Construction of S‑modified Amorphous Fe(OH)₃ on NiSe Nanowires as Bifunctional Electrocatalysts for Efficient Seawater Splitting

Seawater electrolysis is valuable for hydrogen production, but there are significant challenges such as severe Cl– corrosion and competition reaction of the chlorine evolution reaction (CER) due to high Cl– concentrations. Here, a core–shell structure was developed on the nickel foam substrate, consisting of a sulfur-modified amorphous Fe(OH)3 layer on top of a crossing NiSe nanowire (named S–Fe(OH)3/NiSe/NF). The S–Fe(OH)3/NiSe/NF electrode demonstrates outstanding catalytic performance for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) in simulated and natural alkaline seawater electrolytes. The overpotentials at 100 mA/cm2 for the OER in simulated and natural alkaline seawater electrolytes are 234 and 232 mV, respectively. For HER, the values are 331 and 341 mV, respectively, at a current density of 100 mA/cm2. When S–Fe(OH)3/NiSe/NF serves as both the anode and cathode, the electrolyzer demonstrates excellent performance with voltages of 1.85 and 1.87 V at 100 mA/cm2 in simulated and natural seawater electrolytes, respectively. This electrolyzer holds significant promise for practical seawater electrolysis

Large-Scale Production of V₆O₁₃ Cathode Materials Assisted by Thermal Gravimetric Analysis–Infrared Spectroscopy Technology

The kilogram-scale fabrication of V₆O₁₃ cathode materials has been notably assisted by in situ thermal gravimetric analysis (TGA)–infrared spectroscopy (IR) technology. This technology successfully identified a residue of ammonium metavanadate in commercial V₆O₁₃, which is consistent with the X-ray photoelectron spectroscopy result. Samples of V₆O₁₃ materials have been fabricated and characterized by TGA–IR, scanning electron microscopy, and X-ray diffraction. The initial testing results at 125 °C have shown that test cells containing the sample prepared at 500 °C show up to a 10% increase in the initial specific capacity in comparison with commercial V₆O₁₃

Unraveling the Complex Delithiation and Lithiation Mechanisms of the High Capacity Cathode Material V₆O₁₃

V₆O₁₃ is a promising Li-ion battery cathode material for use in the high temperature oil field environment. The material exhibits a high capacity, and the voltage profile contains several plateaus associated with a series of complex structural transformations, which are not fully understood. The underlying mechanisms are central to understanding and improving the performance of V₆O₁₃-based rechargeable batteries. In this study, we present <i>in situ</i> X-ray diffraction data that highlight an asymmetric six-step discharge and five-step charge process, due to a phase that is only formed on discharge. The Li_<i>x</i>V₆O₁₃ unit cell expands sequentially in <i>c</i>, <i>b</i>, and <i>a</i> directions during discharge and reversibly contracts back during charge. The process is associated with change of Li ion positions as well as charge ordering in Li_<i>x</i>V₆O₁₃. Density functional theory calculations give further insight into the electronic structures and preferred Li positions in the different structures formed upon cycling, particularly at high lithium contents, where no prior structural data are available. The results shed light into the high specific capacity of V₆O₁₃ and are likely to aid in the development of this material for use as a cathode for secondary lithium batteries