Effect of nickel doping on the structure, morphology and oxygen evolution reaction performance of Cu-BTC derived...

In this work, nickel (Ni) doped Cu-BTC derived CuCoO₂ (CCO) was successfully synthesized by a solvothermal method, and the effects of Ni doping concentration (such as 1 at%, 3 at% and 5 at%) on the crystal structure, morphology, composition and oxygen evolution reaction (OER) catalytic performance of CuCoO₂ were investigated. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were carried out to characterize the crystal structure, morphology and chemical composition of CuCoO₂ crystals. The results show that Ni ions have been successfully doped into the CuCoO₂ crystal structure and this Ni introduction can reduce its grain size, and 5 at% Ni doped CCO (5NCCO) nanosheets exhibit an average particle size of 386 nm with thicknesses around 28 nm. The optimal Ni@5NCCO electrode needs an overpotential of 409 mV to generate a current density of 10 mA cm^-2 and is able to sustain galvanostatic OER electrolysis for 18 hours with only a minor degradation of 30 mV. The enhanced OER performance may be due to the increase in the catalytic activity area and the improvement in conductivity, which is caused by a decrease in grain size and the formation of a porous structure for Ni doped Cu-BTC derived CuCoO₂.