PbS sensitized TiO₂nanotube arrays with different sizes and filling degrees for enhancing photoelectrochemical properties

Abstract

PbS nanoparticles (PbS NPs), an efficient sensitizer for TiO2 nanotube arrays (TiO2 NAs), were fabricated by the method of sonication-assisted successive ionic layer adsorption and reaction (SILAR). The filling degree and size of PbS NPs can be tuned by changing the repeated cycles (N) of the SILAR process. TiO2 NAs can be fully covered with PbS NPs with a size ranging from less than 4 nm to 25 nm and large aggregates inside and outside the nanotubes when N reaches 15. The growth mechanism of PbS NPs in TiO2 NAs was expounded in great detail in this work. Ultraviolet-visible diffuse-reflectance spectra and surface photovoltage spectroscopy were used to investigate the light absorption properties and the transfer behavior of photogenerated charges in PbS-modified TiO2 NA heterostructures. Results show that the absorption range of TiO2 NAs is extended from the ultraviolet to the visible region by PbS NPs modification. A heterojunction is formed between PbS NPs and TiO2 NAs, facilitating the separation of photogenerated charge carriers. This PbS NPs fully-covered TiO2 NA electrode exhibits the best photoelectrochemical performance in all PbS-sensitized TiO2 NA electrodes, due to a larger number of small PbS NPs (<4 nm). With AM 1.5G illumination at 100 mW cm(-2), its short-circuit current density, open-circuit voltage and photoelectric conversion efficiency are 9.55 mA cm(-2), 0.95 V and 2.83%, respectively.

Synthesis and photoelectrical performance of nanoscale PbS and Bi2S3 co-sensitized on TiO2 nanotube arrays

“…And PbS NPs also can be attached to TiO 2 NAs by a sonicationassisted SILAR method [9]. So, we believed that nanoscale Bi 2 S 3 and PbS can be successively deposited on TiO 2 NAs using two methods mentioned above.…”

“…[13] and [14], PbS NPs of 4 nm or lower has a more negative CB than that of TiO 2 . Previously, we found that PbS NPs (\4 nm) can be fabricated using a sonication-assisted SILAR method when cycle number (n) is 5 [9]. Figure 4a schematically illustrates energy band diagram of PbS, Bi 2 S 3 , and TiO 2 .…”

“…water again for 20 s each. According to our previous study [9], the SILAR cycles were carried out five times under ultrasonic waves of 20 kHz and 100 W to form PbS NPs of lower 4 nm. The sample was denoted as PbS/ Bi 2 S 3 (n)/TiO 2 NAs.…”

“…Previously, we had demonstrated that both Bi 2 S 3 and PbS nanoparticles are efficient sensitizers for TiO 2 NAs [6,9]. Nevertheless, the strategy of TiO 2 sensitized by the single inorganic semiconductor limited the further improvement of the photoelectric performance and light absorption property.…”

Light‐Driven Sustainable Hydrogen Production Utilizing TiO2 Nanostructures: A Review

“…This as‐prepared heterostructure exhibited the ability to capture light range from UV to near‐infrared, and led to chemically degrade various organic pollutions. Besides, chalcogenide compounds including ZnIn 2 S 4 , CuInS 2 , Ag 2 S, In 2 S 3 , PbS, CdSe, MoS 2 , BiS 3 are all utilized for creating heterostructures . 3D hierarchical configurated MoS 2 NS@TiO 2 NB was reported by Zhang and co‐workers via a traditional hydrothermal method, which showed unexceptionable photocatalytic H 2 production activity due to the matched energy level between TiO 2 and MoS 2 , and as a result, the recombination of photogenerated e − –h + pairs was suppressed (Figure c,d,g,h).…”