ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Sustainable and efficient H₂S electrolysis enhanced by acetate-based ionic liquid

Weizhen Kong, Jiaming Mao, Qianqian Peng, Shucan Qin, Longmei Shi, Anshuang Wu, Shengyun Xu, Jianming Shi, Yanrong Liu, and Yunqian Ma

College of Environmental Science and Engineering, Qilu University of Technology (Shandong Academy of Science), Jinan, China

E-mail: yrliu@ipe.ac.cn

Received: 11 March 2025  Accepted: 31 July 2025

Abstract:

High-value-added sulfur products as well as hydrogen (H₂) can be obtained by electrolytic oxidation of hydrogen sulfide (H₂S), which is a promising energy conversion technology that contributes to the resource utilization of the pollutants. In conventional sulfide oxidation reaction (SOR), the recovery of the anodic product typically requires additional acidification treatment, resulting in the unsustainable use of electrolyte. Here, a novel H₂S direct electrolysis system with ionic liquid (IL)-based electrolyte, consisting of acetate-based ILs and NaOH aqueous solution, was investigated. Compared to single NaOH aqueous solution, [Hmim]Ac-based electrolyte showed high H₂S absorption capacity and best electrochemical performance for SOR. Significantly, the anodic sulfur product was proved to be α-sulfur, which could be self-precipitated from the electrolyte without extra acid. The [Hmim]Ac-based electrolyte has the highest equilibrium solubility of sulfur (30.8 g L⁻¹), which was 2–3 times that of the conventional electrolyte of NaOH aqueous solution. It is mainly attributed to the synergistic coupling of ILs and NaOH for H₂S absorption and the modulating effect of ILs. Under constant potential electrolysis at 1.2 V vs RHE in [Hmim]Ac-based electrolyte, the maximum current density reached 194.4 mA cm⁻², the maximum hydrogen production rate reached 3945 μmol h⁻¹, the Faraday efficiency reached 97.9%, and the sulfur recovery of 82.6%. The IL-based electrolyte can be reused for at least three cycles of absorption-electrolysis, holding promise for efficient and continuous electrolysis of H₂S.

Graphical abstract

Keywords: Hydrogen sulfide; Acetate-based ionic liquid; Electrolysis; Sulfur recovery; Hydrogen production

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04286-z

Chemical Papers 79 (11) 7769–7785 (2025)