CoFePBA Nanosheets on Carbon Nanotubes Coupled with Nickel-Encapsulated Carbon Tubules for Efficient and Highly Stable Overall Seawater Electrolysis

The generation of H-2 byseawater electrolysis is limitedby anodic chlorine corrosion and sluggish cathodic hydrogen evolutionreaction (HER). Here, we report a simple approach for developing cobaltiron (CoFe)-based Prussian blue analogue with a nitrogen-doped carbonnanotube composite (CoFePBA/NCNT) and nickel-encapsulatedcarbon tubules (Ni/NCT) as oxygen evolution reaction(OER) and HER catalysts for overall seawater electrolysis utilizinggraphite felt or carbon paper as the catalyst substrate, thus avoidingchlorine corrosion of the metal substrate. Instead of a commonly knownhydrothermal method, a simple brush coating method was employed forcatalyst coating which is feasible for large-scale electrolyzer fabrication.Our developed electrolyzer has shown a low overall seawater splittingvoltage of 1.71 V and a good stability of 50 h in seawater with excellentselectivity for OER over hypochlorite formation at room temperature(26 degrees C). High OER activity is attributed to abundant catalyticsites provided by interconnected CoFePBA nanosheets and high intrinsiccatalytic activity. Moreover, suppressed hypochlorite formation andcorrosion resistance resulting from the synergistic effect of CoFePBAand NCNT make CoFePBA/NCNT||Ni/NCT a potential candidatefor seawater electrolyzers. Our work paves a way to demonstrate seawaterelectrolyzer performance with nonprecious catalysts on a nonmetallicsupport.

Automated summary

Researchers developed a simple method to utilize cobalt iron-based Prussian blue analogue with a nitrogen-doped carbon nanotube composite and nickel-encapsulated carbon tubules as catalysts for oxygen evolution reaction and hydrogen evolution reaction in seawater electrolysis. The catalysts were coated on graphite felt or carbon paper to avoid chlorine corrosion. The electrolyzer showed low voltage and good stability in seawater, with high selectivity for oxygen evolution reaction.