Carbon fiber supported Co/Co3O4-embedded N-doped carbon microparticles for efficient overall seawater splitting and oxygen reduction

Due to low cost and abundance, direct seawater splitting to produce hydrogen is an encouraging strategy to alleviate the consumption of fossil energy, while also avoiding freshwater stress. However, when natural seawater is utilized as the electrolyte, the cat-alysts on the cathode and anode of water splitting should not only have high activity to promote energy efficiency, but also have good stability and durability to resist the corrosion of chloride ions. Herein, a hierarchical carbon-based catalyst for hydrogen and oxygen evolution, ZIF-67/CF-1, was prepared by annealing a composite of ZIF-67 and carbon fiber (CF). It exhibits good electrocatalytic activity and stability for overall splitting in natural seawater and neutral PBS solution. Impressively, when an electrolyzer consisting of ZIF-67/ CF-1||ZIF-67/CF-1 is applied to overall seawater splitting, the current density of 10 mA/cm2 is achieved with a drive voltage of 2.46 V, which is only 0.28 V higher than precious metal -based electrolyzer (Pt/C||IrO2). Meanwhile, ZIF-67/CF-1 shows outstanding catalytic ability for oxygen reduction (E1/2 = 0.84 V, Tafel slope = 66.9 mV/dec), also demonstrating its application potential in rechargeable batteries and fuel cells.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Direct seawater splitting for hydrogen production is a promising strategy to reduce fossil energy consumption and freshwater stress. A hierarchical carbon-based catalyst, ZIF-67/CF-1, was prepared and demonstrated excellent electrocatalytic activity and stability for overall seawater splitting and oxygen reduction. The catalyst showed comparable performance to precious metal-based electrolyzers, indicating its potential application in renewable energy technologies.