Simulated Sunlight Irradiation Research Articles

Facile synthesis of self-nitrogen-doped carbon spheres for high-efficient photocatalytic CO2 reduction to CO

In this work, self-nitrogen-doped carbon microsphere photocatalysts were prepared by hydrothermal and carbonation pyrolysis with first application in photocatalytic CO2 reduction. Coupled with relevant characterization, nitrogen-doped carbon microspheres were successfully prepared and the introduction of nitrogen significantly improved the photogenerated charge separation efficiency and CO2 photoreduction to CO activity, leading to the highest photocatalytic reduction activity with a CO yield of 185.71 μmol g−1 (9 h) under simulated sunlight irradiation. More importantly, its performance remains at about 98 % after ten consecutive cycle tests, indicating the excellent active stability of self-nitrogen-doped carbon spheres. Possible mechanisms for photocatalytic reduction and the role of nitrogen in photocatalytic adsorption and reduction processes are analyzed and proposed. The research provides novel strategies for the design of bifunctional catalysts that offer robust adsorption and efficient reduction, enabling the sustainable conversion of CO2.

Photocatalytic persulfate activation by highly dispersed nano-TiO2 supported by silica for efficient carbamazepine degradation

A silica-loaded nano-TiO2 composite (A-SiO2/TiO2) was prepared by wet-grinding method, using industrial silica (A-SiO2) as the carrier. A-SiO2/TiO2 was used for photocatalytic activation of peroxymonosulfate (PMS) to degrade carbamazepine (CBZ). The A-SiO2/TiO2 containing 20 wt% nano-TiO2 resulted in the CBZ degradation efficiency of 94.83 % after 90 min simulated sunlight irradiation with the presence of PMS. The main reactive species during CBZ degradation in the system of photocatalytic PMS activation by A-SiO2/TiO2 were O2•−, •OH and SO4•−. Compared to nano-TiO2, A-SiO2/TiO2 exhibits enhanced dispersion, increased surface active sites and improved photo-generated carrier separation efficiency, which contributed to enhanced degradation performance.

Highly Effective Fe-Doped Nano Titanium Oxide for Removal of Acetamiprid and Atrazine under Simulated Sunlight Irradiation

Pesticides are widely detected in large quantities in the environment, posing an ecological threat to the human body and ecology. Semiconductor nanomaterials such as nano-titania (nTiO2) have strong photocatalytic degradation efficiency for pollutants. However, the wide bandgap and limited light absorption range inhibit nano-titania’s practical application. Therefore, nTiO2 was modified by Fe3+ doping using the microwave hydrothermal method to improve its photocatalytic performance in this study. Fe-nTiO2 doped with a 1.0% mass ratio was used due to its high photocatalytic performance. Its maximum degradation efficiencies for ACE and ATZ under a 20 W xenon lamp were 88% and 88.5%, respectively. It was found that Fe3+ doping modification distorted the spatial morphology of nTiO2 and shortened the bandgap to facilitate the photocatalytic reaction. The electron paramagnetic resonance results showed that the reactive radicals (1O2, ·OH) produced by photogenerated electrons (e−) and holes (h+) of Fe-nTiO2 were the main active species in the degradation of ACE and ATZ. Additionally, the application of Fe-nTiO2 significantly enhanced the growth of lettuce under sunlight; the degradation efficiencies of ACE and ATZ in lettuce were 98.5% and 100%, respectively. This work provides new insights into the removal of organic contaminants by photocatalysts under sunlight in agriculture.

Photoaged polystyrene microplastics result in neurotoxicity associated with neurotransmission and neurodevelopment in zebrafish larvae (Danio rerio)

Microplastics (MPs) are emerging pollutants widely distributed in the environment, inducing toxic effects in various organisms. However, the neurotoxicity and underlying mechanisms of simulated sunlight-aged MPs have rarely been investigated. In this study, zebrafish (Danio rerio) were exposed to environmentally relevant concentrations (0, 0.1, 1, 10, and 100 μg/L) of virgin polystyrene (V-PS) and aged polystyrene (A-PS) for 120 hpf to evaluate the neurotoxicity. The results demonstrated that simulated sunlight irradiation altered the physicochemical properties (morphology, functional groups, and chemical composition) of V-PS. Exposure to A-PS causes greater toxicity on locomotor ability in larval zebrafish than V-PS. Motor neuron development was disrupted by transgenic (hb9-GFP) zebrafish larvae exposed to A-PS, with significant alterations in neurotransmitter levels (ACh, DA, 5-HT, and GABA) and enzyme activity (AChE, ChAT, and ChE). Further investigation found that exposure to A-PS had a significantly impact on the expression of neurotransmission and neurodevelopment-related genes in zebrafish. These findings suggest that A-PS induces neurotoxicity by its effects on neurotransmission and neurodevelopment. This study highlights the neurotoxic effects and mechanisms of simulated sunlight irradiation of MPs, providing new insights for assessing the ecological risks of photoaged MPs in the environment.

Constructing a Z-Scheme Co3O4/BiOBr Heterojunction to Enhance Photocatalytic Peroxydisulfate Oxidation of High-Concentration Rhodamine B: Mechanism, Degradation Pathways, and Toxicological Evaluations.

Photocatalytic coupling technologies have emerged as popular strategies to increase the treatment efficiency of dye-containing wastewater. Herein, the Z-scheme Co3O4/BiOBr heterojunction (Z-CBH) was constructed and developed as a photocatalytic peroxydisulfate (PDS) activator for the degradation of high-concentration Rhodamine B (RhB). Multiple testing techniques were employed to confirm the formation of Z-CBHs. When 0.1 g·L-1 of Z-CBH20 and 1.0 mmol·L-1 of PDS were added simultaneously under simulated sunlight irradiation, the RhB degradation efficiency could approach 91.3%. Its reaction rate constant (0.01231 min-1) was much beyond the sum of those in the Z-CBH20/light system (0.00436 min-1) and the PDS/light system (0.0062 min-1). h+, •OH, •O2-, SO4•-, and 1O2 were detected as the dominant reactive species for RhB degradation. The potential mechanism of photocatalytic PDS oxidation was proposed. The possible intermediates were determined by high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry assisted with density functional theory and Fukui theory. The possible degradation pathways of RhB degradation were put forward. The toxicological properties of RhB and its intermediates were evaluated by quantitative structure-activity relationship prediction. This work will not only provide a reference for developing photocatalytic persulfate activators but also gain an insight into the degradation pathways of RhB and the toxicity of its intermediates.

Efficient removal of U(VI) from aqueous solution by CNN/UiO-66 under simulated sunlight irradiation: the synergy of adsorption and photocatalysis.

The reduction of soluble U(VI) to insoluble and less toxic U(IV) by photocatalysis is an effective method to control uranium contamination. The graphitic carbon nitride nanosheet (CNN)/UiO-66 composites (CNNU) were prepared by thermal polymerization and solvothermal methods for the removal of U(VI). The morphology, crystal structure and optical properties of composites were analyzed by SEM, XRD, BET, UV-DRS, PL and EIS. The results showed the introduction of UiO-66 increased the specific surface of CNN from 9.07 m2/g to 46.24 m2/g, and effectively suppressed the recombination of photogenerated electrons and holes and improved the photocatalytic activity. The U(VI) removal capacity by adsorption and photocatalysis of CNNU was reached 779.47mg/g, which significantly higher than that of adsorption (478.38mg/g). The adsorption process was found to conform to the pseudo-second-order kinetic model and the Langmuir isothermal model. Meanwhile, U(VI) adsorbed on the CNNU was reduced to U(IV) via e- and ·O2- generated in the photocatalytic process. Therefore, this outstanding performance of CNNU in U(VI) removal is attributed to the synergistic effect of adsorption and photocatalytic reduction.

Fabrication of a superhydrophobic surface with photothermal electrical conversion performance for anti-icing

The development of anti-icing technology is an effective way to decrease the harm caused by ice accumulation on the surface of materials. In this work, the polypropylene with candle soot and micro-nano structures on its surface (the PP/CS replica) is prepared using a template method. The micro-nano structures are formed on the PP/CS replica surface after hot-pressing. The surface water contact angle of the PP/CS replica is up to 163° and the rolling angle is as low as 2°. The PP/CS replica still has superhydrophobic performance after water flow impact, friction and immersion. The freezing time of the water droplet is delayed and the ice adhesion strength is reduced on the PP/CS replica surface, owing to the micro-nano structures. The PP/CS replica surface has excellent photothermal performance, and the surface temperature can reach 89 °C under simulated sunlight illumination, which accelerates the melting of ice. The photothermal electrical conversion is achieved by the combination of the PP/CS replica and the thermoelectric generator, with an output power up to 604 mW. The solar energy can be effectively utilized.

Designing and fabricating a neoteric immobilized Z-scheme V2O5/FeVO4/430-stainless steel foil photocatalyst composite film for tetracycline degradation with synchronous hydrogen production

For traditional photocatalyst composite films, the produced hydrogen and carbon dioxide are mixed together, which is not conducive to the direct use of hydrogen. In this study, a novel immobilized Z-scheme V2O5/FeVO4/430-stainless steel foil (V2O5/FeVO4/430-SSF) photocatalyst composite film was constructed. Thereby, the hydrogen and the carbon dioxide can separately generated on both sides of the photocatalytst film and the pure hydrogen can be obtained. The results show that the photocatalyst composite film prepared under optimal conditions has excellent photocatalytic activity in organic pollutant degradation with simultaneous hydrogen production. Under simulated sunlight irradiation for 120 min, the degradation ratio of tetracycline is 77.53% and the hydrogen production amount reaches 370.81 µmol/dm2. It is hoped that this work could provide some guiding suggestions to designing a photocatalyst composite film for efficient photocatalytic degradation of organic pollutants with simultaneous production of pure hydrogen in the future.

Constructing a 3D Bi2WO6/ZnIn2S4 direct Z-scheme heterostructure for improved photocatalytic CO2 reduction performance

Developing efficient heterojunction photocatalysts with enhanced charge transfer and reduced recombination rates of photogenerated carriers is crucial for harnessing solar energy in the photocatalytic CO2 reduction into renewable fuels. This study employed electrostatic self-assembly techniques to construct a 3D Bi2WO6/ZnIn2S4 direct Z-scheme heterojunctions. The unique 3D structure provided abundant active sites and facilitated CO2 adsorption. Moreover, the optimized Bi2WO6/ZnIn2S4 composite demonstrated an impressive CH4 yield of 19.54 μmol g−1 under 4 h of simulated sunlight irradiation, which was about 8.73 and 16.30-fold higher than pure ZnIn2S4 and Bi2WO6. The observed enhancements in photocatalytic performance are attributed to forming a direct Z-scheme heterojunction, which effectively promotes charge transport and migration. This research introduces a novel strategy for constructing photocatalysts through the synergistic effect of morphological interface modifications.

Core-shell nanoconfinement: Nanoreactors for directional electron migration in photothermal-assisted photocatalytic hydrogen production

Photothermal-assisted photocatalysis play crucial factors in solar to chemical/thermal energy conversion via the light–matter interaction. Herein, a photothermal nanoconfinement reactor comprised of a co-catalyst (Mo2C hollow spheres) as the core and a semiconductor photocatalyst (ZnIn2S4 nanosheets) as the shell was designed for achieving high-efficient photothermal-assisted photocatalytic H2 production. Remarkably, the optimal Mo2C@ZnIn2S4 core–shell nanoreactor attains an astonishing H2 evolution rate of 26.1 mmol g−1 h−1 under simulated sunlight irradiation and apparent quantum efficiencies (AQE, 420 nm) value of 19.4 %. The enhanced photocatalytic H2 production performance is attributed the unique core–shell structure can induce the directional migration of the photo-generated electrons excited by the shell (ZnIn2S4) to the nuclear region (Mo2C) with photothermal property, and effectively transport the electrons to the high-temperature zone through the nanoconfinement effect, thus ensuring the effective separation of the photogenerated carriers. This study provides an innovative design for high-efficient photothermal-assisted photocatalyst based on nanoconfinement effect.

Efficient photodegradation of perfluoroalkyl substances under visible light by hexagonal ZnIn2S4 nanosheets

Perfluoroalkyl substances (PFASs) are typical persistent organic pollutants, and their removal is urgently required but challenging. Photocatalysis has shown potential in PFASs degradation due to the redox capabilities of photoinduced charge carriers in photocatalysts. Herein, hexagonal ZnIn2S4 (ZIS) nanosheets were synthesized by a one-pot oil bath method and were well characterized by a series of techniques. In the degradation of sodium p-perfluorous nonenoxybenzenesulfonate (OBS), one kind of representative PFASs, the as-synthesized ZIS showed activity superior to P25 TiO2 under both simulated sunlight and visible-light irradiation. The good photocatalytic performance was attributed to the enhanced light absorption and facilitated charge separation. The pH conditions were found crucial in the photocatalytic process by influencing the OBS adsorption on the ZIS surface. Photogenerated e− and h+ were the main active species involved in OBS degradation in the ZIS system. This work confirmed the feasibility and could provide mechanistic insights into the degradation and defluorination of PFASs by visible-light photocatalysis.

Coupled piezo-pyro-photocatalysis of oxygen vacancies and Bi quantum dots co-modified BaTiO3 for highly efficient removal of ciprofloxacin

Understanding the synergistic promotion of photocarrier separation by multiple parameters is crucial to developing superior photocatalysts in environmental remediation. In this study, we have engineered BaTiO3 photocatalyst by creating oxygen vacancies (OVs) and decorating Bi quantum dots (QDs) on its surface, and then elucidated its piezo-pyro-photocatalysis and mechanism for ciprofloxacin (CIP) elimination. The optimal OVs-/Bi QDs-engineered sample (labeled as 7 %Bi@BTO-325 °C) exhibits a photodegradation activity, under simulated-sunlight irradiation, that is improved by 3.8 times over that of pristine BTO. This phenomenon can be explained due to the improved visible-light absorption and photocarrier separation by OVs and Bi QDs. Moreover, when the simulated-sunlight illumination (photocatalysis) was companied with ultrasonic irradiation (piezocatalysis) and cold-hot alternation (pyrocatalysis), the coupling of piezo-pyro-photocatalysis shows a further improvement in the CIP removal with a synergistic enhancement factor SF = 1.77. The enhanced piezo-pyro-photocatalysis is ascribed to the fact that the piezoelectric/pyroelectric polarization field facilitates the separation of photocarriers (particularly the bulk photocarriers). Experiment and theory were combined to deeply study the catalysis mechanism. Moreover, the influence of multiple parameters on the CIP elimination was investigated and analyzed by machine learning to establish the best prediction model.

Sunlight assisted highly efficient desorption of ammonia by redox graphene hybrid metal–organic framework photothermal conversion adsorbents

The capture, storage and release of NH3 play a pivotal role in sustainable energy applications. However, to simultaneously achieve high adsorption capacity and low energy desorption remains a challenge. In this work, a novel class of hybrid materials with photothermal conversion performance have been developed by doping redox graphene and metal–organic framework of MOF-303(Al). It is found that the optimized rGO@MOF-303(Al)-8% exhibits high NH3 uptake (17.0 mmol g−1) at 25.0 °C and 1.0 bar and exceptional photothermal conversion performance. Under the irradiation of simulated sunlight, its temperature can be raised to about 75 °C in 10 min. Even under direct natural sunlight irradiation, a stable equilibrium temperature of 53 °C may be achieved. Based on this excellent photothermal conversion performance, we investigated the desorption behavior of ammonia under visible light irradiation for the first time. We found that due to the breakdown of hydrogen bonds of NH3 and N-N, N–H sites of rGO@MOF-303(Al)-8% caused by the rapid rise of temperature, approximately 68% of NH3 could be effectively desorbed in 2-hour irradiation under ambient conditions. In addition, the optimized adsorbent demonstrated remarkable cycling stability. After undergoing 10 cycles, high adsorption capacity and efficient light-induced desorption of NH3 were still maintained Thus, the present study provides a novel concept for high-capacity adsorption and low-energy desorption of NH3 and other industrial gases.

Swallowed Embedding of Nanopetal-Rich Microflowers in Flexible Photocatalytic and Thermoresponsive Functional Composite Fibers.

Developing efficient catalysts to degrade pollutants in water is a very important way to alleviate water pollution. However, it is crucial but challenging to broaden the functions of conventional photocatalysts and improve their environmental adaptability. In this paper, Bi(Er3+/Yb3+)OBr/polyacrylonitrile (BOB-EY/PAN) composite fibers with a swallowed-embedded structure assembled with nanopetal-rich microflowers were designed and fabricated, integrating photocatalytic and temperature-monitoring functions simultaneously. Their unique structure brings a large specific surface area, and the doping of rare earth ions improves the separation efficiency of electron-hole pairs, which enhances the photocatalytic efficiency and endows the fibers with a temperature-monitoring function at the same time. Under simulated sunlight irradiation, the nanofibers show a maximum degradation efficiency of 99.2% for tetracycline hydrochloride (TC) with a degradation constant of K as high as 0.078 min-1. Based on the fluorescence intensity ratio (FIR), the two thermally coupled levels of Er3+ in the nanofibers, 2H11/2 and 4S3/2, provide real-time temperature feedback, displaying a maximum relative sensitivity as high as 0.0215 K-1 at 303 K. Dual-functional BOB-EY/PAN composite nanofibers show great potential for industrial wastewater disposition, providing solutions for wastewater purification in special scenarios.

Modulating the precursors of carbon nitride to boost local electron delocalization for H2O2 photosynthesis to remove oxytetracycline and its antibiotic resistant genes

Artificial H2O2 photosynthesis, one of the brightest strategies toward H2O2 production, is always restricted by the intrinsically charge migration behaviors and redox kinetics of photocatalysts. Herein, different precursors of carbon nitride (C3N4) with urea and melamine (Mel) are synthesized, where C3N4-Urea has more delocalized electrons due to its smaller size and thickness, compared with C3N4-Mel. Under simulated sunlight irradiation, these abundant delocalized electrons rapid reduce oxygen into H2O2, with the rate of 4.9 mmol g−1 h−1 and 2e- transfer selectivity of 98%. In addition, a self-photo-Fenton reaction system is constructed to remove oxytetracycline (OTC) pollutants and its antibiotic resistant genes (ARG) in water, with the degradation rate of 3.75 min−1 for OTC and 0.08 min−1 for tetC ARG. The current approach by modulating the precursors of C3N4 to boost the local electron delocalization offers a promising route for improving the efficiency of artificial H2O2 photosynthesis.

Molecular-scale investigation on the photochemical transformation of dissolved organic matter after immobilization by iron minerals with FT-ICR MS.

The interaction between dissolved organic matter (DOM) and iron minerals has a significant effect on its stabilization and preservation in the environment. In this study, iron minerals with different crystal forms (crystalline goethite and amorphous ferrihydrite) were selected to investigate the photochemical transformation process for DOM immobilized on iron minerals under simulated sunlight irradiation at the molecular scale with the help of Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed that a total of 7148 molecules were detected in alkaline-extractable sedimentary DOM, of which 38.8% and 36.2% were adsorbed by ferrihydrite and goethite, respectively, while there was no selectivity difference between the two iron minerals in terms of DOM adsorption. After simulated sunlight irradiation, the DOM adsorbed by goethite was significantly degraded (58.3%), in which the H/C ratio of the mineral-immobilized DOM increased and the O/C ratio decreased, and the photodegradation primarily involved DOM molecules with high Kendrick mass defect (KMD) values. The results confirmed that the iron mineral types play an important role in the transportation and transformation of DOM, which adds to the understanding of the fate of DOM in natural environments.

A novel CuAl2O4/MoS2/BaFe12O19 magnetic photocatalyst simultaneously coupling type I and Z-scheme heterojunctions for the sunlight-driven removal of tetracycline hydrochloride

A novel CuAl2O4/MoS2/BaFe12O19 photocatalyst is synthesized that simultaneously couples type I and Z-scheme heterojunctions and exhibits high photocatalytic activity for the degradation of TC under simulated sunlight irradiation.

Construction of a BiVO4/VS-MoS2 S-scheme heterojunction for efficient photocatalytic nitrogen fixation.

Photocatalytic nitrogen (N2) reduction to ammonia (NH3), adopting H2O as the electron source, suffers from low efficiency owing to the sluggish kinetics of N2 reduction and the requirement of a substantial thermodynamic driving force. Herein, we present a straightforward approach for the construction of an S-scheme heterojunction of BiVO4/VS-MoS2 to successfully achieve photocatalytic N2 fixation, which is manufactured by coupling an N2-activation component (VS-MoS2 nanosheet) and water-oxidation module (BiVO4 nanocrystal) through electrostatic self-assembly. The VS-MoS2 nanosheet, enriched with sulfur vacancies, plays a pivotal role in facilitating N2 adsorption and activation. Additionally, the construction of the S-scheme heterojunction enhances the driving force for water oxidation and improves charge separation. Under simulated sunlight irradiation (100 mW cm-2), BiVO4/VS-MoS2 exhibits efficient photocatalytic N2 reduction activity with H2O as the proton source, yielding NH3 at a rate of 132.8 μmol g-1 h-1, nearly 7 times higher than that of pure VS-MoS2. This study serves as a noteworthy example of efficient N2 reduction to NH3 under mild conditions.

Polymethylacrylic acid-induced fabrication of hollow hZrO2/g-C3N4 composite photocatalysts: study on solar photocatalytic performance and mechanism insight

Hollow hZrO2/g-C3N4 photocatalysts were developed to efficiently degrade MB and CIP under simulated sunlight irradiation and the mechanism was investigated.

Isomer engineering for deep understanding of aggregation-induced photothermal enhancement in conjugated systems.

Organic photothermal materials based on conjugated structures have significant potential applications in areas such as biomedical diagnosis, therapy, and energy conversion. Improving their photothermal conversion efficiency through molecular design is critical to promote their practical applications. Especially in similar structures, understanding how the position of heteroatoms affects the conversion efficiency is highly desirable. Herein, we prepared two isomeric small D-A molecules with different sulfur atom positions (TBP-MPA and i-TBP-MPA), which display strong and broad absorption in the UV-visible region due to their strong intramolecular charge transfer characteristics. Compared to i-TBP-MPA, TBP-MPA demonstrates aggregation-induced photothermal enhancement (AIPE). Under simulated sunlight (1 kW m-2) irradiation, the stable temperature of TBP-MPA powder reached 60 °C, significantly higher than the 50 °C achieved by i-TBP-MPA. Experimental and theoretical results indicate that the S⋯N non-covalent interactions in TBP-MPA impart a more rigid conjugated framework to the molecule, inducing ordered molecular stacking during aggregation. This ordered stacking provides additional non-radiative transition channels between TBP-MPA molecules, enhancing their photothermal performance in the aggregated state. Under 1 sun irradiation, TBP-MPA achieved a water evaporation rate of 1.0 kg m-2 h-1, surpassing i-TBP-MPA's rate of 0.92 kg m-2 h-1.