Efficient Photocatalytic Degradation of Tetracycline under Visible Light by an All-Solid-State Z-Scheme Ag₃PO₄/MIL-101(Cr) Heterostructure with Metallic Ag as a Charge Transmission Bridge

Abstract

The Z-type Ag/Ag3PO4/MIL-101­(Cr) heterojunction photocatalyst (referred to as AAM-x) was successfully prepared by a simple in situ precipitation method. The photocatalytic activity of the AAM-x samples was evaluated using a common tetracycline (TC) antibiotic. All AAM-x materials are more effective in removing TC than Ag3PO4 and MIL-101­(Cr). Among them, AAM-3 exhibited efficient photodegradation efficiency and excellent structural stability, and the removal rate of TC (20 mg L–1) by AAM-3 (0.5 g L–1) under 60 min of visible light was 97.9%. The effects of photocatalyst dosage, pH, and inorganic anions were also systematically investigated. According to the X-ray photoelectron spectroscopy analysis, metallic silver particles appeared on the surface of the Ag3PO4/MIL-101­(Cr) mixture during the catalyst synthesis. The results of photoluminescence spectra, photocurrent response, EIS, and fluorescence lifetime showed that AAM-3 has a high photogenic charge separation efficiency. An all-solid-state Z-type heterojunction mechanism including Ag3PO4, metallic Ag, and MIL-101­(Cr) is proposed to rationalize the excellent photocatalytic performance and photostability of AAM-x composites and to explain the effect of metallic Ag acting as a charge transfer bridge. The TC intermediates were identified using liquid chromatography–mass spectrometry and possible routes of TC degradation were also discussed. This work provides a viable idea for removing antibiotics by an Ag3PO4/MOF-based heterogeneous structured photocatalyst.

Visible Light-Assisted Degradation of Sulfamethoxazole on 2D/0D Sulfur-Doped Bi2O3/MnO2 Z-Scheme Heterojunction Immobilized Photocatalysts

“…The band gap energy of the prepared materials was determined using the Kubelka− Munk function with the Tauc plot based on the direct band gap (Figure 5b). 11,19,40 Accordingly, the band gap values of bare 2S−Bi 2 O 3 and the 2S-BOMO nanocomposite were found to be 2.14 and 1.58 eV, respectively (Figure 5b), whereas the band gap energy of pure MnO 2 was found to be 2.27 eV, as reported in our previous study. 19 These results suggested the ability of the 2S-BOMO heterojunction to absorb more visible light due to its reduced band gap and achieve the enhanced photocatalytic activity.…”

“…Such a wider range of absorption could enable a red shift of visible light absorption owing to a synergistic effect due to the S doping in Bi 2 O 3 and heterojunction formation between 2S–Bi 2 O 3 and MnO 2 . , Such substantially improved visible light absorption ability could possibly account for the possible improvements in the photocatalytic activity of 2S-BOMO. The band gap energy of the prepared materials was determined using the Kubelka–Munk function with the Tauc plot based on the direct band gap (Figure b). ,, Accordingly, the band gap values of bare 2S–Bi 2 O 3 and the 2S-BOMO nanocomposite were found to be 2.14 and 1.58 eV, respectively (Figure b), whereas the band gap energy of pure MnO 2 was found to be 2.27 eV, as reported in our previous study . These results suggested the ability of the 2S-BOMO heterojunction to absorb more visible light due to its reduced band gap and achieve the enhanced photocatalytic activity.…”

“…9,10 Among heterojunctions, the Z-scheme configuration is most preferred for the possibility of efficient charge transfer of photogenerated electrons from one semiconductor to the other and reducing charge recombination in order to account for the overall improvement in photocatalysis. 11 Another major challenge of photocatalysis is its application in real-world systems due to its small size. Therefore, it is challenging to recover and separate the nanoparticle-based photocatalysts from treated water.…”

“…Numerous studies have been conducted worldwide to uncover alternate methods for the removal of PhACs from different water matrices, including advanced oxidation techniques that merit particular consideration . In particular, the choice of heterogeneous photocatalysis is one of the most researched methods for removing PhACs and is guided by its stability, sustainability, low cost, and ease of operation. , Regardless of its advantages, existing photocatalytic systems face several challenges, including material recovery, recombination of electron–hole pairs, a narrow range of light absorption, reactor design, the toxicity of degradation byproducts, and high cost. ,, Recently, researchers have been addressing the majority of these limitations by developing suitable photocatalysts to overcome many of these drawbacks. , In addition, different modification approaches, including metal and nonmetal doping and formation of heterojunction, have been harnessed due to their ability to achieve high stability, excellent separation and migration of photoexcited charge carriers, and high specific surface area (SSA). , Among heterojunctions, the Z-scheme configuration is most preferred for the possibility of efficient charge transfer of photogenerated electrons from one semiconductor to the other and reducing charge recombination in order to account for the overall improvement in photocatalysis . Another major challenge of photocatalysis is its application in real-world systems due to its small size.…”

Double-Solvent-Induced Derivatization of Bi-MOF to Vacancy-Rich Bi4O5Br2: Toward Efficient Photocatalytic Degradation of Ciprofloxacin in Water and HCHO Gas

“…Figure c demonstrates that the E FB of MBO-50 is −0.68 V vs Ag/AgCl. For the majority of n-type semiconductors, the E FB is 0.1 eV more positive than the conduction band potential ( E CB ), so the E CB of MBO-50 is calculated to be −0.58 V vs NHE . As shown in Figure b, the band gap ( E g ) of MBO-50 is determined to be 2.35 eV, which is obtained by converting the Tauck plot using the equation α h ν = A ( h ν – E g ) n /2 .…”