The lowest HER overpotential we find for the deposited WO3 films (182 mV@10 mA cm− 2) is in the same range or slightly higher compared to previously reported values for undoped WO3 [8] while being in the higher range of HER overpotentials reported for high surface area catalysts of iron-based phosphides (30–235 mV@10 mA cm− 2) [46] and FeNi-layered double hydroxides (down to 59 mV@10 mA cm− 2) [47].