Ni-Alloyed Co₄N Nanowire Arrays for the Photoassisted Electrochemical Water Oxidation

Abstract

Photoelectrochemical hydrogen production technology holds promise for directly and swiftly generating green hydrogen, which is pivotal for human welfare; however, it faces challenges posed by the energetically sluggish oxygen evolution reaction (OER). Cobalt-based nitrides are considered excellent photoelectrochemically active in the OER (PEOER) catalysts, and their conductivity and photoconversion efficiency remain relatively low. This paper presents the fabrication of Ni-alloyed Co4N nanowire arrays on carbon cloth ((Co1–x Ni x )4N NWAs/CC) as PEOER catalysts. By analyzing advanced in situ Raman and X-ray photoelectron spectroscopy (XPS) results, we discovered that Ni not only enhances the conductivity of the catalyst but, more importantly, also creates more photoexcited Co2+ OER centers and favors its reconstruction to CoOOH to charge PEOER. Furthermore, nitrogen plays a critical role in transforming pyridinic nitrogen into other forms of nitrogen to stabilize the catalyst’s structure. These advantages endow (Co0.74Ni0.26)4N NWAs/CC with remarkable PEOER enhancement (988%), which drives the standard current density of 10 mA cm–2 with only a 283 mV overpotential along with good durability. This research provides insights into the PEOER mechanisms of cobalt-based transition metal nitrides, providing a way for designing next-generation PEOER catalysts.