Facile construction of ultrastable alumina anchored palladium catalysts via a designed one pot strategy for enhanced methane oxidation

A highly stable Pd–Al₂O₃ catalyst with anchored palladium species was facilely prepared through a one pot strategy for efficient methane oxidation.

Mechanochemical redox: a calcination-free process to support CoMnOx catalysts

A calcination-free process (mechanochemical redox loading method) to load CoMnO_x onto various supports for efficient and stable CO oxidation.

Engineering well-defined rare earth oxide-based nanostructures for catalyzing C1 chemical reactions

In this review, we summarize the nanostructural engineering and applications of rare earth oxide-based nanomaterials with well-defined compositions, crystal phases and shapes for efficiently catalyzing C1 chemical reactions.

A redox interaction-engaged strategy for multicomponent nanomaterials

The review article focuses on the redox interaction-engaged strategy that offers a powerful way to construct multicomponent nanomaterials with precisely-controlled size, shape, composition and hybridization of nanostructures.

CeOx-Decorated Hierarchical NiCo2S4 Hollow Nanotubes Arrays for Enhanced Oxygen Evolution Reaction Electrocatalysis

Developing hollow self-supported nanotube arrays with hierarchical microporous and abundant multiactive sites shows great promise for oxygen evolution reaction (OER) electrocatalysis. Herein, a facile and low-cost strategy of NiCo₂S₄ hollow nanotubes arrays decorated with CeO_x nanoparticles (NPs) assembled on a flexible support carbon cloth (CC) for enhanced OER performance is reported. The obtained hierarchical nanoarrays CeO_x/NiCo₂S₄/CC exhibited excellent activity toward OER with an overpotential (270 mV) at 10 mA cm^-2, relatively weak Tafel slope, and distinguished durability. CeO_x/NiCo₂S₄/CC nanoarrays not only provide fast electronic transmission and well-defined connection to the substrate but also defective sites and electron transfer by the introduction of CeO_x NPs. This new strategy was offered to construct low-cost and effectively hierarchical structural electrocatalysts containing rare-earth species.

High-surface-area corundum by mechanochemically induced phase transformation of boehmite

In its nanoparticulate form, corundum (α-Al2O3) could lead to several applications. However, its production into nanoparticles (NPs) is greatly hampered by the high activation energy barrier for its formation from cubic close-packed oxides and the sporadic nature of its nucleation. We report a simple synthesis of nanometer-sized α-Al2O3 (particle diameter ~13 nm, surface areas ~140 m2 g−1) by the mechanochemical dehydration of boehmite (γ-AlOOH) at room temperature. This transformation is accompanied by severe microstructural rearrangements and might involve the formation of rare mineral phases, diaspore and tohdite, as intermediates. Thermodynamic calculations indicate that this transformation is driven by the shift in stability from boehmite to α-Al2O3 caused by milling impacts on the surface energy. Structural water in boehmite plays a crucial role in generating and stabilizing α-Al2O3 NPs.

Mechanochemical esterification of waste mulberry wood by wet Ball-milling with tetrabutylammonium fluoride

Esterification of lignocellulosic biomass driven by dry ball-milling suffered from agglomeration of lignocellulosic matters during milling process. In this study, esterification of waste mulberry wood (MW) was carried out by wet ball-milling with water and tetrabutylammonium fluoride (TBAF) to prepare all-wood-plastic composites. Under the same condition, the esterification of MW by wet ball-milling with TBAF presented higher efficiency than that without TBAF which was attributed to catalytic function of F^- ions meanwhile the binding of TBA⁺ to cellulose fibrils hindered the compaction of fibrillated fragments. Pre-ball-milling of MW for 4.0 h apparently promoted the esterification with succinic anhydride. All-wood-plastic composites prepared after 7.0 h succinoylation demonstrated prominent mechanical performance due to strong adhesion of fragments and matrix. This study is supposed to provide an environment-friendly method for efficient conversion of waste lignocellulosic biomass.

Pentacoordinated Al3+ -Stabilized Active Pd Structures on Al2 O3 -Coated Palladium Catalysts for Methane Combustion

Supported Pd catalysts are active in catalyzing the highly exothermic methane combustion reaction but tend to be deactivated owing to local hyperthermal environments. Herein we report an effective approach to stabilize Pd/SiO₂ catalysts with porous Al₂ O₃ overlayers coated by atomic layer deposition (ALD). ²⁷ Al magic angle spinning NMR analysis showed that Al₂ O₃ overlayers on Pd particles coated by the ALD method are rich in pentacoordinated Al³⁺ sites capable of strongly interacting with adjacent surface PdO_x phases on supported Pd particles. Consequently, Al₂ O₃ -decorated Pd/SiO₂ catalysts exhibit active and stable PdO_x and Pd-PdO_x structures to efficiently catalyze methane combustion between 200 and 850 °C. These results reveal the unique structural characteristics of Al₂ O₃ overlayers on metal surfaces coated by the ALD method and provide a practical strategy to explore stable and efficient supported Pd catalysts for methane combustion.

Tunable bimetallic Au-Pd@CeO2 for semihydrogenation of phenylacetylene by ammonia borane

The fabrication of a bimetallic core and ceria shell nanostructure is considered a promising way to promote catalytic performance and stability. Here, we report an Au-Pd@CeO2 core-shell structure with a tunable Au/Pd ratio through a self-assembly autoredox reaction approach. This process involves the sequence reduction of Au and Pd precursors and then self-assembly of CeO2 nanoparticles to encapsulate the noble metal core. The as-obtained samples exhibit excellent activity and selectivity towards the ammonia borane initiated hydrogenation of phenylacetylene with an enhanced stability owing to the protection from outside CeO2 nanoparticles. Through the construction of an Au-Pd bimetallic structure, an electron modification of Pd due to charge transfer between Au and Pd results in an enhanced catalytic performance. Such a strategy is promising for the synthesis of other bimetallic noble core and ceria shell structures for further applications.

Milling Down to Nanometers: A General Process for the Direct Dry Synthesis of Supported Metal Catalysts

Supported catalysts are among the most important classes of catalysts. They are typically prepared by wet-chemical methods, such as impregnation or co-precipitation. Here we disclose that dry ball milling of macroscopic metal powder in the presence of a support oxide leads in many cases to supported catalysts with particles in the nanometer size range. Various supports, including TiO₂ , Al₂ O₃ , Fe₂ O₃ , and Co₃ O₄ , and different metals, such as Au, Pt, Ag, Cu, and Ni, were studied, and for each of the supports and the metals, highly dispersed nanoparticles on supports could be prepared. The supported catalysts were tested in CO oxidation, where they showed activities in the same range as conventionally prepared catalysts. The method thus provides a simple and cost-effective alternative to the conventionally used impregnation methods.

Spatially Confined Tuning the Interfacial Synergistic Catalysis in Mesochannels toward Selective Catalytic Reduction

Low-temperature selective catalytic reduction of nitrogen oxides (NO _x) with NH₃ (NH₃-SCR) has been identified as a promising strategy to mitigate the pollution of NO _x. The fine control of synergistic effect and the suppression of aggregation of the active component, however, are still the challenge because of the weak interaction between the active component and matrix. In this work, a series of Ce-promoted Mn-based heterogeneous catalysts supported on mesoporous silica (SBA-15) with different Mn contents were prepared by two separated impregnation processes. Low-temperature NH₃-SCR activity demonstrates that the Mn content in the catalyst has a great influence on the activity of the NH₃-SCR reaction. The 20% MnO _x-CeO _x/SBA-15 catalyst exhibited the best catalytic performance in a broad temperature window. Moreover, it exhibits enhanced resistance to SO₂ and H₂O and long-term durability during 72 h reaction. The highly dispersive active phase, the formation of solid solution, the high ratio of Ce³⁺, and the spatial confinement effect largely contribute to the outstanding activity and durability of the 20% MnO _x-CeO _x/SBA-15 catalyst. Finally, a monolithic catalyst fabricated by the 20% MnO _x-CeO _x/SBA-15 catalyst powder and cordierite substrate show promising industrial application.

The effect of milling parameters on the mechanochemical synthesis of Pd–CeO2 methane oxidation catalysts

Pd–ceria interaction can be tuned by suitable milling intensity to obtain highly active methane oxidation catalysts.

In situ DRIFT spectroscopy insights into the reaction mechanism of CO and toluene co-oxidation over Pt-based catalysts

The Pt–CeO₂ catalyst with adsorption sites and oxygen-rich vacancies exhibited outstanding activity towards CO and toluene co-oxidation.

Natural clay-supported palladium catalysts for methane oxidation reaction: effect of alloying

Bimetallic Pd-supported halloysite nanotubes revealed outstanding catalytic activity towards catalytic methane oxidation especially PdNi.