Hydrogen energy, as a clean and renewable energy, has attracted much attention in recent years. Water electrolysis via the hydrogen evolution reaction at the cathode coupled with the oxygen evolution reaction at the anode is a promising method to produce hydrogen. Given the shortage of freshwater resources on the planet, the direct use of seawater as an electrolyte for hydrogen production has become a hot research topic. Direct use of seawater as the electrolyte for water electrolysis can reduce the cost of hydrogen production due to the great abundance and wide availability. In recent years, various high-efficiency electrocatalysts have made great progress in seawater splitting and have shown great potential. This review introduces the mechanisms and challenges of seawater splitting and summarizes the recent progress of various electrocatalysts used for hydrogen and oxygen evolution reaction in seawater electrolysis in recent years. Finally, the challenges and future opportunities of seawater electrolysis for hydrogen and oxygen production are presented.

Mixed metal oxide nanocomposites (NCs) comprising Cu–Sr (CS), Sr–Cd (SC), and Cd–Cu (CC) were fabricated via a sol–gel method. Structural investigations of fabricated samples were carried out via X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS). The Maxwell–Wagner model, attributing to poor conducting layers around the conducting grains, was indicated to be followed by all of the NCs while investigating the dielectric properties. The Space-charge polarization and hoping mechanism contributed to low AC conductivity at lower frequencies and high AC conductivity at higher frequencies. The as-synthesized NCs effectively degraded two toxic water contaminants, such as crystal violet (CV) and Congo red (CR). Furthermore, the NCs were also evaluated for humidity sensing measurements. All of the NCs indicated efficient response/recovery time with better stability. The extensive investigation suggested the synthesized NCs, well suited for various optical and microelectronic applications.