Experimental investigation on the electrodeposited nickel-based dichalcogenides for the efficient overall water splitting

Layered transition metal dichalcogenides are effective electrocatalysts for water splitting due to their unique properties such as high electrical conductivity, active site density, and catalytic properties. This study focused on the deposition of Ni-based dichalcogenides (NiX2, where X = S, Se, Te) onto a carbon cloth substrate using a simple one-step electrodeposition method at room temperature with different deposition times (10, 15, and 20 min). The optimized NiS2-15, NiSe2-15, and NiTe2-15 electrocatalysts showed excellent bifunctional electrocatalytic activity for both hydrogen evolution reaction and oxygen evolution reaction in alkaline media. The overpotential values for hydrogen evolution were ∼56 mV, ∼37 mV, and ∼75 mV for NiS2-15, NiSe2-15, and NiTe2-15, respectively, while the overpotential values for oxygen evolution were ∼220 mV, ∼170 mV, and ∼210 mV, respectively. The electrocatalysts maintained stability for 24 h during the evolution reactions. The density functional theory calculations suggested that NiSe2 had a lower ΔGH* value due to its smaller bandgap and inherent metallic characteristics, which is consistent with the experimental results. These findings provide a new direction for designing NiX2 (X = S, Se, Te) nanosheets for electrocatalysis applications.