S-modified NiFe-phosphate hierarchical hollow microspheres for efficient industrial-level seawater electrolysis

Abstract

For sustained hydrogen generation from seawater electrolysis, an efficient and specialized catalyst must be designed to cope with the slow anode reaction and chloride ions (Cl-) corrosion. In this work, an S-modified NiFe-phosphate with hierarchical and hollow microspheres was grown on the NiFe foam skeleton (S-NiFe-Pi/NFF), acting as a bifunctional catalyst to enable industrial-scale seawater electrolysis. The introduction of S distorted the lattice of NiFe-phosphate and regulated the local electronic environment around Ni/Fe active metal, both of which enhanced the electrocatalytic activity. Additionally, the existence of phosphate groups repelled Cl- on the surface and enhanced corrosion resistance, enabling stable long-term operation in seawater. The double-electrode electrolyzer composed of the hollow-structured S-NiFe-Pi/NFF as both cathode and anode exhibited a potential of 1.68 V at 100 mA cm−2 for seawater electrolysis. Particularly, to achieve industrial requirements of 500 mA cm−2, it only required a low cell voltage of 1.8 V and demonstrated a consistent response over 100 h, which outperformed the pair of Pt/C || IrO2. This study provides a feasible idea for the preparation of electrocatalysts that are with both highly activity and corrosion resistance, which is crucial for the implementation of industrial-scale seawater electrolysis.