Solar-driven, highly sustained splitting of seawater into hydrogen and oxygen fuels.

Kuang, Yun; Kenney, Michael J; Meng, Yongtao; Hung, Wei-Hsuan; Liu, Yijin; Huang, Jianan Erick; Prasanna, Rohit; Li, Pengsong et al. · Proc Natl Acad Sci U S A · 2019

basic_science · Level V

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Abstract

Electrolysis of water to generate hydrogen fuel is an attractive renewable energy storage technology. However, grid-scale freshwater electrolysis would put a heavy strain on vital water resources. Developing cheap electrocatalysts and electrodes that can sustain seawater splitting without chloride corrosion could address the water scarcity issue. Here we present a multilayer anode consisting of a nickel-iron hydroxide (NiFe) electrocatalyst layer uniformly coated on a nickel sulfide (NiSx) layer formed on porous Ni foam (NiFe/NiSx-Ni), affording superior catalytic activity and corrosion resistance in solar-driven alkaline seawater electrolysis operating at industrially required current densities (0.4 to 1 A/cm<sup>2</sup>) over 1,000 h. A continuous, highly oxygen evolution reaction-active NiFe electrocatalyst layer drawing anodic currents toward water oxidation and an in situ-generated polyatomic sulfate and carbonate-rich passivating layers formed in the anode are responsible for chloride repelling and superior corrosion resistance of the salty-water-splitting anode.