Self-assembled c-oriented Ni(OH)(2) films for enhanced electrocatalytic activity towards the urea oxidation reaction

This study investigates the electrocatalytic properties of the transparent c-oriented Ni(OH)(2) films self-assembled from colloidal 2D Ni(OH)(2) nanosheets for urea oxidation. The synthesis process yields highly uniform close-packed superlattices with a dominant c-axis orientation. The self-assembled c-oriented Ni(OH)(2) films exhibit advantageous electrocatalytic performance in urea oxidation, presenting significantly lower overpotentials and higher current densities compared to randomly distributed Ni(OH)(2) particles. In-depth in situ impedance analysis and Raman spectroscopy demonstrate that the c-oriented Ni(OH)(2) films possess a higher propensity for a Ni valence transition from +2 to +3 during the urea oxidation process. This finding provides crucial insights into the catalytic behavior and electronic transformations of c-oriented Ni(OH)(2) films, shedding light on their superior electrocatalytic activity for urea oxidation. Overall, this study advances our understanding of urea electrooxidation mechanisms and contributes to the design of efficient urea electrocatalysts.