Construction of seaurchin-like structured Ag2Se-Ag2S-CoCH/NF electrocatalyst with high catalytic activity and corrosion resistance for seawater electrolysis

Abstract

It is extremely necessary and challenging to rationally design highly active, stable and anti-corrosion electrocatalysts for the hydrogen production by seawater electrolysis. Herein, we developed a new and effective strategy of monometallic cation release combined with hydrothermal reaction to successfully construct an Ag2Se-Ag2S-CoCH/NF seaurchin-like heterostructure on nickel foam substrate. The active species exposure, corrosion resistance, H2O dissociation ability and free energy of adsorbed hydrogen in Ag2Se-Ag2S active carrier were concurrently regulated to strikingly promote the HER/OER in alkaline water and seawater electrolysis. Concretely, the incorporation of CoCH into the Ag2Se-Ag2S binary superionic conductor, as reflected by the corresponding characterizations and theoretical calculations (DFT), not only enriches the vacancy defect structure for the effective exposure of active sites, but also strongly emerges the electronic structure effect between Ag2Se-Ag2S and CoCH, bringing about the reduction of hydrogen adsorption free energy. Besides, such unique seaurchin-like heterostructure has a large electrochemically active area and uninterrupted proton-electron transmission function as well as the interlayer anion exchangeability of CoCH nanoneedles to exhibit prominently water dissociation ability and good resistance to chlorine corrosion. Consequently, Ag2Se-Ag2S-CoCH/NF achieves a fairly low HER overpotential of 35 mV at 10 mA cm−2 and an OER overpotential of 440 mV at 100 mA cm−2 in alkaline water and seawater, which is one of the most effective HER electrocatalysts reported so far. Furthermore, Ag2Se-Ag2S-CoCH/NF can be acted as a bifunctional catalyst to display a decent overall seawater splitting performance in alkaline simulated seawater. It also demonstrates outstanding and stable HER activity along with favorable corrosion resistance in natural seawater. This work is important for the rationally constructing of efficient and anti-corrosion electrocatalysts applied in seawater electrolysis.