Efficient capture and conversion of H₂S into H₂ and sulfur in guanidinium ionic liquid-NaOH aqueous solution

Electrochemistry allows for the simultaneous conversion of hydrogen sulfide (H₂S) to hydrogen (H₂) and sulfur, achieving atomic economy, and is a sustainable and cost-effective method. At the same time, an electrolyte with high conductivity and H₂S absorption that can effectively capture H₂S in an electrochemical process is essential. An ionic liquid electrolyte system for the absorption and electrolysis of H₂S was constructed using the guanidine salt ionic liquid with amine-based functional groups as the carrier electrolyte, water as the solvent, and NaOH as the H₂S absorber. The prepared electrolyte ([TMG][IM]-AE-30) showed a strong absorption of H₂S with an equilibrium solubility of 100.82 g L^-1. Under constant potential electrolysis at 1.0 V vs. RHE, the maximum hydrogen production rate reaches 2919.97 μmol h^-1 and the Faraday efficiency reaches 99%, and the anodic product is α-sulfur with a production of 0.881 g after electrolysis for 8 h; the current density and hydrogen production rate are still higher than those of the AE systems after three cycles. Overall, the system has good hydrogen sulfide absorption and electrolysis performances, and [TMG][IM] can effectively improve the H₂S absorption and electrolysis efficiencies.