Trivalent europium ion doped WO3/WS2 semiconductor heterostructure interface for efficient hydrogen evolution reaction under acidic and alkaline dual conditions

Abstract

Designing economical and efficient electrocatalysts for the hydrogen evolution reaction (HER) in acidic and alkaline dual environments continues to be a critical challenge for sustainable hydrogen generation. Designing electrocatalysts with a high density of electrochemically active sites using simple and scalable synthetic approaches is essential for achieving superior catalytic efficiency. In this context, doping strategies and heterostructure engineering have emerged as an effective approach to enhance catalytic activity by optimizing charge transfer dynamics and increasing active site availability. Here, we have designed the Eu³⁺-doped WO₃–WS₂ semiconductor heterostructure nanomaterials as a cathode for the HER. The material was prepared using a two-step process. First, Eu³⁺ doped WO₃ was synthesized by the co-precipitation method and then converted into an oxide–sulfide semiconductor heterostructure using the sulfurization process. The formation of a layered structure, consistently observed in microscopy and supported by phase analysis, is attributed to successful sulfide incorporation. Additionally, the synthesized Eu³⁺:WO₃/WS₂ semiconductor heterostructure exhibits significant HER performance in both 0.5 M H₂SO₄ acidic and 1 M KOH alkaline electrolytes, achieving 10 mA cm⁻² current density with corresponding overpotentials of 291 mV vs. RHE and 333 mV vs. RHE, respectively. This significant catalytic behavior is attributed to the synergistic interaction at the heterostructure interface, which enhances charge transfer kinetics and facilitates improved hydrogen evolution in both electrolytes. Moreover, the Eu³⁺:WO₃/WS₂ heterostructure demonstrates excellent durability, maintaining stable HER performance for 24 hours under acidic conditions and 48 hours in an alkaline environment, highlighting its viability for sustained real-world applications.