Optimization of oxygen evolution activity by tuning band broadening in nickel oxyhydroxide

• Published in: Energy & environmental science 2023-02, Vol.16 (2), p.641-652
• Main Authors: Zhong, Haoyin, Wang, Xiaopeng, Sun, Guangxin, Tang, Yaxin, Tan, Shengdong, He, Qian, Zhang, Jun, Xiong, Ting, Diao, Caozheng, Yu, Zhigen, Xi, Shibo, Lee, Wee Siang Vincent, Xue, Junmin
• Format: Article
• Language: English
• Subjects: Catalysts; Circuits; Electrocatalysts; Electron states; Electron transfer; Iron compounds; Nickel; Nickel compounds; Optimization; Oxygen evolution reactions
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d2ee03413a

Nickel oxyhydroxides (NiOOH) derived from the reconstruction of Ni-based pre-catalysts are active species for the oxygen evolution reaction (OER). Although chemically similar, these NiOOH exhibit differentiated OER activities that show strong correlations to their synthetic origins. To unearth the mechanism behind this, three NiOOH were prepared by subjecting NiS 2 , NiSe 2 and Ni 5 P 4 to chronopotentiometry treatment. We found that a stronger strain leads to a greater NiO 6 octahedron distortion in NiOOH, which results in the broadening of the band (3d electron states with e g symmetry) to a great extent. The increase in band broadening can facilitate electron transfer from the electrocatalysts to the external circuit, which ultimately enhances the catalytic performance. We demonstrated the universality of this concept by extending it to a NiFe oxyhydroxide system. This study shows the first evidence of the relationship between structure and catalytic performance by revealing the role of band broadening, paving the way toward designing efficient OER electrocatalysts. In Ni(OH) 2 , a greater extent of band (3d electron states with e g symmetry) broadening can facilitate electron transfer from the electrocatalyst to the external circuit, leading to higher OER catalytic performance.