Cu₂S Nanorods Decorated with NiFe-Layered Double Hydroxide Nanosheets as Bifunctional Electrocatalysts for Hydrogen Evolution in Alkaline Saline Water/Seawater

The progress of highly efficient and stable nonpreciousmetallic-basedelectrocatalysts for the hydrogen evolution reaction (HER) in salinewater/seawater is of great importance for the mass-scale productionof hydrogen energy. Herein, a nanostructured NiFe-LDH/Cu2S heterostructure is constructed by growing NiFe-LDH nanosheets ontoCu(2)S nanorods. This heterostructure possesses exceptionalHER performances with eta(10) = 36 mV (eta(10) indicates the overpotential at a current density of 10 mA cm(2)) and worked stably over 100 h in alkaline saline water. Moreover,the heterojunction catalyst acts as a bifunctional electrocatalystfor the anode and cathode, achieving a cell voltage of eta(10) = 1.463 V, which is superior to many reported electrocatalysts.The improvement of catalytic performance of NiFe-LDH/Cu2S can be ascribed to the charge redistribution on the heterointerfacethat accelerates the dissociation process caused by the formationof Ni with low electron cloud density. Moreover, the obtained covalentS-O bonds are beneficial to the adsorption of H*. In addition,NiFe-LDH/Cu2S also exhibits considerable catalytic performancesin seawater electrolytes, delivering a cell voltage of eta(10) = 1.483 V with a stability of 27 h. We present a promisingbifunctional electrocatalyst for water electrolysis in alkaline salinewater/seawater which may find wide applications in the area of hydrogenenergy.