Evaluation of Pt Deposition onto Dye‐Sensitized NiO Photocathodes for Light‐Driven Hydrogen Production

The design of photocathodes for the hydrogen evolution reaction (HER), which suitably couple dye‐sensitized p‐type semiconductors and a hydrogen evolving catalyst (HEC), currently represents an important target in the quest for artificial photosynthesis. In the present manuscript, we report on a systematic evaluation of simple methods for the deposition of Pt metal onto dyesensitized NiO electrodes. The standard P1 dye was taken as the chromophore of choice and two different NiO substrates were considered. Both potentiostatic and potentiodynamic procedures were evaluated either with or without the inclusion of an additional light bias. Photoelectrochemical characterization of the resulting electrodes in an aqueous solution at pH 4 showed that all the methods tested are effective to attain photocathodes for hydrogen production. The best performances (maximum photocurrent densities of −40 μA∙cm−2, IPCE of 0.18%, and ⁓60% Faradaic yield) were achieved using appreciably fast, light‐assisted deposition routes, which are associated with the growth of small Pt islands homogenously distributed on the sensitized NiO.