Fabrication of La2O3/g-C3N4 Heterojunction with Enhanced Photocatalytic Performance of Tetracycline Hydrochloride

Zhengru Zhu,Yongqiang Cao,Haiwen Xia,Rina Wu,Hong Li

doi:10.3390/cryst11111349

Abstract

In this study, La2O3/g-C3N4 heterojunction photocatalysts doped with different dosages of La2O3 were constructed by a facile ultrasound-assisted calcination approach. The as-prepared photocatalysts were characterized by XRD, FTIR, FESEM, TEM, XPS, PL and DRS to verify the composite photocatalysts’ purity and to investigate their structural, morphological and elemental composition, and their energy band. According to the results, a type of pure rod–sheet-shaped, heterostructured nanoparticle was successfully obtained. Decorated with 10% La2O3, 2 g/L of the composite sample had a 93% degradation rate for 20 mg/L tetracycline hydrochloride within 2 h under visible light at a pH of 7. After four successive photocatalytic runs, satisfactory stability and reusability was exhibited, with 70% of the tetracycline hydrochloride being removed in the final experiment. Electrons (e−), photogenerated holes (h+), superoxide radical anions (·O2−) and hydroxyl radicals (·OH) were the fundamental active species during the photocatalytic process and were investigated via quenching experiments. Furthermore, possible photocatalytic mechanisms were analyzed in this work.

Highlights

In the past decades, a multitude of unprecedented materials have been fabricated, and subsequently entered the environment, throughout the process of scientific and technological development
Wen et al modified ZnIn2S4 with LaFeO3 to remove MO, and the degradation rate increased by 59% [18]. These results indicate that La and its compounds are advantageous in improving photocatalytic performance, no matter the element loading or heterojunction modification
Distinct diffraction peaks of the CN pattern can be observed, located at 27.48◦ which corresponds to the (002) crystal planes of standard XRD cards for g-C3N4 (JCPDS No.87-1526), indicating its aromatic rings are stacked on the 002 plane [22,23,24]

Summary

Introduction

A multitude of unprecedented materials have been fabricated, and subsequently entered the environment, throughout the process of scientific and technological development. Metal oxides, metal sulfides and noble metal semiconductors were selected to be the “cleaner” of organic pollutants, such as TiO2 and the like. This type of photocatalyst only takes effect under ultraviolet light irradiation with wavelengths shorter than 400 nm [3,4]. The high costs and inefficiency of this method has spurred further research to find an ideal photocatalyst. From this point onward, more and more photocatalytic materials, sensitive under visible light, have been discovered. Sheng et al reported that Fe2O3 had a 66% photodegradation efficiency for MB over a period of 120 min with the assistance of visible light [5]; Liang et al degraded 74.2% of Orange II under 120 min of visible light by using a CdS photocatalyst [6]; and Meng et al employed a Bi2WO6 photocatalyst to remove 95% of Rhb while exposed to 60 min of visible light [7]

Methods

Results

Conclusion