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The production of green hydrogen by a cost-effective electrolysis technology is of paramount importance for future energy supply systems. In this regard, proton exchange membrane (PEM) electrolysis is the technology of choice due to its compactness and high efficiency; however, its dependence on the scarce iridium catalyst jeopardizes the deployment at large scale. Here, we present a low-cost electrolyzer consisting of an assembly of an anion exchange membrane (AEM) and plasma-sprayed electrodes without any precious metals. Several electrode materials are developed and tested in this configuration at 60 °C and feeding 1 M KOH electrolyte. The AEM electrolyzer with NiAlMo electrodes can achieve a potential of 2.086 V at a current density of 2 A cm–2, which is comparable to the performances of industrial MW-size PEM electrolyzers. The cell potential with NiAl anode and NiAlMo cathode is 0.4 V higher at the same current density, but it keeps a stable operation for more than 150 h. Through different post-mortem analyses on the aged electrodes, the degradation mechanism of NiAlMo anode is elucidated. The efficiencies of the developed AEM electrolyzer concept reported herein are close to those of the commercial PEM systems, and thus a cost-effective alternative to this technology is provided based on our results.

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Anion exchange membrane water electrolyzers (AEMWEs) offer a cost-effective technology for producing green hydrogen. Here, an AEMWE with atmospheric plasma spray non-precious metal electrodes was tested in 0.1 to 1.0 M KOH solution, correlating performance with KOH concentration systematically. The highest cell performance was achieved at 1.0 M KOH (ca. 0.4 A cm À 2 at 1.80 V), which was close to a traditional alkaline electrolysis cell with � 6.0 M KOH. The cell exhibited 0.13 V improvement in the performance in 0.30 M KOH compared with 0.10 M KOH at 0.5 A cm À 2. However, this improvement becomes more limited when further increasing the KOH concentration. Electrochemical impedance and numerical simulation results show that the ohmic resistance from the membrane was the most notable limiting factor to operate in low KOH concentration and the most sensitive to the changes in KOH concentration at 0.5 A cm À 2. It is suggested that the effect of activation loss is more dominant at lower current densities; however, the ohmic loss is the most limiting factor at higher current densities, which is a current range of interest for industrial applications.

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Rationally designed free-standing and binder-free Raney-type nickel-molybdenum (ni-Mo) electrodes produced via atmospheric plasma spraying (APS) are developed by correlating APS process parameters with the microstructure of electrodes and their electrochemical performance in alkaline media. the results revealed that the electrode morphology and elemental composition are highly affected by the plasma parameters during the electrode fabrication. It is found that increasing plasma gas flow rate and input plasma power resulted in higher in-flight particle velocities and shorter dwell time, which in result delivered electrodes with much finer structure exhibiting homogeneous distribution of phases, larger quantity of micro pores and suitable content of Ni and Mo. Tafel slope of electrodes decreased with increasing the in-flight particles velocities from 71 to 33 mV dec −1 in 30 wt.% KOH. However, beyond a critical threshold in-flight velocity and temperature of particles, electrodes started to exhibit larger globular pores and consequently reduced catalytic performance and higher Tafel slop of 36 mV dec −1 in 30 wt.% KOH. Despite slightly lower electrochemical performance, the electrodes produced with highest plasma gas flow and energy showed most inter-particle bonded structure as well as highest stability with no measurable degradation over 47 days in operation as HER electrode in 30 wt.% KOH. The Raney-type Ni-Mo electrode fabricated at highest plasma gas flow rate and input plasma power has been tested as HER electrode in alkaline water electrolyzer, which delivered high current densities of 0.72 and 2 A cm −2 at 1.8 and 2.2 V, respectively, representing a novel prime example of HER electrode, which can synergistically catalyze the HER in alkaline electrolyzer. This study shows that sluggish alkaline HER can be circumvented by rational electrode composition and interface engineering. Hydrogen has attracted a lot of attention as a clean energy carrier, due to growing pressure on emissions and depleting reserves of fossil fuel. Alkaline water electrolysis (AWE) is one of the most mature and widely used electrolysis technologies for hydrogen production due to the inexpensive non-precious metal electrodes, low cost components and high durability 1-4. However, AWE operate at significantly lower current densities compared to proton exchange membrane water electrolysis (PEMWE). This can be due to this reason that not only the oxygen