Sulphur-dopant induced breaking of the scaling relation on low-valence Ni sites in nickel ferrite nanocones for water oxidation with industrial-level current density

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 461; p. 141714
• Main Authors: Liu, Hai-Jun, Luan, Ren-Ni, Li, Lu-Yao, Lv, Ren-Qing, Chai, Yong-Ming, Dong, Bin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2023
• Subjects: Electrocatalytic OER; Electron rearrangement; Scaling relation; Spinel-structure; Sulphur doping; Electron rearrangement; Scaling relation; Electrocatalytic OER; Spinel-structure; Sulphur doping
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.141714

[Display omitted] •Sulfur doping NiFe2O4 nanocones arrays on iron foam (S-NiFe2O4/IF) are obtained.•Low-valence Ni in tetrahedron sites are more actives sites than high-valence Fe atom.•S introduction optimizes the adsorption of OER intermediates on Ni sites.•S-NiFe2O4/IF achieves an industrial 500 mA cm−2 at overpotential of 310 mV for 100 h.•An AEM electrolyzer using S-NiFe2O4/IF delivers a 1 A cm−2 current density at 1.79 V. The microstructure of active centers in bimetallic/multimetallic catalysts is under a long-time debate toward oxygen evolution reaction (OER). Here, sulfur doping NiFe2O4 nanocone arrays on iron foams (S-NiFe2O4/IF) is prepared via a scalable hydrothermal method. The favorable 3D nanocone arrays can offer large electrochemical surface area and allow for effective electrolyte access and O2 escape. Physical characterizations confirm low-valence Ni atoms in tetrahedron sites are more actives sites than high-valence Fe atoms in this S-doped bimetallic catalyst. Meanwhile, DFT calculations further verify the S introduction enhances the adsorption and dissociation of water, and optimizes the adsorption of OER intermediates on Ni sites. Therefore, the optimal S-NiFe2O4/IF achieves industrial-level 500 mA cm−2 at an overpotential of only 310 mV and maintains for 100 h in an alkaline medium. In addition, integrating S-NiFe2O4/IF into an anion-exchange membrane water electrolyzer can deliver a current density of 1.0 A cm−2 at 1.79 V.