Ni‐Doped Reduced Graphene Oxide/WS ₂ Heterostructure as a Dual Function Photocatalyst for Photo/Electrochemical Water Splitting and Antibacterial Activity

The integration of WS ₂ with Ni‐doped reduced graphene oxide (Ni‐rGO) forms a novel WS ₂ /Ni‐rGO heterostructure that leverages synergistic effects from enhanced electrical conductivity, abundant active sites, and accelerated charge transfer, positioning it as a highly promising electrocatalyst for the hydrogen evolution reaction (HER). To the best of our knowledge, this WS ₂ /Ni‐rGO system has not been previously reported, highlighting its novelty and potential significance. Detailed optical investigations based on Urbach energy analysis revealed that Ni incorporation increases the Urbach energy, indicating the generation of defect‐induced localized states and enhanced electronic disorder that facilitate charge transport and catalytic activity. The catalyst achieved an impressive H ₂ evolution rate of 1.8 mmol h ⁻¹ g ⁻¹ , with production increasing steadily without saturation, reaching a cumulative 7.17 mmol g ⁻¹ over 4 h. Apparent quantum yield (AQY) was calculated at 14.13%, underscoring exceptional light‐to‐hydrogen conversion efficiency. Tafel slopes of 143.8 mV dec ⁻¹ under photoelectrochemical (PEC) and 157.72 mV dec ⁻¹ under electrocatalytic (EC) conditions indicate favorable H ⁺ adsorption and H ₂ production via the Volmer–Heyrovsky mechanism. Chronoamperometric tests over 10 000 s confirmed long‐term durability with sustained performance. Furthermore, WS ₂ /Ni‐rGO (WNG) exhibited potent antibacterial activity under UV irradiation (253 and 365 nm), completely suppressing proliferation of Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus in spot assays, with no radial colony expansion at 24, 48, or 72 h, in stark contrast to untreated controls showing diameters from 0.20 cm (24 h) to 1.80–2.70 cm (72 h).