CdS/Cu2S co-sensitized TiO2 branched nanorod arrays of enhanced photoelectrochemical properties by forming nanoscale heterostructure

• CdS and Cu2S quantum dots were doped on TiO2 branched nanorod arrays successfully.
• The utilization efficiency of light has been significantly improved.
• The formed heterostructure increased the separate efficiency of electron–hole pairs.
• The whole performance of the PEC water splitting system has been improved.

This paper described a facile method for the design and utilization of three-dimensional TiO2 branched nanorod arrays with CdS and Cu2S quantum dots co-sensitized photoelectrode for photoelectrochemical water splitting. CdS and Cu2S quantum dots were attached on the surface of TiO2 BNRs by successive ionic layer adsorption and reaction (SILAR). The morphology and element composition of the fabricated samples were characterized by field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and the optical features were measured by UV–vis diffuse reflection spectroscopy (UV–vis DRS) and photocurrent density–voltage (I–V) curves. The photocurrent value can be significantly enhanced due to the introduction of CdS and Cu2S quantum dots on the TiO2 BNRs surface. The 9 cycles of CdS and 6 cycles of Cu2S presented the best performance and reached a high photocurrent density to 13.65 mA at 0 V versus Ag/AgCl and hydrogen generation efficiency of 7.74% at −0.467 V versus Ag/AgCl. This enhancement can be attributed to the improved light absorption and the heterojunction formed between CdS and Cu2S, which can greatly promote the introduction and transportation of the photo electrons. This work provided a facile way for the synthesis of high performance photoelectrode for photoelectrochemical water splitting.

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