Dehua Zheng

Developing low-cost, high-activity electrocatalysts for the oxygen evolution reaction (OER) is crucial for advancing anion exchange membrane electrolysis cells (AEMECs). While MoS2 holds great potential as an OER catalyst due to its layered structure, its practical application is hindered by the weak adsorption of *OH and *OOH intermediates. Herein, we report a series of transition metal (Co, Fe, Ni)-doped MoS2 catalysts synthesized via a one-step hydrothermal method. Among them, Co-doped MoS2 exhibits remarkable edge amorphization during catalysis, which creates abundant defects and active sites, thereby promoting the efficient adsorption and conversion of OH-. At high operating potentials, Co dominates the catalytic process; the reduced charge density around Co atoms facilitates OH⁻ adsorption and subsequent *OOH intermediate formation. When assembled into a practical AEMEC, the Pt/C||Co-MoS2 membrane electrode assembly achieves a current density of 1 A cm-2 at a low cell voltage of 1.96 V with good stability. This work demonstrates that heteroatom incorporation can induce edge amorphization in transition metal sulfides, providing an effective strategy for designing high-performance non-precious metal water electrolysis catalysts.

Perovskite oxides (ABO3-δ) are widely used as oxygen electrodes in solid oxide fuel cells (SOFCs) because of their high activity toward the oxygen reduction reaction. Nevertheless, many state-of-the-art Co- and Sr-containing perovskites suffer from large thermal expansion and interfacial degradation, which hinder scale-up and long-term operation. Herein, we develop a Co-/Sr-free oxygen electrode based on A-site Yb-doped CaMnO3-δ (Yb0.1Ca0.9MnO3-δ, denoted Yb0.1CMO). Yb incorporation stabilizes an orthorhombic perovskite phase, decreases the thermal expansion to match gadolinium-doped ceria (GDC), and markedly increases electrical conductivity at 750–850 °C. As a cathode for solid oxide fuel cells (SOFCs), Yb0.1CMO delivers exceptional electrochemical performance, achieving a peak power density of 1.83 W·cm-2 at 800 °C and maintaining long-term stability for over 400 hours, surpassing most reported cathode materials. Combined ex-situ/in-situ characterizations and density functional theory calculations indicate that A-site Yb incorporation enhances electronic transport by shifting the electronic states toward the Fermi level while enabling fast oxygen migration, thereby reducing polarization losses and improving overall cell efficiency. This work demonstrates an effective A-site doping strategy to realize high-performance and durable Co-/Sr-free oxygen electrodes for SOFCs.

In recent years, catalysts based on transition metal sulfides have garnered extensive attention due to their low cost and excellent electrocatalytic activity in the alkaline oxygen evolution reaction. Here, the preparation of Fe‐doped Ni₃S₂ via a one‐step hydrothermal approach is reported by utilizing inexpensive transition metals Ni and Fe. In an alkaline medium, Fe–Ni₃S₂ exhibits outstanding electrocatalytic activity and stability for the OER, and the current density can reach 10 mA cm⁻² with an overpotential of 163 mV. In addition, Pt/C||Fe–Ni₃S₂ is used as the membrane electrode of the anion exchange membrane water electrolyzer, which is capable of providing a current density of 650 mA cm⁻² at a cell voltage of 2.0 V, outperforming the benchmark Ir/C. The principle is revealed that the doping of Fe enhances the electrocatalytic water decomposition ability of Ni₃S₂ by in situ Raman and in situ X‐ray absorption fine structure. The results indicate that the doping of Fe decreases the charge density near Ni atoms, which renders Fe–Ni₃S₂ more favorable for the adsorption of OH⁻ and the formation of ^*OO⁻ intermediates. This work puts forward an effective strategy to significantly improve both the alkaline OER activity and stability of low‐cost electrocatalysts.

The development of actinide materials has provided new strategies for the utilization of nuclear waste, such as depleted uranium, a mildly radioactive waste in the nuclear power industry, which could be a precious resource for many fields, especially water splitting. The catalytic performance of water splitting is limited by the slow kinetics of the oxygen evolution reaction (OER), and it is extremely challenging to design efficient OER catalysts that are highly stable and inexpensive. Here, we design and describe a series of U_5-35%-Co₃O₄ electrocatalysts, which were synthesized using uranyl nitrate as a precursor via a simple and scalable method. Interestingly, when the U/Co molar ratio was 20%, a UCoO₄/Co₃O₄ heterojunction formed with high catalytic efficiency and excellent long-term electrolytic stability. The UCoO₄/Co₃O₄ heterojunction catalyst shows a lower overpotential (280 mV) at a current density of 10 mA cm^-2, and the slope of Tafel is 43.8 mV decade^-1 in a 0.1 M KOH alkaline solution. Soft X-ray absorption spectroscopy shows that the cooperative effect of UCoO₄ and Co₃O₄ can improve the electrochemical activity of the material. This study produced an active U/Co-based catalyst for OER, which provides a simple, scalable, low-cost, and highly efficient catalyst for overall water splitting.

The structural diversity and tunable functionality of the amorphous metal‐organic frameworks (aMOFs) highlights this class of materials as a promising candidate for the development of sustainable energy technologies. The electrocatalytic performance in oxygen evolution reaction (OER) can be greatly improved by incorporating the hetero‐metallics into MOFs. Herein, the OER performance was significantly improved by the incorporation of Fe³⁺ ions into the crystalline cobalt‐based MOF, leading to amorphous structure. Benefiting from the optimized surface morphology and electrochemical surface area, charge transport, was greatly facilitated. The Fe/Co aMOF with 1/4 ratio (labeled as AFC‐MOFs (1 : 4)) exhibited an excellent and stable OER activity, with an ultralow overpotential (256 mV at 10 mA cm⁻²) and Tafel slope of 42.7 mV dec⁻¹. XAS found that the majority of Co²⁺ in AFC‐MOFs (1 : 4) is converted to low‐spin Co³⁺ upon OER, while Fe³⁺ is maintained during the OER process, supporting the synergistic catalytic mechanism between Fe and Co. This material outperforms benchmark IrO₂, which could be attributed to the hollow amorphous structure and the optimized electronic properties.

The synthesis of highly active, stable and cost-effective electrocatalysts for overall water splitting is critical but challenging. Herein, we synthesized nickel-doped pyrrhotite iron sulfide (Fe_0.95−xNi_xS_1.05) nanosheets via a one-pot synthetic route. When tested for oxygen evolution reaction (OER) performance in alkaline solutions, the as-prepared Fe_0.8Ni_0.15S_1.05 catalyst exhibited superior electrocatalytic performance to commercial IrO₂ with a current density of 10 mA cm⁻² at an overpotential of 228 mV, and a Tafel slope of 53 mV dec⁻¹. The hydrogen evolution reaction (HER) activity was achieved on Fe_0.8Ni_0.15S_1.05 with a Tafel slope of 103 mV per decade, and a current density of 10 mA cm⁻² at an overpotential of 263 mV. With nickel doping, the as-prepared pyrrhotite iron sulfide nanosheets can expose more active sites, and hence act as a highly efficient catalyst for overall water splitting.