Electric field driven tourmaline/hematite dual mineral photocatalysis for efficient antibiotic removal.

Hematite (Fe2O3) has garnered attention due to its stability, economic viability, and non-toxic nature. However, the rapid recombination of charge carriers hampers its practical application. On the other hand, tourmaline's inherent surface electric field facilitates the rapid separation of photogenerated electrons and holes. In this study, two directly mined natural minerals, tourmaline and hematite (TFO), were successfully combined. Characterization and experiments indicate that the pronounced enhancement of photocatalytic activity in Fe2O3 is attributed to the electric field effect on the surface of tourmaline. TFO successfully removes 93% of tetracycline (TC, 50 ppm) within 60 min. The reaction rate constant for TFO composite material (0.0410 min-1) is 8.5 times that of tourmaline (0.0048 min-1) and 14.1 times that of hematite (0.0029 min-1). Simultaneously, it markedly improves light absorption and charge carrier separation capabilities. Through simulations of various natural environmental factors, TFO demonstrates excellent practicality. Analyzing and detecting active species revealed the involvement of four types of active species, with ·OH radicals making the most significant contribution. The photocatalytic mechanism was proposed. Furthermore, the degradation pathway of tetracycline and the toxicity of its metabolites were investigated. This work provides additional inspirations and insights for photocatalytic materials performance enhancement and natural resources green governance environment.

Methyl contributes to the directed phosphorus doping of g-C3N4: pH-dependent selective reactive oxygen species enable customized degradation of organic pollutants.

In the photocatalytic degradation process, constructing a controllable composite oxidation system with radicals and nonradicals to meet the requirement for efficient and selective degradation of diverse pollutants is significant. Herein, a methylated and phosphorus-doped g-C3N4 (NPEA) can exhibit selective radical and nonradical species formation depending on the pH values. The NPEA can spontaneously switch the production of active species according to the pH value of the reaction system, exhibiting steady-state concentrations of ·O2- for 11.83 × 10-2 µmol L-1 s-1 (with 92.7 % selectivity) under alkaline conditions (pH = 11), and steady-state concentrations of 1O2 for 5.18 × 10-2 µmol L-1 s-1 (with 88.7 % selectivity) under acidic conditions (pH = 3). The NPEA exhibits stability and universality in the degradation of pollutants with rate constant for sulfamethazine (k = 0.261 min-1) and atrazine (k = 0.222 min-1). Moreover, the LC-MS and Fukui function demonstrated that the NPEA can tailor degradation pathways for pollutants, achieving selective degradation. This study offers a comprehensive insight into the mechanism of the photocatalytic oxidation system, elucidating the intricate interplay between pollutants and reactive oxygen species.

l-Cysteine and barium titanate co-modified enteromorpha biochar as effective peroxymonosulfate activator for atrazine treatment.

In this study, pyrolysis and hydrothermal methods were used for Enteromorpha biochar that was co-modified with l-cysteine and barium titanate (LBCBa). It has great environmental tolerance and can remove 93.0 % of atrazine (ATZ, 10 mg·L-1) within 60 mins of ultrasonic treatment. The enhanced hydrophilicity, electron-donating capability, and piezoelectricity of LBCBa are considered to induce excellent performance. The apparent reaction rate of the LBCBa-2/PMS/ATZ system with ultrasonic was 2.87 times that without ultrasonic. The density functional theory points out that, introducing l-cysteine to carbon edges improves the adsorption of ATZ and peroxymonosulfate (PMS), making PMS easier to activate. This work offered unique insights for fabricating effective catalysts and demonstrated the combination of hydrophilic functional groups and piezoelectricity in improving catalytic performance and stability.

Revealing the synergistic effect between radical and non-radical species of sulfur-doped carbon nitride for ciprofloxacin removal: Based on density functional theory study.

The distinct characteristics of active species produced during the photocatalytic reaction can result in alterations in the degradation routes of organic pollutants with diverse chemical structures. The relationship between the active species and degradation pathways of organic pollutants lacks a direct experimental or characterization method, so in-depth research is still needed to understand the details of their interactions. In this study, sulfur-doped bulk carbon nitride (SBCN) was prepared based on bulk carbon nitride (BCN), and the process of S-doping enhancing the production of O21 was revealed. Through the degradation experiment, the degradation rate of CIP by SBCN reached 91 %, which was higher than that of BCN (66 %). The increase of degradation rate was mainly attributed to the increase of O21. Through the density functional theory (DFT) calculation of CIP and its degradation intermediate, due to the preferential oxidation of CIP by O21, O21 changes the initial degradation direction of CIP, releasing more attack sites for ˙O2-, thereby achieving more efficient degradation of CIP through the synergy of O21 and ˙O2-. In this study, the attack preferences of the active species and their synergistic promotion provide important insights for the efficient photocatalytic degradation of organic pollutants.

Piezoelectricity ameliorates high-valent iron oxo species production in peroxymonosulfate activation for refractory atrazine remediation.

Over the past few years, high-valent iron oxo species (Fe(IV)) have shown considerable promise. However, an improved solution is needed for the bottleneck of unsatisfactory electron transfer efficiency in Fe-based catalyst/PMS systems. In this study, Enteromorpha-derived biochar was pyrolyzed with iron and barium titanate (FeBCBa). Under ultrasonic treatment, it removes 94.5% of atrazine (10 mg/L) within 60 min, and is environmentally friendly. BaTiO3's piezoelectricity enhances Fe(IV) production in FeBCBa, resulting in superior performance. In the ultrasonic condition, the apparent reaction rate was 1.42 times higher than in the non-ultrasonic condition. Using density functional theory calculations, it can be shown that due to the Fe dopant, electrons in ATZ's LUMO are more easily transferred to the catalyst's HOMO, which is beneficial for ATZ removal. The results of this study provide new guidance for constructing stable and efficient catalysts for environmental remediation.

Internal electric fields drive dual S-scheme heterojunctions: Insights into the role of the triple interlaced lattice.

The internal electric field induced by the lattice interfaces in a heterojunction can facilitate charge transfer, thereby improving the photocatalytic performance. However, the details of the relationship between the lattice interfaces and the charge transfer mechanism in heterojunctions remain unclear. In this study, a Bi2WO6/Bi2O2CO3/C3N4 heterojunction (BBC) with an interlaced lattice was prepared, and the role of the interlaced lattice in charge transfer was revealed. Compared to pristine Bi2O2CO3, Bi2WO6, and C3N4, BBC exhibited an increased ciprofloxacin degradation rate constant (0.0573 min-1). A series of experiments were performed to reveal the role of the interlaced lattice interface in the enhanced photocatalytic performance. The results show that the driving force provided by the interlaced lattice interface changes the charge transfer mechanism from a dual Ⅱ-scheme to a dual S-scheme. This work provides profound insights into the effects of lattice interfaces in heterojunctions and the design of efficient photocatalysts.

Facile design of surface electric field driven tourmaline/g-C3N4 layered stacked photocatalysts with enhanced photocatalytic activity for antibiotic removal.

In the field of photocatalysis, Graphitic carbon nitride (g-C3N4) has received a lot of attention for its superior functionality and benefits. However, it suffers from the fatal defect of low charge separation efficiency, which is well addressed by tourmaline's self-contained surface electric field. In this work, tourmaline/g-C3N4 (T/CN) composites were successfully synthesized. Due to its surface electric field effect, tourmaline and g-C3N4 are stacked on top of each other. It makes its specific surface area increase greatly and more active sites are exposed. Additionally, the rapid separation of photogenerated electron holes under the action of electric field promotes the photocatalytic reaction. T/CN exhibited excellent photocatalytic performance under visible light, with 99.9% Tetracycline (TC 50 mg L-1) removal after 30 min. Compared to tourmaline (0.0160 min-1) and g-C3N4 (0.0230 min-1), the T/CN composite's reaction rate constant (0.1754 min-1) was 11.0 and 7.6 times higher. A series of characterizations also determined the structural properties and catalytic performance of the T/CN composites, which were found to have a larger specific surface area, narrower band gap, and higher charge separation efficiency compared to the monomer. In addition, the toxicity of tetracycline intermediates and their degradative pathways were investigated, and the toxicity of the intermediates was found to be reduced. Given the quenching experiments and active substance determination, it was also found that h+ and ·O2- play a major role. This work provides more inspiration for photocatalytic material performance research as well as green innovation for environmental management.

Twisty C-TiO2 /PCN S-Scheme Heterojunction with Enhanced n→π * Electronic Excitation for Promoted Piezo-Photocatalytic Effect.

Herein, a twisty C-TiO2 /PCN (CNT) Step-scheme (S-scheme) heterojunction is fabricated and applied to degrade ciprofloxacin (CIP) with the assistance of ultrasonic vibration and visible light irradiation. The nitrogen-rich twisty polymeric carbon nitride (PCN) can not only induce a non-centrosymmetric structure with enhanced polarity for a better piezoelectric effect but also provide abundant lone pair electrons to promote n→π* transition during photocatalysis. Its hybridization with C-TiO2 particles can construct S-scheme heterojunction in CNT. During the piezo-photocatalysis, the strain-induced polarization electric field in the heterojunction can regulate the electron migration between the two components, resulting in a more effective CIP degradation. With the synergistic effect of ultrasonic vibration and visible light irradiation, the reaction rate constant of CIP degradation by CNT increases to 0.0517 min-1 , which is 1.86 times that of photocatalysis and 6.46 times that of ultrasound. This system exhibits a stable CIP decomposition efficiency under the interference of various environmental factors. In addition, the in-depth investigation found that three pathways and 12 major intermediates with reduced toxicity are produced after the reaction. Hopefully, the construction of this twisty CNT S-scheme heterojunction with enhanced piezo-photocatalytic effect offers inspiration for the design of environmentally functional materials.

Multiscale modification of carbon nitride-based homojunction for enhanced photocatalytic atrazine decomposition.

Herein, PDI-g-C3N4/g-C3N4 homojunction has been fabricated via the multiscale modification strategy to enhance photocatalytic atrazine degradation. The morphological scale modification was realized by multistep thermal condensation, where the released gas could act as templates to form the porous structure. The molecular scale modification was achieved by the pyromellitic diimide (PDI) decoration, which could distort the planar nanosheet to induce a porous structure and provide more chromophores for better light absorption. The electronic scale modification was realized by the built-in electric field between the PDI-g-C3N4/g-C3N4 homojunction interfaces, which suppressed the recombination of photocarriers. The PDI-g-C3N4/g-C3N4 strengthened photocatalytic atrazine degradation was well-adapted to different environmental influence interference. The optimum atrazine degradation rate within one hour reached 90% in a strong acidic condition (pH = 3.09). It was found that the highly pH-dependent ATZ removal is related to the H2O2 generation during photocatalysis. Within one hour, the PDI-g-C3N4/g-C3N4 could generate 147.38 µM H2O2. In addition, 1O2, ·O2-, h+, and ·OH were found to have contributed to the ATZ decomposition. During photocatalysis, 14 intermediates and three pathways for atrazine degradation have been found. Hopefully, this study could pave a way for the development of the multiscale modification for the photocatalyst.

Ultrafast photodegradation of nitenpyram by Ag/Ag3PO4/Zn-Al LDH composites activated by persulfate system: Removal efficiency, degradation pathway and reaction mechanism.

In this study, an investigation is conducted into the degradation of nitenpyram (NTP) using highly efficient APMMO/PDS/Vis system. As photocatalysts, silver phosphate (AP) and calcined Zn-Al layered double hydroxides (MMO) exhibit high efficiency in achieving charge separation. Besides, the injection of electrons into peroxydisulfate (PDS) from the APMMO can contribute to obtaining the species in the active state with higher efficiency. Based on the APMMO/PDS/Vis system, 50 mg/L of nitenpyram (NTP, 50 mL) can be completely removed in 60 min using 0.8 g/L photocatalyst and 0.2 g/L PDS under the optimum condition and visible light (780 nm > λ > 420 nm). Meanwhile, as demonstrated under visible light within 30 min, an ultrahigh degradation efficiency can be achieved by NTP based on APMMO1/PDS/Vis system. Besides, the electron paramagnetic resonance (EPR) technique and radical quenching experiments suggested 1O2, h+, SO4-•, •O2-, and •OH are all contributory to the removal of pollutants. Given the outcomes achieved by LC/MS system and mass spectrometry, the primary degradation intermediates of NTP end up being converted into photodegradation products (such as 2-Chloropyridine, 6-Chloropurine Riboside and dl-Leucine). Additionally, there are three potential photodegradation pathways to NTP degradation have been deployed. Moreover, the NTP light degradation occurring in APMMO1/PDS/Vis system is competent under the three types of real water sample. Accordingly, the high-efficiency APMMO1/PDS/Vis system is fit for use in water pollution control for agricultural productions.

π-π stacking derived from graphene-like biochar/g-C3N4 with tunable band structure for photocatalytic antibiotics degradation via peroxymonosulfate activation.

The severe pollution caused by antibiotics has raised serious concerns in recent decades. In this study, graphene-like Enteromorpha biochar modified g-C3N4 (BC/CN) was synthesized and applied to degrade tetracycline by activating PMS under visible light, obtaining around 90% removal rate within 1 h. The Enteromorpha biochar can provide electron-withdrawing groups to adjust the electronic structure of g-C3N4, and induces more π-π interaction to decline the recombination of photocarriers. The environmental adaptability of the BC/CN/PMS/vis system was confirmed by the TC degradation in different initial pH, coexisting ions, and natural organic materials. In most cases, the system maintained over 78% degradation rate. The kinetics and mechanism of the system indicating that ∙O2-, 1O2 contributed more to the TC photocatalytic degradation than ∙OH, SO4∙-, and h+. During the process, TC underwent serials hydroxylation, demethylation, and ring-opening processes, and produced more than 40 intermediates in three pathways. Moreover, the BC/CN/PMS/vis system was proved to have at least a 50% degradation rate for more tetracyclines and quinolone antibiotics with the same condition.

Application of natural minerals in photocatalytic degradation of organic pollutants: A review.

Photocatalysis is an effective, inexpensive and environmentally friendly technology for the decomposition of various aqueous organic pollutants and plays an increasingly critical role in the degradation of pollutants. Natural minerals are abundant natural resources on Earth and can be obtained directly from nature. Natural minerals are excellent photocatalyst carriers that are environmentally friendly, low in price, and will not cause secondary pollution to the environment. Natural minerals have the characteristics of a large specific surface area, providing more active centres, and adsorbing pollutants to concentrate catalysis. Natural minerals are also excellent photocatalysts, such as haematite and magnetite, which play a very good role in the degradation of water pollutants. Studies that make full use of natural minerals are of great significance. This review covers the latest research on natural minerals as photocatalytic composite materials to degrade organic pollutants in water, including three parts: the classification of natural minerals, the structural description of natural mineral composites, and the photocatalytic degradation of organic pollutants by natural mineral composites. In addition, the current limitations and opinions of natural mineral composites are discussed to achieve better results in applying natural minerals.

Magnetically modified in-situ N-doped Enteromorpha prolifera derived biochar for peroxydisulfate activation: Electron transfer induced singlet oxygen non-radical pathway.

Herein, in-situ N-doped Enteromorpha prolifera derived magnetic biochar (MBC) was prepared by loading Fe3O4. It can effectively activate peroxodisulfate (PDS) to degrade tetracycline (TC) and easy recycling. The removal rate of TC reached 87.2%, and its possible degradation pathway was revealed through a liquid chromatography-mass spectrometer. This work first proposes the mechanism of in-situ N-doping and Fe synergistic effect on PDS activation. Unlike the well-reported role of N doping in activating PDS, except for the edge pyridine N plays a significant role in the activation of PDS. After the load of Fe, the synergistic effect of Fe and graphite N induces a non-radical path dominated by singlet oxygen (1O2) due to the excellent electron transfer function. Through chemical quenching experiment, electron spin detection, and electrochemical analysis, the mechanism of PDS activation by MBC was thoroughly investigate. This research will deepen the understanding of the mechanism of transition metals and carbon materials in synergistically driving PDS activation, and guide biochar-mediated PDS activation in environmental remediation.

Facile one-pot magnetic modification of Enteromorpha prolifera derived biochar: Increased pore accessibility and Fe-loading enhances the removal of butachlor.

In this work, Enteromorpha prolifera derived magnetic biochar (MBC) is prepared for the removal of butachlor (BTR) and characterized. The NaOH added during the magnetic loading process has an activating effect and enhancing the accessibility of the pores. Based on the BET result, the importance of pore accessibility rather than the specific surface area has been proposed. The maximum adsorption capacity of BTR for MBC is 158.5 mg/g. Then, the batch experiment shows that the adsorption of MBC to BTR fitted with the quasi-second-order kinetic model. The effect factors on the BTR removal were studied. Through the result of BET, Raman, XPS and FT-IR, the mechanism of MBC adsorption of butachlor was explored. After 3 cycles, the prepared MBC has a negligible reduction in the removal capacity of BTR, which provides a reference scheme for the large-scale application of Enteromorpha prolifera and the water treatment of BTR.

Dually acid- and GSH-triggered bis(ß-cyclodextrin) as drugs delivery nanoplatform for effective anticancer monotherapy.

The intrinsic poor solubility and limited load capacity of ß-cyclodextrins (ß-CDs) results in reduced bioavailability, rendering the material unsuitable in complex biological environments. In this work, a pair of ß-CDs was methylated and covalently linked with acid-sensitive acylhydrazone and GSH-sensitive disulfide bonds to ensure a precise drug release pattern. The hydrophobic anticancer drug doxorubicin (Dox) was encapsulated inside the hydrophobic core of bis(ß-CD) via hydrophobic association with loading capacity of 24% in weight and a hydrodynamic size of about 100 nm. When exposed to acidic and reductive environments, the acylhydrazone and disulfide bonds were found to be cleaved, resulting in Dox release. Using fluorescence imaging and flow cytometry analysis, the designed bis(ß-CD) were determined to activate the drug release behavior by specific intracellular stimuli (pH and GSH). In vivo studies demonstrated specific drug delivery characteristics and controlled drug release behaviors in the tumor sites, giving rise to high antitumor activity and low toxicity. Taken in concert, this dual stimuli-responsive bis(ß-CD) with superior amphiphilicity and biocompatibility features showed great potential for future clinical applications.

Ti3C2 2D MXene: Recent Progress and Perspectives in Photocatalysis.

In 2011, with the successful isolation of Ti3C2, a door of 2D layered MXene has been opened and received growing attention from researchers. MXene refers to a family of two-dimensional (2D) materials made up of atomic layers of the transition metal, carbide, nitrides, or carbonitrides. Given the large surface area, adjustable surface terminal groups, and excellent conductivity of MXene, it has shown exciting potential in photocatalysis, energy conversion, and many other fields. Among many 2D MXene, Ti3C2 was the most studied for its availability, low cost, facile modification procedure, and outstanding electronic properties. In previous investigations, Ti3C2 has shown huge potential in the photocatalysis area. Ti3C2 in a photocatalysis system can enhance the separation of photoinduced electrons and holes, reduce charge recombination, and thus improve the photocatalysis performance in many systems. To adjust the performance of Ti3C2 in different applications, the properties of Ti3C2 including morphology, structures, and stability are tunable by different post-processing method in the hybridized materials. In this review, an all-around understanding of the fabrication and modification methods of Ti3C2 and their connection to photocatalytic applications of Ti3C2 MXene based materials are presented. Moreover, a summary and our perspectives of Ti3C2 are given for further investigation.