Hierarchical S-Doped Vanadium MOFs with Multiwalled Carbon Nanotubes: A Robust Bifunctional Catalyst for Efficient Water Electrolysis

Developing nonprecious metal-based electrocatalysts with exceptional activity and durability for water electrolysis remains a significant challenge. Herein, we report a highly efficient bifunctional electrocatalyst composed of sulfur-doped vanadium metal–organic frameworks (S@V-MOF) integrated with multiwalled carbon nanotubes (MWCNTs) to promote the synergistic effect between S@V-MOF and MWCNTs and modulate the electronic structure of the catalyst, which eventually enhanced its electrocatalytic performance. The S@V-MOF/MWCNT catalyst loaded at the Ni foam electrode exhibits remarkable activity for both the hydrogen evolution reaction (HER) in acidic media and oxygen evolution reaction (OER) in alkaline media, requiring overpotentials of 48 and 227 mV, respectively, to reach a current density of 10 mA cm–2. Notably, when employed as a bifunctional catalyst in a two-electrode overall water splitting electrochemical cell, the S@V-MOF/MWCNT catalyst-loaded electrode delivers an outstanding cell voltage of 1.53 V at 10 mA cm–2 with exceptional durability. This work provides a promising strategy for designing cost-effective and efficient electrocatalysts for water electrolysis.