Two-dimensional nickel-cobalt bimetallic hydroxides towards urea electrooxidation

The atom-thin metal-based two-dimensional (2D) nanomaterials have exhibited wide application in electrocatalysis because of their particular geometrical and electronic structures. Herein, we report a versatile and simple strategy to synthesize ultrathin nanosheets of nickel-cobalt bimetallic hydroxides (named as NiCo BMHs) through NaBH4 boosted cyanogel hydrolysis strategy. The hydrogen (H-2) bubbles from the NaBH4 decomposition can effectively separate the 2D NiCo BMHs and avoid their self-stacking during the synthesis. As a result, NiCo BMHs with rich nanoholes possess only about 1.5 nm thickness, which results in a high surface area and rich defective atoms. The high surface area, rich edge active atoms, and synergistic effect between Ni2+ and Co2+/ Co3+ species greatly improve the electrocatalytic activity of NiCo BMHs towards urea oxidation reaction (UOR). The potential of UOR at NiCo BMHs is only 1.33 V at 10 mA cm(-2), much lower than that at various reported Ni-based nanomaterials, confirming the high electroactivity of NiCo BMHs.

Automated summary

In this study, ultrathin bimetallic hydroxide nanosheets were successfully synthesized using a cyanogel hydrolysis strategy boosted by NaBH4. The presence of hydrogen bubbles effectively prevented the self-stacking of nanosheets, resulting in high surface area and rich defective atoms. NiCo BMHs exhibited high electrocatalytic activity towards urea oxidation reaction due to their high surface area, rich edge active atoms, and synergistic effect between Ni2+ and Co2+/Co3+ species.