Recombination Of Electron-hole Pairs Research Articles

Exploring Pt-Impregnated CdS/TiO2 Heterostructures for CO2 Photoreduction

This work focuses on the production of methane through the photocatalytic reduction of carbon dioxide using Pt-doped CdS/TiO2 heterostructures. The photocatalysts were prepared using P25 commercial titania and CdS synthesized through a solvothermal methodology, followed by the impregnation of Pt onto the surface to enhance the physicochemical properties of the resulting photocatalysts. The pure and heterostructure-based materials were characterized using X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-Vis), ultraviolet photoelectron spectroscopy (UPS), and photoluminescence spectroscopy (PL). The obtained results show the successful synthesis of the heterostructure impregnated with Pt. Moreover, the observed key role of CdS and Pt nanoparticles in the final semiconductor is to reduce the electron-hole pair recombination rate by acting as an electron sink, which slows down the recombination process and increases the photocatalyst efficiency. Thus, Pt-doped CdS/TiO2 heterostructures with the best observed composition presents better catalytic activity than P25 titania with methane production values being 460 and 397 µmol CH4/g·h, respectively.

Pb-N Chemically Anchors CsPbBr3 on 1D Porous Tubular g-C3N4 for Enhanced Photocatalytic CO2 Reduction.

Halide perovskite CsPbBr3 (CPB) quantum dots (QDs) are considered as a promising candidate for solar-driven CO2 conversion for their unique optoelectronic properties and suitable band structure. However, the CO2 conversion efficiency of pristine CsPbBr3 quantum dots is severely limited due to their rapid electron-hole pair recombination and insufficient active sites. In this study, by immobilizing CPB QDs onto one-dimensional (1D) porous tubular g-C3N4 (TCN), an effective 0D/1D CPB@TCN heterojunction photocatalyst for CO2 reduction is fabricated. Density functional theory (DFT) calculations combined with experimental studies demonstrate that CPB QDs are uniformly anchored on the surface of TCN through Pb-N chemical bonding, resulting in efficient separation and transfer of photogenerated carriers in CPB@TCN photocatalysts. The resultant CPB@TCN photocatalysts exhibit significantly enhanced photocatalytic activity for CO2 reduction with the highest conversion rate of 22.62 μmol·g-1·h-1, which is 5.33-times higher than that of pristine CPB QDs. This work unveils the interfacial bonding mechanism of CPB@TCN heterojunction through Pb-N chemical bond, which provides new insights for the development perovskite-based heterojunction photocatalysts.

A comparative study for optimizing photocatalytic activity of TiO2-based composites with ZrO2, ZnO, Ta2O5, SnO, Fe2O3, and CuO additives

Despite the widespread use of titanium dioxide (TiO2) in photocatalytic applications, its inherent limitations, such as low efficiency under visible light and rapid recombination of electron-hole pairs, hinder its effectiveness in environmental remediation. This study presents a comparative investigation of TiO2-based composites, including TiO2/ZrO2, ZnO, Ta2O3, SnO, Fe2O3, and CuO, aiming to assess their potential for enhancing photocatalytic applications. Photocatalysis holds promise in environmental remediation, water purification, and energy conversion, with TiO2 being a prominent photocatalyst. To improve efficiency and broaden applicability, various metal oxide composites have been explored. Composites were synthesized and characterized using techniques such as XRD, SEM, TEM, and zeta potential analysis to evaluate their structural and morphological properties. Photocatalytic performance was assessed by degrading herbicide Imazapyr under UV illumination. Results revealed that, the photo-activity of all prepared composites were more effective than the photo-activity of commercial hombikat UV-100. The photonic-efficiency is arranged according to the order TiO2/CuO > TiO2/SnO > TiO2/ZnO > TiO2/Ta2O3 > TiO2/ZrO2 > TiO2/Fe2O3 > Hombikat TiO2-UV100. All composites exhibited superior performance, attributed to enhanced light absorption and charge separation. The study underscores the potential of these composites for environmental remediation and energy conservation, offering valuable insights for the development of advanced photocatalysts.

Development of engineered Zn-MOF/g-C3N4 based photoelectrochemical system for real-time sensors and removal of naproxen in wastewater

Naproxen-contaminated water may lead to the accumulation of the drug in aquatic organisms and can pose high risks to an aquatic environment and human beings. Therefore, this work aimed to develop photoelectrochemical sensing and degradation of naproxen (NPX) using zinc-metal organic framework /graphitic carbon nitride thin film-based fluorine-doped tin oxide (Zn-MOF/g-C3N4/FTO) as anode material for the sensing and degradation of naproxen (NPX). The surface morphology, structure, surface property, surface area, optical property, photocurrent, and charge transfer kinetics abilities were studied using different techniques. The nanocomposites showed a superior photocurrent response (0.815 mA cm-2) compared to the original g-C3N4 (0.328 mA cm-2). The photo-anode made of Zn-MOF@g-C3N4/FTO displayed the highest photocurrent value, indicating that the alignment of the two semiconductor bands prevented the quick recombination of electron-hole pairs. Owing to these attractive features, the Zn-MOF/g-C3N4/FTO electrode was applied for photoelectrochemical detection of NPX using chronoamperometry. Interestingly, the nanocomposites-based FTO ascribed a lower detection limit (2.3 ng l-1) with a wide linear range concentration of NPX (0.5 to 200 µg l-1). Additionally, the analytical assessment of repeatability and reproducibility demonstrated robust performance, with commendable relative standard deviations (RSD%) of 2.54 % and 2.40 %, respectively. On the other hand, a remarkable degradation efficiency of 97.52 % was attained when employing a bias potential of 0.1 V during a 2 h photoelectrocatalytic oxidation of NPX. The degradation process was primarily driven by the active participation of holes and hydroxyl radicals in ring opening and subsequent cleavage of by-products. The notable effectiveness of this degradation can be attributed to the combined and synergistic effects of both electrochemical and photocatalytic degradation techniques. The current state demonstrates its effectiveness in the photoelectrochemical sensing and removal of NPX using MOF/g-C3N4 nanocomposites-based electrode materials in wastewater.

Enhancing photocatalytic performance of covalent organic frameworks via ionic polarization

Covalent organic frameworks have emerged as a thriving family in the realm of photocatalysis recently, yet with concerns about their high exciton dissociation energy and sluggish charge transfer. Herein, a strategy to enhance the built-in electric field of series β-keto-enamine-based covalent organic frameworks by ionic polarization method is proposed. The ionic polarization is achieved through a distinctive post-synthetic quaternization reaction which can endow the covalent organic frameworks with separated charge centers comprising cationic skeleton and iodide counter-anions. The stronger built-in electric field generated between their cationic framework and iodide anions promotes charge transfer and exciton dissociation efficiency. Moreover, the introduced iodide anions not only serve as reaction centers with lowered H* formation energy barrier, but also act as electron extractant suppressing the recombination of electron-hole pairs. Therefore, the photocatalytic performance of the covalent organic frameworks shows notable improvement, among which the CH3I-TpPa-1 can deliver an high H2 production rate up to 9.21 mmol g−1 h−1 without any co-catalysts, representing a 42-fold increase compared to TpPa-1, being comparable to or possibly exceeding the current covalent organic framework photocatalysts with the addition of Pt co-catalysts.

In-situ cation-exchange deposited Ag2S/In4SnS8 of Z-type heterojunction coupled with DNA recycling amplification for photoelectrochemical biosensing

Herein, a novel photoelectrochemical (PEC) biosensor was developed utilizing an in situ cation-exchange method to deposit a high-performance Ag2S/In4SnS8, a Z-type heterojunction with co-shared S atoms, as a signal indicator and using DNA recycling amplification for the sensitive and accurate detection of miRNA-141. The photosensitive Ag2S deposited on the In4SnS8 surface not only facilitated the rapid generation of photoelectrons but also formed a Z-type heterojunction with In4SnS8, effectively inhibiting electron-hole pair recombination. This resulted in a considerable improvement in the photoelectric conversion efficiency of Ag2S/In4SnS8, yielding an ∼ 120-fold increase in photocurrent compared to that of In4SnS8 under 660-nm visible-light irradiation. Furthermore, the arborescent DNA structure formed by hybrid chain reaction (HCR) enhanced the steric effect, thereby reducing the PEC response. Importantly, numerous quenchers MnPP competed for light absorption and captured photogenerated electrons in the valence bands of In4SnS8 and Ag2S, reducing electron transfer to the electrode and further considerably reducing the photocurrent. This enabled the sensitive detection of miRNA-141 across a concentration range from 10 amol·L−1 to 100 pmol·L−1, with a limit of detection as low as 3.3 amol·L−1 (S/N = 3). The proposed biosensor exhibits excellent stability and is expected to be applied for detecting clinically relevant disease markers.

Pt loaded CoFe2O4-based nanoparticles for breast cancer treatment with chemodynamic therapy and sonodynamic therapy

Breast cancer is one of the most widespread cancers worldwide in the female population. However, the side effects and toxicity of chemotherapy and radiotherapy are the obstacles to the treatment of breast cancer. Therefore, we developed a Pt loaded CoFe2O4-based nanoparticles (CF@Pt) for breast cancer treatment with chemodynamic therapy (CDT) and sonodynamic therapy (SDT). The Co2+/Co3+ and Fe2+/Fe3+ gave CF@Pt peroxidase-like activity and catalase activity to gain ·OH and O2 in the tumor microenvironment (TME) for CDT. Furthermore, the separation of electron-hole pairs of CF@Pt transferred the O2 into 1O2 in the presence of ultrasound (US) for SDT. The high level of O2 generated by CDT would produce more 1O2 by SDT that promoted the CDT efficiency. Moreover, the addition of Pt limited the recombination of electron-hole pairs and reduced the energy gap to enhance SDT/CDT combination therapy. In addition, CF@Pt could be engulfed by MDA-MB-231 cells and induced the apoptosis while it had good biocompatibility and blood compatibility. This design provided a novel application on the treatment of breast cancer.

A Dual-Active Covalent Triazine Framework Film for Efficient Visible-Light-Driven Hydrogen Peroxide Production.

Photocatalytic hydrogen peroxide production from water and oxygen offers a clean and sustainable alternative to the conventional energy-intensive anthraquinone oxidation method. Compared to powdered covalent triazine frameworks (CTFs), the film morphology of CTFs provides better connectivity in 2D, yielding several advantages: more efficient connections between active sites, reduced electron-hole pair recombination, increased resistance to superoxide radical induced corrosion, and decreased light scattering. Leveraging these benefits, it has incorporated dual active sites for both the oxygen reduction reaction (ORR) and the water oxidation reaction (WOR) into a CTF film system. This dual-active CTF film demonstrated an exceptional hydrogen peroxide production rate of 19460µmolh⁻¹m⁻2 after 1h and 17830µmolh⁻¹m⁻2 after 5h under visible light irradiation (≥420nm) without the need for sacrificial agents.

Designed of dual direct band gap graphdiyne/Co2VO4 S-scheme heterojunction: Enhance the bonding stability of Co active sites to promote photocatalytic hydrogen evolution

The selection of direct band gap semiconductors with high-efficiency electron transitions and the rational adjustment of the d-band center of transition metal atoms can effectively enhance photocatalytic hydrogen evolution. Based on this premise, the double direct band gap graphdiyne/Co2VO4 S-scheme heterojunction was designed via an immersion method. DFT calculation, in-situ XPS and EPR analysis not only provided support for the formation of graphdiyne /Co2VO4 S-scheme heterojunction but also demonstrated that Co maybe served as the most efficient active site for hydrogen evolution. Furthermore, the design of S-scheme heterojunction effectively prolongs the carrier lifetime of the photocatalyst, resolves the deficiency in high electron-hole pair recombination rate of direct band gap semiconductors, and maintains its efficient electronic transition. PDOS analysis revealed that the interaction between graphdiyne and Co2VO4 at the microscopic interface tends to modulate the d-band center of cobalt atoms, resulting in a decrease in electron occupation on antibonding orbitals and consequently enhancing bonding stability at Co active sites. Moreover, introducing graphdiyne effectively increases electron state density near the Fermi level of Co2VO4, facilitating rapid migration of photogenerated charges. This study provides valuable insights into the regulating d-band centers of transition metal and the development of double direct band-gap S- scheme heterojunctions.

Efficient photodegradation of acid orange 7 in water using a facile ultrasound-assisted microwave-combustion synthesized Ag-ZnAl2-xFexO4 solid-solution photocatalyst

This study explores the development of Ag-ZnAl2-xFexO4 solid-solution photocatalysts for Acid Orange 7 (AO7) degradation under visible light irradiation. The microwave auto-combustion method was employed to synthesize these photocatalysts, allowing for the investigation of the influence of Fe substitution (x) on their properties and performance. Characterization techniques revealed a trade-off between Fe content, surface area, pore size, and light absorption capacity. The Ag-ZnAlFeO4 variant achieved an optimal balance, demonstrating exceptional photocatalytic activity for AO7 degradation. This optimized photocatalyst achieved a removal efficiency of 99.3 % under neutral pH conditions, highlighting its effectiveness and potential for practical applications. Interestingly, the mineralization efficiency of AO7 reached 85.2 % after 160 minutes of reaction time. Kinetic studies supported the superior performance of Ag-ZnAlFeO4, attributing its success to its favorable morphology, high surface area, strong light absorption, and minimal electron-hole pair recombination. The proposed degradation mechanism involves light absorption, generation of electron-hole pairs, and their subsequent reactions with water and oxygen molecules to degrade AO7. This work establishes Ag-ZnAl2-xFexO4, particularly Ag-ZnAlFeO4, as a promising visible-light photocatalyst for the efficient degradation of organic pollutants.

Enhanced antibiotic degradation using rGO composites under visible light photocatalysis

A robust reduced graphene oxide (rGO), polyaniline (PANI) with calcium (Ca) and magnesium (Mg) bimetallic nanocomposite was successfully prepared using an in-situ chemical facial reducing method and named rGO@PANI-Ca:Mg. Various spectroscopic techniques, including XRD, SEM, TEM, XPS, and supplementary methods, were utilized to characterize the catalyst phase, microstructure, and optical attributes. The composite's photocatalytic efficiency was assessed by degrading antibiotics such as ciprofloxacin (CP) and tetracycline (TC) using calcium peroxide (CaO2) under visible light irradiation. The rGO@PANI-Ca:Mg composite demonstrates superior degradation efficiency for CP, 45 %, and for TC, 70 %, achieving a correlation coefficient R² of 0.94 and 0.991 respectively. This performance surpasses that of pristine GO, rGO, and rGO@PANI. The heightened photocatalytic activity is ascribed to forming a heterojunction, effectively mitigating electron-hole pair recombination. The incorporation of CaO2 promotes the generation of additional active reactive oxygen species (ROS), particularly OH·, ·O2−, e-, h+, as verified by radical scavenging experiments, indicating an enhancement in the degradation and a potential mechanism is also suggested. The degradation rate of TC, CP, and real wastewater (RW) is about 71 %, 45 %, and 40.98 %, respectively. The composite demonstrates stability and reusability for up to three catalytic cycles. Our experiments also showed that when bacteria were treated with a 2 mg catalyst, the minimum inhibitory concentration (MIC) was determined to be at a 10−3 dilution. This MIC value represents the lowest concentration at which the catalyst effectively inhibited bacterial growth, as evidenced by clear inhibition zones.

Design and Preparation of Heterostructured Cu2O/TiO2 Materials for Photocatalytic Applications.

The extensive use of fossil fuels has sped up the global development of the world economy and is accompanied by significant problems, such as energy shortages and environmental pollution. Solar energy, an inexhaustible and clean energy resource, has emerged as a promising sustainable alternative. Light irradiation can be transformed into electrical/chemical energy, which can be used to remove pollutants or transform contaminants into high-value-added chemicals through photocatalytic reactions. Therefore, photocatalysis is a promising strategy to overcome the increasing energy and environmental problems. As is well-known, photocatalysts are key components of photocatalytic systems. Among the widely investigated photocatalysts, titanium dioxide (TiO2) has attracted great attention owing to its excellent light-driven redox capability and photochemical stability. However, its poor solar light response and rapid recombination of electron-hole pairs limit its photocatalytic applications. Therefore, strategies to enhance the photocatalytic activity of TiO2 by narrowing its bandgap and inhibiting the recombination of charges have been widely accepted. Constructing heterojunctions with other components, including cuprous oxide (Cu2O), has especially narrowed the bandgap, providing a promising means of solving the present challenges. This paper reviews the advances in research on heterostructured Cu2O/TiO2 photocatalysts, such as their synthesis methods, mechanisms for the enhancement of photocatalytic performance, and their applications in hydrogen production, CO2 reduction, selective synthesis, and the degradation of pollutants. The mechanism of charge separation and transfer through the Cu2O/TiO2 heterojunctions and the inherent factors that lead to the enhancement of photocatalytic performance are extensively discussed. Additionally, the current challenges in and future perspectives on the use of heterostructured Cu2O/TiO2 photocatalysts are also highlighted.

Co-Fe Prussian blue Analogues encapsulated graphdiyne nanosheets formed type-II heterojunction for photocatalytic H2 evolution

The energy crisis and environmental pollution are becoming more and more serious, and photocatalytic hydrogen evolution technology can alleviate the above phenomena. In this paper, the type-II heterojunction was successfully constructed with CoFe-PBA/GDY and applied in photocatalytic hydrogen evolution. Density functional theory (DFT) calculations and in-situ XPS analysis were used to infer a potential mechanism for the formation of photocatalytic hydrogen. It was shown that the construction of type-II heterojunction induced the transfer of photogenerated electrons from CoFe-PBA to GDY, and suppressed the recombination of photogenerated electrons and holes in CoFe-PBA/GDY. The highest photocatalytic hydrogen evolution activity of CoFe-PBA/GDY-15 is among them, 71.24 μmol of hydrogen are precipitated in just 4h, 14.07 times that of GDY (5.06 μmol) and 14.97 times that of CoFe-PBA (4.76 μmol). This work provides a new way for constructing type-II heterojunction based on GDY to improve photocatalytic hydrogen evolution.

Emerging Trends in CdS-Based Nanoheterostructures: From Type-II and Z-Scheme toward S-Scheme Photocatalytic H2 Production.

Cadmium sulfide (CdS) based heterojunctions, including type-II, Z-scheme, and S-scheme systems emerged as promising materials for augmenting photocatalytic hydrogen (H2) generation from water splitting. This review offers an exclusive highlight of their fundamental principles, synthesis routes, charge transfer mechanisms, and performance properties in improving H2 production. We overview the crucial roles of Type-II heterojunctions in enhancing charge separation, Z-scheme heterojunctions in promoting redox potentials to reduce electron-hole (e-/h+) pairs recombination, and S-scheme heterojunctions in combining the merits of both type-II and Z-scheme frameworks to obtain highly efficient H2 production. The importance of this review is demonstrated by its thorough comparison of these three configurations, presenting valuable insights into their special contributions and capability for augmenting photocatalytic H2 activity. Additionally, key challenges and prospects in the practical applications of CdS-based heterojunctions are addressed, which provides a comprehensive route for emerging research in achieving sustainable energy goals.

Epitaxial Growth of a Three-Dimensional Hollow and Chestnut Shell Photothermal p-n Junction Photoanode.

The p-n junction, a widely studied semiconductor material structure, offers only limited improvements in photoelectrochemical (PEC) efficiency. Herein, a three-dimensional (3D) p-n junction h-Ta3N5@CoN featuring a stable chestnut shell hollow sphere structure and photothermal effect was synthesized by using an epitaxial growth strategy. The fine fibers within the sphere induce Rayleigh scattering, which scatters unabsorbed light, thereby enabling secondary absorption and enhancing light utilization. The quantum confinement effects generated by CoN fine fibers, which are sized in a few nanometers, inhibit the recombination of electron-hole pairs. Moreover, the lattice matching between Ta3N5 and CoN allows for smoother movement of carriers and nonradiative relaxation phonons along the lattice, thereby enhancing the transport of both carriers and heat. The obtained h-Ta3N5@CoN/FTO p-n junction photoanode, under near-infrared (NIR) auxiliary irradiation, demonstrates a photocurrent of 8.71 mA cm-2 at 1.23 VRHE. Moreover, the h-Ta3N5@CoN+NIR/FTO photoanode can sustain operation for 168 h, which, to my knowledge, surpasses the operational durations of all other Ta3N5-based photoanodes. This study synthesizes three-dimensional hollow chestnut shell photothermal p-n heterojunctions through an epitaxial growth strategy, endowing the material with a more efficient carrier separation and photothermal transfer efficiency.

Engineering Dual Carbon and Nitrogen Vacancies in g-C3N4 for Enhanced Photodegradation of Tetracycline Hydrochloride.

Ultrathin g-C3N4 nanosheets with specific nitrogen vacancies and combined carbon and nitrogen dual vacancies were created by annealing g-C3N4 under different atmospheric conditions. The nanosheets with dual vacancies showed significant improvements in the photodegradation of tetracycline hydrochloride (TC-HCl) compared with both the pristine g-C3N4 and its nitrogen-deficient version. Various techniques, such as Raman spectroscopy, electron spin resonance (ESR), X-ray photoelectron spectroscopy, wavelength-dependent studies, electrochemical methods, and photoluminescence measurements, were used to identify vacancy defects, revealing that performance enhancement was particularly notable under visible light. Density functional theory calculations indicated that dual vacancies introduced a shallow defect state above the valence band, enhancing visible light absorption and reducing electron-hole pair recombination. Conversely, nitrogen vacancies alone formed a deep defect state, which extended light absorption but potentially trapped photoelectrons, limiting their contribution to photoreactions. Radical-scavenging experiments and ESR spin-trap spectra identified the superoxide radical (·O2-) as the primary reactive oxygen species responsible for TC-HCl degradation. A comprehensive degradation pathway for TC-HCl was proposed using liquid chromatography-mass spectrometry data. This research highlights a strategic approach to boost TC-HCl photodegradation by engineering the vacancies in g-C3N4.

Structural, optical, photocatalytic and thermal behaviour of (Nb, Ta) co-doped WO3 nanoparticles and its application in photocatalytic degradation of MG and RhB dyes

In this communication, eco-friendly, cost effective and facile hydrothermal route was adopted to synthesize pure WO3, Nb-doped WO3 and (Nb, Ta) co-doped WO3 nanoparticles. Phase, lattice constants, crystallite size and crystallinity have been evaluated through X-ray diffraction. The insertion of Nb and Ta ions into WO3 nanoparticles was confirmed by XPS, FTIR and EDS studies. HRTEM and SAED micrographs exhibited highly nanocrystalline nature of samples. UV–visible studies was carried out to analyse nature of band gap, band gap energy, extinction coefficient, refractive index, Urbach energy and optical conductivity of prepared samples. Optical band gap was narrowed from 2.94 to 2.49 eV and Urbach energy was extended from 0.08 to 0.35 eV through co-doping of (Nb, Ta) ions into WO3 NPs. Reduction in PL intensity revealed that electron-hole pair recombination rate was decreased with co-doping of (Nb, Ta) ions. The photo-degradation efficiency of (Nb 5 %, Ta 5 %) co-doped WO3 nanophotocatalysts was 93.12 % against MG and 90.11 % against RhB dyes. The rate constant was found to be increased from 0.0107 to 0.0203 min−1 for MG and 0.0086 to 0.0174 min−1 for RhB. Thermal results exhibited the weight loss in three phase degradation processes, and thermal stability. The results showed that (Nb 5 %, Ta 5 %) co-doped WO3 NPs is a potential candidate for practical applications in environmental remediation (organic dyes degradation).

Infrared optoelectronics in twisted black phosphorus

Electrons and holes, fundamental charge carriers in semiconductors, dominate optical transitions and detection processes. Twisted van der Waals (vdW) heterostructures offer an effective approach to manipulate radiation, separation, and collection processes of electron-hole pairs by creating an atomically sharp interface. Here, we demonstrate that twisted interfaces in vdW layered black phosphorus (BP), an infrared semiconductor with highly anisotropic crystalline structure and properties, can significantly alter both recombination and separation processes of electron-hole pairs. On the one hand, the twisted interface breaks the symmetry of optical transition states resulting in infrared light emission of originally symmetry-forbidden optical states along the zigzag direction. On the other hand, spontaneous electronic polarization/bulk photovoltaic effect is generated at the twisted interface enabling effective separation of electron-hole pairs without external voltage bias. This is supported by first-principles calculations and repeated experiments at various twisted angles from 0 to 90°. Importantly, these phenomena can be observed in twisted heterostructures with thickness beyond two-dimensional. Our results suggest that the engineering of vdW twisted interfaces is an effective strategy for manipulating the optoelectronic properties of materials and constructing functional devices.

Recent advances in photocatalytic degradation of persistent organic pollutants: Mechanisms, challenges, and modification strategies

Ecosystems and human health are seriously threatened by persistent organic pollutants (POPs), which are hazardous, resistant to environmental degradation, and have the capability of bioaccumulating. The sources, ecological dispersion, and potential adverse impacts of POPs are investigated in this study, which further highlights the urgent need to develop successful remediation technologies. As it can use light energy to promote degradation, photocatalysis is a promising approach among other methods. The review explores many evolved photocatalyst materials, such as those based on nanomaterials, metal-organic frameworks (MOFs), carbon, and hybrids, highlighting their characteristics and functions in the removal of pollutants. Enhancing photocatalytic performance through modification techniques such as surface changes, doping, and co-catalyst insertion is explored. The focus is on the degrading mechanisms specific to POPs and further examines the basic ideas and processes of photocatalysis. Despite its enormous significance, environmental stability, electron-hole pair recombination, and limited light absorption are some of the obstacles that photocatalysis faces. Finally, this analysis calls for novel materials and optimization techniques to overcome existing constraints and enhance the effectiveness of POP removal, highlighting future directions for photocatalyst research.

In-Situ Construction of Atomic-Level Fe-O Bond Bridges within Fe2N/g-C3N4 Heterojunction for Efficient Visible-Light-Driven Photocatalytic H2 Production.

The limited active sites and faster photogenerated electron-hole pair recombination rate of g-C3N4 restrict its application in photocatalytic H2 production. Constructing heterojunctions has been shown to improve the spatial (directional) separation of photogenerated electrons and holes. However, due to interface mismatch in traditional heterojunction structures and a lack of precise electron transport channels, the photocatalytic efficiency is limited. Here, we developed a two-step calcination approach to create an Fe2N/g-C3N4 heterojunction linked by Fe-O bonds (named as Fe-OCN). The newly formed Fe-O bonds within the heterojunction can act as atomic-level interface electron transfer channels, directly transferring the photogenerated electrons of g-C3N4 to the reactive center Fe2N, significantly improving the charge transfer rate and utilization, thus promoting visible-light-driven photocatalytic H2 production. The optimal Fe-OCN achieved a H2 production rate of 5986.29 μmol g-1 h-1 under visible light, 13.44 times higher than that of the OCN due to efficient charge separation and transfer capabilities. This work provides a constructive reference for the design and synthesis of organic-inorganic heterojunction with chemically bonded interfaces, establishing quick electron transfer channels, and achieving targeted electron transfer.