Modulating Hydroxyl-Rich Interfaces on Nickel-Copper Double Hydroxide Nanotyres to Pre-activate Alkaline Ammonia Oxidation Reactivity.

Abstract

The surface hydroxyl groups of Nix Cu1-x (OH)2 play a crucial role in governing their conversion efficiency into Nix Cu1-x Ox (OH)2-x during the electro-chemical pre-activation process, thus affecting the integral ammonia oxidation reaction (AOR) reactivity. Herein, the rational design of hierarchical porous NiCu double hydroxide nanotyres (NiCu DHTs) was reported for the first time by considering hydroxyl-rich interfaces to promote pre-activation efficiency and intrinsic structural superiority (i.e., annulus, porosity) to accelerate AOR kinetics. A systematic investigation of the structure-function relationship was conducted by manipulating a series of NiCu DHs with tunable intercalations and morphologies. Remarkably, the NiCu DHTs exhibit superior AOR activity (onset potential of 1.31 V with 7.52 mA cm-2 at 1.5 V) and high ammonia sensitivity (detection limit of 9 μm), manifesting one of the best non-noble metal AOR electrocatalysts and electro-analytical electrodetectors. This work deepens the understanding of the crucial role of surface hydroxyl groups on determining the catalytic performance in alkaline medium.