Exposed high-concentration Ir active sites and metal-support interaction endow Ir/MoO2-Mo2C hybrids with high atom
1State Key Laboratory of Green Pesticide, Center for R&D of Fine Chemicals, College of Chemistry and Chemical Engineering, Guizhou University Guiyang Guizhou province 550025 PR China qyuan@gzu.edu.cn.
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Constructing active metal-support interfacial structures is crucial for enhancing the activity and stability of electrocatalysts during the hydrogen evolution reaction (HER) across a wide pH range. Herein, ultrasmall mixed Ir species anchored on MoO2-Mo2C hollow nanoflowers assembled from nanosheets were synthesized via high-temperature sintering (600-800 °C). The X-ray absorption fine structure and X-ray photoelectron spectroscopy revealed the metal-support interaction (MSI) in Ir/MoO2-Mo2C-800. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy and in situ Raman spectroscopy reveal that Ir/MoO2-Mo2C-800 can reconstruct the distribution equilibrium of the hydrogen-bond network of interfacial water to promote water adsorption and dissociation. The highly exposed Ir active sites and MSI enable Ir/MoO2-Mo2C-800 to exhibit extremely low overpotentials of 32 (alkaline), 14 (acidic), and 29 (neutral) mV at 10 mA cm-2, respectively. Moreover, the mass activities of Ir/MoO2-Mo2C-800 (9.23, 60.99, and 8.34 A mg-1 PGM) are 2.68-, 28.27-, and 3.93-fold higher than those of commercial Pt/C (3.45, 2.16, and 2.12 A mg-1 PGM), respectively. The assembled Ir/MoO2-Mo2C-800 ‖ IrO2 anion-exchange membrane (AEM) water electrolyzer demonstrates stable operation for over 700/220 h at a high current density of 0.2/1 A cm-2 and Ir/MoO2-Mo2C-800 can maintain its initial morphology. This study proposes a feasible strategy to achieve highly efficient and stable pH-universal HER by developing electrocatalysts with high concentration Ir active sites and MSI engineering.
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