MOF-derived Mn/Al sulfide electrocatalysts enabling high-faradaic-efficiency water oxidation

Abstract

Green hydrogen generation through electrocatalytic water splitting represents a significant tool for harnessing renewable energy. The progression of highly stable and efficient noble metal-free dual-functional electrocatalysts is crucial for extensive industrial applications. Herein, initially, a porous bimetallic metal-organic frameworks (MOF) such as Mn-MOF@Al-MOF has been synthesized via a solvothermal method. Subsequently, MOF derived different bimetallic chalcogenides at carbon nanostructures such as MnO@Al2O3@C, MnS@Al2S3@C, MnSe@Al2Se3@C and MnTe@Al2Te3@C with suitable chalcogen sources were developed and evaluated its electrocatalytic activity. Among the derived bimetallic chalcogenides, MnS@Al2S3@C outperforms due to the enhanced synergistic interaction between Mn and Al-based composite within the conductive carbon framework, along with the presence of sulfide, which boosts the electrocatalytic performance towards HER and OER with a minimum overpotential of 44 and 196 mV, respectively, at a current density of 10 mA cm⁻2. Additionally, the practical utilization of the MnS@Al2S3@C||MnS@Al2S3@C for overall water splitting yields a low cell voltage of 1.49 V at a current density of 10 mA cm−2 with longevity over 100 h and high Faradaic efficiency of ~100% in a two-electrode configuration in 1.0 M KOH. The activity and stability of the electrocatalyst provide a useful insight into the derivation of a high-efficiency bifunctional electrocatalyst from MOF.