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To address the global challenge posed by excessive carbon dioxide emissions, our research pioneers the transformation of CO2 into valuable hydrocarbon fuels. Central to this approach is the innovation of photocatalysts, engineered to exhibit exceptional photoresponse characteristics. In this research, the CsBr@CuBr2 photocatalyst was innovatively synthesized through a straightforward and effective one-pot method. The catalyst displayed remarkable efficacy, achieving a CO2 photoreduction rate of 201.47 µmol g-1 within just 4 h. The incorporation of CsBr into CuBr2 effectively captures excited-state electrons, thereby significantly enhancing charge separation efficiency. Utilizing in situ DRIFTS and DFT theoretical analysis, the experiment reveals the complex process of CO2 photoreduction to CO. The results of this experiment provide breakthrough insights for the systematic design of metal bromide heterostructures, which possess robust CO2 adsorption/activation potential and notable stability.
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Photocatalysis, as a sustainable and environmentally friendly green technology, has garnered widespread recognition and application across various fields. Especially its potential in environmental disinfection has been highly valued by researchers. This study commences with foundational research on photocatalytic disinfection technology and provides a comprehensive overview of its current developmental status. It elucidates the complexity of the interface reaction mechanism between photocatalysts and microorganisms, providing valuable insights from the perspectives of materials and microorganisms. This study reviews the latest design and modification strategies (Build heterojunction, defect engineering, and heteroatom doping) for photocatalysts in environmental disinfection. Moreover, this study investigates the research focuses and links in constructing photocatalytic disinfection systems, including photochemical reactors, light sources, and material immobilization technologies. It studies the complex challenges and influencing factors generated by different environmental media during the disinfection process. Simultaneously, a comprehensive review extensively covers the research status of photocatalytic disinfection concerning bacteria, fungi, and viruses. It reveals the observable efficiency differences caused by the microstructure of microorganisms during photocatalytic reactions. Based on these influencing factors, the economy and effectiveness of photocatalytic disinfection systems are analyzed and discussed. Finally, this study summarizes the current application status of photocatalytic disinfection products. The challenges faced by the synthesis and application of future photocatalysts are proposed, and the future development in this field is discussed. The potential for research and innovation has been further emphasized, with the core on improving efficiency, reducing costs, and strengthening the practical application of photocatalysis in environmental disinfection.
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Bactérias , Desinfecção , CatáliseRESUMO
The nitrogen-deficient graphitic carbon nitride (g-C3 N4 ) has been prepared, a new excited state absorption (ESA) up-conversion mode is discovered, which is directly induced by structural defects, showing distinct chemical characteristics from those based on lanthanide ions and triplet states chromophores. The abundant N2C vacancies in g-C3 N4 nanosheets work as the crucial intermediate excitation states, which lead to g-C3 N4 upconverted emitting at the wavelength of 436â nm excited by the light with the wavelength of 800â nm. This process is proven to proceed via a two-photon involved ESA mode with a breakthrough quantum efficiency of 0.64 %. Further, we combine N2C vacancies enriched g-C3 N4 with In2 S3 and CdS, and successfully achieved an infrared light driven photocatalytic reactions. These findings offered a new family of up-conversion materials; more semiconductors with various structural defects are potential complementary members.
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In this work, the modulation of activity and selectivity via photoreduction of carbon dioxide under simulated sunlight was achieved by treating P25 and P25/Pt NPs with KOH. It found that KOH treatment could significantly improve the overall conversion efficiency and switch the selectivity for CO. Photoelectric characterizations and CO2 -TPD demonstrated that the synergistic effect of K+ and OH- accelerated the separation and migration of photogenerated charges, and also improved CO2 adsorption level. Significantly, the K ions could act as active sites for CO2 adsorption and further activation. In situ FTIR measurements and DFT calculations confirmed that K+ enhanced the charge density of adjacent atoms and stabilize CO* groups, reducing the reaction energy barrier and inducing the switching of original CH4 to CO, which played a selective regulatory role. This study provides insights into the photocatalytic activity and selectivity of alkali-treated photocatalysts and facilitates the design of efficient and product-specific photocatalysis.
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Utilizing reactive oxygen species (ROS), which are generated by the activation of molecular oxygen (O2) in oxidation reaction, is a promising method for pollutant degradation. However, it is limited by the commonly low efficiency of O2 activation and carrier separation. Herein, as a model system, Ag cocatalyst and Cl doping modified g-C3N4 (Ag/Cl-CN) was constructed to improve the ability of O2 activation. Results showed that Ag/Cl-CN could effectively convert more O2 into ROS than pristine g-C3N4 (CN), and individually decorated CN (Ag-CN and Cl-CN). A series of experiments and DFT calculations revealed that the deposition of Ag could promote charge separation resulting in more charges accumulated around O2 and the introduction of Cl led to a stronger adsorption capacity for O2. Therefore, due to the synergistic effect of Ag cocatalyst and Cl dopant, Ag/Cl-CN generated higher concentrations of O2- and displayed much better activity for photocatalytic degradation of tetracycline (TC) than CN, Ag-CN and Cl-CN.
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Poluentes Ambientais , Luz , Fotólise , Espécies Reativas de Oxigênio , Catálise , Tetraciclina , Antibacterianos/farmacologia , OxigênioRESUMO
To address the environmental crisis caused by excessive emissions of CO2 , the development of effective photocatalysts for the conversion of CO2 into chemicals has emerged as one of the most promising strategies. Herein, beyond those well-studied materials, a rare-earth sulfide-based nanocrystal NaCeS2 is fabricated and investigated for efficient and selective conversion of CO2 into CO, where the role of Ce ions is crucial. Firstly, the hybridization of Ce 4f and Ce 5d orbitals contributes to the photoresponsive band structure of NaCeS2 . Secondly, due to the charge rearrangement supplied by the incompletely filled 4f orbitals of Ce ions, NaCeS2 exhibits excellent charge separation efficiency and CO2 adsorption affinity, reducing the energy barrier for the conversion from CO2 to CO. Moreover, a NaCeS2 -MoS2 heterostructure is also designed to further boost the electron transfer from the Mo site to the Ce site, which results in an improvement of the catalytic reduction yield from 7.24 to 23.42 µmol g-1 within 9 h (both better than TiO2 controls). This work offers a platform for the development of rare-earth-based photocatalysts for CO2 conversion.
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For single-atom (SA)-based catalysis, it is urgent to understand the nature and dynamic evolution of SA active sites during the reactions. In this work, an example of Pt SA-Zn0.5 Cd0.5 S (Pt SA-ZCS) is found to display interesting phenomena when facing the Brownian collision of ions in aqueous photocatalysis. Via synchrotron radiation, surface techniques, microscopy, and theory calculations, the results show that two kinds of Pt sites exist: PtZn-sub -S3 (Pt substituting the Zn site) and Ptads -S2 (Pt adsorbing on the surface). In Na2 S, the S2- can coordinate with Pt atoms and peel them from the Ptads -S2 sites, but leaves more stable PtZn-sub -S3 sites, bringing a low but stable catalytic activity (19.40 mmol g-1 h-1 ). Meanwhile, in ascorbic acid, the ascorbic acid ions show less complex ability with Pt atoms, but can decrease the migration barrier of Ptads -S2 sites (67.18 down to 35.96 mmol g-1 h-1 , 52.03% drop after 6 h). Therefore, the Ptads -S2 sites gradually aggregate into nanoclusters, bringing a high but decayed catalytic activity. Moreover, a Pt SA-ZCS-Sulfur composite is designed mainly covered by PtZn-sub -S3 sites accordingly (max: 79.09 mmol g-1 h-1 , 5% drop after 6 h and QE: 14.0% at 420 nm), showing a beneficial strategy "from mechanism to design principle."
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A single-atomic-site Cu catalyst (SAS-Cu) supported on carbon nitride (CN) material was synthesized by a pyrolyzing coordinated polymer (PCP) strategy. The introduction of a single-atomic Cu site improved the charge transfer and separation efficiency. The reaction rate constant of SAS-Cu1.0 is 4.5 times higher than that of CN. Under the condition of only 0.1 mM sodium persulfate (PS) and 0.1 g/L catalyst, the removal rate of tetracycline (TC) reached 82.5% after 30 min of LED illumination, which greatly improved the utilization of oxidant. Mechanistic analysis shows that there are free radical (â¢O2-, SO4â¢-, â¢OH) and nonradical pathways (1O2 and direct electron transfer) in the system, and they have synergistic effect. Density functional theory (DFT) calculations show that SAS-Cu1.0 can optimize the adsorption and activation of PS. This work illustrates the application value of SAC combined with activated persulfate and the low energy consumption of the LED light in the field of environment, which provides a new strategy for reducing the salinity and treatment cost of treated water.
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Antibacterianos , Tetraciclina , Adsorção , Catálise , ÁguaRESUMO
Solar water splitting is regarded as holding great potential for clean fuels production. However, the efficiency of charge separation/transfer of photocatalysts is still too low for industrial application. This paper describes the synthesis of a Pt-Au binary single-site loaded g-C3N4 nanosheet photocatalyst inspired by the concept of the dipole. The existent larger charge imbalance greatly enhanced the localized molecular dipoles over adjacent Pt-Au sites in contrast to the unary counterparts. The superposition of molecular dipoles then further strengthened the internal electric field and thus promoted the charge transportation dynamics. In the modeling photocatalytic hydrogen evolution, the optimal Pt-Au binary site photocatalysts (0.25% loading) showed 4.9- and 2.3-fold enhancement of performance compared with their Pt and Au single-site counterparts, respectively. In addition, the reaction barrier over the Pt-Au binary sites was lowered, promoting the hydrogen evolution process. This work offers a valuable strategy for improving photocatalytic charge transportation dynamics by constructing polynary single sites.
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Photocatalytic activation of molecular oxygen (O2) is a promising way in oxidative degradation of organic pollutants. However, it suffers from low efficiency mainly due to the limited active sites for O2 activation over traditional photocatalysts. Therefore, we established a single atomic Ag-g-C3N4 (SAACN) catalyst with 10 wt% loading of Ag single sites for boosting the O2 activation during the degradation of tetracycline (TC), and 10 wt% loading of nanoparticle Ag-g-C3N4 (NPACN) was studied as a comparison. When using SAACN, the accumulative concentration of superoxide (â¢O2-), hydroxyl radical (â¢OH), singlet oxygen (1O2) reached up to 0.66, 0.19, 0.33 mmol L-1h-1, respectively, within 120 min, 11.7, 5.7 and 4.9 times compared with those using NPACN, representing 17.24% of dissolved O2 was converted to reactive oxygen species (ROS). When additionally feeding air or O2, the accumulative concentrations of â¢O2-, â¢OH, 1O2 were even higher (air: 4.21, 0.97, 2.02 mmol L-1 h-1; O2: 17.13, 1.32, 9.00 mmol L-1 h-1). The rate constants (k) for degrading the TC were 0.0409 min-1 over SAACN and 0.00880 min-1 over NPACN, respectively (mineralization rate: 95.7% vs. 59.9% after 3 h of degradation). Moreover, the degradation ability of SAACN did not decrease in a wide range of pH value (4-10) or under low temperature (10 °C). Besides the high exposure of Ag single sites, other advances of SAACN were: 1(O2 was more energetic favorable to adsorb on single atomic Ag sites; 2) Positive Ag single sites were easier to obtain the electrons from the surrounding N atoms, and facilitated electron transfer towards adsorbed O2.
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Prata , Tetraciclina , Antibacterianos , Catálise , OxigênioRESUMO
Photoanode material with high efficiency and stability is extensively desirable in photoelectrochemical (PEC) water splitting for green/renewable energy source. Herein, novel heterostructures is constructed via coating rutile TiO2 nanorods with metal organic framework (MOF) materials UiO-66 or UiO-67 (UiO-66@TiO2 and UiO-67@TiO2 ), respectively. The π electrons in the MOF linkers could increase the local electronegativity near the heterojunction interface due to the conjugation effect, thereby enhancing the internal electric field (IEF) at the heterojunction interface. The IEF could drive charge transfer following Z-scheme mechanism in the prepared heterostructures, inducing photogenerated charge separation efficiency increasing as 156% and 253% for the UiO-66@TiO2 and UiO-67@TiO2 , respectively. Correspondingly, the UiO-66@TiO2 and UiO-67@TiO2 enhanced the photocurrent density as approximate two- and threefolds compared with that of pristine TiO2 for PEC water oxidation in universal pH electrolytes. This work demonstrates an effective method of regulating the IEF of heterojunction toward further improved charge separation.
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Recently, ambient electrochemical N2 fixation has gained great attention. However, the commercial Pt-based electrocatalyst hardly shows its potential in this field. Herein, it is found that the isolated Pt sites anchored on WO3 nanoplates exhibit the optimum electrochemical NH3 yield rate (342.4 µg h-1 mg-1 Pt ) and Faradaic efficiency (31.1%) in 0.1 m K2 SO4 at -0.2 V versus RHE, which are about 11 and 15 times higher than their nanoparticle counterparts, respectively. The mechanistic analysis indicates that N2 conversion to NH3 follows an alternating hydrogenation pathway, and positively charged isolated Pt sites with special Pt-3O structure can favorably chemisorb and activate the N2 . Furthermore, the hydrogen evolution reaction can be greatly suppressed on isolated Pt sites decorated WO3 nanoplates, which guarantees the efficient going-on of nitrogen reduction reaction.
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It is known that the low lifetime of photogenerated carriers is the main drawback of elemental photocatalysts. Therefore, a facile and versatile one-step strategy to simultaneously achieve the oxygen covalent functionalization of amorphous red phosphorus (RP) and in situ modification of CdCO3 is reported. This strategy endows RP with enhanced charge carrier separation ability and photocatalytic activity by coupling band-gap engineering and heterojunction construction. The as-prepared nCdCO3 /SO-RP (n=0.1, 0.25, 0.5, 1.0) composites exhibited excellent photocatalytic H2 evolution activity (up to 516.3â µmol g-1 h) from visible-light-driven water splitting (λ>400â nm), which is about 17.6â times higher than that of pristine RP. By experimental and theoretical investigations, the roles of surface oxygen covalent functionalization, that is, prolonging the lifetime of photogenerated carriers and inducing the negative shift of the conduction band potential, were studied in detail. Moreover, the charge transfer mechanism of these composites has also been proposed. In addition, these composites are stable and can be reused at least for three times without significant activity loss. This work may provide a good example of how to promote the activity of elemental photocatalysts by decorating their atomic structure.
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Advanced oxidation processes (AOPs) have been applied to address multiple environmental concerns including antibiotic resistance genes (ARGs). ARGs have shown an increasing threat to human health, and they are either harbored by antibiotic-resistant bacteria (ARB) or free in the environment. However, the control of ARGs has been substantially limited by their low concentration and the limited knowledge about their interfacial behavior. Herein, a novel AOP catalyst, Ag/TiO2/graphene oxide (GO), combined with a polyvinylidene fluoride (PVDF) ultrafiltration membrane was designed with a synergistic interfacial adsorption and oxidation function to inactivate ARGs with high efficiency in both model solutions and in secondary wastewater effluent, especially when the residue concentration was low. Further analysis showed that the mineralization of bases and phosphodiesters mainly caused the inactivation of ARGs. Moreover, the interfacial adsorption and oxidation processes of ARGs were studied at the molecular level. The results showed that GO was rich in sp2 backbones and functional oxygen groups, which efficiently captured and enriched the ARGs via π-π interactions and hydrogen bonds. Therefore, the photogenerated active oxygen species attack the ARGs by partially overcoming the kinetic problems in this process. The Ag/TiO2/GO catalyst was further combined with a PVDF membrane to test its potential in wastewater treatment applications. This work offers an efficient method and a corresponding material for the inactivation and mineralization of intra/extracellular ARGs. Moreover, the molecular-level understanding of ARG behaviors on a solid-liquid interface will inspire further control strategies of ARGs in the future.
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In this work, the chlorine-doped and undoped hydrothermal carbonation carbon (Cl-HTCC, HTCC) photocatalysts were used to study the correlation of their interfacial charge and photocatalytic performance. For degradation of aromatic dye, rhodamine B (RhB), Cl-HTCC manifests much better photocatalytic performance compared with that of undoped HTCC. Besides the slightly enhanced charge transfer brought, the Cl-HTCC showed more negatively interfacial charge and thus a stronger adsorption of positively charged RhB. This made the photogenerated holes (h+) directly react with the adsorbed RhB, which does not require the h+ to produce hydroxyl radical (OH) and reduce its lost during the transformation, thus enhanced the performance of Cl-HTCC. While for undoped HTCC, it showed a weaker adsorption of RhB, and the photogenerated h+ firstly reacted with H2O molecules to produce OH. Then, the OH can attack the RhB. Besides, the intermediates and the degradation pathways are also evaluated here via UPLC-MS. Results show that the interfacial charge also dominated the degradation pathways. This work provides a novel metal-free photocatalyst for environmental remediation and will inspire further efforts to enhance the photocatalytic performance by concerning interfacial conditions.
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A highly efficient Z-scheme photocatalytic system constructed with 1D CdS and 2D CoS2 exhibited high photocatalytic hydrogen-evolution activity of 5.54â mmol h-1 g-1 with an apparent quantum efficiency of 10.2 % at 420â nm. More importantly, its interfacial charge migration pathway was unraveled: The electrons are efficiently transferred from CdS to CoS2 through a transition atomic layer connected by Co-S5.8 coordination, thus resulting in more photogenerated carriers participating in surface reactions. Furthermore, the charge-trapping and charge-transfer processes were investigated by transient absorption spectroscopy, which gave an estimated charge-separation yield of approximately 91.5 % and a charge-separated-state lifetime of approximately (5.2±0.5)â ns in CdS/CoS2 . This study elucidates the key role of interfacial atomic layers in heterojunctions and will facilitate the development of more efficient Z-scheme photocatalytic systems.
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In this work, we report a novel photocatalyst of Eosin Y dye sensitized BiPO4 nanorods via a low-temperature and impregnation adsorption method. It shows enhanced visible-light-driven photocatalytic activity for degrading methylene blue (MB) and 2,4-DCP compared to that of pristine BiPO4 nanorods. The mass ratio of Eosin Y/BiPO4 is varied from 5 wt% to 30 wt% and the optimum value is 15 wt%, showing 46.7 and 10.5 fold greater apparent reaction rates than pristine BiPO4. Moreover, all of the reduced MB was transformed into CO2 and H2O during the photocatalysis, showing the good mineralization ability (almost 100%) of the composite. Furthermore, the photocatalytic mechanism of the composite is also investigated here by the zeta potential, scavenger experiments, Electron Paramagnetic Resonance (EPR), Photoluminescence Spectroscopy (PL), and a series of electrochemical analyses. The results show that (i) e- is the main reactive species and (ii) Eosin Y coated and adsorbed on BiPO4, thus widening the response range to the visible light region and accelerating the charge separation/transfer, resulting in bi-functionally promoted activity.
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Porous metal oxides are promising materials for VOCs (volatile organic compounds) chemical sensors, because they have large specific surface areas and enough internal space for the fast gas diffusion. Recently, metal-organic framework (MOF) materials with varied shapes and sizes have been regarded as good templates for preparing porous metal oxides. Herein, four kinds of Co-MOFs were prepared by altering the ratios of Co2+ ions and 2-methylimidazole at room temperature, which exhibited well-controlled shapes. Then, corresponding porous Co3O4 assembled from nanoparticles was acquired by heating Co-MOFs, and showed a good sensing performance for n-butanol, with a response up to 21.0 toward 100 ppm n-butanol. Moreover, it is found that the shape and the size of Co3O4 assemblies can significantly influence their sensing performances. For porous Co3O4 assemblies, when the nanoparticles are small enough (Ë10 nm), a porous structure with a larger proportion of the nanoparticles close to its surface tends to show a better gas-sensing performance. The findings can be used in the design of gas-sensing materials in the future.
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The unexpected phenomenon and mechanism of the alkali metal involved NH3 selective catalysis are reported. Incorporation of K+ (4.22â wt %) in the tunnels of α-MnO2 greatly improved its activity at low temperature (50-200 °C, 100 % conversion of NOx vs. 50.6 % conversion over pristine α-MnO2 at 150 °C). Experiment and theory demonstrated the atomic role of incorporated K+ in α-MnO2 . Results showed that K+ in the tunnels could form a stable coordination with eight nearby O sp 3 atoms. The columbic interaction between the trapped K+ and O atoms can rearrange the charge population of nearby Mn and O atoms, thus making the topmost five-coordinated unsaturated Mn cations (Mn5c , the Lewis acid sites) more positive. Therefore, the more positively charged Mn5c can better chemically adsorb and activate the NH3 molecules compared with its pristine counterpart, which is crucial for subsequent reactions.
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Herein, we report a BiVO4 quantum dot (QDs)-decorated BiPO4 nanorods 0D/1D heterojunction via an in situ growth method. It showed enhanced visible-light-driven photocatalytic activity for degrading Rhodamine B (Rh B) compared to its pristine counterparts in composite. The mass ratio of BiVO4/BiPO4 was then varied from 3 wt% to 50 wt% and the optimum value was found to be 30 wt%, showing 8.3-fold and 6.3-fold apparent reaction rates higher than those of pristine BiPO4 and BiVO4, respectively. Moreover, all of the reduced Rh B was transformed into CO2 and H2O during the photocatalysis, thus showing the good mineralization ability (almost 100%) of the composite. Furthermore, the photocatalytic mechanism of the composite was also investigated here by the zeta potential, scavenger experiments, electron paramagnetic resonance (EPR), photoluminescence spectroscopy (PL), transient photocurrent and electrochemical impedance spectroscopy (EIS). Results show that (i) ËOH was the main reactive species and (ii) BiVO4 could form a heterojunction with BiPO4, thus widening the response range to the visible region and accelerating the charge separation and transfer.