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Designing efficient anode CO‐tolerant electrocatalysts is critical in low‐temperature fuel cell catalysts fueled either by H2/CO or alcohol. We demonstrate that the incorporation of TiO2 nanocubes (TiO2NCs) on Carbon Vulcan supports, followed by the synthesis of Pt NPs at their surface (Pt/TiO2NCs‐C material), led to improvements in performance towards the electrooxidation of carbon monoxide, ethanol, methanol, ethylene glycol, and glycerol in acidic media relative to the commercial Pt/C and Pt/TiO2‐C counterparts employing commercial TiO2. The nanocubes enabled changes in the electronic properties of Pt NPs while contributing to the bifunctional mechanism as compared to Pt/C and Pt/TiO2‐C with commercial TiO2. Fuel cell experiments fed with H2/CO steam showed that Pt/TiO2NCs‐C employing nanocubes was resistant to CO‐poisoning, yielding superior performance in operational conditions. The results reported herein have important implications for developing electrocatalysts with superior performances in PEMFCs. [ABSTRACT FROM AUTHOR]

We develop herein plasmonic-catalytic Au-IrO 2 nanostructures with a morphology optimized for efficient light harvesting and catalytic surface area; the nanoparticles have a nanoflower morphology, with closely spaced Au branches all partially covered by an ultrathin (1 nm) IrO 2 shell. This nanoparticle architecture optimizes optical features due to the interactions of closely spaced plasmonic branches forming electromagnetic hot spots, and the ultra-thin IrO 2 layer maximizes efficient use of this expensive catalyst. This concept was evaluated towards the enhancement of the electrocatalytic performances towards the oxygen evolution reaction (OER) as a model transformation. The OER can play a central role in meeting future energy demands but the performance of conventional electrocatalysts in this reaction is limited by the sluggish OER kinetics. We demonstrate an improvement of the OER performance for one of the most active OER catalysts, IrO 2 , by harvesting plasmonic effects from visible light illumination in multimetallic nanoparticles. We find that the OER activity for the Au-IrO 2 nanoflowers can be improved under LSPR excitation, matching best properties reported in the literature. Our simulations and electrocatalytic data demonstrate that the enhancement in OER activities can be attributed to an electronic interaction between Au and IrO 2 and to the activation of Ir-O bonds by LSPR excited hot holes, leading to a change in the reaction mechanism (rate-determinant step) under visible light illumination.

In this work we propose the use of statistical mixture design in the construction of a biosensor device based on graphite oxide, platinum nanoparticles and biomaterials obtained from Botryosphaeria rhodina MAMB-05. The biosensor was characterized by electrochemical impedance spectroscopy. Under optimized experimental parameters by factorial design, the biosensor was applied to the voltammetric determination of chlorogenic acid (CGA) measured as 5-O-caffeoylquinic acid (5-CQA). The biosensor response was linear (R 2  = 0.998) for 5-CQA in the concentration range 0.56-7.3 µmol L -1 , with limit of detection and quantification of 0.18 and 0.59 µmol L -1 , respectively. The new biosensing device was applied to quality control analysis based upon the determination of CGA content in specialty and traditional coffee beverages. The results indicated that specialty coffee had a significantly higher content of CGA. Principal component analysis of the voltammetric fingerprint of brewed coffees revealed that the laccase-based biosensor can be used for their discrimination., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In this study, (1→3)(1→6)-β-D-glucan (botryosphaeran) from Botryosphaeria rhodina MAMB-05 was used, for the first time, to immobilize laccase on a carbon black paste electrode modified with gold nanoparticles. The physicochemical characterization of the proposed laccase-biosensor was performed using transmission electron microscopy and electrochemical impedance spectroscopy. The performance of this novel bio-device was evaluated by choosing hydroquinone as a typical model of a phenolic compound. For hydroquinone determination, experimental variables such as enzyme concentration, pH and operational parameters of the electroanalytical technique were optimized. From square-wave voltammograms, a linear dependence between the cathodic current peak and the hydroquinone concentration was observed within the range 2.00-56.5μmolL -1 , with a theoretical detection limit of 0.474μmolL -1 . The proposed method was successfully applied to determine hydroquinone in dermatological cream, and samples from biological and environmental niches. The proposed biosensor device presented good selectivity in the presence of uric acid, various inorganic ions, as well as other phenolic compounds, demonstrating the potential application of this biosensing platform in complex matrices. Operational and analytical stability of the laccase biosensor were evaluated, and demonstrated good intra-day (SD=0.3%) and inter-day (SD=3.4%) repeatability and long storage stability (SD=4.9%)., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Gold nanoparticles (Au NPs) have been widely employed in catalysis. Here, we report on the synthesis and catalytic evaluation of a hybrid material composed of Au NPs deposited at the surface of magnetic cobalt ferrite (CoFe 2 O 4 ). Our reported approach enabled the synthesis of well-defined Au/CoFe 2 O 4 NPs. The Au NPs were uniformly deposited at the surface of the support, displayed spherical shape, and were monodisperse in size. Their catalytic performance was investigated towards the reduction of 4-nitrophenol and the selective oxidation of dimethylphenylsilane to dimethylphenylsilanol. The material was active towards both transformations. In addition, the LSPR excitation in Au NPs could be employed to enhance the catalytic performance, which was demonstrated in the 4-nitrophenol reduction. Finally, the magnetic support allowed for the easy recovery and reuse of the Au/CoFe 2 O 4 NPs. In this case, our data showed that no significant loss of performance took place even after 10 reaction cycles in the oxidation of dimethylphenylsilane to dimethylphenylsilanol. Overall, our results indicate that Au/CoFe 2 O 4 are interesting systems for catalytic applications merging high performances, recovery and re-use, and enhancement of activities under solar light illumination., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The localized surface plasmon resonance (LSPR) excitation in plasmonic nanoparticles can enhance or mediate chemical transformations. Increased reaction rates for several reactions have been reported due to this phenomenon; however, the fundamental understanding of mechanisms and factors that affect activities remains limited. Here, by investigating hydrogenation reactions as a model transformation and employing different reducing agents, H 2 and NaBH 4 , which led to different hydrogenation reaction pathways, we observed that plasmonic excitation of Au nanoparticle catalysts can lead to negative effects over the activities. The underlying physical reason was explored using density functional theory calculations. We observed that positive versus negative effects on the plasmonic catalytic activity is reaction-pathway dependent. These results shed important insights on our current understanding of plasmonic catalysis, demonstrating reaction pathways must be taken into account for the design of plasmonic nanocatalysts., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)