Structural Design of TiO₂/Si Hybrid Photoelectrode and Pt-Free Counter Photoelectrodes for Charge Carrier Separation in Water-Splitting Reactions

Abstract

hybrid photoelectrode (HPE) (photoanode) consisting of TiO 2 and a Si n ++ p ++ nn ++ photoelectrode, and a Pt-free counter photoelectrode (photocathode) consisting of Au or Ag clusters and a Si n ++ pp ++ junction were manufactured and investigated. TiO 2 was deposited on the Si n ++ p ++ nn ++ photoelectrode to widen the spectral selectivity from UV to visible light. The alternative Pt-free counter photoelectrodes were manufactured with a slightly different structure, where Au or Ag clusters were deposited on the n ++ layer of the Si n ++ pp ++ junction. The photocurrent of the Si n ++ p ++ nn ++ photoelectrode and the TiO 2 /Si HPE was measured using the Pt electrode or the Pt-free counter photoelectrodes. The analysis was carried out in the dark and under low-intensity UV light irradiation. The TiO 2 /Si HPE with the Pt-free counter photoelectrode (Ag clusters/Si n ++ p ++ nn ++ junction) showed an increase of up to 74.2% in photocurrent compared with the Pt counter electrode. A deep-insight analysis for the new and simple design of the promising TiO 2 /Si HPE and the Pt-free counter photoelectrodes for hydrogen evolution from water was carried out.