Enhanced Carrier Separation Research Articles

Creating Cation Vacancies in BiOCl Nanosheets Toward Exceptional Visible‐Light‐Driven Photocatalytic CO2 Reduction

AbstractBiOCl‐based materials have emerged as promising photocatalysts for converting CO2 into valuable products and fuels. However, challenges such as low light absorption and inefficient charge carrier separation require effective solutions, with vacancy engineering offering a promising approach. Current research primarily focuses on anion vacancies, leaving cation vacancies less explored. In contrast, this study presents a novel method to enhance visible‐light‐driven photocatalysts by Bi cation vacancies in ultrathin BiOCl nanosheets through a straightforward hydrochloric acid etching process (HAE‐BiOCl). These introduced Bi vacancies not only expand the light absorption range and enhance carrier separation, but also serve as active sites for CO2 adsorption. Additionally, Bi vacancies can effectively lower the activation energy of COOH− species and thereby enhance overall reaction activity. As a result, the HAE‐BiOCl catalyst exhibits exceptional photocatalytic CO2 reduction performance without the need for co‐catalysts or sacrificial agents. It achieves high CO generation rates of 68.39 and 17.43 µmol g−1 h−1 under 300 W Xe lamp and visible light irradiation, respectively. These rates are significantly higher compared to counterparts without vacancy creation and surpass those of most reported Bi‐based photocatalysts. This study underscores the potential of inducing cation vacancies via acid etching as a valuable strategy for advancing photocatalysis.

Heterogeneous visible-light photoredox catalysis with NiCl2@g-C3N4 for induced C(sp2)-H/N[sbnd]H cross-dehydrogenative coupling

A novel photoactive NiCl2@g-C3N4 catalyst system, which effectively drives C(sp2)-H/NH bond formation between quinolin-2(1H)-ones, primary and secondary aliphatic amines under blue light irradiation. The NiCl2@g-C3N4 composite with a NiCl2 loading of 0.7wt% had the highest photoactivity, and the calculated band gap energy value is 2.56 eV The nickel ion could act as an electron acceptor enhancing carrier separation and transfer efficiency, greatly enhanced the photoreaction efficiency of g-C3N4. Preliminary mechanistic studies indicate upon visible light irradiation, the photo-generated electrons and holes act as oxidants, thereby generating amine radicals in the absence of external chemical oxidants. This provides a straightforward and efficient approach for directly 3-aminating quinoxalines-2(1H)-ones. Moreover, the heterogeneous catalyst can be recycled at least six times without significant activity loss.

Numerical optimization of inorganic p-Sb2Se3/n-ZrS2 heterojunction solar cells: achieving high efficiency through SCAPS-1D simulation

p-Sb2Se3 and n-ZrS2 materials show strong potential for cost-effective photovoltaic applications. This study presents a detailed numerical analysis of p-Sb2Se3/n-ZrS2 heterojunction solar cells using SCAPS-1D, focusing on how key parameters such as layer thickness, doping density, and bandgap have affected device performance. Critical photovoltaic metrics, such as built-in voltage (Vbi), carrier lifetime, depletion width (Wd), recombination rates, and photogenerated current, were examined. Our findings demonstrate that optimizing the p-Sb2Se3 absorber layer with a 1.0 eV bandgap, 5000 nm thickness, and doping density of 1020 cm−3 leads to a maximum efficiency of 32.14%, with a fill factor (FF) of 84.57%, short-circuit current density (Jsc) of 47.61 mA cm−2, and open-circuit voltage (Voc) of 0.792 V. For the ZrS2 buffer layer, the best performance was achieved with a 1.2 eV bandgap, 200 nm thickness, and doping density below 1 × 1020 cm−3. These optimized parameters significantly enhanced carrier separation and minimized recombination losses, leading to improved power conversion efficiency. In addition to theoretical optimization, this study emphasizes the practical potential of these materials for real-world applications. The combination of Sb2Se3 and ZrS2 offers a low-cost fabrication process suitable for scalable commercial solar cell production while maintaining high efficiency. These results underscore the viability of p-Sb2Se3/n-ZrS2 heterojunctions as promising candidates for next-generation clean energy solutions.

Interfacial design of pyrene-based covalent organic framework for overall photocatalytic H2O2 synthesis in water

Covalent organic frameworks (COFs) have shown great potential in the photocatalytic production of hydrogen peroxide (H2O2) due to their precisely designed and customized ability. Nevertheless, the quest for efficient overall photosynthesis of H2O2 in pure water without sacrificial agents using COF photocatalysts remains a formidable challenge. Herein, three pyrene-based covalent organic frameworks are synthesized using an advanced interfacial design strategy. By incorporating functional groups of F, H, and OH into a COF skeleton, their wettability and charge-separation properties are fine-tuned. These COFs show great performances as photocatalysts for H2O2 production from water and air by utilizing both the oxygen reduction reaction and water oxidation reaction pathways. Compared to PyCOF-F and PyCOF-H, PyCOF-OH demonstrates superior H2O2 production efficiency due to its improved hydrophilicity and enhanced carrier separation, achieving a remarkable rate of 2961 µmol g−1 h−1 from 25 mL pure water and air. Further, the mechanism of H2O2 production over PyCOF-OH is clarified by combining a series of control experiments, in situ characterizations, and theoretical calculations. This study offers valuable insights into the interfacial design of high-performance photocatalysts for H2O2 synthesis.

Recent Advances in Piezoelectric Coupled with Photocatalytic Reaction System: Synergistic Mechanism, Enhancement Factors, and Application.

The field of photocatalysis has demonstrated numerous advantages in the domains of environmental protection, energy, and materials science. However, conventional modification methods fail to simultaneously enhance carrier separation efficiency, redox capacity, and visible light absorption solely through light activation due to the intrinsic band structure limitations of photocatalysts. In addition to modification methods, the introduction of an external field, such as a piezoelectric field, can effectively address deficiencies in each step of the photocatalytic process and enhance the overall performance. The assistance of a piezoelectric field overcomes the limitations inherent in traditional photocatalytic systems. Hence, this review provides a comprehensive overview of recent advancements in piezoelectric-assisted photocatalysis and thoroughly investigates the interaction between the alternating piezoelectric field and photocatalytic processes. Various ideas for synergistic enhancement of the piezoelectric and photocatalytic properties are also explored. This multifield catalytic system shows remarkable performance in stability, pollutant degradation, and energy conversion, distinguishing it from single catalytic systems. Finally, an in-depth analysis is conducted to address the challenges and prospects associated with piezoelectric photocatalysis technology.

Enhanced photodegradation performance of Zn-BiPO4 on RhB and TC under the synergistic effect of oxygen vacancies and built-in electric field

In this work, Zn2+ ions doped BiPO4 photocatalyst was successfully prepared by one-step hydrothermal method for the first time. The degradation rates of the optimal sample on RhB and TC solution reached 91.5 % and 81.25 % under simulated sunlight exposure for 3 and 5 hours, respectively, while pure BiPO4 only reached 59.22 % and 49.4 %. The improved photocatalytic performance was due to the synergistic effect of oxygen vacancies and built-in electric field. The EPR test demonstrated the generation of more oxygen vacancies in the optimal sample. Additionally, the electrochemical experiments showed that the photocurrent intensity of the optimal sample was about 3 times than that of pure BiPO4, indicating an enhanced carrier separation and transfer ability after doping Zn2+ ions. Through density functional theory (DFT), the incorporated Zn2+ ions caused the contraction of crystal structure and the redistribution of charges, leading to a built-in electric field. As few studies pay attention to the relationship between oxygen vacancies and the built-in electric field. This study has enlightening significance for the construction of photocatalysts with oxygen vacancies and built-in electric field through doping engineering.

Bimetallic Fe, Co-Modified TiO2 Derived from NH2-MIL-125(Ti) as an Efficient Photocatalyst for N2 Fixation

The conversion of nitrogen (N2) and water (H2O) into NH3 by photocatalysis under ambient conditions has been considered an environmentally friendly strategy. However, developing effective catalysts for N2 fixation is still challenging. Herein, we report a bimetallic JH Fe, Co/TiO2 derived from NH2-MIL-125(Ti) by the fast Joule heating (FJH) method for visible–light–driven catalytic N2 fixation. It was found that the photocatalytic N2 reduction efficiency of bimetallic FC@TiO2-JH was improved, enabling an NH3 yield rate of 110.14 µmol g−1 h−1 without any sacrificial agents. Furthermore, the rate was higher than those of Fe@TiO2-JH and Co@TiO2-JH, suggesting that the synergistic effect between Fe and Co broke the electronic equilibrium and increased the center of its d-band, enhancing electronic feedback to the antibonding π* orbitals of N2 while weakening the bonding energy of N≡N. Meanwhile, the rate was about 2.75 times higher than that of FC@TiO2-TF, which was calcined in a tube furnace. It is assumed that FJH might lead to the formation of lattice defects, leading to localized charge deficiency, enhanced carrier separation, and transport. Thus, doping of Fe and Co synergistically interacted with the defects produced from FJH, facilitating the photocatalytic reduction process. As detected, it had a greater ability to separate hole–electron pairs and transferred electrons to adsorbed N2 at faster rates. Our work demonstrates a prospective strategy for designing bimetallic catalysts derived from NH2-MIL-125(Ti) for N2 fixation.

Construction of ZnAl LDH-Derived Sulfides with Etching Modification to Trigger Photocatalytic H2 Production and Degradation Oxidation.

Constructing novel functional photocatalysts represents a promising approach to optimize the energy band structure and facilitate the separation of photogenerated carriers. Layered double hydroxides (LDHs) exhibit notable advantages in photocatalysis due to the exceptional photoelectrochemical properties and elevated number of active surface atoms. However, an unsuitable band gap and limited carrier migration have inhibited their development in photocatalysis. Herein, we propose a novel in situ topological vulcanization strategy for optimizing the photocatalytic activity of ZnAl LDH-derived sulfides (ZnAlSx). The subsequent etching process via a 1 M NaOH solution was introduced to construct the ZnSx photocatalysts. Then, the crystallinity of the crystals was enhanced by etching to further improve the catalytic activity and stability of ZnSx. The as-synthesized ZnSx shows an excellent photocatalytic hydrogen production rate (11.89 mmol/g/h) and tetracycline degradation efficiency (91.94%) under light illumination, and its hydrogen evolution efficiency is approximately 176 and 2 times greater than that of ZnAl LDH and ZnAlSx, respectively. The characterization and density functional theory (DFT) analysis confirmed that the surface electronic properties and energy band structure of ZnAl LDH were significantly optimized after experimental treatment, resulting in enhanced carrier separation and photooxidative reduction capacity. Combining in situ topological vulcanization and etching to realize the functional conversion of ZnAl LDH provides promising insights into the construction of high-performance, low-cost photocatalysts.

Conjugated diamine cation based halide perovskitoid enables robust stability and high photodetector performance

Low-dimensional lead halide materials have proved to be intrinsically stable semiconductor materials. However, the development of one-dimensional (1D) perovskites or perovskitoids with both robust water stability and high optoelectronic performance still faces significant challenges. Here, we report a new class of 1D (TzBIPY)Pb2X6 (X = Cl, Br, I) perovskitoids featuring a π-conjugated diamine cation (TzBIPY = 2,5-di(pyridin-4-yl)thiazolo[5,4-d]thiazole). The TzBIPY2+ cation with delocalized electrons directly contributes to the electronic structure and hence reduces the band gap. Especially, the Br-based material exhibits enhanced carrier separation and transport capacity, benefiting from the improved electronic conjugation together with a type II intramolecular heterojunction between conjugated organic cations and Pb–X octahedra. The (TzBIPY)Pb2Br6 photodetector exhibits an impressive photocurrent on/off ratio of 8.1 × 105, which is much superior to the previous three-dimensional (3D) perovskite benchmark. Additionally, the π-conjugated cations serve as dense protective shields for vulnerable Pb–X inorganic lattice against being attacked by water, thus demonstrating exceptional stability even immersed in water for over 3000 h.

Flexible roles of TiO2 in enhancing carrier separation for the high photocatalytic performance of water treatment under different spectrum sunlight

Construction of heterogeneous-photocatalysts is an effective mean for enhancing charge separation, however, the specific roles of the individual components have not been thoroughly explored. In this article, a heterogeneous-photocatalyst, TiO2/MoO3-x, was constructed, revealing that the two components, TiO2 and MoO3-x, play varying roles under different light spectra. Under full spectrum light, an S-scheme mechanism was achieved, which preserved the high oxidizing and reducing property of MoO3-x and TiO2, facilitating an augmented generation of reactive oxygen species (ROS). Under visible light, the MoO3-x functioned as the donor of hot electrons and the TiO2 served as the receptor platform for these electrons. The presence of the interfacial electric field enabled the transfer of hot electrons, leading to an enhanced ROS generation. Consequently, the TiO2/MoO3-x achieved high photocatalytic activity under both full spectrum and visible light. The optimized TiO2/MoO3-x catalyst demonstrated outstanding antibacterial efficacy, achieving eradication rates of 98.1 % for Staphylococcus aureus, and 99.6 % for Escherichia coli respectively. Additionally, it exhibited substantial degradation activity with a rate of 0.028 min−1 for Rhodamine B (50 mg/L). Furthermore, the TiO2/MoO3-x membrane removed approximately 81.2 % of bacteria from surface water, underscoring the potential of the designed membrane in water purification systems. This article explored the distinct roles and corresponding charge transfer mechanisms of the TiO2 and MoO3-x under full spectrum or visible light, offering innovative ideas for the design of full-spectrum photocatalysts with high efficiency. The straightforward design of membrane-based filtering device demonstrated wide applications for treating wastewater for the removal of dye and bacterial contamination.

Co-doped bismuth vanadate/zinc tungstate heterojunction with dual internal electric fields for efficient photocatalytic reduction of carbon dioxide

Enhanced carriers separation on photocatalysts is crucial for improving photocatalytic activity. In this paper, the Co-doped BiVO4/ZnWO4 S-scheme heterojunctions were constructed to induce double internal electric fields (IEFs) for enhancing charges separation and transfer for efficient photocatalytic reduction of CO2. The photocatalytic CO2 reduction efficiencies of the heterojunctions were significantly enhanced as compared with the counterparts. The optimized Co-doped BiVO4/ZnWO4 exhibited the highest CO yield of 138.4 μmol·g−1·h−1, which were 86.5 and 1.4 folds of the BiVO4 and Co-doped BiVO4. Results of X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and work function demonstrated that charge transfer path of Co-doped BiVO4/ZnWO4 conformed to S-scheme heterojunction mechanism. The kelvin probe force microscopy (KPFM) and density functional theory (DFT) calculations of the differential charge distributions confirmed the existence of double IEFs, which accelerated carrier separation and improved CO2 adsorption and activation. In addition, in-situ Fourier transform infrared spectroscopy (ISFT-IR) revealed that HCOO− was the major intermediate during the CO2 reaction. This study provides a feasible means to develop composite photocatalysts with dual IEFs for effective photocatalytic CO2 reduction.

Lattice Distortion Promotes Carrier Separation to Improve the Photoelectrochemical Water Splitting Performance of Bismuth Vanadate Photoanode

AbstractThe poor carrier separation capability and sluggish water oxidation reaction kinetics are two critical factors that impact the photoelectrochemical (PEC) water splitting performance of the bismuth vanadate (BiVO4) photoanode. Previous studies have demonstrated that doping with rare‐earth elements to induce lattice distortions and loading oxygen evolution reaction (OER) co‐catalysts are effective strategies for enhancing carrier separation capabilities and accelerating the kinetics of the water oxidation reaction. Herein, Cu2+‐doped RuO2 (Cu‐RuO2) particles are anchored onto rare earth element Thulium (Tm)‐doped BiVO4 (Tm‐BiVO4) photoanode substrates, constructing an integrated Cu‐RuO2‐Tm‐BiVO4 photoanode. The newly integrated photoanode not only achieves a photocurrent density of 5.3 mA cm−2 at 1.23 V versus a reversible hydrogen electrode (vs RHE), but also exhibits exceptional stability. A series of detailed physical and chemical characterizations as well as density‐functional theory (DFT) calculations demonstrate that Tm doping induces lattice distortion in BiVO4, enhancing the internal electric field and thereby facilitating carrier separation. Moreover, the anchored Cu‐RuO2 particles not only lattice‐match with the Tm‐BiVO4 photoanode, reducing interfacial transfer resistance, but also expedite the kinetics of the water oxidation reaction. The profound significance of this work is that it offers a reference for the future design and fabrication of novel integrated photoanodes.

Rapid charge extraction via hole transfer layer and interfacial coordination bonds on hematite photoanode for efficient photoelectrochemical water oxidation

Enhancing carrier separation and transport efficiency to achieve efficient water oxidation reaction is an important issue in photoelectrochemical (PEC) water splitting field, and introducing hole transfer layer (HTL) is an effective strategy to improve it. However, the difficulty of charge transfer between HTL and oxygen evolution catalyst (OEC) is a problem unresolved. To ameliorate the situation, we choose CoOOH as HTL and the metal–organic coordination compound constructed by 4,5-Imidazoledicarboxylic acid (IA) and Co/Ni ions as OEC. Using the interfacial coordination bonds as carrier transfer channels, the holes were rapidly extracted from HTL to OEC containing abundant active sites and participate in oxidation reaction. In consequence, the unique design results in a photocurrent density of 2.97 times that of α-Fe2O3 at 1.23 VRHE for the IACN/CoOOH/Fe2O3. This study reveals how the advisable design of photoanode promotes interfacial charge transfer and provides a valuable reference for the design of composite photoanode.

Room temperature preparation of novel g-C3N4/RuNP/ZIF-8 Z-scheme heterojunction for solar-light driven H2 generation

We present a novel approach for the room temperature synthesis and integration of Ru nanoparticles into a Z-scheme heterojunction comprising graphitic carbon nitride (CN) and zeolitic imidazolate framework-8 (ZIF-8). This heterojunction demonstrates outstanding efficiency in sunlight-driven hydrogen (H2) generation via water splitting. Various structural and spectroscopic analyses elucidate Ru nanoparticles' successful incorporation and synergistic effects within the CN/ZIF-8 heterojunction because the decrease in interplanar spacing due to π-π stacking interactions between aromatic rings of tri-s-triazine in CN and imidazole rings in ZIF-8. The Z-scheme configuration facilitates efficient charge separation and promotes H2 production. Additionally, Ru nanoparticles offer alternative electron transfer pathways, enhancing carrier separation and prolonging the lifespan of photoinduced charges compared to CN and ZIF-8 alone. Notably, RZCN-2 heterojunction exhibited significantly enhanced hydrogen production, reaching 5245 μmol g−1 h−1. By analyzing work functions and energy band structures, we demonstrate that the strong interfacial electric fields across the Z-scheme heterojunction effectively mitigate the recombination of photogenerated charges while maintaining the necessary redox capacity for efficient H2 production. The room temperature synthesis and integration of Ru nanoparticles provide a practical and effective strategy for optimizing photocatalytic activity and promoting sustainable energy conversion, thereby advancing photocatalytic technologies.

Regular study of lanthanide oxides for boosting photocatalytic hydrogen production on ZnIn2S4 photocatalysts

Lanthanide oxides have potential advantages for photocatalytic hydrogen production. To systematically investigate the photocatalytic performance of lanthanide oxides on metal sulfides, a series of LnxOy/ZnIn2S4 (LnxOy/ZIS) were synthesized by hydrothermal method. Comprehensive characterization demonstrated that LnxOy synergistically improved the performance of ZnIn2S4 by extending light absorption, reducing contact interface resistance and enhancing carrier separation. The photocatalytic hydrogen evolution (PHE) rates of the LnxOy/ZIS photocatalysts were improved, which were 1.6–4.2 times higher than those of pure ZnIn2S4 (198.0 μmol g−1 h−1). The PHE rates of LnxOy/ZIS decreased with increasing lanthanide atomic number, and when the lanthanides contained variable valence ions, the PHE rates of LnxOy/ZIS were superior to those of neighbouring lanthanides. The heterojunction formed by LnxOy and ZnIn2S4 effectively promoted carrier separation. Lanthanide ions with unoccupied 4 f orbital were more likely to accept electrons and served as a hydrogen adsorption site for further hydrogen reduction. Multivalent ions could also promote the migration of electrons and generate oxygen vacancies to inhibit the recombination of carriers. In conclusion, for ZnIn2S4, lanthanide oxides are promising candidates to improve the performance of PHE. This study provides guidance on the selection of appropriate lanthanide oxides for the construction of efficient sulphur-based heterojunction photocatalysts.

LaCoO3 supported Pt for efficient photo-thermal catalytic reverse water-gas shift via the Mott-Schottky effect

The conversion of CO2 into valuable chemicals like CO through the reverse water–gas shift (RWGS) process is a significant strategy for both mitigating and utilizing atmospheric CO2. It is crucial to enhance catalytic performance for RWGS at low-temperatures by designing efficient photo-thermal co-catalysts with strong photo-response and photo-thermal effects. Herein, Pt nanoparticles (NPs) supported on LaCoO3 with Mott-Schottky heterojunctions were synthesized to improve the performance of RWGS at low-temperatures. The results show that the narrow bandgap of LaCoO3 has excellent light-absorbing properties, generating abundant photo-carriers under light irradiation. The presence of ultra-small Pt NPs effectively reduces carrier recombination, enhancing carrier separation efficiency. 1.0 Pt/LaCoO3 (1.0 wt% Pt loading) at 350 °C under photo-thermal conditions showed a CO2 conversion of 32.9 % and CO production rate of 58.6 mmol gcat−1 h−1. The excellent photo-thermal co-catalytic performance of Pt/LaCoO3 was attributed to the remarkable Mott-Schottky heterojunctions of Pt with high electron density and the narrow bandgap of the support with abundant surface defects. This study provides valuable insights into the development of Mott-Schottky heterojunction catalysts for efficient photo-thermal co-catalytic RWGS at low-temperatures.

Enhancing photoelectrochemical properties of α-Fe2O3 using Zr-doped HfO2 ferroelectric nanoparticles

Hematite (α-Fe2O3) as a semiconductor photoanode for photoelectrochemical (PEC) water splitting is a promising candidate material. However, its PEC performance is limited by the slow charge transfer kinetics at the α-Fe2O3/electrolyte interface. Ferroelectric materials can be used as a tool for carrier separation in photoelectrochemical water splitting due to their spontaneous polarization electric field characteristics. Here, we deposited Hf0.5Zr0.5O2 (HZO) ferroelectric nanoparticles on the surface of α-Fe2O3 and use the spontaneous polarization field of ferroelectric HZO to promote the separation of photogenerated carriers, promote the charge transfer from α-Fe2O3 to the electrolyte, and enhance the PEC of hematite. After depositing the HZO nanoparticles, the photogenerated holes are efficiently extracted from α-Fe2O3 and then directed into the electrolyte to participate in water oxidation reaction at α-Fe2O3/HZO interfaces, which enhanced the charge separation efficiency by 58 % compared to that of pure α-Fe2O3. Consequently, the α-Fe2O3/HZO photoanode exhibits a 65 % boost in photocurrent density, reaching up to 0.28 mA cm−2 at 1.23 V versus the reversible hydrogen electrode (VRHE) compared to that of pure α-Fe2O3. This study introduces a method to engineer the photoanode/ferroelectric interface, enhancing carrier separation and thereby optimizing PEC water splitting performance.

Transition‐Metal‐Doped TiO2 Nanorods with High‐Visible‐Light Response via a Simple Hydrothermal Method

Transition‐metal‐ion doping is an effective method to shorten bandgap and enhance visible‐light absorption of TiO2, but there are still some serious challenges for most doping technologies, such as nonuniform doping, severe lattice damages, metal atoms agglomeration, and inactivated impurities. Herein, a simple and universal hydrothermal method is developed to realize the effective transition‐metal ions doping of TiO2 (including Fe, Co, Mn, Cu, V, and Cr). The photoelectrochemical water splitting performances of Cr‐doped TiO2 nanorods with multifarious Cr ion valence states (Cr3+ or Cr6+ ions), various Cr‐ion concentrations, with or without oxygen vacancy activation are emphatically and systematically studied. Experiments and theoretical calculations demonstrate that the remarkably enhanced carrier separation and injection efficiencies are the key factors to improve the visible‐light photoactivity, benefiting from the homogeneous distribution of impurity atoms and the incorporation of oxygen vacancies. The Cr3+‐ion‐doped TiO2 nanorod arrays with oxygen vacancy activation (Cr3+/Ov–TiO2) displays an impressive incident photon‐to‐electron conversion efficiency of 5.4% at 450 nm visible light, far superior to the pure TiO2 of 0.03%. Furthermore, no obvious photocurrent decay is observed in the Cr3+/Ov–TiO2 photoanode after 12 h continuous light illumination.

Construction of AgI/PCN-224 Z-scheme heterojunction for efficient photocatalytic degradation of tetracycline hydrochloride: Pathways, mechanism and theoretical calculations

The construction of heterojunction structures is pivotal in enhancing carrier separation and photocatalytic activity. Hence, AgI/PCN-224 (APN-x composites) Z-scheme heterojunctions were successfully synthesised using an in-situ precipitation method. The direction of electron migration and the band structures of APN-x were comprehensively investigated using a combination of experimental approaches and density functional theory (DFT) calculations. Owing to the extensive visible-light absorption capabilities of PCN-224 and the high efficiency of photogenerated carrier separation in the Z-scheme heterojunction, the optimally developed APN-3 photocatalyst demonstrated exceptional photodegradation efficiency for tetracycline hydrochloride (TCH). The removal rate of TCH by APN-3 within 120 min reached 91.56%, approximately 4.64 times higher than that achieved by pure AgI. The photocatalytic degradation mechanism was explored using free radical trapping experiments, electron spin resonance (ESR) technology and band structure analysis. Degradation pathways and intermediate products were investigated using liquid chromatography–tandem mass spectrometry (LC–MS).

Tailoring interface and morphology of TiO2 electron transport layer with potassium bitartrate for high-performance perovskite solar cells

The performance of perovskite solar cells (PSCs) has rapidly improved, largely due to advancements in mitigating inherent defects and enhancing interface carrier transport properties. Herein, we provide a facile method to improve the morphology of TiO2 ETLs, suppress defects at interface, and tailor energy level alignment to enhance carrier separation and extraction efficiency by introducing potassium bitartrate (KBT) into the TiO2 electron transport layers (ETLs), achieving high-efficiency and stable PSCs. KBT molecules can enhance the surface smoothness of TiO2 ETLs, resulting in denser and more uniform perovskite films. In addition, the carboxyl groups, hydroxyl groups, and potassium cations containing in KBT improve charge transport efficiency at TiO2/perovskite interface by reducing non-radiative recombination centers in TiO2 and perovskite bottom as well as improving energy level matching. As a result, the target PSC exhibits an obvious improvement in performance with a champion efficiency of 23.35 %, which is greatly improved relative to the control (21.66 %). The long-term operational stability is also remarkably enhanced, after 800 h MPPT, PSCs with KBT remain over 80 % of its initial efficiency. PSCs with KBT-doped ETLs exhibit increased efficiency and stability, highlighting potential of KBT as an interface engineering tool for enhancing PSCs performance.