. The functional properties of the nanoparticles when embedded in a host matrix are covered. In particular the optical properties of noble metal nanoparticles, numerical theory, including Mie and Maxwell–Garnet equations are explained with particular attention on photoluminescence, photochromic and electrochromic properties. The dielectric effect of the host matrix and the influence on the surface plasmon resonance are explored. Future research applications and trends in the field are highlighted.

Boosting Electrochemical Water Oxidation with Metal Hydroxide Carbonate Templated Prussian Blue Analogues

Abstract: The development of efficient and stable catalyst systems with low-cost, abundant, and non-toxic materials is the primary demand for electrochemical water oxidation. A unique method is reported for the syntheses of metal hydroxide carbonate templated Prussian blue analogues (PBAs) on carbon cloth and their outstanding water oxidation activities in alkaline medium. The best water oxidation activity is obtained with cobalt hydroxide carbonate templated t-CoII-CoIII with an overpotential as low as 240 mV to reach a current density of 10 mA cm−2. It produces constant current over 50 h in chronoamperometric measurements. Moreover, the catalysts outperform the activities of the PBAs prepared without any template and even the noble metal catalyst RuO2. Spectroscopic and microscopic studies show that the PBAs are transformed into layered hydroxide–oxyhydroxide structures during electrochemical process and provide the active sites for the water oxidation.

In situ encapsulation of core–shell-structured Co@Co3O4 into nitrogen-doped carbon polyhedra as a bifunctional catalyst for rechargeable Zn–air batteries

Abstract: The traditional oxygen reduction/evolution reaction (ORR/OER) catalysts are mainly noble metal-based materials, but their scarcity and instability impede their practical applications, especially in Zn–air batteries. Hence, identifying a bifunctional catalyst with low-cost and high-stability is very crucial for Zn–air batteries. Herein, we report a simple method to prepare core–shell-structured Co@Co3O4 nanoparticles encapsulated into N-doped carbon polyhedra by carbonization and controlled oxidation of metal–organic frameworks (MOFs), which are then applied as a bifunctional catalyst for Zn–air batteries. Using such a configuration, enhanced performances, including a high power density of ∼64 mW cm−2, a stable voltage profile over 80 h battery operation with four mechanical recharges, a small discharge/charge overpotential of ∼0.66 V and a long-life of 100 cycles for 200 h operation at 5 mA cm−2, have been achieved. These excellent performances can be attributed to abundant graphited carbon and CNTs, high N-doping, plentiful pores, the synergy between the semiconductive Co3O4-coating layer and the conductive Co bulk, and the uniform Co@Co3O4 nanoparticles in this catalyst which effectively improve electrical conductivity/ion transfer and further concertedly promote the catalytic activity towards the ORR/OER. Moreover, the belt-shaped polymer Zn–air battery with this catalyst also shows good electrochemical stability under different deformations.

Preferential oxidation of carbon monoxide catalyzed by platinum nanoparticles in mesoporous silica.

Abstract: Preferential oxidation (PROX) of CO is an important practical process to purify H2 for use in polymer electrolyte fuel cells. Although many supported noble metal catalysts have been reported so far, their catalytic performances remain insufficient for operation at low temperature. We found that Pt nanoparticles in mesoporous silica give unprecedented activity, selectivity, and durability in the PROX reaction below 353 K. We also studied the promotional effect of mesoporous silica in the Pt-catalyzed PROX reaction by infrared spectroscopy using the isotopic tracer technique. Gas-phase O2 is not directly used for CO oxidation, but the oxygen of mesoporous silica is incorporated into CO2. These results suggest that CO oxidation is promoted by the attack of the surface OH groups to CO on Pt without forming water.