An Innovative 500 W Alkaline Water Electrolyser System for the Production of Ultra-Pure Hydrogen and Oxygen Gases

This paper communicates on an innovative, laboratory size alkaline water electrolyser (AWE) system, capable of efficiently producing ultra-pure hydrogen and oxygen gases. The system is composed of a zero-gap, bipolar-electrode stack, equipped with a polymer-based membrane, along with two drying columns for effective purification of H2 and O2 gaseous products. An optimal electrochemical efficiency of the electrolyser stack is provided through the employment of catalytically activated, extended surface-area nickel foam electrodes. Laboratory electrochemical examinations of the electrolyser included a series of galvanostatic AWE and alternating current (a.c.) impedance (single cell) experiments. Complementary examinations covered catalyst’s surface topography analysis by combined SEM (Scanning Electron Microscopy) and EDX (Energy Dispersive X-ray Spectroscopy) techniques along with chromatographic evaluation of the purity of hydrogen and oxygen products.

Correction: The prospects of developing a highly energy-efficient water electrolyser by eliminating or mitigating bubble effects

Correction for ‘The prospects of developing a highly energy-efficient water electrolyser by eliminating or mitigating bubble effects’ by Gerhard F. Swiegers et al., Sustainable Energy Fuels, 2021, 5, 1280–1310, DOI: 10.1039/D0SE01886D.

The prospects of developing a highly energy-efficient water electrolyser by eliminating or mitigating bubble effects

This work considers the prospects of developing a commercially-feasible water electrolyser with 95–100% energy efficiency (relative to the Higher Heating Value, HHV, of hydrogen) at the cells in the near future.

Cryomilled Ni-Co-Se Enables Water Oxidation Electrocatalysts Durable at High Current Densities

The oxygen evolution reaction (OER) limits electrocatalysis due to the high overpotential incurred by the poor reaction kinetics; this problem worsens over time if the performance of the OER electrocatalyst diminishes during operation. Here, we report the synthesis of immiscible Ni-Co-Se nanoparticles (<10 nm) for alkaline OER using milling at a cryogenic temperature. Milling at such low temperatures promotes thermodynamically stable nanocrystalline intermetallics with a high density of coordinatively unsaturated active sites. Using operando synchrotron spectroscopy, electron microscopy, and density functional theory we found that during the OER, Se ions leaches out of the nanocrystalline structure activating the electrocatalyst by hydrating and transforming defective Ni and Co sites into active and stable oxyhydroxides. Activated (NiCo)3Se4 electrocatalyst required only an overpotential of 279 mV at 0.5 A.cm-2 and 329 mV at 1 A.cm-2 for 500 hours in 1M KOH. Using anion exchange membrane, we report the lowest cell voltage for an alkaline water electrolyser delivering 2 A.cm-2 at 2 V.