High-efficiency p–n junction oxide photoelectrodes for photoelectrochemical water splitting

Abstract

Development of all oxide p–n junctions makes a significant advancement in photoelectrode catalysis functional materials. In this article, we report the preparation of TiO₂ nanorod (NR)/Cu₂O photoanodes via a simple hydrothermal method followed by an electrochemical deposition process. This facile synthesis route can simultaneously achieve uniform TiO₂ NR/Cu₂O composite nanostructures and obtain varied amounts of Cu₂O by controlling the deposition time. The photocurrent density of TiO₂ NR/Cu₂O heterojunction photoanodes enhanced the photocatalytic activity with a photocurrent density of 5.25 mA cm⁻² at 1.23 V versus RHE compared to pristine TiO₂ NR photoanodes under the same conditions. It is demonstrated that the presence of Cu₂O has played an important role in expanding the spectral response region and reducing the photogenerated charge recombination rate. More importantly, the results provide new insights into the performance of all oxide p–n junctions as photoanodes for PEC water splitting.