Transition metal (e.g., Mo, W) carbides (TMCs) have been considered as promising alternatives to Pt catalysts for HER due to their low cost and Pt-like electronic structures . Particularly, tungsten carbide shows exceptional performance (e.g., low overpotential and long-term stability) at high current densities stemming from its corrosion resistance nature and high electronic conductivity . Tungsten carbide possesses multiple phases, such as tungsten monocarbide (WC) and tungsten semi-carbide (W2C), exhibiting diverse electrocatalytic properties for HER . The synergetic effects of these phases can lead to improved HER activity by modulating the hydrogen adsorption energy due to different interactions and charge transfer mechanisms at the phase interfaces . Despite recent studies on molybdenum carbide phase optimization in alkaline media , little work has been reported on optimizing tungsten carbide phases for hydrogen evolution reaction (HER) at high current densities (> 3 A/cm 2 ) in acidic media . Thus, optimizing the composition of different tungsten carbide phases is crucial to improving the HER activity of the catalyst.