Friction stir welding (FSW) is a solid-state welding process capable of joining a wide range of light metals. However, liquation and solidification may occur during joining of dissimilar metals which leads to eutectic formation. This article aims to discover the influence of tool rotation speed on the formation of eutectic structure during friction stir welding of aluminum to magnesium. To do so, friction stir welding was performed at 600 and 950 rpm to join pure aluminum and ECO-AZ91 magnesium alloy in a lap configuration. In order to investigate the influence of the welding speed, the welding speeds of 23.5 and 37.5 mm/min were also chosen. Scanning electron microscopy (SEM) was used to study the microstructure of the joints. A shear-tensile test was used to evaluate the joints’ strengths. The fracture surfaces were also studied by SEM. The results revealed that changing the rotation speed directly affects the eutectic formation, whereas the welding speed had no influence. A lower rotation speed resulted in a thin, continuous intermetallic layer, whereas a higher speed led to the formation of a massive Mg-Al₁₂Mg₁₇ eutectic microstructure. The formation of eutectic, as an indicative of liquation, may affect the material flow during the process due to decreasing the friction coefficient between the tool and material. The macrostructure analyses showed that the phase evolution as well as the mechanism of material flow are highly affected by liquation.

Electrocatalytic water splitting driven by renewable energy is a promising strategy for sustainable hydrogen production. However, the slow oxygen evolution reaction (OER) kinetics severely limit the rate of the hydrogen evolution reaction (HER) and the overall energy conversion efficiency of the water electrolyzer. To overcome this challenge, hybrid water electrolysis systems have been developed which replace the sluggish OER with thermodynamically and kinetically favorable biomass (photo-)electro-oxidation. In addition, these system allow for the simultaneous production of value-added chemical products. This review highlights the design strategies related to the host structure remodeling and structure assembly design of two-dimensional (2D) nanomaterial-based (photo)electrocatalysts, as well as their wide application in hybrid water electrolysis. Moreover, the current challenges and emerging strategies for the development of advanced (photo-)electrocatalysts and industrial-scale systems are emphasized.