Colloid self-assembly of c-axis oriented hydroxide thin films to boost the electrocatalytic oxidation reaction

Uniform close-packed superlattice self-assembled from colloidal nanocrystals usually exhibit different chemical and physical properties compared with the homologous bulk materials. Herein, c-oriented NiFe-LDH films (NiFeLDH-F) and Ni(OH)2 films (Ni(OH)2-F) were successfully fabricated by a colloid self-assembly method. The electrocatalytic oxidation properties of the resulting c-oriented NiFe-LDH-F and Ni(OH)2-F were studied towards the oxygen evolution reaction (OER) and the ethanol electrooxidation reaction (EOR), respectively. Due to orderly stacking c-oriented superlattices, the NiFe-LDH-F and Ni(OH)2-F both showed high proton diffusion coefficients, which significantly improved the electrocatalytic activities. The NiFe-LDH-F on the glassy carbon electrode showed an excellent OER electrocatalytic activity with a small overpotential of 220 mV at 10 mA cm-2 and a low Tafel slope of 53.3 mV dec-1. The Ni(OH)2-F showed a superior EOR performance without obvious passivation. This study may open up a new insight into designing efficient and robust materials for superior electrocatalysis..