Using seawater can reduce the dependence on freshwater resources to generate hydrogen by electrocatalytic water splitting. However, the stability and activity of hydrogen evolution reaction (HER) electrocatalysts are highly influenced by the pH of seawater. In this regard, the development of the practical application of HER depends on the creation of highly active non-noble metal electrocatalysts. Here, we propose a technique to optimize the electrocatalytic activity and stability of MoO₃ by utilizing titanium felt as the substrate. We show an HER overpotential as low as 83 mV at −10 mA cm^–2 in neutral pH conditions. The present results show that electrocatalysts based on earth-abundant metals can perform well in saltwater HER, especially at a near-neutral pH (pH ∼ 7). In a neutral saltwater electrolyte (0.55 M PBS + 0.5 M NaCl), this electrocatalyst showed stable performance for 250 h at a constant current density of −100 mA cm^–2, indicating its promising application in seawater-based hydrogen generation. Compared with noble metals, this electrocatalyst provides a cost-effective option for economic seawater hydrogen generation, promoting the potential of seawater electrolysis.

Nanofibers and nanorods of NiCo- and NiCoFe- oxides and phosphides were synthesized by hydrothermal methods, followed by phosphidation to yield (Ni,Co)P, (Ni,Co)2P, and FeP. The materials were evaluated as electrocatalysts for the oxygen evolution reaction (OER) in water splitting in the presence of a magnetic field in two electrolytes: 1 M KOH and 1 M phosphate buffer saline (PBS) solution. A standard electrochemical cell was equipped with disk magnets directed perpendicular to the electric field. The magnetic field affected the catalyst interface and increased the reaction rate. The best catalyst was found to be NiCoP, and the overpotential (at 10 mA/cm2) was reduced from 330 to 260 mV when a magnetic field of 100 mT was applied and further to 170 mV when a magnetic field of 200 mT was applied. NiCoP has the highest proportion of magnetic domains aligned due to having the highest saturation magnetization (Ms), remanence magnetization (Mr), and the lowest coercivity (Hc). The mixed transition metal phosphide catalysts were found to partly transform into (Ni,Co)3(PO4)2during electrocatalysis; however, they still responded to a change in the magnetic field. The results show that a weak magnetic field can improve the performance of electrocatalysts based on certain transition metals in a neutral pH electrolyte mimicking seawater.

Using seawater to generate green hydrogen through electrolysis is a promising strategy for energy conversion. However, direct seawater splitting to form green hydrogen suffers drawbacks from electrode corrosion due to chlorine and other impurities. Herein, we demonstrate direct electrochemical seawater splitting using a forward osmosis membrane coupled with an electrolysis cell. By using this cell, high activity (270 mV at 10 mA/cm(2)) and decent stability (up to 6 days) are achieved by utilizing RuO2-(Ni,Co)(3)O-4 catalyst in a neutral electrolyte. This system is further studied in various electrolytes under neutral to alkaline conditions. This proof of concept shows that seawater splitting could be coupled with semipermeable membranes, allowing for direct utilization of seawater without pretreatment or purification and evading the challenges posed by impurities.

Subjecting phosphotungstic acid solutions to low pH in combination with introduction of polyvalent cations led to the formation of nanostructured microspheres of approximately 2 μm in size, as shown by scanning electron microscopy, which were almost insoluble and resistant to degradation at neutral and high pH. These microspheres were composed of secondary nanospheres with diameters around 20 nm as revealed by transmission electron microscopy and atomic force microscopy. Investigations of the crystal structure of a potential intermediate of this process, namely, acidic lanthanum phosphotungstate, [La(H₂O)₉](H₃O)₃[PW₁₂O₄₀]₂(H₂O)₁₉, showed a tight network of hydrogen bonding, permitting closer packing of phosphotungstic acid anions, thereby confirming the mechanism of the observed self-assembly process. The new material demonstrated promising electrochemical properties in oxygen evolution reactions with the high stability of the obtained electrode material.