Photodeposition of metal sulfide quantum dots on titanium(iv) dioxide and the applications to solar energy conversion

Abstract

Heteronanojunction systems consisting of narrow gap semiconductors represented by metal sulfides and TiO(2) are highly expected as visible-light-active photocatalysts and the key materials for various photoelectrochemical devices. The common central issue is increasing efficiency of the light-induced interfacial electron transfer from the metal sulfide quantum dots (QDs) to TiO(2). We have newly developed simple and versatile low-temperature photodeposition techniques for directly coupling metal sulfide QDs and TiO(2) by taking advantage of its photocatalysis and the photoinduced surface superhydrophilicity. This critical review summarizes the recent developments in the photodeposition techniques and their unique characteristics. Subsequently to the Introduction, a theoretical view of the interfacial electron transfer is presented to obtain the guidelines for the design of the heteronanojunction systems. Then, the itemized description is given for the photodepositions of several kinds of metal sulfides on TiO(2) followed by the summary of the features of the photodeposition technique. Finally, the applications of the resulting heteronanojunction systems to the photocatalysts and QD-sensitized solar cells are described, and the excellent performances are discussed by relating with the features of the photodeposition technique (87 references).

Photogeneration of hydrogen from water using CdSe nanocrystals demonstrating the importance of surface exchange

“…Although the use of semiconductors for photochemical water splitting dates back to a report by Fujishima and Honda in 1972 with TiO 2 and UV light, the challenge was to use SCs with absorption maxima that better matched the solar spectrum (66). There have been numerous reports describing efforts in this direction and several recent reviews offer a summary of systems used and results obtained (67)(68)(69)(70)(71)(72)(73)(74)(75). Semiconductor nanoparticles that exhibit size-constrained electronic properties represent a large and important class of possible light absorbers for the two half-reactions of water splitting.…”

Lead selenide–Titanium dioxide heteronanojunction formation by photocatalytic current doubling-induced two-step photodeposition technique

“…Also, PbSe is known to possess a much larger Bohr radius (46 nm) than PbS (20 nm) [16]. For this feature, the band edge levels or the band gap can be easily controlled by the quantum confinement, which is important for the efficient electron injection into TiO 2 to be achieved [9]. Further, recent studies have demonstrated that PbSe has a great potential for enhancing the efficiency of solar cells through the multiple exciton generation [17,18].…”

“…This in-situ technique possesses the following unique characteristics. First, QDs are directly deposited on the TiO 2 surface without using linker molecules, which enables the efficient photoinduced interfacial electron transfer [9].…”

Construction of dual-channel for optimizing Z-scheme photocatalytic system

“…In the past decades, semiconductor photocatalysis as a promising and eco-friendly technology has attracted extensive attention due to the energy shortages and environmental crisis problem [1][2][3][4][5][6] . Owing to the limitation of narrow light responsive range and fast recombination rate of photogenerated charge carriers [7][8][9][10][11] , photocatalytic technology doesn't achieve breakthrough in term of its practical application.…”