Molybdenum carbide catalyst for the reduction of CO to CO: surface science aspects by NAPPES and catalysis studies.

Carbon dioxide is a greenhouse gas, and needs to be converted into one of the useful feedstocks, such as carbon monoxide and methanol. We demonstrate the reduction of CO with H as a reducing agent, via a reverse water gas shift (RWGS) reaction, by using a potential and low cost MoC catalyst. MoC was evaluated for CO hydrogenation at ambient pressure as a function of temperature, and CO : H ratio at a gas hourly space velocity (GHSV) of 20 000 h.

Why the thin film form of a photocatalyst is better than the particulate form for direct solar-to-hydrogen conversion: a poor man's approach.

We demonstrated an easy method to improve the efficiency of photocatalysts by an order of magnitude by maximizing light absorption and charge carrier diffusion. Degussa titania (P25) and Pd/P25 composite photocatalyst thin films coated over regular glass plates were prepared and evaluated for solar hydrogen production in direct sunlight with aqueous methanol. It is worth noting that only UV light present in direct sunlight (∼4%) was absorbed by the catalysts.

New Strategy toward a Dual Functional Nanocatalyst at Ambient Conditions: Influence of the Pd-Co Interface in the Catalytic Activity of Pd@Co Core-Shell Nanoparticles.

Bimetallic nanostructures with a combination of noble and nonnoble metals hold promise for improving catalyst activity and selectivity. Here, we report the synthesis of Pd@Co (PC) core-shell morphology nanoparticles with three different ratios of palladium (Pd) and cobalt (Co), and a possibility to fine tune the ratio of core and shell thickness. PC exhibits superior and selective hydrogenation as well as oxidation catalytic activity at ambient or near-ambient conditions.

ZnO-ZnS Heterojunctions: A Potential Candidate for Optoelectronics Applications and Mineralization of Endocrine Disruptors in Direct Sunlight.

Simple solution combustion synthesis was adopted to synthesize ZnO-ZnS (ZS) nanocomposites using zinc nitrate as an oxidant and a mixture of urea and thiourea as a fuel. A large thiourea/urea ratio leads to more ZnS in ZS with heterojunctions between ZnS and ZnO and throughout the bulk; tunable ZnS crystallite size and textural properties are an added advantage. The amount of ZnS in ZS can be varied by simply changing the thiourea content.

Mechanistic Aspects of Wet and Dry CO Oxidation on CoO Nanorod Surfaces: A NAP-UPS Study.

Catalytic activity, electronic structure, and the mechanistic aspects of CoO nanorod (NR) surfaces have been explored for CO oxidation in dry and wet atmosphere using near-ambient pressure ultraviolet photoelectron spectroscopy. Presence of water with CO + O plummets the catalytic activity because of the change in the electronic nature from predominantly oxide (without water in feed) to a CoO surface covered by a few intermediates. However, at ≥375 K, the CoO surface recovers and regains the oxidation activity, at least partially, even in the presence of water.

Enhancement in Rate of Photocatalysis Upon Catalyst Recycling.

Recyclability is an important aspect for heterogeneous photo-catalysts. Ease of recovery and stability of the photo-catalyst in terms of efficiency over the number of cycles are highly desired and in fact it is ideal if the efficiency is constant and it should not decrease marginally with each cycle. Presented here is a seminal observation in which the photocatalytic activity is shown to improve with increasing number of catalytic cycles (it is 1.

An attempt to correlate surface physics with chemical properties: molecular beam and Kelvin probe investigations of CeZrO thin films.

What is the correlation between physical properties of the surfaces (such as surface potential, electronic nature of the surface), and chemical and catalysis properties (such as chemisorption, sticking probability of surface)? An attempt has been made to explore any correlation that might exist between the physical and chemical properties of thin film surfaces. Kelvin probe microscopy (KPM) and the molecular beam (MB) methods were employed to carry out the surface potential, and oxygen adsorption and oxygen storage capacity (OSC) measurements on CeZrO thin films. A sol-gel synthesis procedure and spin-coating deposition method have been applied to make continuous nanocrystalline CeZrO (x = 0-1) (CZ) thin films with uniform thickness (35-50 nm); however, surface roughness and porosity inherently changes with CZ composition.

Exploration of magnetically separable Ag@AgxNiy core/graded-alloy-shell nanostructures.

We report novel bimetallic Ag@AgxNiy core@graded-alloy-shell nanoparticles (CGAS NPs), i.e. single Ag core NPs shelled by an AgxNiy graded alloy and stabilized by the CTAB surfactant employing a novel synthesis method.

Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate.

Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement.

UV photoelectron spectroscopy at near ambient pressures: mapping valence band electronic structure changes from Cu to CuO.

Valence band (VB) changes and hence electronic structure evolution was directly observed with low kinetic energy (KE) electrons at near ambient pressure (NAP) conditions with He I photon source in a custom built laboratory ambient pressure photoelectron spectrometer (Lab-APPES). Polycrystalline Cu surfaces were gradually oxidized in O2 to Cu2O, to a mixture of Cu2O + CuO, and finally to CuO between 300 and 625 K and at NAP. Typical VB features for Cu, Cu2O, and CuO were observed, and the results corroborate well with core level and Auger spectral changes.

Solid-State NMR investigations of a MgCl2·4(CH3)2CHCH2OH molecular adduct: a peculiar case of reversible equilibrium between two phases.

MgCl2·xROH molecular adducts are extensively employed as a support material for Ziegler-Natta polyolefin catalysis. However, their structural properties are not well understood. Recently, we reported on the preparation of an isobutanol adduct, MgCl2·4(CH3)2CHCH2OH (MgiBuOH) ( Dalton Trans.

Modulation of Reaction Kinetics for the Tuneable Synthesis of Gold Nanoparticles and Quantum Clusters: Application of Gold Quantum Clusters as "Turn-Off" Sensing Probe for Sn Ions.

The syntheses of gold nanoparticles (Au NPs) and gold quantum clusters (Au QCs) that employ cefadroxil (CFX; an antibiotic) as both reducing and capping agents are reported. The HAuCl /CFX concentration, temperature, and pH are crucial factors in the modulation of the nucleation and growth kinetics of the reaction, and consequently, in guiding the size and morphology of as-synthesized Au NPs. Interesting results are observed if the reaction is performed under different pH conditions.