Coupling Strategic Engineering Increased the Heterointerface Density of Bimetallic Oxyhydroxide/Carbide Electrocatalyst for Kinetic Promotion of Electrochemical-/Solar-Driven Water Splitting

A promising efficient bifunctional electrocatalyst was developed by coupling OER- and HER-active catalysts to unlock large-scale, sustainable hydrogen production through water splitting. Herein, we report a coupling strategy to fabricate FeOOH-Mo2C heterostructure by integrating OER (FeOOH)- and HER (Mo2C)-active catalysts, which demands low overpotential of 261 mV (93 mV dec-1) and 163 mV (102 mV dec-1) toward OER and HER, respectively. The systematic analysis on FeOOH-Mo2C with pristine catalysts inferred that the synergistically improved catalytic performance might be credited to the electronic modulation between FeOOH and Mo2C due to the coupling effect. The charge-accumulated active sites of FeOOH-Mo2C hiked to ∼16.3- and ∼50.1-folds than pristine FeOOH and Mo2C, respectively. Furthermore, FeOOH-Mo2C reflected higher TOF of 0.074 × 10-3 s-1 (OER) and 0.016 × 10-3 s-1 (HER). The improved OER kinetics was further supported by Bode analysis performed at various potentials. The temperature effect inferred that the heterojunction reduced the activation energy of FeOOH-Mo2C (2.97 kJ/mol) compared to those of FeOOH (4.03 kJ/mol) and Mo2C (6.14 kJ/mol). The alkaline electrolyzer FeOOH-Mo2C(+,-) and solar-driven electrolyzer required an impressive potential of 1.53 V to reach 10 mA cm-2, supporting it as an advanced bifunctional electrocatalyst which optimized the charge transfer for OER and HER. The present coupling strategy provides a new foundation to tailoring cost-effective electrocatalysts for pure hydrogen production with net-zero emission.