Intercalated and Surface-Adsorbed Phosphate Anions in NiFe Layered Double-Hydroxide Catalysts Synergistically Enhancing Oxygen Evolution Reaction Activity

• Published in: Langmuir Vol. 40; no. 19; pp. 10384 - 10392
• Main Authors: Ding, Shiqing, Zheng, Bo, Wang, Xiaofeng, Zhou, Yue, Pan, Zhaorui, Chen, Yan, Liu, Guangxiang, Lang, Leiming
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.05.2024
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/acs.langmuir.4c01200

The oxygen evolution reaction (OER), a crucial semireaction in water electrolysis and rechargeable metal–air batteries, is vital for carbon neutrality. Hindered by a slow proton-coupled electron transfer, an efficient catalyst activating the formation of an O–H bond is essential. Here, we proposed a straightforward one-step hydrothermal procedure for fabricating PO4 3–-modified NiFe layered double-hydroxide (NiFe LDH) catalysts and investigated the role of PO4 3– anions in enhancing OER. Phosphate amounts can efficiently regulate LDH morphology, crystallinity, composition, and electronic configuration. The optimized sample showed a low overpotential of 267 mV at 10 mA cm–2. Density functional theory calculations revealed that intercalated and surface-adsorbed PO4 3– anions in NiFe LDH reduced the Gibbs free energy in the rate-determining step of *OOH formation, balancing oxygen-containing intermediate adsorption/dissociation and promoting the OER. Intercalated phosphate ions accelerated precatalyst dehydrogenation kinetics, leading to a rapid reconstruction into active NiFe oxyhydroxide species. Surface-adsorbed PO4 3– interacted favorably with adsorbed *OOH on the active Ni sites, stabilizing *OOH. Overall, the synergistic effects of intercalated and surface-adsorbed PO4 3– anions significantly contributed to enhanced OER activity. Achieving optimal catalytic activity requires a delicate equilibrium between thermodynamic and kinetic factors by meticulously regulating the quantity of introduced PO4 3– ions. This endeavor will facilitate a deeper comprehension of the influence of anions in electrocatalysis for OER.