RF MAGNETRON SPUTTERED WS2 THIN FILMS ON TI AND TI/CNWS SUBSTRATES: STRUCTURAL CHARACTERIZATION AND HER PERFORMANCE

Hydrogen evolution reaction (HER) electrocatalysts based on earth-abundant materials are promising alternatives to noble metal catalysts. In this work, WS₂ thin films were deposited on titanium substrates by RF magnetron sputtering with deposition times ranging from 30 to 120 min to investigate the influence of film thickness on structural and electrochemical properties. In addition, Ti/CNWs/WS₂ composite electrodes were fabricated by combining vertically aligned carbon nanowalls (CNWs) with a WS₂ catalytic layer. Raman spectroscopy confirmed the successful formation of multilayer WS₂ films. Electrochemical measurements revealed that HER performance strongly depends on the WS₂ deposition time. Among the investigated samples, the Ti/WS₂ electrode prepared with a deposition time of 90 min exhibited the highest catalytic activity, delivering an overpotential of 294 mV at 10 mA cm^-2 and the lowest charge transfer resistance (Rct = 15.9 Ohm) within the Ti/WS₂ series. Following electrochemical activation, the overpotential further decreased to 144 mV. Electrochemical impedance spectroscopy (EIS) showed that the incorporation of CNWs significantly enhanced charge-transfer kinetics, reducing the Rct to 3.7 Ohm. However, despite the improved electron transport, the Ti/CNWs/WS₂ electrode did not outperform Ti/WS₂ in HER activity, indicating that catalytic performance depends not only on charge-transfer properties but also on the density and accessibility of active sites. These findings highlight the importance of optimizing WS₂ film thickness and electrode architecture for efficient hydrogen production.

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