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As the oxygen evolution reaction (OER) imposes a high energy barrier during electrochemical water splitting, designing highly efficient, stable, and cost-effective electrocatalysts for OERs is an ongoing challenge. In this study, we present a facile approach to prepare villi-shaped Ni−Fe hydroxides incorporated with oxalate derived from Ni−Fe oxalate through the in situ precipitation growth and subsequent immersion in an alkaline solution. The electrode with an optimized Ni−Fe ratio improves the OER kinetics, on which the electronic structure of the active site is adjusted based on a mutual effect between the adjacent nickel and iron atoms. The OER performance was significantly better than that of monometallic Ni(OH) 2 and pristine Ni foam, with a low overpotential of 277 mV at 100 mA cm −2 and excellent stability. The enhanced OER performance is ascribed to the advanced intrinsic electrocatalytic activity of the electrode as a result of the synergetic effect of optimized Ni−Fe ratio mixing at the atomic level which leads to an increased surface area, a high number of active sites, and a reduced charge transfer resistivity.

CuC2O4⋅x H2O was facilely prepared on a Cu–Ni alloy substrate by in situ precipitation‐induced growth by using a mixture of sodium persulfate, hydrogen peroxide, and oxalic acid. Thermal annealing allowed the conversion of CuC2O4⋅x H2O to leaf‐like CuO nanostructures with a thickness of a few tens of micrometers of sub‐sized nanoparticles, which were applied for fabricating binder‐free anodes for lithium‐ion batteries. Ni was a nucleation site for CuC2O4⋅x H2O, which was uniformly formed on the entire substrate. The concentration of each component in the mixture solution caused significant morphological changes because of the different elution of copper ions. CuO nanostructures annealed at 550 °C showed large areal and gravimetric capacity with excellent capacity retention of 95.5 % after 200 cycles at a high current density because of their appropriate structural morphology, which not only allowed the formation of a stable solid electrolyte interphase layer but also enabled a reversible reaction during the charge/discharge process.

Lithium-ion batteries (LIBs) with high energy density and safety under fast-charging conditions are highly desirable for electric vehicles. However, owing to the growth of Li dendrites, increased temperature at high charging rates, and low specific capacity in commercially available anodes, they cannot meet the market demand. In this study, a facile one-pot electrochemical self-assembly approach has been developed for constructing hybrid electrodes composed of ultrafine Fe 3 O 4 particles on reduced graphene oxide (Fe 3 O 4 @rGO) as anodes for LIBs. The rationally designed Fe 3 O 4 @rGO electrode containing 36 wt % rGO exhibits an increase in specific capacity as cycling progresses, owing to improvements in the active sites, electrochemical kinetics, and catalytic behavior, leading to a high specific capacity of 833 mAh g À 1 and outstanding cycling stability over 2000 cycles with a capacity loss of only 0.127 % per cycle at 5 A g À 1 , enabling the full charging of batteries within 12 min. Furthermore, the origin of this abnormal improvement in the specific capacity (called negative fading), which exceeds the theoretical capacity, is investigated. This study opens up new possibilities for the commercial feasibility of Fe 3 O 4 @rGO anodes in fast-charging LIBs.

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