Engineering the Heterostructured Ni<sub>9</sub>S<sub>8</sub>–FeO<sub><i>x</i></sub> Nanoarrays for Electrocatalytic (Sea)Water Splitting
Weiping Xiao, Yuhang Chen, Changwang Ke, Fengyan Han, Caiqin Wang, Xiaofei Yang
Abstract
Constructing transition metal multiphase composites can improve the electrocatalytic efficiency of (sea)water splitting via interfacial interaction between adjacent active sites. Herein, the self-supporting Ni m S n -FeO x heterostructure is in situ grown on nickel foam (NF) through a corrosion engineering approach, which displays abundant dendritic array structures, endowing the material with abundant active sites and high electrocatalytic active area. The control of introducing Fe 3+ and sulfur precursors can effectively trigger the phase transiting from Ni 3 S 2 to Ni 9 S 8, generating more S vacancies, which could reduce the reaction energy barrier and improve the electrocatalytic performance. Simultaneously, the presence of Fe–S bonding at the sulfide/oxide interface brings a strong electronic interaction, which enables the tuning of the adsorption energy of the reaction intermediates and accelerates the catalytic reaction kinetics. As a result, the Ni 9 S 8 –FeO x /NF-Fe 8.0 catalyst presents low overpotentials of 159 mV and 190 mV for oxygen evolution reaction at 100 mA cm –2 under 1 M KOH solution and simulated seawater conditions, respectively. The overall water splitting incorporating the Ni 9 S 8 –FeO x /NF-Fe 8.0 as both anode and cathode provides the potential of 1.707 V in 1 M KOH and 1.794 V in simulated seawater at 100 mA cm –2 . This research furnishes an efficient strategy toward the design of advanced transition metal heterogeneous composites with strong interfacial interaction for (sea)water splitting.