Oxygen evolution reaction (OER) is a key process for many energy devices such as electrolyzers and rechargeable metal-air batteries. Tremendous studies have been devoted to obtaining cost-effective, efficient and durable OER catalysts. Among them, nickel-based materials are considered to be promising candidates for OER in alkaline media. However, their performances are still below the expectation and the active sites are often controversial.
Recently, Associate Professor Yuqin Zou from Hunan University and Professor Xia Lu from Sun Yat-sen University proposed an interlayer ligand engineering strategy on β-Ni(OH)2 for OER.
The alkoxyl substituted β-Ni(OH)2 are facilely prepared by an one-step solvothermal reaction. Assisted by subsequent powder X-ray diffraction (PXRD) and crystalline structure computational simulation, the corresponding chemical formula can be described as Ni[(OH)1-y(L)y]2 (0?y?1), in which L represents alkoxyl ligands. The selected alkoxyl could be methoxyl, ethoxyl, propoxyl and isopropoxyl, or even the combination of methoxyl and ethoxyl. Owing to the chain length, electronegativity and hydrophilicity differences of these alkoxyl, the alteration of electron configuration and three-phase interfaces of Ni[(OH)1-y(L)y]2 are achieved, and the ethoxyl substituted one (NiEt) shows great potential to be efficient OER catalysts (Figure 1).
Combining with X-ray absorption spectroscopy (XAS) and other ex situ physical analysis, the critical active species of NiEt is formed via hydroxylation and subsequent de-protonation, existing as high valent Niδ+ (3<δ?3.66). According to the further operando XAS studies, the corresponding reaction pathway is tracked and catalysis mechanism is proposed.
See the article:He JY, Zou YQ, Huang YC, Li CH, Liu YB, Zhou L, Dong CL, Lu X, Wang SY. Interlayer Ligand Engineering of β-Ni(OH)2 for Oxygen Evolution. Sci. China Chem., 2020, DOI:10.1007/s11426-020-9844-2 .