Reduced Mo-doped NiCo₂O₄ with rich oxygen vacancies as an advanced electrode material in supercapacitors

Reduced Mo-doped NiCo₂O₄ (R-Mo-NiCo₂O₄) was facilely prepared through a dual-defect strategy. Mo-doped NiCo layered double hydroxide (Mo-NiCo-LDH) was used as the precursor and calcined in an air atmosphere, and the resultant Mo-doped NiCo₂O₄ (Mo-NiCo₂O₄) was further reduced by NaBH₄. The number of oxygen vacancies in the obtained R-Mo-NiCo₂O₄ is significantly increased by both Mo doping and NaBH₄ reduction, resulting in greatly enhanced electrical conductivity and facilitated charge transfer. Finally, the R-Mo-NiCo₂O₄ was used as the electrode material in supercapacitors, which displayed greatly improved electrochemical performance, such as higher specific capacity (285.8 mA h g^-1 at 1 A g^-1), rate capability (86.1%) and cycling stability (87.4% retention after 5000 cycles).