High-Efficiency Photochemical Water Splitting of CdZnS/CdZnSe Nanostructures

Abstract

We have prepared and employed TiO 2 /CdZnS/CdZnSe electrodes for photochemical water splitting. The TiO 2 /CdZnS/CdZnSe electrodes consisting of sheet-like CdZnS/CdZnSe nanostructures (8–10 μ m in length and 5–8 nm in width) were prepared through chemical bath deposition on TiO 2 substrates. The TiO 2 /CdZnS/CdZnSe electrodes have light absorption over the wavelength 400–700 nm and a band gap of 1.87 eV. Upon one sun illumination of 100 mW cm −2 , the TiO 2 /CdZnS/CdZnSe electrodes provide a significant photocurrent density of 9.7 mA cm −2 at −0.9 V versus a saturated calomel electrode (SCE). Incident photon-to-current conversion efficiency (IPCE) spectrum of the electrodes displays a maximum IPCE value of 80% at 500 nm. Moreover, the TiO 2 /CdZnS/CdZnSe electrodes prepared from three different batches provide a remarkable photon-to-hydrogen efficiency of 7.3 ± 0.1% (the rate of the photocatalytically produced H 2 by water splitting is about 172.8 mmol · h −1 · g −1 ), which is the most efficient quantum-dots-based photocatalysts used in solar water splitting.