Influence of the Precipitation Agent in the Deposition−Precipitation on the Formation and Properties of Au Nanoparticles Supported on Al2O3

In Situ Grown CoMn2 O4 3D-Tetragons on Carbon Cloth: Flexible Electrodes for Efficient Rechargeable Zinc-Air Battery Powered Water Splitting Systems

The integration of energy conversion and storage systems such as electrochemical water splitting (EWS) and rechargeable zinc-air battery (ZAB) is on the vision to provide a sustainable future with green energy resources. Herein, a unique strategy for decorating 3D tetragonal CoMn₂ O₄ on carbon cloth (CMO-U@CC) via a facile one-pot in situ hydrothermal process, is reported. The highly exposed morphology of 3D tetragons enhances the electrocatalytic activity of CMO-U@CC. This is the first demonstration of such a bifunctional activity of CMO-U@CC in an EWS system; it achieves a nominal cell voltage of 1.610 V @ 10 mA cm^-2 . Similarly, the fabricated rechargeable ZAB delivers a specific capacity of 641.6 mAh g_zn ^-1 , a power density of 135 mW cm^-2 , and excellent cyclic stability (50 h @ 10 mA cm^-2 ). Additionally, a series of flexible solid-state ZABs are fabricated and employed to power the assembled CMO-U@CC-based water electrolyzer. To the best of the authors' knowledge, this is the first demonstration of an in situ-grown binder-free CMO-U@CC as a flexible multifunctional electrocatalyst for a built-in integrated rechargeable ZAB-powered EWS system.

Influence of Co-Precipitation Agent on the Structure, Texture and Catalytic Activity of Au-CeO2 Catalysts in Low-Temperature Oxidation of Benzyl Alcohol

The aim of the study was to establish the influence of a co-precipitation agent (i.e., NaOH–immediate precipitation; hexamethylenetetramine/urea–gradual precipitation and growth of nanostructures) on the properties and catalytic activity of as-synthesized Au-CeO2 nanocomposites. All catalysts were fully characterized with the use of XRD, nitrogen physisorption, ICP-OES, SEM, HR-TEM, UV-vis, XPS, and tested in low-temperature oxidation of benzyl alcohol as a model oxidation reaction. The results obtained in this study indicated that the type of co-precipitation agent has a significant impact on the growth of gold species. Immediate co-precipitation of Au-CeO2 nanostructures with the use of NaOH allowed obtainment of considerably smaller and more homogeneous in size gold nanoparticles than those formed by gradual co-precipitation and growth of Au-CeO2 nanostructures in the presence of hexamethylenetetramine or urea. In the catalytic tests, it was established that the key factor promoting high activity in low-temperature oxidation of benzyl alcohol was size of gold nanoparticles. The highest conversion of the alcohol was observed for the catalyst containing the smallest Au particle size (i.e., Au-CeO2 nanocomposite prepared with the use of NaOH as a co-precipitation agent).

Facile synthesis of Au/Al2O3nanocomposites for improving the detection sensitivity of adenosine triphosphate

Alumina is widely recognized as chemically inert, and resistant to oxidation and high temperature.

Oxidation of citronellal to citronellic acid by molecular oxygen using supported gold catalysts

The oxidation of citronellal to citronellic acid was studied using molecular oxygen as oxidant and gold-containing supported catalysts under aqueous conditions. The reactions were carried out at 60-90 degrees C, with 200 Nml min(-1) O2 and at pH values from 9 to 12. The alumina- or titania-supported catalysts were synthesized according to the deposition-precipitation procedure using urea or NaOH. Mechanistic studies have revealed that radical-initiated reactions lead to undesired by-products especially at pH <9, that is, the C=C bond is attacked and a diol is primarily formed probably via an epoxide intermediate. This side reaction can be suppressed to a large extent by increasing the pH to 12 and by raising the catalyst/oxygen ratio. Furthermore, detailed studies on the influence of reaction time, pH value, reactant concentration and amount of catalyst show that citronellic acid can be obtained in over 90% yield with total conversion of citronellal at pH 12 and a temperature of 80 degrees C.