Bioelectrocatalysis with a palladium membrane reactor.

Enzyme catalysis is used to generate approximately 50,000 tons of value-added chemical products per year. Nearly a quarter of this production requires a stoichiometric cofactor such as NAD/NADH. Given that NADH is expensive, it would be beneficial to regenerate it in a way that does not interfere with the enzymatic reaction.

Direct HO Synthesis, without H Gas.

We report here the direct hydrogenation of O gas to form hydrogen peroxide (HO) using a membrane reactor without H gas. Hydrogen is sourced from water, and the reactor is driven by electricity. Hydrogenation chemistry is achieved using a hydrogen-permeable Pd foil that separates an electrolysis chamber that generates reactive H atoms, from a hydrogenation chamber where H atoms react with O to form HO.

Quantification of the Effect of an External Magnetic Field on Water Oxidation with Cobalt Oxide Anodes.

Here, we quantify the effect of an external magnetic field (β) on the oxygen evolution reaction (OER) for a cobalt oxide|fluorine-doped tin oxide coated glass (CoO|FTO) anode. A bespoke apparatus enables us to precisely determine the relationship between magnetic flux density (β) and OER activity at the surface of a CoO|FTO anode. The apparatus includes a strong NdFeB magnet ( = 450 ± 1 mT) capable of producing a magnetic field of 371 ± 1 mT at the surface of the anode.

Electrolysis Can Be Used to Resolve Hydrogenation Pathways at Palladium Surfaces in a Membrane Reactor.

For common hydrogenation chemistries that occur at high temperatures (where H is adsorbed and activated at the same surface which the substrate must also adsorb for reaction), there is often little consensus on how the reactions (e.g., hydro(deoxy)genation) actually occur.

Physical Separation of H Activation from Hydrogenation Chemistry Reveals the Specific Role of Secondary Metal Catalysts.

An electrocatalytic palladium membrane reactor (ePMR) uses electricity and water to drive hydrogenation without H gas. The device contains a palladium membrane to physically separate the formation of reactive hydrogen atoms from hydrogenation of the unsaturated organic substrate. This separation provides an opportunity to independently measure the hydrogenation reaction at a surface without any competing H activation or proton reduction chemistry.

Photoelectrochemical Decomposition of Lignin Model Compound on a BiVO Photoanode.

The photoelectrochemical decomposition of lignin model compounds at a BiVO photoanode is demonstrated with simulated sunlight and an applied bias of 2.0 V. These prototypical lignin model compounds are photoelectrochemically converted into the corresponding aryl aldehyde and phenol derivatives in a single step with conversion of up to ≈64 % over 20 h.

Strain Influences the Hydrogen Evolution Activity and Absorption Capacity of Palladium.

Strain engineering can increase the activity and selectivity of an electrocatalyst. Tensile strain is known to improve the electrocatalytic activity of palladium electrodes for reduction of carbon dioxide or dioxygen, but determining how strain affects the hydrogen evolution reaction (HER) is complicated by the fact that palladium absorbs hydrogen concurrently with HER. We report here a custom electrochemical cell, which applies tensile strain to a flexible working electrode, that enabled us to resolve how tensile strain affects hydrogen absorption and HER activity for a thin film palladium electrocatalyst.

Synthesis and optical and electronic properties of core-modified 21,23-dithiaporphyrins.

Core-modified 21,23-dithiaporphyrins, meso-substituted with both electron-withdrawing 4-phenylcarboxylic acids and related butyl esters, and electron-donating phenyldodecyl ethers were synthesized. The porphyrins displayed broad absorbance profiles that spanned from 400 to 800 nm with molar absorptivities ranging from 2500 to 200000 M(-1) cm(-1). Electrochemical experiments showed the dithiaporphyrins undergo two consecutive, one-electron, quasi-reversible oxidations and reductions at -1.