Separation Efficiency Of Charge Carriers Research Articles

Nickel ion (Ni2+) doping induced formation of W18O49/W3O8 bulk homojunction for enhancing photo-assisted energy storage

The photo-assisted charging supercapacitors that integrate solar energy conversion and energy storage in one device have inspired great interests. In this work, a bulk homojunction W18O49/W3O8 was prepared through doping Ni2+ in W18O49, and was used as the active material of photoelectrodes. The Ni-doped W18O49/W3O8 photoelectrodes exhibited superior photoelectric property and excellent capacity for energy storage. The optimal WN2 photoelectrode showed a specific capacitance of 667.7 F.g−1 at current density of 4 A.g−1 under light illumination, which was 19.4% higher than that in dark. The photogenerated charge carriers and the efficient separation of charge carriers induced by homojunction could be responsible for the photo-enhanced charge storage. After cycling test, WN2 photoelectrode retained about 92% of its initial specific capacitance without irradiation, and surprising 102% of its initial specific capacitance with irradiation. The electrochemical energy storage process of WN2 photoelectrode was found to be dominated by bulk solid-state diffusion, and the mechanism analysis provided theoretical evidence for photo-assist enhanced electrochemical performance of the prepared electrodes.

A novel BiOBr/rGO photocatalysts for degradation of organic and antibiotic pollutants under visible light irradiation: Tetracycline degradation pathways, kinetics, and mechanism insight

In this study, the BiOBr/rGO nanocomposite photocatalysts are fabricated by a facile solvothermal method. The BiOBr growth on reduced graphene oxide (rGO) sheet could improve BiOBr's photocatalytic activity by increasing its adsorption ability, surface area, and charge carriers' separation efficiency. The prepared nanocomposites were characterized by XRD, Raman, FESEM, EDS, XPS, and UV–visible DRS. The BiOBr/rGO (BRG) nanocomposites showed improved photocatalytic activity for the photodegradation of Rhodamine B (RhB) dye and Tetracycline (TC) under visible light irradiation. Rhodamine B and tetracycline degradation efficiency were about 96% and 73% within 120 min under visible light irradiation. The PL analysis indicates that BiOBr/rGO nanocomposite exhibited maximum separation efficiency of photoinduced charge carriers. The trapping test confirmed that O2− and h+ are significant active photodegradation species. The GC-MS spectra detected the two plausible transformation routes of tetracycline degradation. The current work presented a low-cost and facile approach for fabricating Bi-based composites.

Constructing a type-II heterojunction of AgI/CO32−-Bi2O2CO3 for enhanced photocatalytic degradation of organic pollutants

The construction of heterojunctions is a well-established approach for enhancing the photocatalytic efficiency of semiconductor materials. To improve the photocatalytic activity of CO32−-Bi2O2CO3, AgI/CO32−-Bi2O2CO3 type-II heterojunction photocatalysts were synthesized using an electrostatic self-assembly method with varying composite ratios. The performance of AgI/CO32−-Bi2O2CO3 catalyst was investigated by photocatalytic degradation of 2-Hydroxy-1, 4-naphthoquinone and levofloxacin under a 300 W xenon lamp (λ ≥ 420 nm). The results demonstrated that the composite photocatalyst (0.5ACBOC), prepared by incorporating 0.5 mL of AgNO3 and KI, exhibited exceptional photocurrent responsiveness and efficient charge carrier separation. 0.5ACBOC displayed the highest degradation efficiency towards 2-Hydroxy-1,4-naphthoquinone (67.5%) and levofloxacin (78.0%). Free radical capture experiments and electron paramagnetic resonance (EPR) analysis revealed ·O2− as a crucial reactive species in the photodegradation process. Moreover, the photocatalytic degradation of 2-Hydroxy-1,4-naphthoquinone exhibited consistent removal efficiency even after undergoing four cycles, thereby demonstrating the excellent cycle stability of the composite catalyst. These findings highlight that AgI/CO32−-Bi2O2CO3 can be easily synthesized and holds great potential as a photocatalyst for efficient degradation of organic pollutants.

Enhanced photocatalytic CO2 reduction via single-atom Au anchored on ZnIn2S4 nanosheets

In this study, we systematically investigated the effect of single-atom gold (Au) loaded on ZnIn2S4 nanosheets on the photocatalytic reduction of carbon dioxide (CO2). Utilizing a photodeposition method, we successfully dispersed single-atom Au uniformly on the surface of ZnIn2S4 nanosheets. Under simulated sunlight irradiation, the Au-loaded catalyst demonstrated a higher yield and selectivity in the CO2 reduction reaction compared to the pure ZnIn2S4 nanosheets. Surface photovoltage testing revealed that the addition of Au significantly enhanced the separation efficiency of photo-generated charge carriers, thereby improving the photocatalytic efficiency. Density functional theory calculations indicated that the loading of single-atom Au reduced the reaction energy barrier from CO2 to CO, enhancing the selectivity of photocatalytic CO2 reduction. This research not only developed an efficient catalyst for CO2 reduction but also provided deep insights into the mechanism of single-atom catalysts in the photocatalytic CO2 reduction process through extensive experimental and theoretical analysis.

Synthesis and transformation of graphene-like structures from bamboo waste for photoelectrochemical devices

This study presents a sustainable and versatile approach to synthesize graphene-like structures from bamboo waste for application in photoelectrochemical (PEC) devices. Due to its high cellulose content, bamboo, a locally available and renewable resource, is a perfect precursor for producing graphene-like materials. The synthesis process involves bamboo waste pyrolysis, followed by treatments with different solvents: ultrapure water (UPW), NaOH, and green tea extract. Characterization techniques confirmed the successful transformation of bamboo waste into carbon-rich, graphene-like materials with varying surface properties. The electrochemical characterization showed that the graphene-like materials could transfer electrons very well with a high current response compared to charcoal as a precursor. PEC evaluations revealed their potential as photoanodes, exhibiting efficient light absorption and charge carrier separation. This research emphasizes the significance of bamboo waste as a valuable precursor for eco-friendly graphene-like materials, offering a sustainable pathway for developing efficient PEC devices and green energy technologies.

Enhanced photocatalytic performance of MXene-Modified cation-exchanged CoFe-LDH/CoFeCrO4 heterostructure for Antibiotic degradation and hydrogen production through synergistic charge dynamics

Systemizing an effective charge-transfer channel across a junction interface replete with ample active sites for enhancing the photocatalytic activity of semiconducting materials presents a formidable challenge. Here, we present a novel approach based on an in situ hydrothermal method for synthesizing CoFe-Layered Double Hydroxide (LDH)/CoFeCrO4 heterojunction materials that were partially derived from CoFe-LDH. These materials synergistically interact with Ti3C2 MXene nanosheets facilitating multi-interface interactions. Indeed, the highest tetracycline hydrochloride degradation rate of nearly 92% in 2 h was achieved because of the intense synergy between the CoFe-LDH/CoFeCrO4 heterojunction material optimized with 7.5 wt% of MXene nanosheets (CMC-7.5). This degradation performance was 3.1 times greater than that of the original CoFe-LDH. Further, CMC-7.5 produces the highest H2 gas of 458.79 μmol h−1g−1 from a photocatalytic water splitting reaction. The formation of a Schottky energy barrier between the partially derived CoFe-LDH/CoFeCrO4 unit and MXene promoted the fast transfer of photogenerated electrons from CoFe-LDH/CoFeCrO4 to the surface of MXene, thereby providing a plethora of active sites for photocatalytic reactions. Photoelectrochemical assessments using transient and linear sweep voltammetry along with electrochemical impedance spectroscopy confirmed efficient charge carrier transfer. Moreover, the optimized CMC-7.5 photoelectrode has a superior integral area and exhibited excellent stability over 100 cycles. Finally, the study outlines the construction of several advanced materials with multi-interface heterojunctions involving cation-exchanged LDH derivatives with high photogenerated charge carrier separation efficiency and minimal interfacial migration resistance to serve as stability benchmarks for practical applications.

A visible-light-driven dual Z-scheme CeVO4/g-C3N4/LaNiO3 hierarchical nanostructure photocatalyst for effective removal of organic pollutants

The major obstacle to restrict the practical application of photocatalysts is the low separation efficiency of photo-induced charge carriers. To overcome the above problem, a novel ternary CeVO4/g-C3N4/LaNiO3 hierarchical nanostructure photocatalyst with dual Z-scheme heterojunction is designed and fabricated by feat of semiconductor energy levels matching engineering. First, one-dimensional (1D) LaNiO3 nanobelts are fabricated by an electrospinning technique. Second, zero-dimensional (0D) g-C3N4 nanoparticles are fixed on 1D LaNiO3 nanobelts through a direct gas-solid reaction. Finally, 1D CeVO4 needle-like nanorods are fixed on g-C3N4/LaNiO3 hierarchical nanostructures through a hydrothermal method. Following exposure to visible-light irradiation for 180 min, the optimized CeVO4/g-C3N4/LaNiO3 hierarchical nanostructure photocatalyst exhibits the highest photocatalytic degradation rate (87.57%) for tetracycline hydrochloride (TCH). Additionally, under the same conditions, the photocatalyst demonstrates its broad applicability by effectively degrading various organic pollutants, including methylene blue (MB) (60.56%), bisphenol A (BPA) (68.00%), ibuprofen (IBU) (57.56%), cefuroxime sodium (CRO) (77.34%), carbamazepine (CBZ) (59.65%) and ciprofloxacin (CIP) (75.16%). The exceptional photocatalytic performance of the CeVO4/g-C3N4/LaNiO3 hierarchical nanostructure photocatalyst can be attributed to the formation of a dual Z-scheme heterojunction among the 1D CeVO4 needle-like nanorods, 0D g-C3N4 nanoparticles, and 1D LaNiO3 nanobelts. The photocatalyst has a large specific surface area and suitable semiconductor energy band positions, providing the hierarchical nanostructures with numerous surface-active sites, rapid charge transfer ability and small charge recombination rate. The design ideas and preparation method proposed in this work have guiding significance for developing other dual Z-scheme heterojunction photocatalysts.

Construction of novel Ru-embedded bulk g-C3N4 photocatalysts toward efficient and sustainable photocatalytic hydrogen production

Novel Ru-embedded bulk graphitic carbon nitride (g-C3N4) photocatalysts containing different wt% of Ru (0.5–2 % wt) were synthesized by a simple mixing method of ruthenium complex with g-C3N4. The photocatalytic activity of the synthesized photocatalysts was assessed for hydrogen production in an aqueous solution containing methanol with and without Pt. The optimal hydrogen production rate of the most active photocatalyst (0.8 % Ru/CN) was 246 μmol/h without Pt and 1021 μmol/h with Pt, which was more than two times higher than pure g-C3N4. Various physiochemical techniques such as X-ray diffraction (XRD), N2 adsorption-desorption isotherms, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence spectroscopy (PL) and transition photocurrent response (PC) were applied to investigate the origin of activity of the Rux/CN photocatalysts. Results indicated that the loading of g-C3N4 with Ru nanoparticles enlarged its surface area and enhanced visible light absorption. Importantly, Ru nanoparticles promoted the charge carrier separation and transfer efficiency of g-C3N4 revealed by the PL and PC measurements, enhancing the photocatalytic activity of the embedded photocatalyst. Furthermore, XPS proved the existence of Ru (II) of RuO2 and metallic Ru0. The Ru-embedded g-C3N4 showed high photocatalytic activity, which makes them attractive materials for further applications in photocatalysis.

Enhanced Fenton-like catalysis through in-situ bismuth defection in Bi/CuBi2O4: Vacancy mechanisms

Alleviating the concentration of hazardous bacteria by photocatalysts is an efficient way for treating ballast water. In this work, we present the synthesis of in-situ Bi vacancies on Bi/CuBi2O4, which is assisted by H2O2 for Fenton-like photocatalytic potential in deactivating marine microorganisms in natural seawater (Yellow Sea, China), the optimal Bi vacancy content (3BCBO) is determined and exhibits superior photocatalytic inactivation performance, additional H2O2 activation enhances the production of •OH for comprehensive oxidation, with •OH confirmed as the dominant reactive species. Density functional theory (DFT) calculations highlight the synergistic of vacancies and metallic Bi play a pivotal role in decreasing the energy barrier of H2O2 adsorption for •OH improving production, promotes efficient separation of charge carriers and utilization of visible light, the co-effect of metallic Bi nanoparticles and bismuth defection mechanisms effectively inhibit the madness thriving of marine microorganisms, this work offers an ideal and promising perspective for ballast water treatment on ships.

Synthesis of Au‐decorated WO3 nanoplates for simultaneous oxidation of RhB and reduction of Cr(VI) under visible light irradiation

AbstractTungsten oxide (WO3) nanoplates were synthesized by a simple chemical precipitation technique. These nanoplates were decorated by Au nanoparticles via photoreduction route. The obtained samples were characterized by field emission scanning electron microscopy, X‐ray diffractometry and UV–vis diffuse reflectance spectroscopy to investigate their morphological, structural and optical properties. The SEM images show the plate morphology with the size in the range of 50–150 nm, their thickness ≈10 nm; spherical‐like Au nanoparticles ≈20 nm were attached to the surface of the WO3 plates. These materials were applied for the simultaneous photocatalytic degradation of Rhodamine B (RhB) and Cr(VI) under visible light. Due to the efficient separation of photoinduced charge carriers and the enhanced visible light absorption ability, the photocatalytic performance of Au‐decorated WO3 nanoplates was higher. The main active species responsible for the photodegradation reactions were identified by different scavengers and a photocatalytic mechanism was proposed. This work represents that WO3 nanoplates are a promising candidate for the degradation of organic and inorganic pollutants from the industrial wastewater under sun light exposure.

CdS nanorods decorated with non-precious metal Bi spheres for photocatalytic hydrogen production

It is well known that precious metals decoration strategies can effectively improve the charge separation efficiency. Unfortunately, the high price limits their large-scale application. Nevertheless, the cheap transition metal Bi has a similar effect as precious metals. Therefore, we take a simple solvothermal method to reduce and aggregate Bi3+ into bismuth nano-spheres (Bi0). CdS nanorods were modified with Bi spheres to create a hybrid material called x% Bi–CdS, which combines a metal and a semiconductor for photocatalytic hydrogen production. The results of the experiment indicate that the hydrogen evolution rate of the 5% Bi–CdS sample is 1501.52 μmol g−1 h−1, which is 4.2 times greater than that of pure CdS nanorods. This significant enhancement in photocatalytic activity can be attributed to the presence of Bi spheres, which induce a surface plasmon resonance (SPR) effect. This effect boosts the absorption of visible light and enhances the separation efficiency of charge carriers. The study not only provides a solution for the preparation of low-cost CdS-based materials, but also confirms the feasibility of inexpensive Bi metals to replace precious metals as co-catalysts to improve the photocatalytic efficiency.

Single-layer GaInS3: Water-splitting photocatalyst with high solar conversion efficiency and long carrier lifetime from first-principles investigation

Two-dimensional (2D) materials with a high solar to hydrogen (STH) conversion are in high demand due to the escalating energy crisis and environmental degradation. The STH efficiency is strongly correlated with the charge carrier separation, which can be improved by the inside electric dipole. Herein, the water-splitting capabilities of single-layer (SL) GaInS3 are explored by employing first-principles calculations. Theoretical outcomes reveal that SL GaInS3 exhibits a large intrinsic electric dipole and has a thermally stable structure at 300 K. SL GaInS3 displays a direct bandgap of 1.83 eV, as well as suitable band edges and abundant visible absorption (105 cm−1) for solar-driven water-splitting. The electronic structure and carrier mobility calculations demonstrate the high separation efficiency of charge carriers, which is strongly affirmed by the quite long carrier lifetime of 8.26 ns. The overpotential analysis of charge carriers suggests that the oxygen generation of SL GaInS3 can be accomplished without a cocatalyst, while hydrogen generation can be completed with the aid of cocatalysts. The STH efficiency of SL GaInS3 reaches up to 16.8%, apparently surpassing the commercial standard (10%). In brief, the high STH and long carrier lifetime promise the possible application of SL GaInS3 for solar water splitting. What's more, this work provides straight evidence that 2D photocatalysts with inside dipoles exhibit a long carrier lifetime.

Closing the loop: Waste carbon transformation into solar fuels via CdS/Bi2WO6 heterojunction

The advancement of semiconductor photocatalysis is acknowledged for its prowess as an eco-friendly, energy-efficient, and cost-effective method facilitating diverse organic transformations, including CO2 photoreduction. Despite its merits, there remains room for enhancing the selectivity and efficiency of these photocatalysts. In this study, we successfully synthesized heterojunction nanocomposites comprising CdS and Bi2WO6 semiconductors to drive the CO2-to-methanol conversion, achieving a maximum yield of 9450 μmol/g. Notably, CO (1048 μmol/g) and H2 (482 μmol/g) were also produced using water within a 16-h photocatalytic period, yielding an average production rate of ∼590 μmol/g-h. Triethylamine played a crucial role by providing electrons to the reaction system. The recovered photocatalyst exhibited consistent performance over five cycles of photoreduction experiments. Various spectroscopic and microscopic techniques were employed to analyze the optical, catalytic, and morphological properties of both the fresh and recovered photocatalysts. The introduced S-scheme heterojunction photocatalyst stands out for its efficient charge carrier separation, enhancing redox capacity, and holds promise as a source for novel strategies to improve the efficiency of CO2 photoreduction experiments.

Enhanced solar Photocatalysis: Zinc oxide modified Yb2Zn-TiO6 doped g-C3N4 heterostructures for bromothymol blue mineralization and bacterial inhibition

A new composite material, ZnO/Yb2Zn-TiO6@g-C3N4 has been synthesized by simple hydrothermal process. This composite has been characterized using various material characterization techniques and was found to have a heterojunction amongst Yb2Zn-TiO6 and g-C3N4, leading to higher light absorption and poorer charge carrier recombination rates. Furthermore, the evaluation of the charge carrier density revealed that the incorporation of small sized ZnO (40 nm) into Yb2Zn-TiO6@g-C3N4 led to heightened disintegration of the photoinduced charge carriers. This observation implies that the presence of said metal oxide enhances the photocatalytic performance by greatly promoting the effective separation of charge carriers for various applications. When tested with bromothymol blue, the 20 wt% ZnO/Yb2Zn-TiO6@g-C3N4 composite showed a photodegradation rate several times greater (98 %) than individual ZnO, C3N4 and Yb2Zn-TiO6, respectively. The degradation efficiency of the ZnO/Yb2Zn-TiO6@g-C3N4 nanostructure in the absence of light was 24 %. The increased photoactivity of the composite material is due to the efficient separation of charge carriers and also due to the high redox capabilities resulting from the heterojunction. The composite also demonstrated stable photocatalytic performance over five cyclic runs and was effective in treating real printed ink wastewater. Furthermore, ZnO/Yb2Zn-TiO6@g-C3N4 was found to have excellent antibacterial properties in opposition to Escherichia coli, (Inhibition = 16(±0.2) mm) as well as Bacillus subtilis (Inhibition = 22(±0.3) mm). The MIC of the said nanomaterials against Escherichia coli as well as Bacillus subtilis were 50 µg/mL and 30 µg/mL respectively. The detailed explanation of the photodegradation mechanism was also provided. The use of this composite material can help to reduce the harmful effects of contaminants and microbes in aquatic environments and promote environmental sustainability.

Large reduction in band gap and conduction mechanisms in Bi0.5Na0.5TiO3-based ceramics with a sizable polarization

Low band gap ferroelectrics that exhibit high polarization at ambient conditions are highly desirable for achieving efficient charge carrier separation in photovoltaic applications. In this work, a well-designed Co/Nb-modified Bi0.5Na0.5TiO3 system (1-x)Bi0.5Na0.5TiO3-xCaCo0.5Nb0.5O3 with x=0.00–0.20 offers a platform with the characteristics of low band gap and high ferroelectric polarization simultaneously. A structural phase transition from rhombohedral to monoclinic structure as the x content increases, which is verified by XRD analysis. Specifically, the x=0.10 ceramic exhibited a considerable high remanent polarization of 20.2 μC/cm2 and a low band gap of 2.18 eV, approximately 31% lower than that for a pure BNT sample (∼3.13 eV). However, the leakage current significantly increased with an increase in the x content, where it exceeded by more than three orders of magnitude for the x=0.20 sample in comparison to the pure BNT sample. Current-voltage characteristics revealed that space-charge-limited conduction was the primary conduction mechanism within the ceramics with x<0.20, which can be attributed to the free carriers confined by oxygen vacancies. On the other hand, field-assisted ionic conduction was revealed to be the primary conduction mechanism in the sample corresponding to x=0.20 at room temperature. We ascribe these mechanisms to oxygen vacancies and multivalent cobalt ions based on the XPS analysis. An improved understanding of conduction mechanism sheds light on leakage current problems and facilitates the design of BNT-based ferroelectric devices with excellent insulating character for high-performance photoelectric and photovoltaic applications.

Enhanced photocatalytic nitrogen fixation performance via in situ constructing BiO2–x/NaNbO3 heterojunction

The fabrication of heterojunction catalysts is an effective strategy to enhance charge separation efficiency, thereby boosting the performance of photocatalysts. In this study, BiO2–x nanosheets were synthesized through a hydrothermal process and loaded onto NaNbO3 microcube to construct a series of BiO2–x/NaNbO3 heterojunctions for photocatalytic N2 fixation. Results indicated that 2.5% BiO2–x/NaNbO3 had the highest photocatalytic performance. The NH3 production rate under simulated solar light reached 406.4 μmol·L−1·g−1·h−1, which reaches 2.6 and 3.8 times that of NaNbO3 and BiO2–x, respectively. BiO2–x nanosheets primarily act as electron trappers to enhance the separation efficiency of charge carriers. The strong interaction between BiO2–x and NaNbO3 facilitate the electron migration between them. Meanwhile, the abundant oxygen vacancies in BiO2–x nanosheets may facilitate the adsorption and activation of N2, which may be another possible reason of the high photocatalytic activity of the BiO2–x/NaNbO3. This study may offer new insights for the development of semiconductor materials in photocatalytic nitrogen fixation.

Interface-engineered dual Z-scheme of BiVO4/NH2-MIL-125(Ti)/POF photoanode with enhanced photoelectrochemical performance

The key factors that restrain the decomposition activity of photoelectrocatalysis (PEC) are poor redox ability and low charge separation rate. In this work, the dual Z-scheme BiVO4/NH2-MIL-125(Ti)/POF (BiVO4/NM125(Ti)/POF) heterojunctions were successfully established for visible-light driven PEC degradation of phenol. As expected, the optimum BiVO4/NM125(Ti)/POF photoanode exhibited outstanding PEC performance with near-total degradation of phenol within 2 h of illumination. The evaluated activity was assigned to high charge transfer rate and dual Z-scheme heterostructures with double electron transport channels. The fabrication of dual Z-scheme heterojunctions improved a more efficient separation of photo-induced charge carriers while holding a higher redox ability to generate more reactive oxygen species (ROS) such as O2•− and •OH to decompose organic pollutants. In addition, excellent chemical stability and recyclability were also achieved after five times cycles, and the degradation pathway of phenol was also put forward. Finally, the quantitative structure-activity relationship (QSAR) was applied to forecast phenol and its degradation products toxicity. This research gives novel insights into establishing highly effective photoanode with promising applications for organic contaminants degradation, and offers in-depth understanding of charge separation and migration in PEC process.

Enhanced photocatalytic performance of Bi2MoO6 via strain engineering through collaborative optimization of indium doping and oxygen vacancies

Investigating lattice strain manipulation as an emerging strategy for improved photocatalysis, we introduce lattice strain into Bi2MoO6 nanosheets through synergistic indium doping and oxygen vacancies (OVs). Structural analysis reveals distinct compressive and tensile effects induced by indium doping and OVs, respectively, leading to localized lattice strain intensification. The optimized photocatalyst displays significantly enhanced tetracycline, ciprofloxacin, oxytetracycline, and norfloxacin removal activity due to increased active sites and improved charge carrier separation efficiency induced by lattice strain. Elucidation of tetracycline cleavage pathways and assessment of intermediate molecule toxicity are presented. This collaborative approach, merging doping and OVs for lattice strain induction, provides crucial insights for advancing bismuth-based photocatalysts.

Preparation and enhanced photocatalytic properties of Cu31S16/Cu9S5 heterojunction composite

A heterojunction photocatalytic material Cu31S16/Cu9S5 was successfully synthesized through a facile solvothermal method by controlling the reaction temperature. The phase composition, morphology, absorbance and surface area were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffusion reflection and Brunauer–Emmett–Teller (BET). Transient photocurrent response and electrochemical impedance spectroscopy (EIS) were measured to support the generation and transfer of the photoinduced charge carriers. The heterojunction Cu31S16/Cu9S5 showed superior separation efficiency of the photoinduced charge carriers. The photocatalytic performance of the Cu31S16/Cu9S5 was evaluated through degrading high-concentration methyl orange (MO) solution under visible light. The degradation rate of MO solution increased to 94.8% in 60 min, showing the most remarkable photocatalytic ability. Moreover, a probable photocatalytic mechanism of the Cu31S16/Cu9S5 was discussed.

Three-Dimensional Tetrathiafulvalene-Based covalent organic frameworks for efficient photocatalytic nitrogen fixation

Preparing photocatalytic nitrogen-fixing catalysts that can effectively produce ammonia under mild conditions is an urgent problem to be solved. Herein, we for the first time present two three-dimensional tetrathiafulvalene-based covalent organic frameworks with high crystallinity and permanent pores, termed 3D-TTF-COFs, specifically designed for photocatalytic nitrogen fixation. The incorporation of TTF-based building blocks not only enhances light absorption capabilities but also facilitates the rapid transfer of photoexcited electrons, ensuring efficient charge carrier separation. It is worth noting that the resultant COFs exhibit remarkable NH3 generation rates of 313.8 ± 5.6 and 106.8 ± 4.2 μmol g−1h−1 under visible light irradiation, surpassing the performance of most photocatalyst materials reported so far. Furthermore, these COFs maintain structural integrity and excellent performance during cyclic testing. Additionally, we carried out density functional theory calculations to elucidate the reaction mechanism between N2 and NH3. This work provides a feasible strategy for constructing 3D COFs to achieve efficient photocatalytic nitrogen fixation.