Abstract
Hydrogen evolution reaction (HER) electrocatalysts based on earth-abundant materials are promising alternatives to noble metal catalysts. In this work, WS 2 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/WS 2 composite electrodes were fabricated by combining vertically aligned carbon nanowalls (CNWs) with a WS 2 catalytic layer. Raman spectroscopy confirmed the successful formation of multilayer WS 2 films. Electrochemical measurements revealed that HER performance strongly depends on the WS 2 deposition time. Among the investigated samples, the Ti/WS 2 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/WS 2 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/WS 2 electrode did not outperform Ti/WS 2 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 WS 2 film thickness and electrode architecture for efficient hydrogen production.