Bifunctional Mo₄O₁₁ Nanosheets-Engineered Co-Ni alloy nanowires enable High-Efficiency seawater electrolysis and Zn-Seawater battery

This study reports an electrocatalyst derived from multi-valent Mo₄O₁₁ nanosheets coupled Co-Ni (CN) nanowires (NW) (denoted as CN@Mo₄O₁₁) with improved catalytic coherency for both high-performance seawater splitting and Zn-seawater battery. The CN@Mo₄O₁₁ material significantly enhances the catalytical activity with a low overpotential of 63 mV/69 mV for hydrogen evolution and 100 mV/120 mV for oxygen evolution, respectively, to attain 10 mA⋅cm⁻² in alkaline freshwater/seawater. An electrolyzer cell of CN@Mo₄O_11(+,-) exhibits a low cell voltage of 1.40 V/1.44 V at 10 mA‧cm⁻² during alkaline freshwater/seawater splitting with an excellent performance retention of 98.6 %/97.6 % after a long-term operation for 50 h. The solar cell coupled electrolyzer also delivers a high solar to hydrogen conversion efficiency of 15.54 %/16.1 % in alkaline freshwater/seawater. A Zn-seawater battery based on CN@Mo₄O₁₁ cathode also delivers high current and power densities of 82 mA‧cm⁻² and 27.6 mW‧cm⁻², respectively, with a stable discharge time of 40 h. The CN@Mo₄O₁₁ heterostructure imparts favorable density of states and optimized adsorption energy for HER and OER, as deduced from DFT calculations, leading to improved overall catalytic performance and corrosion resistance in seawater. Results of this work clearly prove that this proposed catalyst architecture indeed has a huge potential for both seawater splitting and Zn-seawater battery fabrication.