Noble metal

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

Atomic-Scale Insights into the Low-Temperature Oxidation of Methanol over a Single-Atom Pt1-Co3O4 Catalyst

Abstract: Heterogeneous catalysts with single‐atom active sites offer a means of expanding the industrial application of noble metal catalysts. Herein, an atomically dispersed Pt1‐Co3O4 catalyst is presented, which exhibits an exceptionally high efficiency for the total oxidation of methanol. Experimental and theoretical investigations indicate that this catalyst consists of Pt sites with a large proportion of occupied high electronic states. These sites possess a strong affinity for inactive Co2+ sites and anchor over the surface of (111) crystal plane, which increases the metal–support interaction of the Pt1‐Co3O4 material and accelerates the rate of oxygen vacancies regeneration. In turn, this is determined to promote the coadsorption of the probe methanol molecule and O2. Density functional theory calculations confirm that the electron transfer over the oxygen vacancies reduces both the methanol adsorption energy and activation barriers for methanol oxidation, which is proposed to significantly enhance the dissociation of the CH bond in the methanol decomposition reaction. This investigation serves as a solid foundation for characterizing and understanding single‐atom catalysts for heterogeneous oxidation reactions.

Nanocoral-like composite of nickel selenide nanoparticles anchored on two-dimensional multi-layered graphitic carbon nitride: A highly efficient electrocatalyst for oxygen evolution reaction

Abstract: Oxygen evolution reaction is a significant half-reaction for water splitting, while its sluggish kinetics and high-cost catalyst hinder the commercial application. In this work, we report a novel nanocoral-like NiSe2/g-C3N4 composite as highly efficient catalyst for water oxidation in 1.0 M KOH solution. Based on the support of multi-layered g-C3N4, NiSe2/g-C3N4 composite exhibits favorable electrocatalytic performances with low overpotential of 290 mV at current density of 40 mA cm−2 and low onset potential of 1.38 V (vs. RHE). In addition, NiSe2/g-C3N4 composite delivers higher current density (199 mA cm−2) than those of pure NiSe2 (142 mA cm−2) and multi-layered g-C3N4 (112 mA cm−2) at potential of 2.0 V (vs. RHE). Furthermore, NiSe2/g-C3N4 composite exhibits an excellent long-term electrochemical stability for 10 h. The outstanding electrocatalytic properties above suggest that NiSe2/g-C3N4 composite is a candidate for the substitution of noble metal based catalyst for oxygen evolution reaction.

A Multisite Strategy for Enhancing the Hydrogen Evolution Reaction on a Nano‐Pd Surface in Alkaline Media

Abstract: The hydrogen evolution reaction (HER) on a noble metal surface in alkaline media is more sluggish than that in acidic media due to the limited proton supply. To promote the reaction, it is necessary to transform the alkaline HER mechanism via a multisite catalyst, which has additional water dissociation sites to improve the proton supply to an optimal level. Here, this study reports a top-down strategy to create a multisite HER catalyst on a nano-Pd surface and how to further fine-tune the areal ratio of the water dissociation component to the noble metal surface in core/shell-structured nanoparticles (NPs). Starting with Pd/Fe3O4 core/shell NPs, electrochemical cycling is used to tune the coverage of iron (oxy)hydroxide on a Pd surface. The alkaline HER activity of the core/sell Pd/FeOx(OH)2−2x NPs exhibits a volcano-shaped correlation with the surface Fe species coverage. This indicates an optimum coverage level where the rates of both the water dissociation step and the hydrogen formation step are balanced to achieve the highest efficiency. This multisite strategy assigns multiple reaction steps to different catalytic sites, and should also be extendable to other core/shell NPs to optimize their HER activity in alkaline media.

Photo-reduced Cu/CuO nanoclusters on TiO 2 nanotube arrays as highly efficient and reusable catalyst

Abstract: Non-noble metal nanoparticles are becoming more and more important in catalysis recently. Cu/CuO nanoclusters on highly ordered TiO2 nanotube arrays are successfully developed by a surfactant-free photoreduction method. This non-noble metal Cu/CuO-TiO2 catalyst exhibits excellent catalytic activity and stability for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with the presence of sodium borohydride (NaBH4). The rate constant of this low-cost Cu/CuO based catalyst is even higher than that of the noble metal nanoparticles decorated on the same TiO2 substrate. The conversion efficiency remains almost unchanged after 7 cycles of recycling. The recycle process of this Cu/CuO-TiO2 catalyst supported by Ti foil is very simple and convenient compared with that of the common powder catalysts. This catalyst also exhibited great catalytic activity to other organic dyes, such as methylene blue (MB), rhodamine B (RhB) and methyl orange (MO). This highly efficient, low-cost and easily reusable Cu/CuO-TiO2 catalyst is expected to be of great potential in catalysis in the future.

Challenges and opportunities in the bottom-up mechanochemical synthesis of noble metal nanoparticles

Abstract: Mechanochemistry is a promising alternative to solution-based protocols across the chemical sciences, enabling different types of chemistries in solvent-free and environmentally benign conditions. The use of mechanical energy to promote physical and chemical transformations has reached a high level of refinement, allowing for the design of sophisticated molecules and nanostructured materials. Among them, the synthesis of noble metal nanoparticles deserves special attention due to their catalytic applications. In this review, we discuss the recent progress on the development of mechanochemical strategies for the controlled synthesis of noble metal nanostructures. We start by covering the fundamentals of different preparation routes, namely top-down and bottom-up approaches. Next, we focus on the key examples of the mechanochemical synthesis of non-supported and supported metal nanoparticles as well as hybrid nanomaterials containing noble metals. In these examples, in addition to the principles and synthesis mechanisms, their performances in catalysis are discussed. Finally, a perspective of the field is given, where we discuss the opportunities for future work and the challenges of mechanochemical synthesis to produce well-defined noble metal nanoparticles.