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The electrocatalytic oxygen evolution reaction (OER) is an arduous step in water splitting due to its slow reaction rate and large overpotential. Herein, we synthesized glycerate-anion-intercalated nickel–iron glycerates (NiFeGs) using a one-step solvothermal reaction. We designed various NiFeGs by tuning the molar ratio between Ni and Fe to obtain Ni4Fe1G, Ni3Fe1G, Ni3Fe2G, and Ni1Fe1G, which we tested for their OER performance. We initially analyzed the catalytic performance of powder samples immobilized on glassy carbon electrodes using a binder. Ni3Fe2G outperformed the other NiFeG compositions, including NiFe layered double hydroxide (LDH). It exhibited an overpotential of 320 mV at a current density of 10 mA cm–2 in an electrolytic solution of pH 14. We then synthesized carbon paper (CP)-modified Ni3Fe2G as a self-supported electrode (Ni3Fe2G/CP), and it exhibited a high current density (100 mA cm−2) at a low overpotential of 300 mV. The redox peak analysis for the NiFeGs revealed that the initial step of the OER is the formation of γ-NiOOH, which was further confirmed by a post-Raman analysis. We extensively analyzed the catalyst's stability and lifetime, the nature of the active sites, and the role of the Fe content to enhance the OER performance. This work may provide the motivation to study metal-alkoxide-based efficient OER electrocatalysts that can be used for alkaline water electrolyzer applications. [ABSTRACT FROM AUTHOR]

Tailoring the precise construction of non‐precious metals and carbon‐based heterogeneous catalysts for electrochemical oxygen evolution reaction (OER) and methanol oxidation reaction (MOR) is crucial for energy conversion applications. Herein, this work reports the composite of Ni doped Fe2O3 (Ni−Fe2O3) with mildly oxidized multi‐walled CNT (O−CNT) as an outstanding Mott‐Schottky catalyst for OER and MOR. O−CNT acts as a co‐catalyst which effectively regulates the charge transfer in Ni−Fe2O3 and thus enhances the electrocatalytic performance. Ni−Fe2O3/O−CNT exhibits a low onset potential of 260 mV and overpotential 310 mV @ 10 mA cm−2 for oxygen evolution. Being a Mott‐Schottky catalyst, it achieves the higher flat band potential of −1.15 V with the carrier density of 0.173×1024 cm−3. Further, in presence of 1 M CH3OH, it delivers the MOR current density of 10 mA cm−2 at 1.46 V vs. RHE. The excellent electrocatalytic OER and MOR activity of Ni−Fe2O3/O−CNT could be attributed to the synergistic interaction between Ni‐doped Fe2O3 and O−CNT. [ABSTRACT FROM AUTHOR]

We designed a heterostructure of Fe3S4@Ni3S2, as a potent oxygen evolution reaction (OER) electrocatalyst in an alkaline medium. Intriguingly, Fe3S4@Ni3S2 exhibits low onset potential of 290 mV and overpotential of 360 mV at a current density of 10 mA cm−2. We examined the OER kinetics of Fe3S4@Ni3S2 using distribution function of relaxation times (DFRT), which are attained with the help of impedance spectroscopy genetic programming (ISGP). ISGP reveals the occurrences of three events of OER, manifested as peaks in the DFRT, such as active material or pores (P2), charge transfer (P1'), and production rate of intermediates (P1) in case of Fe3S4@Ni3S2 at different faradic overpotentials. The effective resistance of each phenomenon can be easily calculated. It decreases with an increase in conductivity at high overpotentials for all the three, which suggests the high performance of the as‐synthesized composite due to faster kinetics. Further, structural investigation of the catalyst employing x‐ray photoelectron spectroscopy is elaborated and it is suggested that the catalyst activation takes place by the constant exchange of anions between electrode and electrolyte during electrochemical oxidation. [ABSTRACT FROM AUTHOR]

Here, we report a facile upscaled ambient pressure CVD-assisted synthesis of low-temperature phase silver selenide (β-Ag 2 Se) on Ag foil and its first-reported application (in its pristine form) as an ORR catalyst. The exfoliated β-Ag 2 Se via XRD, EDS, HRTEM, AFM, and HRSEM determines its stoichiometry and its hollow layered fern-like morphology. Differential scanning calorimetry (DSC) further confirms that the final product is the low-temperature phase β-Ag 2 Se. Electrochemical oxygen reduction reaction (ORR) of exfoliated β-Ag 2 Se exhibits a strong oxygen reduction current with an onset potential of 0.88 V/RHE under alkaline conditions, indicating the oxygen reduction property of β-Ag 2 Se. The significant value of limiting current (3 mA cm−2) as well as small Tafel slope (68.5 mV dec−1) substantiates β-Ag 2 Se as a superior layered transition metal chalcogenide suitable for various energy-related applications (typically fuel cells and metal-air batteries). Image, graphical abstract [ABSTRACT FROM AUTHOR]