The development of efficient and durable bifunctional electrocatalysts based on earth-abundant elements for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is critical for advancing sustainable hydrogen production. Herein, a facile one-step hydrothermal strategy was developed to synthesize Ru-doped α-MnO 2 nanoneedles grown on carbon paper (Ru 0.02 MnO 2 /CP) as a novel bifunctional electroccatalyst. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses revealed that Ru incorporation induces uniform lattice distortion in MnO 2 , significantly increasing the density of oxygen vacancies and catalytically active Mn 3+ sites. The structural modifications enhance the intrinsic electrochemical activity and structural stability of MnO 2 during HER/OER in alkaline media. The optimized Ru 0.02 MnO 2 /CP catalyst exhibited exceptional bifunctional performance, achieving low overpotentials of 107 mV (HER) and 261 mV (OER) at 10 mA cm −2 . Furthermore, stability testing under continuous operation reveals <6 % activity loss over 100 h at 10 mA cm −2 . Density functional theory (DFT) calculations revealed that Ru doping optimizes the adsorption/desorption energetics of reaction intermediates (*H for HER; *OH for OER), effectively lowering the kinetic barriers and overpotentials for both half-reactions. This work provides a rational strategy for designing high-performance and cost-effective bifunctional electrocatalyst, advancing their potential application in scalable water electrolysis for sustainable hydrogen production.
Enhancing the inherent activity of transition metal-based compounds involving Ni and Fe for the electrocatalytic oxygen evolution reaction (OER) is of vital importance, especially NiFe layered double hydroxide (LDH). Here, we doped erbium (Er) into NiFe LDH (Er–NiFe LDH) nanostructures using simple liquid-phase synthesis. The OER activity tests at the same mass loading demonstrated that Er–NiFe LDH has a smaller overpotential and lower Tafel slope than undoped NiFe LDH and commercial RuO 2 powders, needing only a small overpotential of 243 mV to achieve a constant current at 10 mA cm -2 . Additionally, Er–NiFe LDH was grown in situ on hydrophilic carbon paper substrates (Er–NiFe LDH@CP) to fabricate a three-dimensional (3D) electrode with large catalyst loading, which is favorable for analyzing the stability of morphology structure and elementary components after OER measurement. The galvanostatic measurement suggested that the Er–NiFe LDH@CP electrode possess higher electrochemical durability than a modified glassy carbon electrode due to the stronger mechanical binding between Er–NiFe LDH nanostructures and carbon paper substrate. More importantly, physical characterizations (e.g., SEM and XPS) revealed that Er–NiFe LDH has an excellent stability of morphology, and Ni, Fe, and Er still exist on the catalyst 24 h after the operation. This work provides an effective way for improving the inherent catalytic activity and stability of polymetallic OER catalysts in the future.
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