Two-dimensional MOF derived NiFe-VOx with high catalytic activity and corrosion resistance for seawater splitting

Developing highly efficient and corrosion resistance electrocatalysts for seawater splitting can produce H₂ as well as alleviate the shortage of freshwater. In this work, two-dimensional Ni-Fe metal-organic framework on Ni foam (NF) is in situ transferred into NiFe-VO_x/NF. Electrochemical measurements demonstrate that the optimized NiFe₄-VO_x/NF only requires 285 mV of overpotential to achieve a current density of 100 mA cm⁻² in alkaline natural seawater. In addition, the catalyst can run stably for at least 100 h at high current density in alkaline natural seawater. The post analysis indicates that during the electrochemical reaction process, NiFe₄-VO_x can transfer into high active Fe(Ni)OOH, therefore improving the catalytic activity of oxygen evolution reaction (OER). What is exciting is that the metavanadate ions formed on the catalyst surface can act as a corrosion resistant layer, effectively avoiding the corrosion of chloride ions. This work not only provide a new catalyst for seawater splitting, but also reveals the mechanisms for the improved catalytic activity and resistance to corrosion, which can inspire the development of electrocatalysts for seawater splitting.