Europium Sulfide Driven at Bipolar-Polymerized Polypyrrole: A Highly Active Photoelectrocatalyst for Hydrogen Evolution Reaction

Water photoelectrolysis has attracted much attention to produce hydrogen as a green material and has great energy output. Transition metals, especially lanthanides, have shown outstanding photoactivated properties with efficient stability. Here, for the first time, europium sulfide (EuS) film nanostructures are driven on the Au electrode assisted by synthesized polypyrrole through a two-step bipolar electrochemistry procedure. The generated polypyrroles show an effective role in capturing EuS to wrinkle on the electrode surface, which indicates the formation of a highly stable inorganic–organic composite of EuS/polypyrrole. The resulting material is characterized by many advanced techniques such as XPS, SEM, DRS, PL, and FTIR. After that, it was utilized as a cathode electrode for photoelectrocatalytic water reduction aimed at producing hydrogen. Results demonstrate that it shows interesting activity toward hydrogen evolution reaction (HER) in low overpotential of as half reaction of water splitting, in which the onset potential of H+ reduction begins at ∼0.0 V and 10 mA cm–2 current density is achieved at −0.08 V vs RHE. Fascinatingly, the light irradiation significantly reduces the energy barriers of HER, where it begins at ∼0.1 V vs RHE. This research opens new perspectives toward the synthesis of inorganic–organic structures for catalytic reactions.