Ni-Co hydroxide nanosheets on plasma-reduced Co-based metal-organic nanocages for electrocatalytic water oxidationElectronic supplementary information (ESI) available. See DOI: 10.1039/c9ta00070d

Development of highly efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) with high electrical conductivity and chemical stability is critical for various energy conversion devices and systems, yet still remains a formidable challenge. Herein, we develop a novel porous 3D hybrid nanostructure decorated with nickel cobalt layered double hydroxides (NiCo LDHs) on the surface of the functional ZIF-67 template with rich oxygen vacancies (V O ) etched by O 2 -Ar radio frequency (RF) plasma. The as-prepared NiCo LDH@ZIF-67-V O /NF hybrid materials exhibit excellent OER performance evidenced by the competitive potential of 1.52 V at the current density of 10 mA cm −2 in alkaline medium. Moreover, the Tafel slope of 58 mV dec −1 is much lower compared to that of noble metal oxide and other counterpart catalysts. Our experimental and theoretical calculation results reveal that incorporation of V O into the NiCo LDH@ZIF-67-V O /NF composite can efficiently tune the electronic structure and also increase the water adsorption energy, ultimately accelerating the OER process. The work presents a novel strategy for designing highly efficient composite electrode materials with rich oxygen vacancies for the effective, scalable electrocatalytic water oxidation. Development of highly efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) with high electrical conductivity and chemical stability is critical for various energy conversion devices and systems, yet still remains a formidable challenge.