N,Cu-Codoped Carbon Nanosheet/Au/CuBi₂O₄ Photocathodes for Efficient Photoelectrochemical Water Splitting

In this paper, we successfully fabricated CuBi₂O₄ and nitrogen,cuprum-codoped carbon nanosheet (N,Cu–C) heterostructure connected by Au nanoparticles, which was applied in photoelectrochemical (PEC) water splitting for the first time. The Au nanoparticle in situ decoration on the material surface was carried out by simple photoreduction. Owing to the plasmon resonance effect and low charge transfer resistance of Au nanoparticles, CuBi₂O₄/Au/N,Cu–C hybrids exhibited enhanced photocurrent compared with traditional CuBi₂O₄ and CuBi₂O₄/N,Cu–C. Typically, the as-prepared photoelectrode displayed an optimal photoelectric conversion (0.17%, at 0.4 V vs RHE) and PEC photocurrent (0.31 mA cm^–2, at 100 mW cm^–2 and 0.5 V vs RHE) that is about 5 times that of pure CuBi₂O₄. The enhanced PEC water splitting ability can be mainly attributed to the N,Cu-codoped carbon nanosheets as the passivation layer and Au nanoparticles as an electron relay for electron transport and a plasmonic photosensitizer for increased light absorption.