Nanostructured Intermetallic Nickel Silicide (Pre)Catalyst for Anodic Oxygen Evolution Reaction and Selective Dehydrogenation of Primary Amines

Abstract

The development of novel earth-abundant metal-based catalysts to accelerate the sluggish oxygen evolution reaction (OER) is crucial for the process of large-scale production of green hydrogen. To solve this bottleneck, herein, a simple one-pot colloidal approach is reported to yield crystalline intermetallic nickel silicide (Ni2Si), which results in a promising precatalyst for anodic OER. Subsequently, an anodic-coupled electrosynthesis for the selective oxidation of organic amines (as sacrificial proton donating agents) to value-added organocyanides is established to boost the cathodic reaction. A partial transformation of the Ni2Si intermetallic precatalyst generates a porous nickel(oxy)hydroxide phase modified with oxidic silicon species as unequivocally demonstrated by a combination of quasi in situ Raman and X-ray absorption spectroscopy as well as ex situ methods. The activated form of the catalyst generates a geometric current density of 100 mA cm−2 at an overpotential (η100) of 348 mV displaying long-term durability over a week and high efficiency in paired electrolysis.