Construction of Z-scheme Ag-AgBr/Bi2O2CO3/CNT heterojunctions with remarkable photocatalytic performance using carbon nanotubes as efficient electronic mediators

A novel Ag/Bi/Bi2O2CO3 photocatalyst effectively removes antibiotic-resistant bacteria and tetracycline from water under visible light irradiation

Currently, achieving dual applications of Bi2O2CO3-based photocatalysts in photocatalytic degradation and sterilization under visible-light conditions is challenging. In this study, a novel Ag/Bi/Bi2O2CO3 visible-light photocatalyst with bimetallic doping and rich oxygen vacancies was successfully synthesized using a one-pot hydrothermal crystallization method. The existence of oxygen vacancies was verified by X-ray photoelectron spectroscopy (XPS) and Electron spin resonance (ESR) analysis. The experimental results showed that Ag/Bi/Bi2O2CO3 killed ∼100% (log 7) of antibiotic-resistant Escherichia coli (AR-E. coli) within 60 min and degraded 83.81% of tetracycline (TC) within 180 min under visible light irradiation. Moreover, Ag/Bi/Bi2O2CO3 can still remove 61.07% of TC in water after 5 cycles, showing excellent photocatalytic cycle stability and reusability. The possible degradation pathway of TC was determined by liquid chromatography-mass spectrometry. It was found that the main active substances in the photocatalytic disinfection of AR-E. coli were 1O2, h+, and ·OH, while 1O2 was the dominant active species in the photocatalytic degradation of TC. This study presents a promising Bi2O2CO3-based visible light photocatalyst for treating both antibiotics (TC) and antibiotic-resistant bacteria (AR-E. coli) in water.

Constructing a Titanium Silicon Molecular Sieve-Based Z-Scheme Heterojunction with Enhanced Photocatalytic Activity

Titanium silicon molecular sieve (TS-1) is an oxidation catalyst that possesses a long lifetime of charge transfer excited state, high Ti utilization efficiency, large specific surface area, and good adsorption property; therefore, TS-1 acts as a Ti-based photocatalyst candidate. In this work, TS-1 coupled Bi2MoO6 (TS-1/BMO) photocatalysts were fabricated via a facile hydrothermal route. Interestingly, the optimized TS-1/BMO-1.0 catalyst exhibited a decent photodegradation property toward tetracycline hydrochloride (85.49% in 120 min) under the irradiation of full spectrum light, which were 4.38 and 1.76 times compared to TS-1 and BMO, respectively. The enhanced photodegradation property of the TS-1/BMO-1.0 catalyst could be attributed to the reinforced light-harvesting capacity of the photocatalyst, high charge mobility, and suitable band structure for tetracycline hydrochloride degradation. In addition, the mechanism of photocatalytic degradation of tetracycline hydrochloride by the TS-1/BMO-1.0 catalyst was reasonably proposed based on the band structure, trapping, and ESR tests. This research provided feasible ideas for the design and construction of high-efficiency photocatalysts for contaminant degradation.

Construction of novel Ag/AgI/Bi4Ti3O12 plasmonic heterojunction: A study focusing on the performance and mechanism of photocatalytic removal of tetracycline

As a result of the insufficient absorption of visible light, the application of Bi4Ti3O12 in the field of photocatalysis is limited. Ag/AgI was uniformly modified on the surface of the nanoflower bulb of Bi4Ti3O12 by simple precipitation method and photodeposition. The fabricated Ag/AgI/Bi4Ti3O12 obtained an ultra-high tetracycline (TC) removal rate under visible light irradiation. And the synergetic effects caused by the surface plasmon resonance (SPR) effect of Ag, the photosensitivity of AgI and the p-n heterojunction are the key to improving the photocatalytic performance of materials. Besides, four plausible photodegradation pathways of TC were proposed and its intermediates were evaluated for toxicity, showing a significant decrease in toxicity after photoreaction.

In Situ Fabrication of an S-Scheme NaNbO3/Bi2O2CO3 Heterojunction for Enhanced Performance in Photocatalytic Nitrogen Fixation

In this study, NaNbO3 microcubes were introduced during the preparation of Bi2O2CO3 nanosheets to construct a series of NaNbO3/Bi2O2CO3 heterojunctions with varying NaNbO3 content. Their photoactivities for N2 fixation were examined and compared. Results demonstrated that 7.5% NaNbO3/Bi2O2CO3 had the highest photoactivity. The NH3 production rate under simulated solar light is 453.1 μmol L-1 g-1 h-1, representing 2.0 and 3.8-fold increases compared to those of Bi2O2CO3 and NaNbO3, respectively. A comprehensive investigation encompassing the physical and chemical properties of the NaNbO3/Bi2O2CO3 photocatalyst was conducted. Bi2O2CO3 nanosheets were discovered to be distributed on the NaNbO3 microcubes surface. The addition of NaNbO3 exhibited nearly no effect on the photoabsorption performance and specific surface area of the Bi2O2CO3. However, the tight contact between NaNbO3 and Bi2O2CO3 and their appropriate band positions led to the formation of a heterojunction structure between them. The electron drift occurring in the interface region induces the creation of an internal electric field and energy band bending. This facilitates the transfer of photogenerated electrons and holes through an S-scheme mechanism, achieving efficient separation without compromising the redox performance. As a result, the NaNbO3/Bi2O2CO3 composite exhibits exceptional performance in the photocatalytic nitrogen fixation reaction. This study expands the application of S-scheme photocatalysts in the field of N2 reduction and provides insights into the preparation of efficient S-scheme photocatalysts.

Efficient charge separation and transfer in a one-dimensional carbon nanotube/tungsten oxide p-n heterojunction composite for solar energy conversion

Efficient and cost-effective photocatalysts for solar energy conversion represent a rapidly advancing and compelling area of research. In our study, we employed theoretical calculations to design a novel composite material consisting of a one-dimensional (1D) carbon nanotube (CNT) and tungsten oxide (W18O49) p-n heterojunction. This composite material was successfully synthesized using a straightforward solvothermal method, and we thoroughly investigated the charge separation and transfer mechanism. Our findings revealed that the composite material exhibited a superior photocurrent response. Notably, the CNTs/W18O49-2 sample demonstrated a significantly higher photocurrent under both AM 1.5G and infrared light irradiation, outperforming the individual components under AM 1.5G by a substantial factor of 30. This remarkable enhancement in performance can be attributed to the efficient charge separation and transfer facilitated by the built-in electric field created at the interface through the p-n heterojunction. Our study introduces a pioneering integration of CNTs and 1D tungsten oxide, resulting in a composite structure with a p-n heterojunction-a concept that has not been extensively explored previously. The results confirmed the formation of this unique one-dimensional structure and a p-n heterojunction, which has outstanding properties for various applications. These findings provide a robust foundation for the design of photocatalytic interfaces and offer a fresh approach to the development of high-performance photocatalysts.

Recent Advances in Carbon-Based Materials for Adsorptive and Photocatalytic Antibiotic Removal

Antibiotics have been a primary environmental concern due to their widespread dispersion, harmful bioaccumulation, and resistance to mineralization. Unfortunately, typical processes in wastewater treatment plants are insufficient for complete antibiotic removal, and their derivatives in effluent can pose a threat to human health and aquatic communities. Adsorption and photocatalysis are proven to be the most commonly used and promising tertiary treatment methods. Carbon-based materials, especially those based on graphene, carbon nanotube, biochar, and hierarchical porous carbon, have attracted much attention in antibiotic removal as green adsorbents and photocatalysts because of their availability, unique pore structures, and superior physicochemical properties. This review provides an overview of the characteristics of the four most commonly used carbonaceous materials and their applications in antibiotic removal via adsorption and photodegradation, and the preparation of carbonaceous materials and remediation properties regarding target contaminants are clarified. Meanwhile, the fundamental adsorption and photodegradation mechanisms and influencing factors are summarized. Finally, existing problems and future research needs are put forward. This work is expected to inspire subsequent research in carbon-based adsorbent and photocatalyst design, particularly for antibiotics removal.