Cost-Effective Vertical Carbon Nanosheets/Iron-Based Composites as Efficient Electrocatalysts for Water Splitting Reaction

Developing low-cost and highly active catalysts is vital to achieve efficient electrochemical water splitting for hydrogen production, which is considered as a very promising approach for renewable energy storage. Herein, an efficient and cost-effective electrode architecture constructed by vertically aligned carbon nanosheets (VCNs) and iron oxyhydroxide/nitride (VCNs@FeOOH//VCNs@Fe₄N) is designed and synthesized for water splitting in alkaline medium. Benefiting from the highly exposed active sites, accelerated mass and electron transport, and synergistic effect of multiple components, the composite electrodes deliver unprecedented catalytic performance with high activity and excellent durability. The VCNs@FeOOH composite electrode exhibits an overpotential of as low as 179 mV at 10 mA cm^-2 for oxygen evolution reaction (OER), while VCNs@Fe₄N shows a low overpotential of 172 mV for hydrogen evolution reaction (HER) at 10 mA cm^-2. More significantly, a full electrolyzer cell with VCNs@Fe₄N as the cathode and VCNs@FeOOH as the anode exhibits an appealing operation voltage of 1.6 V at 10 mA cm^-2 with superior durability. The present results provide new insight into designing robust catalysts toward practical water splitting devices and metal-air batteries.