Aqueous organic and redox-mediated redox flow batteries : A Review

Redox flow batteries (RFBs) are among the most investigated technologies for large scale energy storage applications. Since the first commercialization of all-vanadium RFB (in the early 90’s), the technology has evolved towards the development of new systems. This review focuses on three innovative concepts including aqueous organic RFB (AO-RFB), dual-circuit RFB and redox solid booster-based RFB. We will highlight the recent advances in the last five years and discuss the main challenges encountered. Particularly, we focused on the utilization of redox-mediated process to reach higher energy density than conventional RFB

Biomimetic versus enzymatic high-potential electrocatalytic reduction of hydrogen peroxide on a functionalized carbon nanotube electrode

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Effects of biochar on soil microbial communities: A meta-analysis

International audienceChanges in soil microbial communities may impact soil fertility and stability because microbial communities are key to soil functioning by supporting soil ecological quality and agricultural production. The effects of soil amendment with biochar on soil microbial communities are widely documented but studies highlighted a high degree of variability in their responses following biochar application. The multiple conditions under which they were conducted (experimental designs, application rates, soil types, biochar properties) make it difficult to identify general trends. This supports the need to better determine the conditions of biochar production and application that promote soil microbial communities. In this context, we performed the first ever meta-analysis of the biochar effects on soil microbial biomass and diversity (prokaryotes and fungi) based on high-throughput sequencing data. The majority of the 181 selected publications were conducted in China and evaluated the short-term impact (<3 months) of biochar. We demonstrated that a large panel of variables corresponding to biochar properties, soil characteristics, farming practices or experimental conditions, can affect the effects of biochar on soil microbial characteristics. Using a variance partitioning approach, we showed that responses of soil microbial biomass and prokaryotic diversity were highly dependent on biochar properties. They were influenced by pyrolysis temperature, biochar pH, application rate and feedstock type, as wood-derived biochars have particular physico-chemical properties (high C:N ratio, low nutrient content, large pores size) compared to non-wood-derived biochars. Fungal community data was more heterogenous and scarcer than prokaryote data (30 publications). Fungal diversity indices were rather dependent on soil properties: they were higher in medium-textured soils, with low pH but high soil organic carbon. Altogether, this meta-analysis illustrates the need for long-term field studies in European agricultural context for documenting responses of soil microbial communities to biochar application under diverse conditions combining biochar types, soil properties and conditions of use

Direct Electrochemistry of Bilirubin Oxidase from Magnaporthe orizae on Covalently-Functionalized MWCNT for the Design of High-Performance Oxygen-Reducing Biocathodes

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Complexes of the Bis(di-tert-butyl-aniline)amine Pincer Ligand: The Case of Copper

International audienceTheN,N-bis(2-amino-3,5-di-tert-butylphenyl)amine pincer ligand was coordinated to copper. Depending on the copper source, a mononuclear complex1(+)or a trimer2could be isolated and were structurally characterized. Complex1(+)consists of two deprotonated iminobenzoquinone ligands coordinated to a Cu(I) center. Complex2is trinuclear with a (3:3) (M:L) stoichiometry, featuring a three-fold repetition of a unit made of a Cu(II) center coordinated to a tridentate ligand radical-dianion. In2, the metal ions are bridged by an anilido nitrogen. The coordination sphere of each copper is completed to four by a neighboring iminosemiquinone moiety. Complex1(+)belongs to an electron-transfer series. The paramagnetic complexes1and1(2+)were generated and characterized by EPR and Vis-NIR spectroscopy. Complex1exhibits an isotropic resonance at g = 2.00, which is reminiscent of Cu(I) iminosemiquinone species. The dication1(2+)exhibits a metal-based ground spin state and hence is described as a Cu(II) iminobenzoquinone complex. Both1and1(+)show a NIR band (954, 980 nm) of high intensity (> 20 mm(-1) cm(-1)) assigned to ligand-based charge transfer transitions. Two-electron reduction of1produces2via ligand release and disproportionation. Conversely, oxidation of2affords1(+). Finally, carbon-nanotube-supported complex2is active towards electrocatalytic reduction of H2O2

Electrocatalytic O 2 Reduction at a Bio-inspired Mononuclear Copper Phenolato Complex Immobilized on a Carbon Nanotube Electrode

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Clicked Bifunctional Dendrimeric and Cyclopeptidic Addressable Redox Scaffolds for the Functionalization of Carbon Nanotubes with Redox Molecules and Enzymes

International audienceCarbon nanotube electrodes were modified with ferrocene and laccase using two different click reactions strategies and taking advantage of bifunctional dendrimers and cyclopeptides. Using diazonium functionalization and the efficiency of oxime ligation, the combination of both multiwalled carbon nanotube surfaces and modified dendrimers or cyclopeptides allows the access to a high surface coverage of ferrocene in the order of 50 nmol cm–2, a 50-fold increase compared to a classic click reaction without oxime ligation of these highly branched macromolecules. Furthermore, this original immobilization strategy allows the immobilization of mono- and bi-functionalized active multicopper enzymes, laccases, via copper(I)-catalyzed azide–alkyne cycloaddition. Electrochemical studies underline the high efficiency of the oxime-ligated dendrimers or cyclopeptides for the immobilization of redox entities on surfaces while being detrimental to electron tunneling with enzyme active sites despite controlled orientation

Catalytic layer - membrane electrode assembly methods for optimum formation of triple phase boundaries and fuel cell performances.

Proton Exchange Membrane Fuel Cell (PEMFC), designed mainly for mobility applications, converts chemical energy to electrical energy. The formation of electrodes for PEMFC is a delicate balancing of transport media. Conductivity of gas, electrons, and protons known as a triple phase boundary (TPB), plays a key role on the fuel cell operation and performances. Currently, in order to overcome some performance limitations in a practical PEMFC operation, R&D strategies have been focused on the Pt replacing by non-noble based metal catalysts or decrease the overall Pt loading to below of 0.1 mgPt.cm–2 by 2030 (DOE Targets), as well as the optimization of the TPB structure. Furthermore, we present here a critical overview from different deposition techniques used in the fabrication of MEA’s and the effects on the TPB formation. In particular, we discussed Print-Light Synthesis as a new emerging technology for catalyst deposition and nanostructuration onto a broad range of supports

Oriented Immobilization of [NiFeSe] Hydrogenases on Covalentlyand Noncovalently Functionalized Carbon Nanotubes for H2/AirEnzymatic Fuel Cells

International audienceWe report the oriented immobilization of [NiFeSe] hydrogenases on both covalently and noncovalently modified carbon nanotubes (CNTs) electrodes. A specific interaction of the [NiFeSe] hydrogenase from Desulfomicrobium baculatum with hydrophobic organic molecules was probed by electrochemistry, quartz crystal microbalance with dissipation monitoring (QCM-D), and theoretical calculations. Taking advantage of these hydrophobic interactions, the enzyme was efficiently wired on anthraquinone and adamantane-modified CNTs. Because of rational immobilization onto functionalized CNTs, the O-2-tolerant [NiFeSe]-hydrogenase is able to efficiently operate in a H-2/air gas-diffusion enzymatic fuel cell