FeP Nanocatalyst with Preferential [010] Orientation Boosts the Hydrogen Evolution Reaction in Polymer-Electrolyte Membrane Electrolyzer

The development of nonprecious metal electrocatalysts for polymer-electrolyte membrane (PEM) water electrolysis is a milestone for the technology, which currently relies on rare and expensive platinum-group metals. Half-cell measurements have shown iron phosphide materials to be promising alternative hydrogen evolution electrocatalysts, but their realistic performance in flow-through devices remains unexplored. To fill this gap, we report herein the activity and durability of FeP nanocatalyst under application-relevant conditions. Our facile synthesis route proceeds via impregnation of an iron complex on conductive carbon support followed by phosphorization, giving rise to highly crystalline nanoparticles with predominantly exposed [010] facets, which accounts for the high electrocatalytic activity. The performance of FeP gas diffusion electrodes toward hydrogen evolution was examined under application-relevant conditions in a single cell PEM water electrolysis at 22 °C. The FeP cathode exhibited a current density of 0.2 A cm–2 at 2.06 V, corresponding to a difference of merely 0.07 W cm–2 in power input as compared to state-of-the-art Pt cathode, while outperforming other nonprecious cathodes operated at similar temperature. Quantitative product analysis of our PEM device excluded the presence of side reactions and provided strong experimental evidence that our cell operates with 84–100% Faradaic efficiencies and with 4.1 kWh Nm–3 energy consumption. The FeP cathodes exhibited stable performance of over 100 h at constant operation, while their suitability with the intermittency of renewable sources was demonstrated upon 36 h operation at variable power inputs. Overall, the performance as well as our preliminary cost analysis reveal the high potential of FeP for practical applications.</p

Hydrogen from electrochemical reforming of C1–C3 alcohols using proton conducting membranes

This study investigates the production of hydrogen from the electrochemical reforming of short-chain alcohols (methanol, ethanol, iso-propanol) and their mixtures. High surface gas diffusion Pt/C electrodes were interfaced to a Nafion polymeric membrane. The assembly separated the two chambers of an electrochemical reactor, which were filled with anolyte (alcohol&nbsp;+&nbsp;H2O or alcohol&nbsp;+&nbsp;H2SO4) and catholyte (H2SO4) aqueous solutions. The half-reactions, which take place upon polarization, are the alcohol electrooxidation and the hydrogen evolution reaction at the anode and cathode, respectively. A standard Ag/AgCl reference electrode was introduced for monitoring the individual anodic and cathodic overpotentials. Our results show that roughly 75% of the total potential losses are due to sluggish kinetics of the alcohol electrooxidation reaction. Anodic overpotential becomes larger as the number of C-atoms in the alcohol increases, while a slight dependence on the pH was observed upon changing the acidity of the anolyte solution. In the case of alcohol mixtures, it is the largest alcohol that dictates the overall cell performance. © 2017 Hydrogen Energy Publications LLC</p

Rational design and validation of a Tip60 histone acetyltransferase inhibitor

Histone acetylation is required for many aspects of gene regulation, genome maintenance and metabolism and dysfunctional acetylation is implicated in numerous diseases, including cancer. Acetylation is regulated by histone acetyltransferases (HATs) and histone deacetylases and currently, few general HAT inhibitors have been described. We identified the HAT Tip60 as an excellent candidate for targeted drug development, as Tip60 is a key mediator of the DNA damage response and transcriptional co-activator. Our modeling of Tip60 indicated that the active binding pocket possesses opposite charges at each end, with the positive charges attributed to two specific side chains. We used structure based drug design to develop a novel Tip60 inhibitor, TH1834, to fit this specific pocket. We demonstrate that TH1834 significantly inhibits Tip60 activity in vitro and treating cells with TH1834 results in apoptosis and increased unrepaired DNA damage (following ionizing radiation treatment) in breast cancer but not control cell lines. Furthermore, TH1834 did not affect the activity of related HAT MOF, as indicated by H4K16Ac, demonstrating specificity. The modeling and validation of the small molecule inhibitor TH1834 represents a first step towards developing additional specific, targeted inhibitors of Tip60 that may lead to further improvements in the treatment of breast cancer

Histone methyltransferase Dot1 and Rad9 inhibit single-stranded DNA accumulation at DSBs and uncapped telomeres

Cells respond to DNA double-strand breaks (DSBs) and uncapped telomeres by recruiting checkpoint and repair factors to the site of lesions. Single-stranded DNA (ssDNA) is an important intermediate in the repair of DSBs and is produced also at uncapped telomeres. Here, we provide evidence that binding of the checkpoint protein Rad9, through its Tudor domain, to methylated histone H3-K79 inhibits resection at DSBs and uncapped telomeres. Loss of DOT1 or mutations in RAD9 influence a Rad50-dependent nuclease, leading to more rapid accumulation of ssDNA, and faster activation of the critical checkpoint kinase, Mec1. Moreover, deletion of RAD9 or DOT1 partially bypasses the requirement for CDK1 in DSB resection. Interestingly, Dot1 contributes to checkpoint activation in response to low levels of telomere uncapping but is not essential with high levels of uncapping. We suggest that both Rad9 and histone H3 methylation allow transmission of the damage signal to checkpoint kinases, and keep resection of damaged DNA under control influencing, both positively and negatively, checkpoint cascades and contributing to a tightly controlled response to DNA damage

dTip60 HAT Activity Controls Synaptic Bouton Expansion at the Drosophila Neuromuscular Junction

Background: Histone acetylation of chromatin plays a key role in promoting the dynamic transcriptional responses in neurons that influence the neuroplasticity linked to cognitive ability, yet the specific histone acetyltransferases (HATs) that create such epigenetic marks remain to be elucidated. Methods and Findings: Here we use the Drosophila neuromuscular junction (NMJ) as a well-characterized synapse model to identify HATs that control synaptic remodeling and structure. We show that the HAT dTip60 is concentrated both pre and post-synaptically within the NMJ. Presynaptic targeted reduction of dTip60 HAT activity causes a significant increase in synaptic bouton number that specifically affects type Is boutons. The excess boutons show a suppression of the active zone synaptic function marker bruchpilot, suggesting defects in neurotransmission function. Analysis of microtubule organization within these excess boutons using immunohistochemical staining to the microtubule associated protein futsch reveals a significant increase in the rearrangement of microtubule loop architecture that is required for bouton division. Moreover, a-tubulin acetylation levels of microtubules specifically extending into the terminal synaptic boutons are reduced in response to dTip60 HAT reduction. Conclusions: Our results are the first to demonstrate a causative role for the HAT dTip60 in the control of synaptic plasticity that is achieved, at least in part, via regulation of the synaptic microtubule cytoskeleton. These findings have implication

Ionically conducting supports for oxidation catalysis

SSCI-VIDE+CARE+PVEInternational audienceThis study reports isotopical labelling experiments during propane oxidation on nanodispersed Pt nanoparticles supported either on Yttria-Stabilized Zirconia, an O2- ionic conductor, or on non-conductive ceramics (ZrO2, SiO2) showing high metallic dispersions. 18O2 Temperature-Programmed Desorption and oxygen exchange experiments have shown that YSZ lattice oxygen species continuously migrate toward the Pt surface to such an extent that the gas phase oxygen adsorption is strongly inhibited [1]. This is not the case when the Pt nanoparticles are supported on ZrO2 or SiO2, where the propane mainly reacts with gaseous oxygen. This underlines the strong impact of the YSZ oxygen species on the propane combustion mechanism. The oxygen ions containing in the support can act as predominant oxidizing species. This finding open new routes to design smart and efficient high surface specific area metal-supported catalysts for hydrocarbon oxidation reactions involved in environmental catalysis

Applications of yttria stabilized zirconia (YSZ) in catalysis

This article describes recent advances in the use of yttria stabilized zirconia (YSZ), an oxygen ion conductor, for catalytic applications. This ceramic material combines different functionalities such as good thermal stability, selective bulk oxygen mobility and high surface oxygen vacancy concentration. These properties have been first exploited, utilizing YSZ as dense membranes, in the field of solid oxide fuel cells and electrochemical promotion of catalysis. More recently, YSZ, as nanometric powders, has also been considered as a promising support for metallic nanoparticles or as a catalyst itself. This paper summarizes the main applications of YSZ in the aforementioned fields, explains the underlying phenomena and finally provides perspectives for future applications of YSZ

Applications of yttria stabilized zirconia (YSZ) in catalysis

SSCI-VIDE+CARE+MTS:FSA:PVEInternational audienc

Electrochemical Promotion of Catalysis mechanistic studies utilizing isotopical labeling

International @ AIR+MTS:FSA:ABO:PVEInternational audienceElectrochemical promotion of catalysis (EPOC) is a very promising concept for boosting catalytic processes and advancing the frontiers of catalysis. EPOC utilizes electrochemical catalysts which are composed of catalytic films interfaced on solid electrolyte membranes. Ions contained in these electrolytes are electrochemically supplied onto the catalyst surface and act as promoting agents to modify the catalyst electronic properties. This study presents, for the first time, an operando investigation of the EPOC mechanism by using isotopic oxygen. Propane and propene combustion were implemented on Pt/YSZ electrochemical catalysts because these two reactions exhibit opposite behaviors upon applied overpotentials. Propane oxidation exhibits an electrophobic enhancement (reaction increases upon positive polarization of the catalyst-electrode) while propene oxidation is electrophilic