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

Abstract

A TiO2/Si hybrid photoelectrode (HPE) (photoanode) consisting of TiO2 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. TiO2 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 TiO2/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 TiO2/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 TiO2/Si HPE and the Pt-free counter photoelectrodes for hydrogen evolution from water was carried out.