Electronic Structure Tuning in Ni₃FeN/r-GO Aerogel toward Bifunctional Electrocatalyst for Overall Water Splitting

Abstract

Searching for the highly active, stable, and high-efficiency bifunctional electrocatalysts for overall water splitting, e.g., for both oxygen evolution (OER) and hydrogen evolution (HER), is paramount in terms of bringing future renewable energy systems and energy conversion processes to reality. Herein, three-dimensional (3D) NiFeN nanoparticles/reduced graphene oxide (r-GO) aerogel electrocatalysts were fabricated using precursors of (Ni,Fe)/r-GO alginate hydrogels through an ion-exchange process, followed by a convenient one-step nitrogenization treatment in NH at 700 °C. The resultant materials exhibited excellent electrocatalytic performance for OER and HER in alkaline media, with only small overpotentials of 270 and 94 mV at a current density of 10 mA cm, respectively. The good performance was attributed to abundant active sites and high electrical conductivity of the bimetallic nitrides and efficient mass transport of the 3D r-GO aerogel framework. Furthermore, an alkaline electrolyzer was set up using NiFeN/r-GO as both the cathode and the anode, which achieved a 10 mA cm current density at 1.60 V with durability of 100 h for overall water splitting. Density functional theory calculations support that NiFeN (111)/r-GO is more favorable for overall water splitting since the surface electronic structure of NiFeN is tuned by transferring electrons from NiFeN cluster to the r-GO through interaction of two metal species. Thus, the currently developed NiFeN/r-GO with superior water-splitting performance may potentially serve as a material for use in industrial alkaline water electrolyzers.

Recent Development of Ni/Fe‐Based Micro/Nanostructures toward Photo/Electrochemical Water Oxidation

“…In recent years, researchers are also focused on the Ni/Fe‐based hybrid catalyst because of the fast mass transport and good stability. For example, Yang and co‐workers designed the 3D Ni 3 FeN nanoparticles/reduced graphene oxide (r‐GO) aerogel electrocatalysts 49. The obtained materials exhibited excellent electrocatalytic performance for OER and HER in an alkaline medium, and had small overpotentials of 270 and 94 mV at a current density of 10 mA cm −2 , respectively.…”

Antiperovskites with Exceptional Functionalities

“…Its smaller Tafel slope (38 mV dec −1 ) and higher TOF value (0.46 s −1 at η = 350 mV) further confirming its superior OER catalytic activity. Meanwhile, when loaded on reduced graphene oxide (r‐GO) aerogels, the resultant Ni 3 FeN/r‐GO materials can exhibit a greatly enhanced HER performance (overpotential of 94 mV) while maintaining an efficient OER performance (overpotential of 270 mV) in alkaline media. Ni 3 FeN/r‐GO was used as both the cathode and the anode to build an alkaline electrolyzer, and a 10 mA cm −2 current density at 1.60 V with a durability of 100 h for overall water splitting was successfully achieved.…”

Fe‐CoP Electrocatalyst Derived from a Bimetallic Prussian Blue Analogue for Large‐Current‐Density Oxygen Evolution and Overall Water Splitting

“…Up to date, tremendous achievements have been acquired in the development of earth‐abundant element‐based electrocatalysts, including transition‐metal oxides/hydroxides,6 chalcogenides,7 phosphides,8 nitrides,9 and carbides 10. Among them, metal phosphides have been extensively investigated as high‐performance electrocatalysts for HER, showing low overpotential and small tafel slope in the acidic media 11.…”