Mo3S4Clusters as an Effective H2Evolution Catalyst on Protected Si Photocathodes

This work shows how a molecular Mo 3 S 4 cluster bonded to a photoelectrode surface via a phosphonate ligand can be a highly effective co-catalyst in photocathodic hydrogen evolution systems. Using a TiO 2 protected n + p Si photocathode, H 2 evolution occurs with an onset of +0.33 V vs. RHE in an acid solution with this precious metal-free system. Using just the red part of the AM1.5 solar spectrum (λ > 635 nm), a saturation current of 20 mA/cm 2 is achieved from an electrode containing Mo 3 S 4 dropcasted onto a 100 nm TiO 2 /7 nm Ti/n + p Si electrode.