Noble metal

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

Boosting up the Low Catalytic Activity of Silver for H2 Production on Ag/TiO2 Photocatalyst: Thiocyanate as a Selective Modifier

Abstract: Noble metal cocatalysts like Pt have been widely employed as an essential ingredient in many kinds of photocatalytic materials for solar hydrogen production. The high material cost of Pt is the biggest limitation. Silver is far less expensive but much less active than Pt and Au as a hydrogen evolving catalyst. Here we demonstrate a new strategy to boost up the activity of silver in Ag/TiO2 for photocatalytic H2 production via forming a simple surface complexation of thiocyanate (SCN–) on silver. The addition of thiocyanate in the suspension of Ag/TiO2 markedly enhanced the photocatalytic production of H2 by about 4 times. Thiocyanate was not consumed at all during the photoreaction, which ruled out the role of thiocyanate as an electron donor. Such a positive role of thiocyanate was not observed with bare TiO2, Pt/TiO2, and Au/TiO2. The selective chemisorption of thiocyanate on silver was confirmed by the analyses of Raman spectroscopy and spot-profile energy-dispersive spectroscopy. In the presence of th...

Oxygen vacancy enhanced catalytic activity of reduced Co3O4 towards p-nitrophenol reduction

Abstract: With the aim of replacing noble metal-based catalysts, many efforts have been devoted to the development of highly active non-noble metal-based catalysts for the reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) by NaBH4. As a typical transition metal oxide, pristine Co3O4 is normally considered to be poorly active towards the reduction of p-NP to p-AP. In this work, the catalytic activity of pristine Co3O4 was remarkably enhanced by a facile surface reduction with aqueous NaBH4. With the characterization results of various techniques such as XRD, TEM, H2-TPR and XPS, the enhancement in the catalytic activity was attributed to the oxygen vacancies generated during the surface reduction process. The catalytic activity of reduced Co3O4 was found to be strongly dependent on the reduction time and NaBH4 concentration used for catalyst preparation. Through the surface reduction with 0.05 mol/L aqueous NaBH4 for 40 min, the as-prepared reduced Co3O4 showed the best catalytic activity in term of the shortest induction time (

Effects of support identity and metal dispersion in supported ruthenium hydrodeoxygenation catalysts

Abstract: Substituted phenols are the most recalcitrant oxygenates in conventional pyrolysis oils and the dominant oxygenates in lower-oxygen content, formate-assisted pyrolysis oils (FAsP). Ru catalysts with a wide range of dispersion on carbon, silica, alumina, and titania supports were synthesized, characterized and evaluated for hydrodeoxygenation (HDO) activity using phenol as a model compound. Metal content, phase, and particle size were determined with ICP-OES, EXAFS/XANES, and CO pulse chemisorption, respectively. High dispersion of ruthenium on the supports converts more phenol to products. The majority of catalysts predominantly catalyze the hydrogenation (HYD) route typical of noble metal catalysts. A highly dispersed Ru/TiO2 catalyst shows unusually high selectivity toward direct deoxygenation (DDO) and outstanding activity. We suggest that the DDO pathway on titania involves a bifunctional catalyst, where hydrogen creates reduced titania sites, created by hydrogen spillover, that interact strongly with the phenol hydroxyl group.

Study of interaction of ethylene glycol/PVP phase on noble metal powders prepared by polyol process

Abstract: Noble metal powders (Au, Ag, Pt, Pd and Ru) have been synthesized by the polyol process in both the nanometer and submicron scales (sans Pd, Pt and Ru). They have been characterized by both microscopic (TEM and SEM) as well as spectroscopic techniques (FT-IR and XPS). Infrared spectroscopy was employed to study the colloid particles in the presence of ethylene glycol and PVP and the results show that the interaction between the organic phase and the metal particles vary according to the particle size. The role of the solvent, ethylene glycol, during the reduction process was also investigated and we observe formation of >C=O vibration band after the reduction process implying that the solvent reduces the metal ions thereby getting oxidized. XPS measurements carried out on the colloidal sols have shown the presence of the organic phase adsorbed onto the metal particles.

Crystallized RuTe2 as unexpected bifunctional catalyst for overall water splitting

Abstract: Bifunctional catalysis for water splitting is for the first time realized on Ru noble metal in the form of crystallized RuTe2 nanoparticles on graphene Super activity to the state-of-the-art Pt and RuO2 is found for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) because of the high degree of crystallinity, uniform distribution of nanoparticles, and electronic effect in the catalyst system It offers a low cell voltage of 157 V to drive 10 mA cm−2, 100 mV lower than that of Pt/C-RuO2 benchmark electrodes in an alkaline electrolyte, along with a pretty good chemical and structural stability in the strong corrosive environment The theory calculation confirms the superior intermediates adsorption property because of the Ru/Te synergism, and Pt like/RuO2 like character for water splitting reaction It is a very promising catalyst in the alkaline electrolyzer due to the reliable catalytic ability and relatively low price (1/4 Pt)