Seawater is one of the most abundant and clean hydrogen atom resources on our planet, so hydrogen production from seawater splitting has notable advantages. Direct electrolysis of seawater would not be in competition with growing demands for pure water. Using green electricity generated from renewable sources (e.g., solar, tidal, and wind energies), the direct electrolytic splitting of seawater into hydrogen and oxygen is a potentially attractive technology under the framework of carbon-neutral energy production. High selectivity and efficiency, as well as stable electrocatalysts, are prerequisites to facilitate the practical applications of seawater splitting. Even though the oxygen evolution reaction (OER) is thermodynamically favorable, the most desirable reaction process, the four-electron reaction, exhibits a high energy barrier. Furthermore, due to the presence of a high concentration of chloride ions (Cl⁻) in seawater, chlorine evolution reactions involving two electrons are more competitive. Therefore, intensive research efforts have been devoted to optimizing the design and construction of highly efficient and anticorrosive OER electrocatalysts. Based on this, in this review, we summarize the progress of recent research in advanced electrocatalysts for seawater splitting, with an emphasis on their remarkable OER selectivity and distinguished anti-chlorine corrosion performance, including the recent progress in seawater OER electrocatalysts with their corresponding optimized strategies. The future perspectives for the development of seawater-splitting electrocatalysts are also demonstrated.

Protonic ceramic fuel cells (PCFCs) are more suitable for operation at low temperatures due to their smaller activation energy (E_a). Unfortunately, the utilization of PCFC technology at reduced temperatures is limited by the lack of durable and high-activity air electrodes. A lot number of cobalt-based oxides have been developed as air electrodes for PCFCs, due to their high oxygen reduction reaction (ORR) activity. However, cobalt-based oxides usually have more significant thermal expansion coefficients (TECs) and poor thermomechanical compatibility with electrolytes. These characteristics can lead to cell delamination and degradation. Herein, we rationally design a novel cobalt-containing composite cathode material with the nominal composition of Sr₄Fe₄Co₂O_13+δ (SFC). SFC is composed of tetragonal perovskite phase (Sr₈Fe₈O_23+δ, I4/mmm, 81 wt.%) and spinel phase (Co₃O₄, Fd3̄m, 19 wt.%). The SFC composite cathode displays an ultra-high oxygen ionic conductivity (0.053 S·cm⁻¹ at 550 °C), superior CO₂ tolerance, and suitable TEC value (17.01 × 10⁻⁶ K⁻¹). SFC has both the O²⁻/e⁻ conduction function, and the triple conducting (H⁺/O²⁻/e⁻) capability was achieved by introducing the protonic conduction phase (BaZr_0.2Ce_0.7Y_0.1O_3−δ, BZCY) to form SFC+BZCY (70 wt.%:30 wt.%). The SFC+BZCY composite electrode exhibits superior ORR activity at a reduced temperature with extremely low area-specific resistance (ASR, 0.677 Ω·cm² at 550 °C), profound peak power density (PPD, 535 mW·cm⁻² and 1.065 V at 550 °C), extraordinarily long-term durability (> 500 h for symmetrical cell and 350 h for single cell). Moreover, the composite has an ultra-low TEC value (15.96 × 10⁻⁶ K⁻¹). This study proves that SFC+BZCY with triple conducting capacity is an excellent cathode for low-temperature PCFCs.

To enhance the performance and widespread use of solid oxide fuel cells (SOFCs), addressing the low-temperature (< 650 °C) electrochemical performance and operational stability issues of cathode materials is crucial. Here, we propose an innovative approach to enhance oxygen ion mobility and electrochemical performance of perovskite oxide by substituting some oxygen sites with chlorine anions. The designed SrTa_0.1Fe_0.9O_3-δ-xCl_x (x = 0.05 and 0.10) exhibits improved performance compared to SrTa_0.1Fe_0.9O_3-δ (STF). SrTa_0.1Fe_0.9O_2.95-δCl_0.05 (STFCl0.05) shows the lowest area-specific resistance (ASR) value on Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte. At 600 °C, STFCl0.05 achieves an ASR value of 0.084 Ω·cm², and a single cell with STFCl0.05 reaches a higher peak power density (PPD) value (1143 mW·cm^-2) than that with STF (672 mW·cm^-2). Additionally, besides exhibiting excellent oxygen reduction reaction (ORR) activity at lower temperatures, the STFCl0.05 cathode demonstrates good CO₂ tolerance and operational stability. Symmetrical cell operation lasts for 150 h, and single cell operation endures for 720 h without significant performance decline. The chlorine doping approach effectively enhances ORR activity and stability, making STFCl0.05 a promising cathode material for low-temperature SOFCs.

Solid oxide fuel cells (SOFCs) offer a significant advantage over other fuel cells in terms of flexibility in the choice of fuel. Ammonia stands out as an excellent fuel choice for SOFCs due to its easy transportation and storage, carbon-free nature and mature synthesis technology. For direct-ammonia SOFCs (DA-SOFCs), the development of anode catalysts that have efficient catalytic activity for both NH₃ decomposition and H₂ oxidation reactions is of great significance. Herein, we develop a Mo-doped La_0.6Sr_0.4Fe_0.8Ni_0.2O_3−δ (La_0.6Sr_0.4Fe_0.7Ni_0.2Mo_0.1O_3−δ, LSFNM) material, and explore its potential as a symmetrical electrode for DA-SOFCs. After reduction, the main cubic perovskite phase of LSFNM remained unchanged, but some FeNi₃ alloy nanoparticles and a small amount of SrLaFeO₄ oxide phase were generated. Such reduced LSFNM exhibits excellent catalytic activity for ammonia decomposition due to the presence of FeNi₃ alloy nanoparticles, ensuring that it can be used as an anode for DA-SOFCs. In addition, LSFNM shows high oxygen reduction reactivity, indicating that it can also be a cathode for DA-SOFCs. Consequently, a direct-ammonia symmetrical SOFC (DA-SSOFC) with the LSFNM-infiltrated doped ceria (LSFNM-SDCi) electrode delivers a superior peak power density (PPD) of 487 mW cm⁻² at 800 °C when NH₃ fuel is utilised. More importantly, because Mo doping greatly enhances the reduction stability of the material, the DA-SSOFC with the LSFN-MSDCi electrode exhibits strong operational stability without significant degradation for over 400 h at 700 °C.