Abstract
The increasing discharge of dyes and antibiotic pollutants in water has brought serious environmental problems. However, it is difficult to remove such pollutants effectively by traditional sewage treatment technologies. Semiconductor photocatalysis is a new environment-friendly technique and is widely used in aqueous pollution control. TiO2 is one of the most investigated photocatalysts; however, it still faces the main drawbacks of a poor visible-light response and a low charge-separation efficiency. Moreover, powder photocatalyst is difficult to be recovered, which is another obstacle limiting the practical application. In this article, g-C3N4/TiO2 heterojunction is simply immobilized on a glass substrate to form an all-solid-state Z-scheme heterojunction. The obtained thin-film photocatalyst was characterized and applied in the visible-light photodegradation of colored rhodamine B and tetracycline hydrochloride. The photocatalytic performance is related to the deposited layers, and the sample with five layers shows the best photocatalytic efficiency. The thin-film photocatalyst is easy to be recovered with stability. The active component responsible for the photodegradation is identified and a Z-scheme mechanism is proposed.
Highlights
Water pollution has become serious in recent decades due to the rapid development of industrialization [1]
The photocatalytic technique provides an alternative strategy to solve the above problem since it converts solar energy directly into useful energy for degrading organic pollutants into harmless components [2]
It is necessary to modify pristine TiO2 to simultaneously satisfy the requirements for practical applications of photocatalytic techniques, such as intensive visible-light response, high photogenerated-carriers separation efficiency, good stability, and strong redox capabilities [7,8,9]. g-C3N4 is a recently emerged nonmetallic photocatalyst with a narrow bandgap (2.7 eV), demonstrating prominent features such as a visible-light response, good chemical stability, and easy synthesis [10,11,12]
Summary
Water pollution has become serious in recent decades due to the rapid development of industrialization [1]. It is necessary to modify pristine TiO2 to simultaneously satisfy the requirements for practical applications of photocatalytic techniques, such as intensive visible-light response, high photogenerated-carriers separation efficiency, good stability, and strong redox capabilities [7,8,9]. Wang et al [13] reported the efficient water splitting by using g-C3N4 as the visible-light photocatalyst in 2009. This has evoked great interests, and diverse approaches have been proposed to improve the photocatalytic efficiency. The powder photocatalyst is difficult to be recovered from the solution for further use, which is another obstacle restraining the wide application of the photocatalytic technique in water treatment [16,17,18]. The active reagent is identified and a Z-scheme mechanism is proposed
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