Unraveling the Enhanced Electrochemical Performances of Nickel Aluminum Sulfide Lattices for Overall Water Splitting and as Counter Electrode Materials for Dye-Sensitized Solar Cells

The development of a high-performance precious metal-freemultifunctionalelectrocatalyst for overall water splitting is a promising sign forfuture energy research. Here, a new strategy has been followed forthe synthesis of novel-structured binary metal chalcogenide electrocatalysts,such as nickel aluminum sulfide (NiAl2S4) ornickel aluminum selenide (NiAl2Se4) spinels.The new chalcogenides, NiAl2S4 or NiAl2Se4, were confirmed by different physicochemical characterizations.Using a 316 stainless steel (SSL) mesh electrode as a three-dimensionalconducting substrate, the electrocatalytic overall water splittingreaction was studied. Here, NiAl2S4 spinel outperformedthe other metal chalcogenide in terms of electrocatalytic activityand charge transport in the hydrogen evolution reaction (HER), theoxygen evolution reaction (OER), and overall water splitting in alkalinemedium. Moreover, NiAl2S4 spinel provided thefinest electrocatalytic efficiencies compared to other benchmark electrocatalystswith minimized overpotentials, such as 47 or 290 mV for HER or OER,respectively, to reach the current density of 20 mA cm(-2). In overall water splitting studies, a two-electrode system wasformulated to show a very low potential of 1.54 V at a current densityof 20 mA cm(-2). Further, the prepared NiAl2S4 electrocatalyst-loaded 316 SSL electrode demonstratedexcellent durability in HER, OER, and overall water splitting reactions.The obtained Faradaic efficiency was 97%, which is due to the two-dimensionalsheet-like morphology of NiAl2S4, enabling ahigh active surface area for efficient water electrolysis. Furthermore,NiAl2S4 spinel performed well as a counter electrode(CE) material in dye-sensitized solar cells, with an efficiency of5.02% compared to Pt (5.38%) on the fluorine-doped indium tin oxideelectrode.