Synthesis and photoeletrochemical performance of AuAg@CdS double-walled nanotubes

Bifunctional Ag-Decorated CeO2 Nanorods Catalysts for Promoted Photodegradation of Methyl Orange and Photocatalytic Hydrogen Evolution

The photodegradation of organic pollutants and photocatalytic hydrogen generation from water by semiconductor catalysts are regarded as the of the most promising strategies to resolve the crisis of global environmental issues. Herein, we successfully designed and prepared a series of silver-decorated CeO₂(Ag/CeO₂) photocatalysts with different morphologies by a facile hydrothermal route. The physical properties, charge transfer behavior and photocatalytic performances (degradation and hydrogen evolution) over diverse catalysts with nanocubes, nanoparticles and nanorods shapes were comprehensively studied. It was found that the Ag-decorated CeO₂ nanorods (Ag/R-CeO₂) demonstrate the best activity for both photocatalytic methyl orange (MO) degradation and photocatalytic H₂ production reaction with attractive stability during cycling tests, suggesting its desirable practical potential. The superior performance of Ag/R-CeO₂ can be ascribed to (1) the facilitated light absorption due to enriched surface oxygen vacancies (OVs) and plasmonic Ag nanoparticles on nanorods, (2) the facilitated photo-excited charge carrier (e⁻-h⁺) separation efficiency on a metal/oxide hybrid structure and (3) the promoted formation of active reaction intermediates on surface-enriched Ag and oxygen vacancies reactive sites on Ag/CeO₂ nanorods. This study provides a valuable discovery of the utilization of abundant solar energy for diverse catalytic processes.

Gold nanotubes: synthesis, properties and biomedical applications

This review (with 106 references) summarizes the latest progress in the synthesis, properties and biomedical applications of gold nanotubes (AuNTs). Following an introduction into the field, a first large section covers two popular AuNTs synthesis methods. The hard template method introduces anodic alumina oxide template (AAO) and track-etched membranes (TeMs), while the sacrificial template method based on galvanic replacement introduces bimetallic, trimetallic AuNTs and AuNT-semiconductor hybrid materials. Then, the factors affecting the morphology of AuNTs are discussed. The next section covers their unique surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS) and their catalytic properties. This is followed by overviews on the applications of AuNTs in biosensors, protein transportation, photothermal therapy and imaging. Several tables are presented that give an overview on the wealth of synthetic methods, morphology factors and biological application. A concluding section summarizes the current status, addresses current challenges and gives an outlook on potential applications of AuNTs in biochemical detection and drug delivery.Graphical abstract.

Nitrate reduction via micro-electrolysis on Zn-Ag bimetal combined with photo-assistance

A selective and efficient chemical reduction of nitrate to nitrogen gas using micro-electrolysis on ZnAg combined with a photo-assisted reduction in the presence of formic acid was investigated. The 99.58% removal of nitrate, 0.073 min^-1 of rate constant and 94.3% nitrogen selectivity were achieved in Zn-Ag/hv/HCOOH system under the initial pH 2.5, 13.8 mmol/L of formic acid and 60 g/L of Zn-0.06%Ag dose at 60 min. The Zn-Ag/hv/HCOOH system had the highest removal rate and nitrogen selectivity for nitrate reduction compared with the alone or two combinations of ZnAg bimetals, formic acid, and UV-A. Furthermore, the co-existence anions of HCO₃^- and CO₃^2- showed a negative effect on nitrate reduction while SO₄^2- had slightly promoted the reduction process. During the nitrate reduction by Zn-Ag/hv/HCOOH process, rapid reduction of NO₃^- to NO₂^- was primarily caused by ZnAg bimetal. Subsequently, the conversion of NO₂^- to N₂ was mainly owing to the produced CO₂^- by the reaction of formic acid and UV-A. The results suggested a novel strategy of chemical reduction combined with photoreduction for denitrification with high reaction kinetic as well as high nitrogen gas selectivity.