Growth of vertically aligned nanosheet-like structured nickel-cobalt hydroxide thin films and their electrochemical properties

Nickel-cobalt (Ni-Co) hydroxide thin films were directly prepared on the fluorine-doped tin oxide (FTO)-coated glass substrates using the facile and cost-effective wet-chemical method at a low-temperature of 75-90 degrees C with different growth durations. The nanosheet-like structures were interconnected with each other and vertically aligned on the surface of the FTO/glass substrate, leading to the formation of a porous thin film. As the growth time increased, the morphology of the nanosheet-like structures was well-preserved. The growth of vertically aligned nanosheet-like structures of the Ni-Co hydroxide grown at 90 degrees C was faster than that of the sample grown at 75 degrees C. The distribution of the nanosheet-like structures became denser with increasing temperature and time. The mass-and area-specific capacitances of the Ni-Co hydroxide thin film grown at 90 degrees C for 8 h were similar to 528 F/g and similar to 42.3 mF/cm(2), respectively, at a scan rate of 2 mV/s and reasonably good capacitance retention of similar to 94% at a scan rate of 50 mV/s over 1500 cycles, which indicated superior electrochemical performance compared with that of the sample grown at 75 degrees C for 8 h. This shows that the vertically well-aligned nanosheet-like structured Ni-Co hydroxide thin films have great potential as cost-effective electrochemical capacitance electrodes.

Automated summary

Nickel-cobalt (Ni-Co) hydroxide thin films were prepared on FTO-coated glass substrates using a wet-chemical method at low temperatures. The vertically aligned nanosheet-like structures formed a porous film, and their growth rate increased with temperature. The distribution of the structures became denser with increasing temperature and time. The Ni-Co hydroxide thin film grown at 90 degrees C for 8 h showed superior electrochemical performance compared to the sample grown at 75 degrees C for 8 h, indicating its potential as a cost-effective capacitance electrode.