Enhanced Oxygen Evolution Reaction Activity and Structural Stability of Sulfur and Manganese Substituted Co(OH)2

Abstract

The search for efficient, cost-effective, and sustainable energy sources is a crucial challenge for the modern world.1, 2 In this regard, the development of effective electrocatalysts for water splitting, specifically the oxygen evolution reaction (OER), is a critical aspect of renewable energy technology.3, 4 In recent years, layered double hydroxides (LDHs) have emerged as promising materials for electrocatalysis due to their unique structural and electronic properties.5, 6 This study presents the synthesis and characterization of sulfur and manganese substituted Co(OH)2 as electrocatalysts for the oxygen evolution reaction (OER). The research employed a range of structural and physical characterization techniques, including XRD, EDX, SEM, TEM, and XPS to investigate the synthesized materials.The OER activity was measured via LSV curves in 1 M KOH solution which showed that the S-Mn-Co(OH)2 has significantly low over-potential of 250 and 275 mV for current densities of 10 and 50 mA cm-2 when compared with the Co(OH)2. Additionally, the S–Mn–Co(OH)2 catalyst demonstrated after a 15 hours treatment at 50 mA cm−2 and in 1 M KOH only an overpotential increase of 34 mV and thus excellent stability. High-resolution transmission electron microscopy (HRTEM) analysis confirmed sheet like structure, while the XPS analysis revealed an increase in electron density around the Co owing to the presence of Co2+ and Co3+ in the sample. PXRD and HRTEM analysis also showed a slight reduction in the interlayer gap, indicating further stabilization of the layered structure. Both, stabilized the layered structure and increased electron density around Co could be reason for the enhanced OER performance and be important insights into the role of cation and anion substitution for enhancing LDH OER catalysts. References S. Chu and A. Majumdar, nature, 2012, 488, 294-303.M. M. Rahman, I. Khan, D. L. Field, K. Techato and K. Alameh, Renewable Energy, 2022, 188, 731-749.Y. Feng, H. Yang, X. Wang, C. Hu, H. Jing and J. Cheng, International Journal of Hydrogen Energy, 2022.X. Liu, Y. Han, Y. Guo, X. Zhao, D. Pan, K. Li and Z. Wen, Advanced Energy and Sustainability Research, 2022, 3, 2200005.P. Shandilya, R. Sharma, R. K. Arya, A. Kumar, D.-V. N. Vo and G. Sharma, International Journal of Hydrogen Energy, 2022, 47, 37438-37475.A. Hameed, M. Batool, Z. Liu, M. A. Nadeem and R. Jin, ACS Energy Letters, 2022, 7, 3311-3328.