Gongzhen Cheng

The development of a γ-NiOOH surface layer on NiFe_alloy/NiFeN as well as Fe doping improved the adsorption energy of the oxygen-containing species and increased the OER catalytic activity.

The tremendous potential of high-entropy alloys (HEA) in the electrocatalysis of the oxygen evolution reaction (OER) is well known, but many issues pertaining to building more reliable HEA systems to maximize its synergistic advantages and explaining their complex electrochemical interface behavior need to be discussed. Herein, a convenient composite metal–organic framework (MOF) co-pyrolysis method is designed to reconstruct the precursor in a high-temperature inert atmosphere and prepare a core–shell structure nitrogen-containing carbon nanotube-coated six-metal alloy (FeCoNiVCrZn HEA) as an excellent alkaline medium OER catalyst. It can achieve a working current density of 10 mA cm⁻² at 249 mV overpotential, and the current fluctuation range is less than 3.12% after constant voltage operation for an extended time in 1 M KOH electrolyte. Its electrocatalytic activity and stability surpass those of the same type of alloy catalyst and commercial IrO₂/C catalyst. We tracked the trend of the concentration and chemical state of metal ions between two phases during the electrochemical process and found that the interface reconfiguration of the high-entropy alloy is regulated by the characteristic transition metal migration behavior. On this basis, through density functional theory (DFT) calculation, we further explored the alkaline medium surface metal dissolution and surface reconfiguration behavior and verified that the active MOOH (M = Fe, Co and Ni) phase plays a key role in the reaction steps for the adsorption of the oxygen species. This work provides a unique perspective for the study of HEA in OER structure optimization and interface behavior and shows a new prospect for the development of advanced OER electrocatalysts.

In this study, we explord the catalytic activity of NiCoFe_phosphide nanosheets as highly active and stable catalysts for OER. Electrochemical analysis exhibits a low overpotential of 259 mV in (1 M KOH), achieving a current density of 10 mA cm⁻² with a low Tafel slope of 50.47 mV dec⁻¹.

In this study, we explord the catalytic activity of MoCoFephosphide nanosheets as highly active and stable catalysts for OER. Electrochemical analysis exhibits a low overpotential of 250 mV in (1 M KOH), achieving a current density of 10 mA cm⁻² with a low Tafel slope of 43.38 mV dec⁻².

Oxygen evolution reaction (OER) is a critical anodic reaction of electrochemical water splitting, developing a high‐efficiency electrocatalyst is essential. Transition metal‐based catalysts are much more cost‐effective if comparable activities can be achieved. Among them, fluorides are rarely reported due to their low aqueous stability of coordination and low electric conductivity. Herein, a NiCo bimetallic fluoride with good crystallinity is designed and constructed, and significantly enhanced catalytic activity and conductivity are observed. The inevitable oxidation of transition metal ions at high potential and the dissociation of F⁻ are attributed to the low aqueous stability of coordination. The theoretical researches predicte that transition metal fluorides should have a strong tendency to electrochemical reconstruction. Therefore, based on the observations on their electrochemical behavior, high‐resolution transmission electron microscopy, X‐ray photoelectron spectroscopy, and bode plots, it is further demonstrated that surface reconstruction occurred during the electrochemical process, meanwhile a significant increase of electrochemically active area, which is created by F migration, are also directly observed. Additionally, DFT calculation results show that the electronic structure of the catalysts is modulated by the bimetallic centers, and this reconstruction helps optimizing the adsorption energy of oxygen‐containing species and improves OER activity.

We report a VFeNi/VO(OH)₂ catalyst with abundant oxygen vacancies. It can achieve advanced OER activity and ultra-high stability in a long electrocatalysis test.

In this work, Ni-MOF-Fe-2 was fabricated by using Fe ³⁺ etching bulk Ni MOF, and the as-prepared catalyst showed significantly enhanced OER performances, which exhibited a low overpotential (η ₁₀ = 269 mV) and remarkable durability in 1 M KOH.