A facile strategy for the synthesis of hierarchical TiO₂/CdS hollow sphere heterostructures with excellent visible light activity

Abstract

A sonochemical method has been developed to fabricate hierarchical TiO2/CdS hollow sphere heterostructures with excellent photocatalytic activity.

CdS nanoparticles decorated anatase TiO 2 nanotubes with enhanced visible light photocatalytic activity

“…4 shows the optical properties of P25, TNT CdS and CdS/TNTs. It was observed that P25 and TNTs exhibited photoresponse in the UV region with a wavelength below 390 nm due to its large energy band gap (3.2 eV), which is typical of anatase titania [33]. It was noted that blank CdS showed a sharp absorption edge at around 550 nm, it is well known that CdS has a narrow energy band gap and thus shows better visible light response ability.…”

“…As can be seen in Fig. 5a, the elemental composition on the surface of CdS/TNTs are S, C, Cd, Ti and O, which correspond to the values of the binding energy at 162.2 eV, 285.6 eV, 405.8 eV, 458.8 eV and 531.4 eV, respectively [33]. The XPS spectrum for the C 1s peak might be attributed to the adventitious carbonaceous species formed in the process of sample preparation [32].…”

“…Fig. 5c shows the O 1s XPS spectrum of CdS/TNTs, the asymmetric peaks located at 529.7 and 531.6 eV can be seen, the binding energy at 531.6 eV was ascribed to the oxygen of surface hydroxyl groups (-OH), and that at 529.7 eV was assigned to the lattice oxygen of TiO 2 [33]. Fig.…”

“…5b), the binding energies of Ti 2p 3/2 and Ti 2p 1/2 in CdS/TNTs are 458.6 and 464.2 eV, respectively. This can be ascribed to Ti 4+ on the surface of CdS/TNTs [33]. Fig.…”

“…To improve the visible light photocatalytic activity, many efforts have been made, such as dye sensitisation [19], doping [20][21][22][23][24], and coupling with low bandgap semiconductors like PbS [25], CdTe [26], CdSe [27], ZnFe 2 O 4 [28], Cu 2 O [29], and CdS [18,[30][31][32]. Among the low bandgap semiconductors, CdS has attracted much attention, it can be excited by visible light to produce electrons and holes due to the narrow band gap of 2.42 eV [33]. Previous studies have shown that in the CdS/TiO 2 system, heterojunctions between TiO 2 and CdS nanoparticles are formed and the conduction band (CB) of CdS is about 0.5 eV (more negative than that of TiO 2 ).…”