Simulated Solar Light Irradiation Research Articles

Natural iron-containing minerals catalyze the degradation of polypropylene microplastics: a route to self-remediation learnt from the environment.

Virgin and environmentally aged polypropylene (PP) micropowders (V-PP and E-PP, respectively) were used as reference microplastics (MPs) in comparative photo- and thermo-oxidative ageing experiments performed on their mixtures with a natural ferrous sand (NS) and with a metal-free silica sand (QS). The ferrous NS was found to catalyze the photo-oxidative degradation of V-PP after both UV and simulated solar light irradiation. The catalytic activity inthe V-PP/NSmixture was highlighted by the comparatively higher fraction of photo-oxidized PP extracted in dichloromethane, and the higher carbonyl index of the bulk polymer extracted with boiling xylene, when compared with theV-PP/QSmixture. Similarly, NS showed a catalytic effect on the thermal degradation (at T = 60°C) of E-PP. The results obtained indicate that, under suitable environmental conditions (in this case, an iron-containing sediment or soil matrix, combined with simulated solar irradiation), the degradation of some types of MPs could be much faster than anticipated. Given the widespread presence of iron minerals (including the magnetite and iron-rich serpentine found in NS) in both coastal and mainland soils and sediments, a higher than expected resilience of the environment to the contamination by this class of pollutants is anticipated, and possible routes to remediation of polluted natural environments by eco-compatible iron-based minerals are envisaged.

Elevated symmetric supercapacitor performance and simulated solar light-functioning H2O2 production using single-step fabricated 2D/2D NiAl-based LDH/CoNi-based MOF nanohybrid

Combining photocatalytic hydrogen peroxide (H2O2) production with supercapacitors offers a synergistic solution to address both solar-driven catalysis and energy storage challenges. In this connection, this study explored a novel, one-step thermal impregnation method for synthesizing a high-performance nanohybrid material. The unique combination of nickel-aluminum layered double hydroxides (NiAl-L) and Co/Ni-based metal-organic framework (CoNi-M) synergistically enhances electrochemical performance, leading to improved energy storage capacity. Interestingly, the NiAl-L/CoNi-M nanohybrid heterojunction exhibits remarkable characteristics in a three-electrode system, achieving an impressive specific capacitance of 2672.3 Fg–1 at 1 A g–1. It also demonstrates outstanding cyclic stability, retaining 93.6% of its capacity even after 5000 galvanostatic charge-discharge (GCD) cycles. Moreover, the symmetrical supercapacitor device made of NiAl-L/CoNi-M demonstrates outstanding performance, sustaining 90.9% capacity after 5000 GCD cycles, with a specific capacitance of 309.7 Fg–1 at 1 Ag–1 and a high energy density of 43 WhKg–1. Additionally, the synergistic combination of NiAl-L and CoNi-M enhances the photocatalytic performance, achieving an H2O2 evolution rate of 334.86 μmol L–1 h–1 under simulated solar light irradiation. This rate is 2.61, 3.81, and 5.81 times greater than that of pure CoNi-M, Co-M, and NiAl-L, respectively, highlighting the potential of NiAl-L/CoNi-M nanohybrid for sustainable energy application.

Selective Photocatalytic CO2 Reduction Through Plasmonic Z‐Scheme Ag‐Bi2O3‐ZnO Heterostructures

AbstractCombination of plasmonic noble metal with semiconductors offers a promising and potential solar energy harvesting and conversion route. Herein, plasmonic Z‐scheme Ag‐Bi2O3‐ZnO (AgBZ) heterostructure is designed and synthesized via solution combustion and photo‐deposition method. Metallic Ag nanoparticles (NPs) were deposited over Bi2O3‐ZnO heterostructure; thus, they exhibit strong visible light absorption owing to surface plasmon resonance (SPR). The photocatalytic efficiency of the synthesized catalysts is investigated by the photocatalytic CO2 reduction to fuels under simulated solar light irradiation. The present system has shown an outstanding photocatalytic CO2 reduction and excellent selectivity of CO. The evolved rate of CO fuel, the amount of CO produced per unit time, over optimized Ag‐Bi2O3‐ZnO (3AgBZ) heterostructures was (96.74 μmol g−1/h) which was approximately 12 times larger than that of Bi2O3‐ZnO (0AgBZ) and 49‐fold than the quantity of evolved CO fuels over pure ZnO photocatalyst. The percentage of evolved CO to CH4 fuels over optimized Ag‐Bi2O3‐ZnO (3AgBZ) heterostructures was about 50 : 1compared to that of 2 : 3 over Bi2O3‐ZnO (0AgBZ). The great improvement and the high selectivity would be ascribed to the synergistic effect of metallic surface plasmon resonance and the Z‐scheme charges transfer system. This work would open a window to construct a single photocatalyst with different charge separation systems and excellent CO2 reduction selectivity. Finally, the mechanism for the enhanced photocatalytic performance by the synergistic effect was described and discussed.

0D/1D CuO-Cu2O/ZnO p-n heterojunction with high photocatalytic activity for the degradation of dyes and Naproxen

The development of highly active photocatalysts with broad spectrum response is of paramount importance for photocatalytic applications. Herein, heterostructured CuO-Cu2O/ZnO photocatalysts were prepared in a single step and under mild conditions using a photodeposition process which allows to deposit CuO-Cu2O particles with an average size of ca. 2.4 nm on the surface of ZnO nanorods. The p-n heterojunction built between CuO-Cu2O and ZnO allows to increase both the visible light response of the photocatalyst and the charge separation. The CuO-Cu2O(10%)/ZnO catalyst exhibits the highest activity for the degradation of dyes (Rhodamine B and Remazol Brilliant Blue R) and of Naproxen under simulated solar light irradiation. Based on scavenging experiments, holes, superoxide radicals O2●- and singlet oxygen 1O2 are the dominant species involved in the photocatalytic degradation and a mechanism is proposed. Due to its high stability and photocatalytic performance in various water matrices, the CuO-Cu2O(10%)/ZnO nanohybrid is of high potential for the large scale remediation of organic pollutants in wastewater.

Conjugated Polymer/Recombinant Escherichia coli Biohybrid Systems for Photobiocatalytic Hydrogen Production.

Biohybrid photocatalysts are composite materials that combine the efficient light-absorbing properties of synthetic materials with the highly evolved metabolic pathways and self-repair mechanisms of biological systems. Here, we show the potential of conjugated polymers as photosensitizers in biohybrid systems by combining a series of polymer nanoparticles with engineered Escherichia coli cells. Under simulated solar light irradiation, the biohybrid system consisting of fluorene/dibenzo [b,d]thiophene sulfone copolymer (LP41) and recombinant E. coli (i.e., a LP41/HydA BL21 biohybrid) shows a sacrificial hydrogen evolution rate of 3.442 mmol g-1 h-1 (normalized to polymer amount). It is over 30 times higher than the polymer photocatalyst alone (0.105 mmol g-1 h-1), while no detectable hydrogen was generated from the E. coli cells alone, demonstrating the strong synergy between the polymer nanoparticles and bacterial cells. The differences in the physical interactions between synthetic materials and microorganisms, as well as redox energy level alignment, elucidate the trends in photochemical activity. Our results suggest that organic semiconductors may offer advantages, such as solution processability, low toxicity, and more tunable surface interactions with the biological components over inorganic materials.

In-situ construct CuInS2/Bi/Bi2MoO6 S-scheme/Schottky dual heterojunctions catalyst for enhanced photocatalytic degradation of diclofenac sodium

In this paper, the S-scheme/Schottky heterojunction photocatalyst (CuInS2/Bi/Bi2MoO6, CIS/Bi/BMO) was successfully constructed via a facile in-situ solvothermal method, aimed at enhancing its photocatalytic performance. The results of the study on the photocatalytic degradation of diclofenac sodium (DCF) under simulated solar light irradiation revealed that the as-prepared composite exhibited remarkable catalytic efficiency in comparison to the pristine Bi2MoO6 and CuInS2. The plasmonic bismuth (Bi) was formed during the solvothermal process. Subsequently, CuInS2 and Bi were grown on the surface of Bi2MoO6 leading to forming CIS/BMO S-scheme heterojunction, along with a Schottky junction between Bi and Bi2MoO6. The use of ethylene glycol as a support was the main reason for the significant improvement in photocatalytic efficiency in the degradation of DCF. Moreover, the probable photocatalytic mechanisms for the degradation of DCF had been proposed based on the active species quenching experiments. The eleven degradation products were detected by HPLC-MS, and the degradation reaction pathway of DCF was deduced. Additionally, the CIS/Bi/BMO photocatalyst exhibited a consistently high removal rate after four cycles. This study proposes a new strategy for designing efficient S-scheme/Schottky heterojunction photocatalysts for solar energy conversion.

Thermal treatment impact on the evolution of active phases in layered double hydroxide-based ZnCr photocatalysts: Photodegradation and antibacterial performance

Abstract This study investigated the influence of thermal treatment on the photocatalytic performance of ZnCr layered double hydroxide-based mixed metal oxides in the degradation of methylene blue and brilliant cresyl blue organic dyes under simulated solar light irradiation. The photocatalysts were synthesized using a simple coprecipitation method and subjected to thermal treatment at temperatures ranging from 100°C to 900°C. Additionally, the study explored the antibacterial activity against Escherichia coli and Staphylococcus aureus using a novel antibacterial experimental setup. It not only involved the introduction of ZnCr samples into BioPeptone/prepared cell suspension to enhance photocatalyst–bacteria cell contact but also included research on antibacterial activity induced by solar irradiation and also in the absence of light, providing crucial insights into photocatalytic antibacterial activity of ZnCr photocatalysts. Despite satisfactory efficiencies observed for all thermally treated ZnCr samples (removal efficiency ranging from 40% to 90%), ZnCr 900 (thermally treated at 900°C) exhibited exceptional performance, achieving nearly 100% removal efficiency and complete growth inhibition for both bacteria. Integrating these findings with structural and textural characterization data, as well as kinetic studies, our comprehensive analysis enhances the understanding of structure-dependent photocatalytic activities. These insights open possibilities for the application of ZnCr photocatalysts in water purification and environmental remediation.

Efficient peracetic acid activation by high-index facets of Cu2O under simulated solar light: The crucial role of uncoordinated Cu atoms

Tuning the facets of transition-metal catalysts to achieve effective micropollutant removal via peracetic acid (PAA) activation is a promising approach. However, within this process, the correlation between PAA activation and the atomic arrangement of the exposed facets is ambiguous. Herein, we present a comprehensive study wherein a series of Cu2O materials, with typical high-index facets ({211}, {311}, and {332}) and low-index facets ({100}, {110}, and {111}), were synthesized. These materials were used to investigate facet-dependent PAA activation for tetracycline (TC) degradation under simulated solar light irradiation. The results demonstrate that Cu2O with high-index {332} facets exhibit the optimal TC degradation (96.65 % within 20 min), and its kobs values are 1.52 and 2.01 times those of Cu2O with {311} and {211} facets, respectively. Detailed identification of the active species proved that •OH, 1O2, and the electron transfer process induced by the reactive Cu (I)–PAA* complexes were involved in TC degradation. In contrast to the {211} and {311} facets, PAA demonstrated a heightened tendency for adsorption and activation into active species on the {332} facets because of the denser uncoordinated Cu atoms. In addition, the facet heterojunction composed of {332} and {100} facets was conducive to the separation of photogenerated electron-hole pairs and charge migration, thus promoting the Cu(II)/Cu(I) cycle. In the practical applicability evaluation, Cu2O with {332} facets effectively removed multiple pollutants as well as actual pharmaceutical wastewater. This study provides a novel strategy for PAA activation by regulating the exposed facets of the catalyst.

Tailoring MOF-5 Photocatalysts: Low-Temperature Synthesis and Solvent Variations for Enhanced Performance in Dye Degradation

Metal-organic frameworks (MOFs) are emerging as pivotal porous crystalline materials with diverse applications. Typically, MOFs are synthesized using solvothermal techniques at high temperatures and pressures. In this study, a novel approach was employed to synthesize zinc-based MOFs, specifically MOF-5, at low temperatures (up to 50 °C) via chemical mixing at standard pressures. Varying the temperature and solvents, N-methyl-2-pyrrolidone (NMP) and N,N-dimethylformamide (DMF), in the chemical mixing process, the highest yield of the material was observed with DMF at 50 °C (M1). Two additional samples, M2 and M3, are synthesized at room temperature using DMF and NMP, respectively. Despite similarities in XRD, Raman, and FTIR analyses confirming successful MOF-5 formation, noticeable differences in sample morphology arise due to distinct synthesis conditions, particularly solvent and temperature variations. The MOF-5 samples exhibit UV absorption with varying band gaps. Notably, when employed as photocatalysts for organic dye (methylene blue) degradation, M2 outperforms others, achieving an impressive 85% degradation under simulated solar light irradiation. This work underscores the significance of tuning MOF photocatalyst properties through tailored synthesis routes, recognizing the profound impact of morphology and elemental composition on enhancing photocatalytic dye degradation performance. Copyright © 2024 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A facile method for boosting the graphitic carbon nitride's photocatalytic activity based on 0D/2D S-scheme heterojunction nanocomposite architecture

Graphitic carbon nitride (g-C3N4) has received significant interest as a metal-free photocatalyst. The S-scheme photocatalytic system has great potential to improve the charge separation in semiconductor photocatalysts. In this study, we have fabricated non-toxic and low-cost photocatalytic nanocomposites of 0D/2D S-scheme heterojunction composed of iron oxide and graphitic carbon nitride by a facile method. The developed facile method provides a sustainable way with a high atom economy to further enhance the photocatalytic performance of exfoliated g-C3N4. The 0D-iron oxide/2D-C3N4 exhibited nearly 10 times better than bulk g-C3N4 and almost 60 % better than exfoliated g-C3N4 under simulated solar light irradiation. The experimental results demonstrated that the effective charge-carrier mechanism led to an improved generation of reactive oxygen species (ROSs), resulting in an impressive photocatalytic performance. A serial photocatalytic test was also conducted to understand photocatalytic reaction mechanisms with various scavengers.

Platinum-Modified Rod-like Titania Mesocrystals with Enhanced Photocatalytic Activity

Photocatalysis is considered as an environmentally friendly method for both solar energy conversion and environmental purification of water, wastewater, air, and surfaces. Among various photocatalytic materials, titania is still the most widely investigated and applied, but more efforts must be carried out considering the synthesis of highly efficient photocatalysts for multifarious applications. It is thought that nanoengineering design of titania morphology might be the best solution. Accordingly, here, titania mesocrystals, assembled from crystallographically oriented nanocrystals, have been synthesized by an easy, cheap, and “green” solvothermal method (without the use of surfactants and templates), followed by simple annealing. The obtained materials have been characterized by various methods, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and diffuse reflectance spectroscopy (DRS). It has been found that the as-obtained photocatalysts exhibit a unique nanorod-like subunit structure with excellent crystalline and surface properties. However, pristine titania is hardly active for a hydrogen evolution reaction, and thus additional modification has been performed by platinum photodeposition (and silver as a reference). Indeed, the modification with only 2 wt% of noble metals results in a significant enhancement in activity, i.e., ca. 75 and 550 times by silver- and platinum-modified samples, respectively, reaching the corresponding reaction rates of 37 μmol h−1 and 276 μmol h−1. Additionally, titania mesocrystals exhibit high oxidation power under simulated solar light irradiation for the degradation of antibiotics within the tetracycline group (tetracycline (TC), ciprofloxacin (CIP), norfloxacin (NOR) and oxytetracycline hydrochloride (OTC)). It has been found that both experimental results and the density functional theory (DFT) calculations confirm the high ability of titania mesocrystals for oxidative decomposition of tetracycline antibiotics.

Simulated solar light-driven degradation of micropollutant in water by biochar-based metal-free catalyst: Regulation strategies for electronic structure and morphology engineering

The biochar/h-BN/g-C3N4 (BNC) composite photocatalyst with a spherical sheet cluster structure, was successfully synthesized. Under simulated solar light irradiation, the photocatalytic degradation rate of reactive red 120 by BNC was 87.94 % within 90 min, corresponding to a 3.57-fold higher kinetic constant than that of g-C3N4. The band structure and electron transfer path in BNC were determined using characterizations and density functional theory (DFT) calculations, confirming a type II heterojunction forming. The attraction of h-BN to h+ by electrostatic interaction and biochar's capacity for both electron transfer and storage were confirmed. Doping of biochar was also found to enhance light absorption and provide O vacancy. The existence of piezoelectric effect assisted the movement of photogenerated carriers to the material surface. In the system, the main active oxidation species were h+ and ·O2–. By calculating optical characteristics, the practical activity of photocatalysts is evaluated. Results indicated that the optimal dosage of BNC was 0.5 g/L in the planar reactor, corresponding to an optical thickness of 2.61 calculated by the six-flux radiation absorption–scattering model (SFM). Biochar doping was found to enhance light absorption. A novel photocatalytic mechanism was proposed for promising matel-free BNC.

Ultrafast photosensitized degradation of xanthates by using methylene blue as photosensitizer under simulated and natural solar light irradiation: Operational parameters, mechanism and toxicity evolution

Xanthates have attracted considerable attention due to their broad applications in mineral flotation process and unique natures including environmental persistence and toxicity. This study proposed an innovative approach for the efficient xanthates treatment from mineral processing wastewater. Methylene blue (MB) with good water solubility and strong light absorption in visible range was used as the photosensitizer to degrade potassium ethyl xanthate (PEX) under homogeneous conditions. MB, even at a very low concentration (0.5 mg/L), was found to rapidly remove PEX in only 10 min whether under simulated or natural solar light irradiation. Besides, the influences of various operational parameters, including photosensitizer dosage, PEX concentration, pH, light intensity, common ions, and water source on the photosensitized oxidation process was evaluated and analyzed. The possible degradation path of PEX was investigated depending on the intermediates detected by Liquid chromatography-mass spectrometry (LC-MS), and the photosensitized degradation mechanism was further speculated and validated by the radicals quenching experiments and electron paramagnetic resonance (EPR) spectroscopy. Furthermore, the toxicity of PEX was assessed against Bullfrog tadpole and Lemna minor, and it was found to be greatly reduced after treating with MB photosensitization. Overall, it is the first time that MB is proved to be an outstanding candidate for actual flotation wastewater treatment, providing a more efficient, economical and greener alternative to conventional methods.

Synthesis and photocatalytic activity of BiOI particles: An efficient visible-light-driven degradation of organic pollutants in aqueous environments

Bismuth oxyiodide (BiOI) particles were successfully fabricated through solvothermal activation using bismuth (III) nitrate pentahydrate and potassium iodide as precursors. The photocatalytic activities of BiOI were investigated under the influence of synthesis temperature (120–200 °C) with a fixed duration of 12 h. The physical-chemical properties of the samples were systematically investigated using X-ray diffraction, scanning electron microscopy, N2-sorption isotherm techniques, and pH of the point of zero charge (pHpzc). The prepared BiOI exhibited a single phase with a non-uniform 2D morphology with different sizes, an average crystallite size of 30 nm, and a BET surface area of 20.71 m²g−1. The zero-point charge was determined to be 7.7. The photocatalytic performance under simulated solar light irradiation was investigated by examining the effects of dye initial concentration, catalyst dose, and dye pH. Remarkably, BiOI synthesized at 160 °C demonstrated an impressive 85% removal efficiency of 10 ppm MO (methyl orange) at normal pH levels (pH 6.8) within 120 min under visible light irradiation, along with the highest rate constant of 0.01418 min−1. The quenching effects of different scavengers indicate the significant role of reactive O2•– and a minor role of hVB+ and •OHads in the photocatalytic process. These findings underscore the potential of BiOI particles as efficient photocatalysts for environmental applications, particularly in the degradation of organic pollutants in water using solar light irradiation.

Performance of a Solar-Driven Photocatalytic Membrane Reactor for Municipal Wastewater Treatment

The increasing demand for efficient wastewater treatment technologies, driven by global population growth and industrialisation, highlights the necessity for advanced, reliable solutions. This study investigated the efficacy of a slurry photocatalytic membrane reactor (PMR) for the advanced removal of organic pollutants, quantified via chemical oxygen demand (COD), under natural and simulated solar light irradiation. Employing two variants of iron-doped titania as photocatalysts and a polysulfone-based polymeric membrane for the separation process, the investigation showcased COD removal efficiencies ranging from 66–85% under simulated solar light to 52–81% under natural sunlight over a 7 h irradiation period. The overall PMR system demonstrated COD removal efficiencies of 84–95%. The results confirmed the enhanced photocatalytic activity afforded by iron doping and establish solar-powered slurry PMRs as an effective, low-energy, and environmentally friendly alternative for the advanced treatment of municipal wastewater, with the research providing valuable insights into sustainable water management practices.

Construction of ternary Ni2P/ZIF-8/CdS composite for efficient photocatalytic hydrogen production and pollutant degradation: Accelerating separation of photogenerated carriers

Constructing heterojunctions for efficient charge separation is a crucial method to boost photocatalytic activity. Initially, zeolitic imidazolate framework-8 (ZIF-8) nanoparticles were synthesized in situ on the surface of cadmium sulfide (CdS) nanoflowers, creating a novel ZIF-8/CdS composite material. Subsequently, a ternary Ni2P/ZIF-8/CdS composite was fabricated for photocatalytic hydrogen production and pollution reduction. The optimally obtained Ni2P/ZIF-8/CdS composites showed excellent photocatalytic efficiency and structural stability under simulated solar light irradiation. The hydrogen production rate of Ni2P/ZIF-8/CdS composite was 21.05 mmol h−1 g−1. Additionally, Ni2P/ZIF-8/CdS degraded malachite green (MG) with 99% efficiency. It was found that the proximity of sulfides to porous MOFs accelerated the separation of light-induced charges. Nickel phosphide (Ni2P) played a vital role in photocatalytic reactions, serving the dual function of capturing photogenerated electrons and accelerating separation of photogenerated carriers. Mechanistic and characterization studies revealed that constructing heterojunction between CdS and ZIF-8 could promote photogenerated carrier transport, enhance the separation efficiency of photogenerated carriers, ultimately improving the photocatalytic hydrogen production performance and degradation efficiency.

Design of novel solar-light-induced KBi6O9I/Ag–AgVO3 nanophotocatalyst with Ag-bridged Z-scheme charge carriers separation and boosted photo-elimination of hospital effluents

In this research, a novel solar-light-induced KBi6O9I/Ag–AgVO3 nanophotocatalyst with an Ag-bridged Z-scheme structure has been designed and synthesized through a sonochemical method to photo-degrade antibiotic hospital contaminants under simulated solar-light irradiation. Synthesized nanophotocatalysts with varying KBi6O9I to Ag–AgVO3 weight ratios underwent N2 Adsorption-Desorption, XRD, TEM, UV–Vis DRS, FESEM and PL analyses. The Ag-bridged Z-scheme-structured KBi6O9I/Ag–AgVO3 (1:1) nanophotocatalyst, demonstrated broad light absorption within the solar-light spectrum and showcased effective photocatalytic efficacy in degrading tetracycline antibiotic (88.3% and 83.5% removal for 25 and 50 mg/L, respectively, after 120 min). This performance outperformed other composited photocatalysts, as well as pure Ag–AgVO3 and KBi6O9I photocatalysts. The enhanced degradation efficiency of the KBi6O9I/Ag–AgVO3 (1:1) composite can be ascribed to the synergistic interaction of various elements. These include the surface plasmon resonance impact of silver nanoparticles, their pronounced sensitivity to solar irradiation, and the Z-scheme heterojunction configuration. Collectively, these factors work together to minimize the recombination rate of photoinduced electron-hole pairs, thereby amplifying the efficacy of photodegradation. Furthermore, the KBi6O9I/Ag–AgVO3 (1:1) composite photocatalyst displayed sustained pollutants elimination performance even after undergoing four consecutive cycles.

S-scheme homojunction and activate site engineering over TiO2 for highly efficient photocatalytic nitrogen fixation

The presence of efficient catalytic active sites and an ample supply of electrons are the two indispensable factors for achieving photocatalytic nitrogen fixation. Herein, the Fe-doped TiO2 S-scheme anatase/rutile homojunction (F-T-A/R) was synthesized as a brilliant photocatalyst for photocatalytic nitrogen fixation from N2 to NH3 under ambient atmosphere. The optimized F-T-A/R photocatalyst (A/R = 98:2, Fe-2 wt%) exhibits an unprecedented NH3 generation rate of 358 μmol gcat-1h−1 in water solvent and under simulated solar light irradiation. Experimental and theoretical studies reveal that the constructed S-scheme homojunction in F-T-A/R is conducive to fluent charge separation and adequate supply of electrons on rutile with higher nitrogen fixing activity, while the tuned local electronic structure of oxygen vacancy with Fe doping is engineered to strengthen active sites, synergistically enhancing the photocatalytic nitrogen fixation.

S-scheme Bi12TiO20/Bi4Ti3O12 heterojunction immobilized on 3D-printed support as a monolithic photocatalyst for NO removal

Photocatalysis is recognized as one of the most promising techniques for environment purification. However, the inconvenient recovery of powder photocatalysts significantly impeded their practical applications. Immobilization of the photocatalysts on supports to form monolithic photocatalysts is an effective method to solve this problem. Herein, a monolithic photocatalyst Bi12TiO20/Bi4Ti3O12/SiOC is fabricated by growing optimal Bi12TiO20/Bi4Ti3O12 S-scheme heterojunction onto 3D-printed porous SiOC support. On one side, S-scheme heterojunction facilitates the separation of photoinduced electrons and holes while retaining their strong redox ability. On the other side, the porous structure favors mass transport and improves light harvesting by reflecting the light several times. Under simulated solar light irradiation, the NO removal efficiency of the monolithic photocatalyst Bi12TiO20/Bi4Ti3O12/SiOC is 16.4 %. Furthermore, the composite has good stability and reusability, suggesting its great potential in practical application. The possible photocatalytic mechanism is proposed according to systematic experiments and density functional theory (DFT). This work provides a rational reference for constructing efficient photocatalysts for environmental purification.

Insightful properties-performance study of Ti–Cu–O heterojunction sonochemically embedded in mesoporous silica matrix for efficient tetracycline adsorption and photodegradation: RSM and ANN-based modeling and optimization

This study aims to provide a comprehensive evaluation of the photocatalytic properties and performance of the Cu–Ti–O heterojunction sonochemically embedded in the mesoporous silica matrix. Various characterization analyses and adsorption/photodegradation experiments were performed to assess the potential of the sample for tetracycline (TC) removal. The characterization results indicated that sonication contributes to better dispersion of Ti–Cu–O species, resulting in more uniform particle sizes, stronger semiconductors-silica interaction, and less agglomeration. Furthermore, sonication significantly affected the optical nanocomposite features, leading to an improvement in charge carrier separation and a decrease in the band gap of Ti–Cu–Si (S) by approximately 2.6 eV. Based on the textural results, the ultrasound microjets increased the surface area and pore volume, which facilitate mass transfer and provide suitable adsorption sites for TC molecules. Accordingly, Cu–Ti–Si (S) demonstrated higher adsorption capacity (0.051 g TC/g adsorbent) and eliminated TC significantly faster (0.0054 L.mg−1.min−1) than a non-sonicated sample during 120 min of irradiation, resulting in 2.84 times improvement in the constant rate. In addition, experimental results were accurately modeled using a central composite design in combination with response surface methodology (RSM) and artificial neural networks (ANN) to predict and optimize TC photodegradation. Both RSM and ANN models revealed excellent predictability for TC degradation efficiency, with R2 = 99.47 and 99.71%, respectively. At optimal operational conditions (CTC = 20 ppm, photocatalyst dosage = 1.15 g.L−1, pH = 9, and irradiation time = 100 min), more than 95% and 87% of TC were degraded within the UV (375 W) and simulated solar light (400 W) irradiation periods, respectively. It was observed that the Cu–Ti–Si (S) nanocomposite maintained remarkable stability after four cycles with only a negligible 3% loss of activity, owing to the superior interaction between the bimetallic heterojunction and the silica matrix.