Photosensitization of TiO2 Nanotube Arrays with Nanocrystalline Pbs

Ying-Chin Lim,Nur Farah Atikah Harun,Lim Ying Pei,Nurul Munirah Hamdan

doi:10.14419/ijet.v7i4.14.27789

Abstract

Narrow bandgap lead sulfide (PbS) nanoparticles, which may expand the light absorption range to visible region, have attracted tremendous interest serving as promising sensitizer in coupled semiconductor for photoelectrochemical cell. In this study, PbS were deposited onto titania nanotubes by successive ionic layer adsorption and reaction (SILAR) method. During the SILAR deposition, the growth of PbS onto titania nanotubes (PbS/TNT) had been tuned by tailoring the concentration of the precursor solution. The sample microstructure was characterized using Energy Dispersive X-Ray (EDX), Field Emission Scanning Electron Microscopy (FESEM) and X-Ray Diffraction (XRD). By varying the concentration of precursor solution, size and distribution of PbS nanoparticles could be tuned. Upon growth of PbS onto TNT, all samples showed enhanced photocurrent response ascribed to the changes in microstructure and optical properties of the synthesized samples. At 100 mM solution concentration dipped for 5 SILAR cycles, the sample demonstrated the highest peak photocurrent density of 890 mA/cm2 and a corresponding photoconversion efficiency of 0.55% compared to the as-prepared TNT (36 mA/cm2). The PbS/TNT composite could be considered as an excellent photoelectrode material applied in the solar conversion devices due to its high visible light harvesting capability.Â Â Â Â

Highlights

Bulk titania (TiO2) has low quantum efficiency by means, having high charge carriers’ recombination rates
A work by Rhana et al reported that the successive ionic layer adsorption and reaction (SILAR) cycle play an important role to tune the photocatalytic and photovoltaic properties of titania sensitised with PbS by monitoring the degradation of methylene blue under visible light irradiation [6]
TiO2 nanotube (TNT) was prepared by electrochemical anodization of Ti followed by deposition of PbS onto the calcined TNT film via SILAR method producing PbS deposit on titania (PbS/TNT)

Summary

Introduction

Bulk titania (TiO2) has low quantum efficiency by means, having high charge carriers’ recombination rates. Both optimal material and proper architecture are essential to limit the recombination of photoinduced charge carriers. Bulk TiO2 has lower surface area due to its large size and limits its application To overcome this problem, TiO2 nanotube (TNT) is favorable due to its small size and hollow structure that can greatly increase the active surface area and enhance the efficiency of its application as photocatalyst for wastewater treatment [1]. TiO2 is a large band gap semiconductor that can only be excited under the ultraviolet irradiation resulting in low utilization of solar energy. A previous work by Zhang et al (2016) demonstrated that the deposition of PbS had resulted in change of sample surface roughness and subsequently modified the band gap structure, flat band potential, lifetime and transport of the photo-induced charge carriers [12]

Methods

Results

Conclusion