Experimental and Theoretical Validation of High Efficiency and Robust Electrocatalytic Response of One-Dimensional (1D) (Mn,Ir)O2:10F Nanorods for the Oxygen Evolution Reaction in PEM-Based Water Electrolysis

Development of highly efficient, earth-abundant, and cost-effective electrocatalysts for the kinetically sluggish and energy-intensive anodic oxygen evolution reaction (OER) is crucial for realizing the large-scale commercialization of proton exchange membrane based water electrolysis (PEMWE). Herein, we report the results of one-dimensional (1D) nanorods (NRs) containing an ultralow amount of noble metal (iridium, Ir) and 10 wt % fluorine (F) doped (Mn0.8Ir0.2)O2:10F as an efficient anode electrocatalyst, synthesized via a simple hydrothermal and wet chemical approach for the acidic OER. The as-synthesized (Mn0.8Ir0.2)O2:10F NRs demonstrate promising electrocatalytic performance for the OER with significantly lower overpotential (η) and higher current density than state of the art IrO2 and many other electrocatalysts containing noble metal/reduced noble metal. Owing to the presence of 1D channels of the nanorod architecture and the unique electronic structure obtained upon formation of an F-containing solid solution, the (Mn0.8Ir0.2)O2:10F NRs exhibit low charge transfer resistance (∼2.5 Ω cm2), low Tafel slope (∼38 mV dec–1), low water contact angle (∼18°), high electrochemical active surface area (ECSA ≈ 704.76 m2 g–1), high roughness factor (∼2114), and notable OER performance with ∼6-, ∼2.1-, and ∼2.2-fold higher electrocatalytic activity in comparison to IrO2, (Mn0.8Ir0.2)O2 NRs and a 2D thin film of (Mn0.8Ir0.2)O2:10F, respectively. The significantly higher ECSA and BET specific activity (0.11 mA cm−2BET), mass activity (40 Ag–1), and TOF (0.01 s–1) at an overpotential (η) of 220 mV suggest the intrinsically higher catalytic activity of (Mn0.8Ir0.2)O2:10F NRs in comparison to other as-synthesized electrocatalysts. In addition, (Mn0.8Ir0.2)O2:10F NRs function as robust electrocatalysts by delivering a current density of 10 mA cm–2 at η ≈ 200 mV and displaying long-term durability, devoid of any degradation of the catalytic activity, suggesting the structural robustness for displaying prolonged OER activity. Herein, on the basis of the synergistic effects of tailoring of 2D material length scales into a 1D nanorod framework and the corresponding formation of an F-substituted unique solid solution structure (as validated by density functional theory), (Mn0.8Ir0.2)O2:10F NRs offer promise for an efficient OER in PEMWE.