Synergistic engineering of morphology and electronic structure in constructing metal-organic framework-derived Ru doped cobalt-nickel oxide heterostructure towards efficient alkaline hydrogen evolution reaction

Abstract

Hydrogen generation by alkaline electrochemical water splitting urgently requires new techniques capable of fabricating efficient and robust electrocatalysts for hydrogen evolution reaction (HER). However, it remains a major challenge to achieve this aim through a conjoint modulation in morphology and electronic structure. Herein, a metal–organic framework-derived (MOF-derived) Ru doped cobalt–nickel oxide heterostructure grown on Ni foam (Ru-Co3O4-NiO-NF) is fabricated by a simple and scalable preparation method. Systematic experimental characterizations verify that through a tailored low-temperature annealing process, the resulted Ru-Co3O4-NiO-NF can effectively inherit the advantageous two-dimensional (2D) nanosheet morphology of Co-MOF precursor and simultaneously maintain the mechanical robustness of three-dimensional (3D) Ni foam, which are beneficial for active site exposure and charge or mass transport. Furthermore, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculation are hired to reveal that Ru-doping and Co3O4-NiO heterointerface can collectively regulate the electronic state of Ni and Co sites, thus optimizing the H2O adsorption/desorption and proton adsorption in alkaline HER process. As expected, the optimized Ru-Co3O4-NiO-NF is much more active than the commercial Pt-C (20 wt%) for electrocatalytic HER in 1 M KOH, exhibiting the low overpotential of 44 mV and 115 mV at the current density of 10 mA cm−2 and 100 mA cm−2. Moreover, the obtained self-supported electrode material can maintain catalytic activity over 60 h at 100 mA cm−2 without significant decay. This study provides a new perspective for constructing the advanced MOF-derived alkaline HER self-supported electrocatalysts by synergistic engineering of morphology and electronic structure for future energy application.