Iron-doped nickel hydroxide heterostructures derived from in-situ grown nickel complex nanotube arrays for efficient overall water splitting

Optimizing the nickel-based heterojunction catalysts during overall water splitting remains a significant challenge. Herein, based on metastable ion etching engineering, a trace amount of Fe-doped Ni/Ni(OH) 2 nanotube array coated with carbon (FNNA@C/NF) is successfully synthesized. Specifically, a small amount of Fe 3+ , generated from the partial oxidation of Fe 2+ , selectively etches the grain boundaries of the Ni metal substrate, resulting in the formation of a unique nanotube structure. Electrochemical test results demonstrate that it has exceptional hydrogen evolution reaction activity (29.7 mV–10 mA cm −2 ) and oxygen evolution reaction activity (300.1 mV–100 mA cm −2 ), along with stable operation for 100 h at a current density of 100 mA cm −2 during overall water splitting. The outstanding performance is primarily attributed to the Fe-doped Ni/Ni(OH) 2 heterojunction, obtained through mild pyrolysis, optimizes electron transfer and enhances interfacial reaction kinetics. Meanwhile, the unique nanotube array structure increases the active surface area and improves interfacial mass transfer efficiency. This work offers novel insights and theoretical guidance for designing high-performance nickel-based heterojunction catalysts.