Multilayered TNAs/SnO2/PPy/ß-PbO2 anode achieving boosted electrocatalytic oxidation of As(III).

Dealing with arsenic pollution has been of great concern owing to inherent toxicity of As(III) to environments and human health. Herein, a novel multilayered SnO2/PPy/ß-PbO2 structure on TiO2 nanotube arrays (TNAs/SnO2/PPy/ß-PbO2) was synthesized by a multi-step electrodeposition process as an efficient electrocatalyst for As(III) oxidation in aqueous solution. Such TNAs/SnO2/PPy/ß-PbO2 electrode exhibited a higher charge transfer, tolerable stability, and high oxygen evolution potential (OEP). The intriguing structure with a SnO2, PPy, and ß-PbO2 active layers provided a larger electrochemical active area for electrocatalytic As(III) oxidation. The as-synthesized TNAs/SnO2/PPy/ß-PbO2 anode achieved drastically enhanced As(Ⅲ) conversion efficiency of 90.72% compared to that of TNAs/ß-PbO2 at circa 45.4%. The active species involved in the electrocatalytic oxidation process included superoxide radical (•O2-), sulfuric acid root radicals (•SO4-), and hydroxyl radicals (•OH). This work offers a new strategy to construct a high-efficiency electrode to meet the requirements of favorable electrocatalytic oxidation properties, good stability, and high electrocatalytic activity for As(III) transformation to As(V).

Exploring the Fundamental Roles of Functionalized Ligands in Platinum@Metal-Organic Framework Catalysts.

The metal nodes, functionalized ligands, and uniform channels of metal-organic frameworks (MOFs) are typically utilized to regulate the catalytic properties of metal nanoparticles (MNPs). However, though the ligand functionalization could impact the properties of the metal nodes and channels, which might further regulate the catalytic activity and selectivity of MNPs, related research in the design of MNP/MOF catalysts was usually neglected. Herein, we synthesized a series of Pt@UiO-66 composites (Pt@UiO-66-NH2, Pt@UiO-66-SO3H, and Pt@UiO-66) with slightly different organic ligands, which enhanced steric hindrance and contributed to multipathway electron transfer in selective hydrogenation of linear citronellal. The selectivity toward citronellol was gradually improved along with the increased size of functional groups (hydrogen, amino groups, and sulfo groups) on organic ligands, which enhanced steric hindrance provided by channels. In addition, the X-ray photoelectron spectroscopy measurements also revealed that the electronic state of Pt NPs was regulated through multipathway electron transfer from Pt NPs to metal nodes, between organic ligands and Pt NPs/metal nodes. Our research proved that the ligand functionalization altered physiochemical properties of the channels and metal nodes, further together managing the catalytic performance of Pt NPs through enhanced steric hindrance and multi-pathway electron transfer.

Metal-Organic Framework Derivatives for Improving the Catalytic Activity of the CO Oxidation Reaction.

Metal-organic framework (MOF)-based derivatives have attracted an increasing interest in various research fields. However, most of the reported papers mainly focus on pristine MOF-based derivatives, and research studies on functional MOF-based derivative composites are rare. Here, a simple strategy has been reported to design functional MOF-based derivative composites by the encapsulation of metal nanoparticle (MNP) in MOF matrixes (MNP@MOF) and the high-temperature calcination of MNP@MOF composites. The as-prepared MNP@metal oxide composites with a hierarchical pore structure exhibited excellent catalytic activity and high stability for the CO oxidation reaction.

Controlled Encapsulation of Functional Organic Molecules within Metal-Organic Frameworks: In Situ Crystalline Structure Transformation.

Functional organic molecules/metal-organic frameworks composites can be obtained by in situ crystalline structure transformation from ZIF-L to ZIF-8-L under double solvent conditions. Interestingly, the as-prepared molecules/ZIF-8-L composites with the leaf-like morphology exhibit good fluorescence properties and size selectivity in fluorescent quenchers due to the molecular sieving effect of the well-defined microporous ZIF-8-L.