Abstract
Electrochemical deposition as a liquid phase epitaxial growth method is widely used to fabricate different kinds of hierarchical structures. As a typical heterostructure, TiO2/PbS is widely utilized in the areas of photovoltaics and photocatalysis. Oriented TiO2 nanorod (NR) arrays can provide direct pathways for the electron transport of photoanode. However, the lattice mismatch between TiO2 NR sides and PbS is very large; PbS nanoparticles (NPs) only formed on the top of TiO2 NRs. To solve this problem, TiO2/CdS core/shell nanocables were firstly prepared electrochemically because the lattice ratio between TiO2 and CdS was 0.916; and then, PbS NPs were successfully deposited over CdS shells (the lattice ratio between CdS and PbS was 0.697) to form TiO2/CdS/PbS hierarchical heterostructures. Experimental results demonstrated that the CdS interlayer could effectively promote the growth of PbS NPs on the surface and improve the fill factor and short current density of the photoanodes.
Highlights
Various heterostructures have been utilized in the areas of photovoltaics [1,2,3,4,5] and photocatalysis [6, 7], such as CdS [8, 9], CdSe [10, 11], CdTe [12], PbS [2, 13], PbSe [14,15,16,17,18], and AgSe [19] over the surface of TiO2 [20,21,22] and ZnO [23,24,25], with different morphologies such as multilayered films, core/shell nanocables, and spherical dots
With a suitable lattice distance between PbS and TiO2, CdS was selected to coat on the surface of TiO2 nanorods and PbS quantum dots (QDs) were epitaxially grown all over the surface of TiO2/CdS nanocables to form a TiO2/CdS/PbS heterostructure
This strategy solves the difficulty to directly grow PbS quantum dots (QDs) on TiO2 NR arrays and makes use of the optoelectronic property of PbS QDs for superior photovoltage characteristics of the TiO2/CdS/PbS photoanode
Summary
Various heterostructures have been utilized in the areas of photovoltaics [1,2,3,4,5] and photocatalysis [6, 7], such as CdS [8, 9], CdSe [10, 11], CdTe [12], PbS [2, 13], PbSe [14,15,16,17,18], and AgSe [19] over the surface of TiO2 [20,21,22] and ZnO [23,24,25], with different morphologies such as multilayered films, core/shell nanocables, and spherical dots. The preparation of the TiO2/PbS/CdS heterostructure was formed in two steps.
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