Study of borohydride ionic liquids as hydrogen storage materials

Stability of borohydrides is determined by the localization of the negative charge on the boron atom.Ionic liquids(ILs) allow to modify the stability of the borohydrides and promote new dehydrogenation pathways with a lower activation energy. The combination of borohydride and IL is very easy to realize and no expensive rare earth metals are required. The composite of the ILs with complex hydrides decreases the enthalpy and activation energy for the hydrogen desorption. The Coulomb interaction between borohydride and IL leads to a destabilization of the materials with a significantly lower enthalpy for hydrogen desorption. Here, we report a simple ion exchange reaction using various ILs, such as vinylbenzyltrimethylammonium chloride([VBTMA][Cl]), 1-butyl-3-methylimidazolium chloride([bmim][Cl]), and 1-ethyl-1-methylpyrrolidinium bromide([EMPY][Br]) with NaBH4 to decrease the hydrogen desorption temperature. Dehydrogenation of 1-butyl-3-methylimidazolium borohydride([bmim][BH4]) starts below 100℃. The quantity of desorbed hydrogen ranges between 2.4 wt% and 2.9 wt%, which is close to the theoretical content of hydrogen. The improvement in dehydrogenation is due to the strong amine cation that destabilizes borohydride by charge transfer.

An Analytical Model for the Electrolyser Performance Derived from Materials Parameters

Hydrogen is seen as a key element for the transition from a fossil fuel based economy to a renewable, sustainable economy. Hydrogen can be used either directly as an energy carrier or as a feedstock for the reduction of CO2 to synthetic hydrocarbons. Hydrogen can be produced by electrolysis, decomposing water in oxygen and hydrogen. This paper presents an overview of the three major electrolysis technologies: acidic (PEM), alkaline (AEL) and solid oxide electrolysis (SOEC). An updated list of existing electrolysers and commercial providers is provided. Most interestingly, the specific prices of commercial devices are also given when available. Despite tremendous development of the PEM technology in the past decades, the largest and most efficient electrolysers are still alkaline. Thus, this technology is expected to play a key role in the transition to the hydrogen society. A detailed description of the components in an alkaline electrolyser and an analytical model of the process are provided. The analytical model allows investigating the influence of the different operating parameters on the efficiency. Specifically, the effect of temperature on the electrolyte conductivity—and thus on the efficiency—is analyzed. It is found that in the typical range of operating temperatures for alkaline electrolysers of 65°C - 220°C, the efficiency varies by up to 3.5 percentage points, increasing from 80% to 83.5% at 65°C and 220°C, respectively.

In vivo polydopamine coating of Rhodobacter sphaeroides for enhanced electron transfer

Recent advances in coupling light-harvesting microorganisms with electronic components have led to a new generation of biohybrid devices based on microbial photocatalysts.These devices are limited by the poorly conductive interface between phototrophs and synthetic materials that inhibit charge transfer.This study focuses on overcoming this bottleneck through the metabolically-driven encapsulation of photosynthetic cells with a bio-inspired conductive polymer.Cells of the purple non sulfur bacterium Rhodobacter sphaeroides were coated with a polydopamine(PDA)nanoparticle layer via the self-polymerization of dopamine under anaerobic conditions.The treated cells show preserved light absorption of the photosynthetic pigments in the presence of dopamine concentrations ranging between 0.05–3.5 mM.The thickness and nanoparticle formation of the membrane-associated PDA matrix were further shown to vary with the dopamine concentrations in this range.Compared to uncoated cells,the encapsulated cells show up to a 20-fold enhancement in transient photocurrent measurements under mediatorless conditions.The biologically synthesized PDA can thus act as a matrix for electronically coupling the light-harvesting metabolisms of cells with conductive surfaces.

Enhancing bioelectricity generation in microbial fuel cells and biophotovoltaics using nanomaterials

Microbial fuel cells and biophotovoltaics represent promising technologies for green bioelectricity generation.However,these devices suffer from low durability and efficiency that stem from their reliance on living organisms to act as catalysts.Such limitations can be overcome with augmented capabilities enabled by nanotechnology.This review presents an overview of the different nanomaterials used to enhance bioelectricity generation through improved light harvesting,extracellular electron transfer,and anode performance.The implementation of nanomaterials in whole-cell energy devices holds promise in developing bioelectrical devices that are suitable for industry.

Polydopamine-coated photoautotrophic bacteria for improving extracellular electron transfer in living photovoltaics

Living photovoltaics are microbial electrochemical devices that use whole cell–electrode interactions to convert solar energy to electricity.The bottleneck in these technologies is the limited electron transfer between the microbe and the electrode surface.This study focuses on enhancing this transfer by engineering a polydopamine(PDA)coating on the outer membrane of the photosynthetic microbe Synechocystis sp.PCC6803.This coating provides a conductive nanoparticle shell to increase electrode adhesion and improve microbial charge extraction.A combination of scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV–Vis absorption,and Raman spectroscopy measurements were used to characterize the nanoparticle shell under various synthesis conditions.The cell viability and activity were further assessed through oxygen evolution,growth curve,and confocal fluorescence microscopy measurements.The results show sustained cell growth and detectable PDA surface coverage under slightly alkaline conditions(pH 7.5)and at low initial dopamine(DA)concentrations(1 mM).The exoelectrogenicity of the cells prepared under these conditions was also characterized through cyclic voltammetry(CV)and chronoamperometry(CA).The measurements show a three-fold enhancement in the photocurrent at an applied bias of 0.3 V(vs.Ag/AgCl[3 M KCl])compared to non-coated cells.This study thus lays the framework for engineering the next generation of living photovoltaics with improved performances using biosynthetic electrodes.

cell2mol:encoding chemistry to interpret crystallographic data

The creation and maintenance of crystallographic data repositories is one of the greatest data-related achievements in chemistry.Platforms such as the Cambridge Structural Database host what is likely the most diverse collection of synthesizable molecules.If properly mined,they could be the basis for the large-scale exploration of new regions of the chemical space using quantum chemistry(QC).Yet,it is currently challenging to retrieve all the necessary information for QC codes based exclusively on the available structural data,especially for transition metal complexes.To overcome this limitation,we present cell2mol,a software that interprets crystallographic data and retrieves the connectivity and total charge of molecules,including the oxidation state(OS)of metal atoms.We demonstrate that cell2mol outperforms other popular methods at assigning the metal OS,while offering a comprehensive interpretation of the unit cell.The code is made available,as well as reliable QC-ready databases totaling 31k transition metal complexes and 13k ligands that contain incomparable chemical diversity.