Visible Light Absorption Range Research Articles

Electronic and photocatalytic properties of Cu4 cluster-modified Ag/g-C3N4 single-atom catalysts: A hybrid DFT study

Increasing the active sites on the catalyst surface has been a key goal to increase the catalyst efficiency. This paper presents an efficient conversion of solar energy into chemical energy, realized by a Cu4 cluster-assisted single-atom catalyst (Ag-doped g-C3N4). The catalyst enhances charge transfer and light absorption, and the unique advantages of this approach in the field of photocatalysis are substantiated by density functional theory. Under the synergistic effect of Cu4 clusters, the electronic state density distribution of the Ag single-atom catalyst substrate is drastically altered, which realizes the increase of substrate active sites and rapid charge separation and transfer. Compared with the pristine substrate g-C3N4, the new electronic state distribution and the generation of impurity energy levels lead to the narrowing of the band gap from 2.77 to 1.83 eV, accelerating the transfer and separation of electrons and holes, and enlarging the visible light absorption range from 410 to 760 nm, thus improving the solar energy utilization. Despite the reduced band gap, the conduction and valance band edges of (Ag, Cu4) codoped g-C3N4 still have sufficient potential to split water. Therefore, to improve the photocatalytic performance under visible light, simultaneous codoping of the Ag single atom and Cu4 cluster on g-C3N4 is an effective strategy. The study provides theoretical support for further optimization of single-atom catalysts.

Enhanced Photoelectrochemical Water Splitting of In2S3 Photoanodes by Surface Modulation with 2D MoS2 Nanosheets

Photoanodes with ample visible-light absorption and efficient photogenerated charge carrier dynamics expedite the actualization of high-efficiency photoelectrochemical water splitting (PEC-WS). Herein, we fabricated the heterojunction nanostructures of In2S3/MoS2 on indium-doped tin oxide glass substrates by indium sputtering and sulfurization, followed by the metal–organic chemical vapor deposition of 2D MoS2 nanosheets (NSs). The photocurrent density of In2S3/MoS2 was substantially enhanced and higher than those of pristine In2S3 and MoS2 NSs. This improvement is due to the MoS2 NSs extending the visible-light absorption range and the type-II heterojunction enhancing the separation and transfer of photogenerated electron–hole pairs. This work offers a promising avenue toward the development of an efficient photoanode for solar-driven PEC-WS.

Interstitial N-Doped TiO2 for Photocatalytic Methylene Blue Degradation under Visible Light Irradiation

Photocatalysis is a promising method for methylene blue (MB) degradation due to its effectiveness and environmental compatibility. Among the photocatalysts, titanium dioxide (TiO2) has been widely used for MB degradation due to its exceptional photocatalytic activity. However, the wide bandgap limits the degradation efficiency of TiO2 under visible light. Here, an interstitial nitrogen-doped TiO2 (5%NT/TiO2) used thiourea as the N source was fabricated for visible light-derived MB degradation. The 5%NT/TiO2 exhibited an extended absorption range of visible light. Moreover, photoelectrochemical measurements showed an improvement in the photocurrent response and charge transfer behavior on N/TiO2. Thus, 5%NT/TiO2 had enhanced photocatalytic activity compared with pristine TiO2 and substitutive N-doped TiO2 (5%NAB/TiO2). The accelerated photocatalytic MB degradation process on N/TiO2 could be mainly attributed to the interstitial N doping, which caused the appearance of new energy states and extended optical properties. Through comparing the impact of interstitial and substitutive in TiO2 activity, our work proposes a suitable form of element doping to enhance the optical properties and photocatalytic activity of TiO2 and even other semiconductors, providing guidance for future work.

Photocatalytic H2 evolution over CuCoSe2 nanoparticles decorated TiO2 nanosheets with S-scheme charge separation route

The construction of S-scheme heterojunctions via exploring semiconductors with suitable energy band structures can effectively improve the photocatalytic performance of TiO2. In this work, CuCoSe2/TiO2 heterojunction were prepared using solvent evaporation strategy by their different surface charge properties. The investigation indicates that rates of H2 evolution (rH2) of the system increases significantly from 138.1 (TiO2) to 3773.8 μmol·g−1·h−1 (CuCoSe2/TiO2). It is found that the incorporation of CuCoSe2 can extend the visible light absorption range of the system, increase the electrochemically active surface area, facilitate charge generation and decrease the transfer resistance, reduce the H2 production overpotential and the water contact angle. Further investigation reveals that a bimetallic selenide CuCoSe2 exhibit superior enhancement activity compared to their monometallic selenides (CuSe2, CoSe2) due to the synergistic effect of Co and Cu. Especially, the charge transfer between CuCoSe2 and TiO2 follows S-scheme charge separation route, which can effectively enhance charge separation/migration, reserve e− with strong reducing ability in TiO2, thereby promoting the H2 evolution kinetics. Moreover, the heterojunction also demonstrates exceptional stability throughout the cycle experiment. The present work establishes an experimental basis for the advancement of highly efficient and stable bimetallic selenides related heterojunctions in the field of photocatalytic H2 evolution.

Precise Regulation of Interlayer Stacking Modes in Trinuclear Copper Organic Frameworks for Efficient Photocatalytic Reduction of Uranium(VI).

The interlayer stacking modes of 2D covalent-organic frameworks (COFs) directly influence their structural features, ultimately determining their functional output. However, controllably modulating the interlayer stacking structure in traditional 2D metal-free COFs, based on the same building blocks, remains challenging. Here, two trinuclear copper organic frameworks are synthesized successfully with different interlayer stacking structures: eclipsed AA stacking in Cu3-PA-COF-AA and staggered ABC stacking in Cu3-PA-COF-ABC, using the same monomers. Remarkably, various functionalities, including porosity and electronic and optical properties, can be effectively regulated by interlayer stacking. As a result, Cu3-PA-COF-AA and Cu3-PA-COF-ABC exhibit significantly different activities toward the photoreduction of U(VI), presenting a promising strategy for removing radioactive uranium pollution. Due to its broader visible-light absorption range and superior photogenerated carrier migration and separation efficiency, Cu3-PA-COF-AA achieves a U(VI) removal ratio of 93.6% without additional sacrificial agents in an air atmosphere-≈2.2 times higher than that of Cu3-PA-COF-ABC (42.0%). To the best of the knowledge, this is the first study to elucidate the effect of interlayer stacking in COFs on the photocatalytic activity of U(VI) reduction. This finding may inspire further exploration of the structure-function relationship in COFs as photocatalysts and their potential for photoinduced removal of radionuclides.

Boron nitride quantum dots supported hollow NH2-MIL-125 drive photo-Fenton-PMS system for photocatalytic tetracycline degradation: Contribution of tannic acid etching

NH2-MIL-125(Ti) materials had great potential for photocatalytic applications but had low activity due to exciton effect and narrow absorption range of visible light. The surface oxygen-containing negative functional groups of boron nitride quantum dots (BNQDs) could overcome these defects, but due to the low load capacity, a higher specific surface area of the substrate was usually required. In this paper, a hollow Ti-MOF material was developed by etching technology. The hollow structure formed by tannic acid etching broadened the absorption range of visable light and provided more alternative surfaces for loading BNQDs. The 85.2% of high tetracycline (TC) removal efficiency for the best sample (BNQDs-5@20-Ti-MOF + PMS) was obtained, which was about 56.8 and 1.9 times of the 20-Ti-MOF and BNQDs-5@20-Ti-MOF, respectively. BNQDs-5@20-Ti-MOF + PMS system showed a great TC degradation efficiency in a wide pH range (pH = 5–9). In addition, reaction temperature and the inorganic ions did not show significant inhibition effect for TC removal. Both free radical and non-free radical pathways were involved in the TC degration by BNQDs-5@20-Ti-MOF + PMS system, among which O2•− and 1O2 played the key roles. Interestingly, multiple 1O2 production paths contributed to the high efficiency and stability of BNQDs-5@20-Ti-MOF + PMS system. This study revealed a reasonable combination of Ti-MOF and BNQDs, which provided a new efficient photocatalyst for environmental remediation.

First principles study on photocatalytic water decomposition of ZnO/WS2 heterojunctions

The generation of clean energy hydrogen through solar-driven water decomposition is an effective solution to the current global energy shortage and environmental pollution. In this paper, ZnO/WS2 heterojunction is constructed based on first-principles. The effect of uniaxial strain and vacancy defects (VZn, VO, VS, V2S) on electronic and optical properties of ZnO/WS2 heterojunction are calculated. The results indicate that the bandgap of the heterojunction is decreased and the visible absorption range is expanding. Additionally, the built-in electric field of the heterojunction is determined to be oriented from ZnO to WS2, which enhances the efficiency of carrier separation. Band-edge position analysis indicates that ZnO/WS2 heterojunctions exhibit good redox water properties under an applied compressive strain of −2 %. Finally, the visible light absorption range of the heterostructures is also expanded by introducing VS and V2S vacancy defects. However, it exhibits a superior ability to oxidize and reduce water only under VZn defects. The corresponding photocatalytic mechanism of ZnO/WS2 heterojunctions is discussed.

Intercalated Architecture of the Ca2A2Z5 Monolayer with High Electron Mobilities and High Power Conversion Efficiencies.

The exploration of novel two-dimensional (2D) materials with a direct band gap and high mobility has attracted huge attention due to their potential application in electronic and optoelectronic devices. Here, we propose a feasible way to construct multiatomic monolayer Ca2A2Z5 (A = Al and Ga and Z = S, Se, and Te) by first-principles calculations. Our results indicated that the energies of α1-phase Ca2A2Z5 are slightly lower than those of experimentally synthesized α3-phase-like Ca2A2Z5 monolayers with excellent structural stability. Moreover, the α1- and α3-phase Ca2A2Z5 monolayers possess not only direct band gaps but also high electron mobilities (up to ∼103 cm2 V-1 s-1), demonstrating an intriguing range of visible light absorption. Importantly, α1- and α3-phase Ca2Ga2Se5 monolayers are good donor materials, and the corresponding Ca2Ga2Se5/ZrSe2 type-II heterostructures exhibit desirable power conversion efficiencies of 22.4% and 22.9%, respectively. Our findings provide a feasible way to explore new 2D materials and offer several Ca2A2Z5 candidate monolayers for the application of high-performance solar cells.

Ultrasensitive miRNA-let-7a detection based on AgInS2 quantum dots co-sensitization and CRISPR/Cas12a induced strand displacement reaction for signal amplification

The evolution of breast cancer is usually accompanied by abnormal expression of miRNA-let-7a. Sensitive gauging of miRNA-let-7a is crucial for breast cancer monitoring and prognosis. Herein, a novel photoelectrochemical (PEC) biosensor was served as miRNA-let-7a detection on the basis of the coupling of co-sensitization and CRISPR/Cas12a-mediated strand displacement amplification (SDA). In short, AgInS2 quantum dots (QDs), characterized by a wide visible light absorption range and a stable photocurrent response, have an obvious sensitizing effect on TiO2/Bi2MoO6. Under the condition of without miRNA-let-7a, the AgInS2 fixed DNA probe was located near the surface of the TiO2/Bi2MoO6 electrode, forming a co-sensitive structure. During the detection process, hairpin DNA2 (HP2) specifically recognized miRNA-let-7a through base complementary pairing, triggering the SDA reaction to convert massive double-stranded DNA (dsDNA). The dsDNA product then triggered CRISPR/Cas12a lateral cleavage activity, causing AgInS2-sensitized DNA to leave the electrode surface and the co-sensitization effect to disappear, further reducing the photocurrent. Using a dual effect for signal amplification, the biosensor platform had linear detection capability within the scope of 0.01–10 nM, and the detection limit was 3.35 pM. The biosensor which was fabricated effectively provided an excellent platform for the effective monitoring of various tumor biomarkers in clinical detection.

Synthesis and recent developments of MXene-based composites for photocatalytic hydrogen production

Abstract The energy crisis has already seriously affected the daily lives of people around the world. As a result, designing efficient catalysts for photocatalytic hydrogen evolution (PHE) is a promising strategy for energy supply. Co-catalyst modification can significantly enhance the photocatalytic activity of single semiconductors, overcoming limitations posed by their narrow visible light absorption range and high electron–hole recombination rate. MXene-based composites demonstrate immense potential as co-catalysts for photocatalytic hydrogen production owing to their distinctive two-dimensional layered structure and outstanding photoelectrochemical properties, and further research and development efforts surrounding MXene-based composites will contribute significantly to the progress of sustainable energy technologies. In this review, we offer a comprehensive overview of synthesis methods for MXene and MXene-based composites, highlight illustrative instances of binary and ternary MXene-based composites in PHE, and explore potential avenues for future research and expansion of MXene-based composites.

Novel Br-doped Bi2WO6 photocatalyst for high-efficiency removal of norfloxacin: mechanism and photocatalytic activity.

In this work, the bismuth tungstate (Bi2WO6) photocatalyst was successfully prepared, and the pure Bi2WO6 was modified with Br (Br-Bi2WO6). The effects of different experimental conditions on the degradation of norfloxacin (NOR) solution under visible light were investigated. The Br-Bi2WO6 photocatalyst was characterized by FTIR, XRD, SEM, BET, XPS, DRS, EIS, and EPR. The results show that the Br-modified Bi2WO6 photocatalyst can effectively improve the photocatalytic performance. The best photocatalytic performance of Br-Bi2WO6 was observed when the doping amount of Br was 3%. The degradation percentage of norfloxacin can reach 94.67%. The presence of anions and cations (Cl-, SO42-, Ag+, and Cu2+) in the solution significantly inhibited the photocatalytic activity of 3%Br-Bi2WO6. The photocatalytic degradation of norfloxacin by 3%Br-Bi2WO6 was not greatly affected in the presence of HCO3- and NO3-. The characterization analysis showed that Br was successfully doped on the Bi2WO6 photocatalyst, and the original structure of Bi2WO6 was not destroyed by the addition of Br. Br doping increased the specific surface area of Bi2WO6 and decreased the band gap of Bi2WO6 resulting in a broader visible light absorption range. In addition, Br doping promoted the migration rate of photogenerated electron-hole pairs. The ·O2- and h+ played a major role in the photodegradation of norfloxacin, and the mechanism of photocatalytic degradation of norfloxacin by Br-Bi2WO6 was proposed.

Ferrocene-based 2D metal–organic framework nanosheet for highly efficient photocatalytic seawater uranium recovery

Sustainable uranium supply is critical for the long-term development of nuclear energy. The photocatalytic reduction of soluble hexavalent uranium to insoluble tetravalent uranium using photocatalysts has been recognized as a highly promising method for uranium recovery. However, existing photocatalysts face limitations such as restricted visible-light absorption and poor charge transfer capability, which hinder their photocatalytic uranium recovery performance. In this work, 1,1′-ferrocene dicarboxylic acid (FcDA) was introduced to synthesize the photocatalyst Zr-Fc-MOF3. The incorporation of FcDA broadened the visible light absorption range and reduced the band gap of Zr-Fc-MOF3, thereby enhancing electron-hole pair separation and carrier transport efficiencies. Moreover, the two-dimensional (2D) nanosheet structure of Zr-Fc-MOF3 provided a large surface area, allowing full exposure of active sites. Additionally, Fe(II) in FcDA generated photoelectrons upon light excitation to facilitate uranium reduction, and the recyclable redox behavior of Fe(II) conferred high reusability of the photocatalyst. Consequently, Zr-Fc-MOF3 demonstrated a high photocatalytic uranium recovery capacity of 8.29 mg g−1 over 10 days in natural seawater (NSW), with a uranium recovery rate of 0.829 mg g−1 d−1, surpassing most other photocatalysts applied in NSW. These findings suggest that designing 2D nanosheet materials with ligands capable of efficient photoelectron generation is a promising approach for developing high-performance uranium recovery photocatalysts.

Effect of carboxyl group on photoelectrochemical performance of TiO2nanowire arrays for water splitting.

TiO2is one of the most studied semiconductor materials for the photoelectrochemical water splitting to hydrogen production, but it only responds to ultraviolet light. The introduction of organic compound is one of the common means to expand the visible light response of TiO2. In this work, rutile TiO2nanowire arrays (NWs) were grown on conductive glass by a modified solvothermal method using oleic acid as the key additive. The obtained TiO2NWs are characterized using x-ray diffraction, x-ray photoelectron spectroscopy, infrared spectroscopy and electrochemical characterization. The results show that the carboxyl groups arising from oleic acid are chemically bonded with the TiO2NWs in the form of chelating bidentate, which increases the visible light absorption range and active sites of TiO2, and reduces the transfer resistance between the photoelectrode and the electrolyte. The photocurrent density is doubled to 0.17 mA cm-2at 1.23 V vs. RHE. This work provides a novel idea for the design of metal oxide semiconductor photoanodes by adsorbing organic compounds.

Design and modification thienonaphthalimides based non-fullerene acceptors for organic solar cells with high photovoltaic performance in visible light absorption range

Herein, we theoretically designed and characterized eight new thienonaphthalimides-based non-fullerene acceptor (NFA) materials (MT1–MT8) derived from 1ad molecule for organic solar cells (OSCs) devices. In this study, density functional theory (DFT) and time-dependent density functional theory were used to perform theoretical characters of all molecules. All computational analysis were successfully done at mPW1PW91/6-31g(d,p) DFT level. Compared with R (3.25 eV), MT4 showed better planarity and narrower band gap of 2.470 eV. A relatively lower excitation energy (2.039 eV) and binding energy (0.431 eV) were also found in MT4. Meanwhile, molecular electrostatic potential, transition density matrix and hole-electron analyses proved that MT4 had better photovoltaic and photophysical properties than R. We also designed J52-Cl:MT4 blend compound to study the charge transfer behavior at the interface which shown successful shift of electrons from donor to acceptor. Therefore, our newly designed molecules have the potential of being good NFAs for efficient OSC devices.

Synthesis of iron phthalocyanine/CeO2 Z-scheme nanocomposites as efficient photocatalysts for degradation of 2,4-dichlorophenol.

Modulating the photogenerated electrons of CeO2 to activate O2 and efficiently photocatalytic degradation of chlorophenols is a highly desired goal. Herein, we have successfully fabricated an FePc/CeO2 heterojunction through H-bond induced assembly. The photocatalytic degradation of 2,4-DCP by the amount-optimized FePc/CeO2 nanocomposite was improved by 3 times compared with that by pure CeO2. By means of electron paramagnetic resonance (EPR) and single wavelength photocurrent spectroscopy, it is confirmed that the excellent photocatalytic performance is mainly attributed to the formation of the Z-scheme heterojunction, which promotes charge separation and transfer, and the introduction of FePc broadens the visible light absorption range of the heterojunction. Moreover, O2 temperature-programmed-desorbed curves and electrochemical O2 reduction measurement results demonstrate that the single Fe-N4(II) site in FePc is more conducive to promoting O2 activation than that of other metal phthalocyanines. Based on in situ FT-IR and liquid chromatography-tandem mass spectrometry (LC-MS/MS), a possible reaction pathway of 2,4-DCP degradation was proposed. This study provides a novel strategy for preparing CeO2 based Z-scheme heterojunctions with abundant monoatomic sites for pollutant degradation.

A novel hydrogen-bonded organic framework/g-C3N4 heterojunction for improved sulfadiazine photodegradation via effective electron transfer

As one of the most widely used antibiotics, sulfamethoxazole (SDZ) poses significant health risks to the ecological environment by causing harm to aquatic organisms and accelerating evolution of antibiotic resistant bacteria. Metalloporphyrin hydrogen-bonded organic framework (PFC-72) demonstrates promising prospect in the field of photocatalysis owing to its high specific surface area, wide light harvesting range, stable physical and chemical properties, and semiconductor properties. Herein, we constructed an efficient photocatalyst PFC-72/g-C3N4 by one-step solvent thermal method for photocatalytic degradation of SDZ. When doping content of PFC-72 is 10 %, photocatalytic degradation efficiency of SDZ can reach 96.82 % after 120 min of visible light irradiation, and PFC-72/g-C3N4 exhibits excellent structural stability. The photocatalytic efficiency of SDZ is improved by increasing specific surface area, enhancing absorption range of visible light, and inhibiting recombination of photogenerated electron-hole pairs. In addition, photodegradation pathways of SDZ in PFC-72/g-C3N4 was determined by UPLC-MS/MS analysis. Finally, dominant reactive species (·O2−, hVB+, and ·OH) in the system were detected through free radical masking experiments, and photocatalytic mechanism was clarified. This work investigates a novel and efficient porphyrin-HOF based photocatalyst, which has great potential for degradation of SDZ.

TiO2 embedded in AC-COFs/SiO2 composites with core-shell structure for improved photocatalytic degradation performance of tetracycline

The excellent photocatalytic properties of covalent organic frameworks (COFs) and Titanium dioxide (TiO2) have been a hot research topic. However, the extensive application of the COFs and TiO2 in photocatalysis is restricted by their easy agglomeration and poor visible light usage, respectively. In this research, acyl chloride-covalent organic frameworks (AC-COFs) prepared by ultrasound assisted synthesis method was attached to the surface of silica oxides (SiO2) prepared by the modified Stöber method with high specific surface area and high porosity through amino groups to form a core-shell structure, which effectively solved the problem of easy agglomeration of the AC-COFs. Subsequently, TiO2 was loaded onto the surface of the AC-COFs@SiO2 composites to create high-performing TiO2/AC-COFs@SiO2 composites with a wide visible light absorption range (λ=409 nm), a narrow band gap (Eg=2.32 eV) and strong adsorption performance (Qm=314.47 mg/g). Compared with SiO2, the adsorption performance of this composite material was improved by 1.5 times. Meanwhile, the formed binary heterogeneous structure effectively reduces carrier recombination rate and releases more active substances like h+ and ·OH, so the catalyst has excellent self-cleaning and cyclic stability under the combined effect of adsorption and photocatalysis. It was found that tetracycline (TC) completely degrades after 50 min and the degradation rate decreasing by only 2.8 % after six cycles.

Investigation of the mechanism and stability of highly efficient photocatalytic degradation of Methylene blue using Ni doped CdS photocatalyst

Methylene blue (MB) is commonly utilized in chemical indicators, dyes, biological colors, and pharmaceuticals. Its aqueous solution is poisonous and carcinogenic, posing a significant threat to the ecological environment. The wurtzite-phase NixCd1−xS was synthesized using the hydrothermal technique in this study. Ni doped CdS enhanced its photocatalytic efficiency and resistance to photocorrosion, enabling its application in the photocatalytic destruction of MB. The incorporation of Ni did not change the crystal structure and microstructure of CdS, but increased the visible light absorption range and decreased the band gap width slightly, which promoted the migration of photogenerated electrons and reduced their recombination with holes, resulting in higher photogenerated carrier separation efficiency of NixCd1−xS. The photocatalytic decolorization rate of Ni0.06Cd0.94S for 100 mL of 10 mg/L MB at 240 min is 91.3 %, and the reaction rate constant is 0.01102 min−1, which is 4.42 times that of wurtzite-phase CdS. The photocatalytic mechanism of NixCd1−xS and its composite was analyzed using trap experiments in conjunction with the band structure of the sample. Additionally, the stability of NixCd1−xS was evaluated. The results indicated that the stability was superior to that of CdS. The findings demonstrate that Ni0.06Cd0.94S exhibits good catalytic activity and stability, making it a viable catalyst for the photocatalytic degradation of organic pollutants in water.

Design of a novel direct Z-scheme BiOIO3/Bi2WO6 heterojunction for enhanced photocatalytic degradation of norfloxacin under visible light

The unique electronic structure, appropriate bandgap energy, and excellent electron transfer capability make bismuth-based semiconductors hotspots in the field of photocatalysis. Novel BiOIO3/Bi2WO6 Z-scheme heterojunctions were fabricated via in-situ hydrothermal synthesis. The BIOBIW-3 heterojunctions (BiOIO3:Bi2WO6=0.25:0.8, mole ratio) exhibited excellent photocatalytic activity for norfloxacin (NOR), with a degradation efficiency of 90.41 % after 90 min of photoreaction and a reaction kinetic constant of 0.02132 min−1, which was 5.02 and 9.35 times higher than that of BIO and BIW, respectively. The superior photocatalytic performance can be attributed to the intimate interface between BiOIO3 and Bi2WO6, as well as the staggered energy band structure that facilitates the formation of a Z-type heterojunction. This not only widens the range of visible light absorption but also enhances the separation and transfer of photogenerated carriers while maintaining a high capacity for redox reactions. The dominant active species in the degradation process were photogenerated holes (h+) and superoxide (∙O2−) radicals, and an in-depth exploration of the possible mechanism was conducted. Furthermore, the effects of various parameters, including solution pH, catalyst dosage, and NOR concentration on the photocatalytic degradation of NOR were also investigated. The prepared BiOIO3/Bi2WO6 heterojunctions exhibited remarkable photocatalytic performance and chemical stability, presenting a novel research direction for employing layered bismuth-based materials in the degradation of fluoroquinolone antibiotic wastewater.

Ag-bridged Z-scheme AgI/NU-1000 heterojunction for enhanced photocatalytic degradation of sulfamethazine: Pathways, mechanism insight, and DFT calculations

Constructing heterojunction structures is a crucial approach for improving carrier separation efficiency and expanding the visible-light absorption range of photocatalysts. Herein, a series of Ag-bridged Z-scheme (AgI/NU-1000) heterojunction photocatalysts were successfully prepared using a simple in-situ precipitation method. The photodegradation efficiency of the AgI/NU-1000 samples was assessed by degrading sulfamethazine under visible-light conditions. The optimized AgI/NU-10000.35 (AN-2) photocatalyst exhibited exceptional photodegradation activity, achieving a degradation rate of 89.68 % within 40 min. The toxicity test results proved that the solution degraded by AN-2 exhibited no detrimental effects on biological growth, thereby demonstrating its potential practical application value. Electrochemical and photochemical tests demonstrated that the creation of a Z-scheme heterojunction was favorable for the separation of photogenerated carriers. Density functional theory (DFT) calculations and X-ray photoelectron spectroscopy were used to clarify the electron migration direction within the AgI/NU-1000 heterojunction. Possible degradation pathways and mediate products were investigated using high-performance liquid chromatography–mass spectrometry and DFT calculations. This work demonstrates the potential application of AgI/NU-1000 composite materials in environmental treatment.