Synthesis and Photocatalytic Activity of TiO2/CdS Nanocomposites with Co-Exposed Anatase Highly Reactive Facets.

Yi-En Du,Caifeng Zhang,Huiling Liu,Kai Hou,Xianjun Niu,Xinru He

doi:10.3390/molecules26196031

Abstract

In this work, TiO2/CdS nanocomposites with co-exposed {101}/[111]-facets (NH4F-TiO2/CdS), {101}/{010} facets (FMA-TiO2/CdS), and {101}/{010}/[111]-facets (HF-TiO2/CdS and Urea-TiO2/CdS) were successfully synthesized through a one-pot solvothermal method by using [Ti4O9]2− colloidal solution containing CdS crystals as the precursor. The crystal structure, morphology, specific surface area, pore size distribution, separation, and recombination of photogenerated electrons/holes of the TiO2/CdS nanocomposites were characterized. The photocatalytic activity and cycling performance of the TiO2/CdS nanocomposites were also investigated. The results showed that as-prepared FMA-TiO2/CdS with co-exposed {101}/{010} facets exhibited the highest photocatalytic activity in the process of photocatalytic degradation of methyl orange (MO), and its degradation efficiency was 88.4%. The rate constants of FMA-TiO2/CdS was 0.0167 min−1, which was 55.7, 4.0, 3.7, 3.5, 3.3, and 1.9 times of No catalyst, CdS, HF-TiO2/CdS, NH4F-TiO2/CdS, CM-TiO2, Urea-TiO2/CdS, respectively. The highest photocatalytic activity of FMA-TiO2/CdS could be attributed to the synergistic effects of the largest surface energy, co-exposed {101}/{010} facets, the lowest photoluminescence intensity, lower charge-transfer resistance, and a higher charge-transfer efficiency.

Highlights

Since Fujishima and Honda discovered that titanium dioxide (TiO2) could photodecompose water to produce hydrogen in the 1970s [1], TiO2, as a traditional semiconductor material, has been widely utilized in the fields of photocatalytic degradation of pollutants, dye-sensitized solar cells, lithium-ion batteries, gas sensors, etc., due to its relatively good chemical stability, low cost, non-toxicity, and environmentally friendly nature [2,3,4]
The photocatalytic degradation of methyl orange (MO) performance of the asobtained TiO2/cadmium sulfide (CdS) nanocomposites was investigated under ultraviolet irradiation
The sharp (004) diffraction peak in the TiO2/CdS nanocomposites represents the preferential growth of anatase {001} facets [36]

Summary

Introduction

Since Fujishima and Honda discovered that titanium dioxide (TiO2) could photodecompose water to produce hydrogen in the 1970s [1], TiO2, as a traditional semiconductor material, has been widely utilized in the fields of photocatalytic degradation of pollutants, dye-sensitized solar cells, lithium-ion batteries, gas sensors, etc., due to its relatively good chemical stability, low cost, non-toxicity, and environmentally friendly nature [2,3,4]. TiO2 is subject to many limitations in industrial application due to its relatively large bandgap (anatase: ~3.2 eV, rutile: ~3.0 eV) and the relatively rapid recombination rate of photogenerated electrons and holes [5,6]. Recent studies have shown that changing the crystal phase, grain size, morphology, specific surface area, heterogeneous structure, and exposed facets of TiO2 is an effective way to increase the photocatalytic activity. The configuration of heterogeneous structure with exposed highly reactive facets plays an important role in improving the charge separation efficiency and photocatalytic activity of TiO2 [7]. It is necessary to design and synthesize TiO2-based semiconductor composite photocatalyst with exposed highly reactive facets to broaden its optical light absorption range and accelerate the separation of photogenerated electrons and holes, improving the photocatalytic efficiency [8,9]. To extend the light absorption range of TiO2 to the visible region, numerous efforts have been made to combine TiO2 with other semiconductors, such as Fe2O3 [10], CdS [11], Cu2O [12], Ag3PO4 [13], WO3 [14], ZnS [15], and

Methods

Results

Conclusion