A ternary hybrid CdS/SiO2/TiO2 photoanode with enhanced photoelectrochemical activity
In this study, a novel ternary hybrid CdS/SiO 2 /TiO 2 film was proposed as the phonoanode for the photocatalytic fuel cell. The samples were characterized by X-ray diffraction, scanning electron microscopy and UV–vis absorption. The photoelectrochemical activity of the ternary hybrid electrode was characterized by the photocurrent-time transient response, linear sweep voltammetry and electrochemical impedance spectroscopy. It was shown that CdS/SiO 2 /TiO 2 yielded much higher photoelectrochemical activity than CdS/TiO 2 and bare TiO 2 did. The photoanode with CdS/SiO 2 /TiO 2 showed the highest photocurrent density of 4.6 mA cm −2 , exhibiting a 40% improvement over the conventional CdS/TiO 2 photoanode. The roles of SiO 2 and CdS in such a ternary configuration were elaborated. It was demonstrated that CdS could act as an excellent visible light captaturer to generate photo-induced charge carriers, and SiO 2 as a passivation layer to suppress the interfacial recombination of electrons and holes. Moreover, SiO 2 could allow for more CdS to be deposited at the photoanode owing to its high adsorption capacity . In addition, the effects of the SiO 2 content and the SILAR cycle time on the performance of the CdS/SiO 2 /TiO 2 photoanode were investigated. An optimal SiO 2 content of 10% could yield the best performance. Increasing the SILAR cycle time could improve the photoelectrochemical activity.
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