Boosting oxygen evolution reaction activity with Mo incorporated NiFe-LDH electrocatalyst for efficient water electrolysis.

This work demonstrates a simple and scalable methodology for the binder-free direct growth of Mo-doped NiFe-layered double hydroxides on a nickel substrate via an electrodeposition route at room temperature. A three-dimensional (3D) nanosheet array morphology of the electrocatalyst provides immense electrochemical surface area as well as abundant catalytically active sites. Mo incorporation in the NiFe-LDH plays a crucial role in regulating the catalytic activity of oxygen evolution reaction (OER). The prepared electrocatalyst exhibited low overpotential (i.e., 230 mV) at 30 mA cm-2 for OER in an alkaline electrolyte (i.e., 1 M KOH). Furthermore, the optimized Mo-doped NiFe-LDH electrode was used as an anode in a laboratory-scale in situ single cell test system for alkaline water electrolysis at 80 °C with a continuous flow of 30 wt% KOH, and it shows the efficient electrochemical performance with a lower cell voltage of 1.80 V at a current density of 400 mA cm-2. In addition, an admirable long-term cell durability is also demonstrated by the cell for 24 h. This work encourages new designs and further development of electrode material for alkaline water electrolysis on a commercial scale.

Evaluation of Chloride-Ion Diffusion Characteristics of Wave Power Marine Concrete Structures.

Wave power marine concrete structures generate electrical energy using waves. They are exposed to a multi-deterioration environment because of air and hydrostatic pressure and chloride attack. In this study, the effect of air pressure repeatedly generated by water level change of wave power marine concrete structures on the chloride-ion diffusion of marine concrete was analyzed. The chloride-ion diffusion of wave power marine concrete structures was evaluated. The results show that the air chamber and bypass room, which were subjected to repetitive air pressures caused by water level changes, showed a higher water-soluble chloride-ion content compared to the generator room and docking facility, which were subjected to atmospheric pressure. Field exposure tests and indoor chloride attack tests were performed using fabricated specimens to analyze the effect of pressure on chloride-ion penetration. It was confirmed that Portland blast furnace slag had a greater inhibitory effect on chloride-ion penetration than ordinary Portland cement. The concrete specimens subjected to pressure showed increased capillary pores and micro-cracks. We devised an equation for calculating the diffusion coefficient based on measured data and estimating the diffusion coefficient for the location receiving repeated air pressure by using the diffusion coefficient of the location receiving general atmospheric pressure.