Selective photoelectrocatalytic degradation of recalcitrant contaminant driven by an n-P heterojunction nanoelectrode with molecular recognition ability

Innovations and challenges in adsorption-based wastewater remediation: A comprehensive review

Water contamination is an escalating emergency confronting communities worldwide. While traditional adsorbents have laid the groundwork for effective water purification, their selectivity, capacity, and sustainability limitations have driven the search for more advanced solutions. Despite many technological advancements, economic, environmental, and regulatory hurdles challenge the practical application of advanced adsorption techniques in large-scale water treatment. Integrating nanotechnology, advanced material fabrication techniques, and data-driven design enabled by artificial intelligence (AI) and machine learning (ML) have led to a new generation of optimized, high-performance adsorbents. These advanced materials leverage properties like high surface area, tailored pore structures, and functionalized surfaces to capture diverse water contaminants efficiently. With a focus on sustainability and effectiveness, this review highlights the transformative potential of these advanced materials in setting new benchmarks for water purification technologies. This article delivers an in-depth exploration of the current landscape and future directions of adsorbent technology for water remediation, advocating for a multidisciplinary approach to overcome existing barriers in large-scale water treatment applications.

Selective removal of sulfamethoxazole by a novel double Z-scheme photocatalyst: Preferential recognition and degradation mechanism

Sulfamethoxazole (SMX) is a significant environmental concern due to its adverse effects and ecological risks. SMX elimination in aquatic environments via photocatalysis presents a viable solution, given its high oxidation potential. However, such a solution remains controversial, primarily due to a lack of selectivity. Here we introduce a molecularly imprinted TiO2@Fe2O3@g-C3N4 (MFTC) photocatalyst designed for the selective degradation of SMX. To assess MFTC's selectivity, we applied it to degrade synthetic wastewater containing SMX alongside interfering species sulfadiazine (SDZ), ibuprofen (IBU), and bisphenol A (BPA). The results demonstrated a selective degradation efficiency rate of 96.8%, nearly twice that of competing pollutants. The molecularly imprinted sites within the catalyst played a crucial role by selectively capturing SMX and enhancing its adsorption, thereby improving catalytic efficiency. The degradation process involved •OH and •O2- free radicals, with a newly proposed double Z-scheme mechanism and potential pathway for SMX degradation by the MFTC photocatalytic system. This study enriches the application of photocatalysis using molecularly imprinted nanocomposite materials for treating complex pollutant mixtures in water.

Electrochemical sensor for sensitive detection of bisphenol A based on molecularly imprinted TiO2 with oxygen vacancy

Bisphenol A (BPA) is an endocrine disrupting chemical and broadly used in plastics. The leakage of BPA in food and water cycles poses a significant risk to the environment and human health. Thus, monitoring the concentration of BPA to avoid its potential risk is highly important. In this work, a simple and efficient oxygen deficient molecularly imprinted TiO2 electrochemical sensor was proposed for the detection of BPA. The introduction both oxygen vacancies and molecular imprinting evidently enhanced the electrochemical oxidation signal of BPA. The sensor had a good linear response ranging from 0.01 μM to 20 μM with a limit of detection of 3.6 nM. Additionally, the sensor showed remarkable stability, reproducibility and interference resistant ability. It also exhibits excellent recovery during the detection of real water. These findings suggested that the sensor has the potential to be developed as a simple, efficient and low-cost monitoring system for the monitoring of BPA in water.

Dissolved organic matter promotes photocatalytic degradation of refractory organic pollutants in water by forming hydrogen bonding with photocatalyst

Removing refractory organic pollutants in real water using photocatalysis is a great challenge because coexisting dissolved organic matter (DOM) can quench photogenerated holes and thus prevent generation of reactive oxygen species (ROS). Herein, for the first time, we develop a hydrogen bonding strategy to avoid the scavenging of photoexcited holes, by which DOM even promotes photocatalytic degradation of refractory organic pollutants. Theoretical calculations combined with experimental studies reveal the formation of hydrogen bonding between DOM and a hydroxylated S-scheme heterojunction photocatalyst (Mo-Se/OHNT) consisting of hydroxylated nitrogen doped TiO2 (OHNT) and molybdenum doped selenium (Mo-Se). The hydrogen bonding is demonstrated to change the interaction between DOM and Mo-Se/OHNT from DOM-Ti (IV) to a hydrogen bonded complexation through the hydroxyl/amine groups of DOM and the OHNT in Mo-Se/OHNT. The formed hydrogen network can stabilize excited-state of DOM and inject its electron to the conduction band rather than the valence band of the OHNT upon light irradiation, realizing the key to preventing hole quenching. The electron-hole separation in Mo-Se/OHNT is consequently improved for generating more ROS to be involved in removing refractory organic pollutants. Moreover, this hydrogen bonding strategy is generalized to nitrogen doped zinc oxide and graphitic carbon nitride and applies to real water. Our findings provide a new insight into handling the DOM problem for photocatalytic technology towards water and wastewater treatment.

Preparation of site-specific Z-scheme g-C3N4/PAN/PANI@LaFeO3 cable nanofiber membranes by coaxial electrospinning: Enhancing filtration and photocatalysis performance

The coaxial electrospinning method for preparation of g-C₃N₄/polyacrylonitrile (PAN)/polyaniline (PANI)@LaFeO₃ cable fiber membrane (PC@PL) was designed for adsorption-filtration-photodegradation of pollutants. A series of characterization results show that LaFeO₃ and g-C₃N₄ nanoparticles (NPs) are respectively loaded in the inner and outer layers of PAN/PANI composite fibers to construct the site-specific Z-type heterojunction system with spatially separated morphologies. The PANI in cable not only possesses abundant exposed amino/imino functional groups for adsorption of contaminant molecules but also due to the excellent electrical conductivity works as a redox medium for collecting and consuming the electrons and holes from LaFeO₃ and g-C₃N₄, which can efficiently promote photo-generated charge carriers separation and improve the catalytic performance. Further investigations demonstrate that as a photo-Fenton catalyst LaFeO₃ in PC@PL catalyzes/activates the H₂O₂ generated in situ by LaFeO₃/g-C₃N₄, further enhancing the decontamination efficiency of the PC@PL. The porous, hydrophilic, antifouling, flexible and reusable properties of the PC@PL membrane significantly enhance the mass transfer efficiency of reactants by filtration effect and increase the amount of dissolved oxygen, thus producing massive •OH for degradation of pollutants, which maintains the water flux (1184 L m^-2. h^-1 (LMH)) and the rejection rate (98.5%). Profiting from its unique synergistic effect of adsorption, photo-Fenton and filtration, PC@PL exhibits wonderful self-cleaning performance and distinguished removal rate for methylene blue (97.0%), methyl violet (94.3%), ciprofloxacin (87.6%) and acetamiprid (88.9%) within 75 min, disinfection (100% Escherichia coli (E. coli) and 80% Staphylococcus aureus (S.aureus) inactivation)) and excellent cycle stability.

Plasma-Assisted Fabrication of Molecularly Imprinted NiAl-LDH Layer on Ni Nanorod Arrays for Glyphosate Detection

An inorganic-framework molecularly imprinted NiAl layered double hydroxide (MI-NiAl-LDH) with specific template molecule (glyphosate pesticide, Glyp) recognition ability was prepared on Ni nanorod arrays (Ni NRAs) through electrodeposition followed by a low-temperature O₂ plasma treatment. The freestanding Ni/MI-NiAl-LDH NRA electrode had highly enhanced sensitivity and selectivity. The electrocatalytic oxidation of Glyp was proposed to occur at Ni³⁺ centers in MI-NiAl-LDH, and the current response depended linearly on the Glyp concentration from 10.0 nmol/L to 1.0 μmol/L (R² = 0.9906), with the limit of detection (LOD) being 3.1 nmol/L (S/N = 3). An exceptional discriminating capability with tolerance for other similar organophosphorus compounds was achieved. Molecular imprinting (N and P residues) affected the electronic structure of NiAl-LDH, triggering the formation of highly active NiOOH sites at relatively lower anodic potentials and substantially enhancing the electrocatalytic oxidation ability of the NiAl-LDH interface toward the C-N bonds in Glyp. In combination with the surface enrichment effect of MI-NiAl-LDH toward template molecules, the electrochemical oxidation signal intensity of Glyp increased significantly, with a greater peak separation from interfering molecules. These results challenge the common belief that the excellent performance of inorganic-framework molecularly imprinted interfaces arises from their specific adsorption of template molecules, providing new insight into the development of high-performance organic-pollutant-sensing electrodes.

Accurate Removal of Toxic Organic Pollutants from Complex Water Matrices

Characteristic emerging pollutants at low concentration have raised much attention for causing a bottleneck in water remediation, especially in complex water matrices where high concentration of interferents coexist. In the future, tailored treatment methods are therefore of increasing significance for accurate removal of target pollutants in different water matrices. This critical review focuses on the overall strategies for accurately removing highly toxic emerging pollutants in the presence of typical interferents. The main difficulties hindering the improvement of selectivity in complex matrices are analyzed, implying that it is difficult to adopt a universal approach for multiple targets and water substrates. Selective methods based on assorted principles are proposed aiming to improve the anti-interference ability. Thus, typical approaches and fundamentals to achieve selectivity are subsequently summarized including their mechanism, superiority and inferior position, application scope, improvement method and the bottlenecks. The results show that different methods may be applicable to certain conditions and target pollutants. To better understand the mechanism of each selective method and further select the appropriate method, advanced methods for qualitative and quantitative characterization of selectivity are presented. The processes of adsorption, interaction, electron transfer, and bond breaking are discussed. Some comparable selective quantitative methods are helpful for promoting the development of related fields. The research framework of selectivity removal and its fundamentals are established. Presently, although continuous advances and remarkable achievements have been attained in the selective removal of characteristic organic pollutants, there are still various substantial challenges and opportunities. It is hopeful to inspire the researches on the new generation of water and wastewater treatment technology, which can selectively and preferentially treat characteristic pollutants, and establish a reliable research framework to lead the direction of environmental science.

Toward Selective Oxidation of Contaminants in Aqueous Systems

The presence of diverse pollutants in water has been threating human health and aquatic ecosystems on a global scale. For more than a century, chemical oxidation using strongly oxidizing species was one of the most effective technologies to destruct pollutants and to ensure a safe and clean water supply. However, the removal of increasing amount of pollutants with higher structural complexity, especially the emerging micropollutants with trace concentrations in the complicated water matrix, requires excessive dosage of oxidant and/or energy input, resulting in a low cost-effectiveness and possible secondary pollution. Consequently, it is of practical significance but scientifically challenging to achieve selective oxidation of pollutants of interest for water decontamination. Currently, there are a variety of examples concerning selective oxidation of pollutants in aqueous systems. However, a systematic understanding of the relationship between the origin of selectivity and its applicable water treatment scenarios, as well as the rational design of catalyst for selective catalytic oxidation, is still lacking. In this critical review, we summarize the state-of-the-art selective oxidation strategies in water decontamination and probe the origins of selectivity, that is, the selectivity resulting from the reactivity of either oxidants or target pollutants, the selectivity arising from the accessibility of pollutants to oxidants via adsorption and size exclusion, as well as the selectivity due to the interfacial electron transfer process and enzymatic oxidation. Finally, the challenges and perspectives are briefly outlined to stimulate future discussion and interest on selective oxidation for water decontamination, particularly toward application in real scenarios.

Targeted degradation of refractory organic compounds in wastewaters based on molecular imprinting catalysts

Efficient removal of low-concentration refractory pollutants is a crucial problem to ensuring water safety. The use of heterogeneous catalysis of molecular imprinting technology combined with traditional catalysts is a promising method to improve removal efficiency. Presently, the research into molecular imprinting targeting catalysts focuses mainly on material preparation and performance optimization. However, more researchers are investigating other applications of imprinting materials. This review provides recent progress in photocatalyst preparation, electrocatalyst, and Fenton-like catalysts synthesized by molecular imprinting. The principle and control points of target catalysts prepared by precipitation polymerization (PP) and surface molecular imprinting (S-MIP) are introduced. Also, the application of imprinted catalysts in targeted degradation of drugs, pesticides, environmental hormones, and other refractory pollutants is summarized. In addition, the reusability and stability of imprinted catalyst in water treatment are discussed, and the possible ecotoxicity risk is analyzed. Finally, we appraised the prospects, challenges, and opportunities of imprinted catalysts in the advanced oxidation process. This paper provides a reference for the targeted degradation of refractory pollutants and the preparation of targeted catalysts.

Selective removal of common cyanotoxins: a review

The development of cyanobacterial blooms can have adverse effects on water bodies and may produce cyanotoxins. Several physical and chemical methods have been applied to remove cyanotoxins, but they have been significantly challenged due to extensive energy footprint and over-used chemicals, which limits practical application on a large scale. Selective removal has been regarded as the most promising approach recently for the elimination of prevalent and major bloom-forming cyanotoxins (e.g., microcystins and cylindrospermopsin) as natural organic matters and radical scavengers are ineluctably present in real scenarios. This paper reviews current advancements in research on selective oxidation and adsorption of cyanotoxins. Its goal is to provide comprehensive information on the treatment mechanism and the process feasibility involved in the cyanotoxin removal from real-world waters. Moreover, perspectives of cyanotoxin control and in situ selective elimination approaches are also reviewed. It is expected that the information gathered and discussed in this review can provide a useful and novel reference and direction for future pilot-scale applications.

Innovative utilization of molecular imprinting technology for selective adsorption and (photo)catalytic eradication of organic pollutants

The rapid development of industrialization and urbanization results in a numerous production of various organic chemicals to meet the increasing demand in high-quality life. During the synthesis and utilization of these chemical products, their residues unavoidably emerged in environments to severely threaten human's health. It is thus urgent to exploit effective technology for readily removing the organic pollutants with high selectivity and good reusability. As one of the most promising approaches, molecular imprinting technology (MIT) employs a chemically synthetic route to construct artificial recognition sites in highly-crosslinked matrix with complementary cavity and functional groups to target species, which have been attracting more and more interest for environmental remediation, such as the selective adsorption/separation and improved catalytic degradation of pollutants. In this review, MIT is first introduced briefly to understand their preparing process, recognition mechanism and common imprinted systems. Then, their specific binding affinities are demonstrated for selectively adsorbing and removing target molecules with a large capacity. Furthermore, the innovative utilization of MIT in catalytic eradication of pollutants is comprehensively overviewed to emphasize their enhanced efficiency and improved performances, which are classified by the used catalytically-active nanocrystals and imprinted systems. After summarizing recent advances in these fields, some limitations are discussed and possible suggestions are given to guide the future exploitation on MIT for environmental protection.

Efficient Self-Driving Photoelectrocatalytic Reactor for Synergistic Water Purification and H2 Evolution

The photoelectrocatalytic (PEC) technique has attracted much attention to getting clear energy and environmental purification. Simultaneous reactions of solar energy generation could be used to apply for practical applications to maximize the functionality of reactor systems. Herein, we crafted a self-driving photoelectrocatalytic reactor system, comprising platinum (Pt) modified p-Si nanowires (Pt/Si-NWs) as a photocathode and TiO₂ nanotube arrays (TiO₂-NTAs) as a photoanode for synergistic H₂ evolution and water purification, respectively. Hydrogen evolution in the cathode chamber and environmental remediation in the anode chamber were achieved with the aid of appropriate bandgap illumination and self-built bias voltage. The mismatch of Fermi levels between TiO₂-NTAs and Si-NWs reduced the recombination rates of photoinduced electrons and holes through the formation of Z scheme and inner electric filed. The synergistic PEC reactions exhibited much higher activities than those achieved using other systems so far. This basic principal could be applied for fabricating other PEC reactors in photoelectro conversion devices and be established as design guidelines for reactors to maximize the PEC performance.

Carbon quantum dots-decorated TiO2/g-C3N4 film electrode as a photoanode with improved photoelectrocatalytic performance for 1,4-dioxane degradation

In this study, carbon quantum dots (CQDs) were used to decorate a TiO₂/g-C₃N₄ (TCN) film electrode. The morphological, optical, and electrochemical properties of the TiO₂/g-C₃N₄/CQDs nanorod arrays (TCNC NRAs) film were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and electrochemical impedance spectroscopy (EIS). The improved optical properties, photoelectrochemical properties and photoelectrocatalytic (PEC) performance of photoanode can be observed by doping CQDs onto the TCN NRAs film. Compared with TiO₂ NRAs and TCN NRAs, the narrower band gap of 2.47 eV and longer lifetime of photoinduced electron-hole pairs were observed in the TCNC NRAs. Under visible light irradiation and a bias voltage of 1.2 V, the photocurrent density and 1,4-dioxane (1,4-D) removal rate of PEC process with TCNC NRAs electrode reached 0.16 mA/cm² and 77.9%, respectively, which was 2.5 times and 1.5 times of that with TCN NRAs electrode. TCNC NRAs electrode could keep >75% of the 1,4-D removal rate during five cycles tests. High PEC performance with TCNC NRAs electrode could be attributed to the enhanced charge separation and the change of electron transfer mechanism from typical heterojunction to Z-scheme, which may increase the active species production and change the dominant reactive species from O₂·^- to ·OH. Our experimental results should be useful for studying the degradation of 1,4-D and developing efficient PEC materials.

Selective removal and persulfate catalytic decomposition of diethyl phthalate from contaminated water on modified MIL100 through surface molecular imprinting

Adsorptive removal of phthalate esters from wastewater combined with their persulfate (PS) catalytic degradation has attracted the attention of many researchers. In this study, the adsorptive and catalytic properties of an MIL100 material obtained by a green synthetic route have been optimized by a surface molecular imprinting technique. Results have shown that there are two steps in the molecular imprinting process. A polymerization is first carried out in the internal channels of the material and the imprinting layer is then formed on the surface. The relative proportions of the starting materials for the synthesis have been optimized through the design of a three-dimensional response surface. The amount of pollutant adsorbed was increased fourfold after surface imprinting, reaching 13.6 mg g^-1. The homogeneity of the recognition sites has been evaluated by dynamics calculations and the Freundlich equation. The selective adsorption ability of the material for diethyl phthalate was improved, and the process involved chemical adsorption. The catalytic properties of the material after imprinting were increased about 1.5-fold, indicating that selective adsorption is important. Such molecularly imprinted polymers may potentially serve as good functional materials for the removal of phthalate esters from wastewater.

Recent progress on carbon nanomaterials for the electrochemical detection and removal of environmental pollutants

Rapid global industrialization and explosive population growth have resulted in an increase in the discharge of harmful and toxic compounds. These toxic inorganic gases, volatile organic compounds, heavy metals, personal care products, endocrine-disrupting chemicals, dyes, and pharmaceuticals are destroying the balance in the Earth and increasing environmental toxicity at an alarming rate. Thus, their detection, adsorption and removal are of great significance. Various carbon nanomaterials including carbon nanotubes, graphene, mesoporous carbon, carbon dots, and boron-doped diamond have been extensively utilized and further proven to be ideal candidates for resolving environmental problems, emerging as adsorbents, electrochemical sensors and electrodes. Herein, we review the recent advances, progress and achievements in the design and properties of carbon nanomaterials and their applications for the electrochemical detection and removal of environmental pollutants.

Photochemical Protection of Reactive Sites on Defective TiO2- x Surface for Electrochemical Water Treatment

The electrode is the key in electrochemical process for water and wastewater treatment. Many nonstoichiometric metal oxides are active electrode materials but have poor stability under strong anodic polarization due to their susceptible nature of the oxygen vacancies on surface and subsurface as defective reactive sites. In this work, a novel photochemical protecting strategy is proposed to stabilize the defective reactive sites on the TiO_{2- x} surface and subsurface for long-term anodic oxidation of pollutants. With this strategy, a novel photoassisted electrochemical system at low anodic bias is further constructed. Such a system exhibits a high protecting capacity at a low operation cost for electrochemical degradation of bisphenol A (BPA), a typical persistent organic pollutant. Its excellent photochemical protecting capacity is found to be mainly attributed to the mild non-band-gap excitation pathways on the defective TiO_{2- x} electrode under both visible-light irradiation and moderate anodic polarization. Under real sunlight irradiation, a 20 run cyclic test for BPA degradation demonstrates the excellent performance and stability of the constructed system at low bias without significant oxygen evolution. Our work provides a new opportunity to utilize the defective and reactive TiO_{2- x} for efficient, stable, and cost-effective electrochemical water treatment with the aid of its photo- and electrochemical bifunctional properties.

Amalgamation of N-graphene quantum dots with nanocubic like TiO2: an insight study of sunlight sensitive photocatalysis

In this work, a sunlight-sensitive photocatalyst of nanocubic-like titanium dioxide (TiO₂) and N-doped graphene quantum dots (N-GQDs) is developed through a simple hydrothermal and physical mixing method. The successful amalgamation composite photocatalyst characteristics were comprehensively scrutinized through various physical and chemical analyses. A complete removal of bisphenol A (BPA) is attained by a synthesized composite after 30 min of sunlight irradiation as compared to pure TiO₂. This clearly proved the unique contribution of N-GQDs that enhanced the ability of light harvesting especially under visible light and near-infrared region. This superior characteristic enables it to maximize the absorbance in the entire solar spectrum. However, the increase of N-GQDs weight percentage has created massive oxygen vacancies that suppress the generation of active radicals. This resulted in a longer duration for a complete removal of BPA as compared to lower weight percentage of N-GQDs. Hence, this finding can offer a new insight in developing effective sunlight-sensitive photocatalysts for various complex organic pollutants degradation.

Conductive diamond: synthesis, properties, and electrochemical applications

This review summarizes systematically the growth, properties, and electrochemical applications of conductive diamond.

Electrochemical oxidation of 4-chlorophenol for wastewater treatment using highly active UV treated TiO2 nanotubes

In the present work, we report on a facile UV treatment approach for enhancing the electrocatalytic activity of TiO₂ nanotubes. The TiO₂ nanotubes were prepared using an anodization oxidation method by applying a voltage of 40 V for 8 h in a DMSO + 2% HF solution, and further treated under UV light irradiation. Compared with Pt and untreated TiO₂ nanotubes, the UV treated electrode exhibited a superior electrocatalytic activity toward the oxidation of 4-chlorophenol (4-ClPh). The effects of current density and temperature on the electrochemical oxidation of the 4-ClPh were also systematically investigated. The high electrocatalytic activity of the UV treated TiO₂ nanotubes was further confirmed by the electrochemical oxidation of other persistent organic pollutants including phenol, 2-, 3-, 4-nitrophenol, and 4-aminophenol. The total organic carbon (TOC) analysis revealed that over 90% 4-ClPh was removed when the UV treated TiO₂ electrode was employed and the rate constant was 16 times faster than that of the untreated TiO₂ electrode; whereas only 60% 4-ClPh was eliminated at the Pt electrode under the same conditions. This dramatically improved electrocatalytic activity might be attributed to the enhanced donor density, conductivity, and high overpotential for oxygen evolution. Our results demonstrated that the application of the UV treatment to the TiO₂ nanotubes enhanced their electrochemical activity and energy consumption efficiency significantly, which is highly desirable for the abatement of persistent organic pollutants.

Enhanced photocatalytic water-splitting performance using Fe-doped hierarchical TiO2 ball-flowers

The photocatalytic water-splitting behavior of hierarchically structured TiO₂ ball-flowers with different Fe ion contents was studied, in order to elucidate the effects of Fe doping on their water-splitting performance. It was found that with the increase of Fe doping content, the hydrogen evolution rate increased initially and then decreased. The highest hydrogen evolution of 697 μmol g^-1 is observed for 2Fe/TiO₂, after 4 h of light irradiation, which was five times greater than that in the case of pure TiO₂ who has 140 μmol g^-1 hydrogen evolution after 4 h of light irradiation. This improvement in the water-splitting efficiency owing to optimized Fe doping could be attributed to an enhancement in the visible-light absorption characteristics and an increase in the number of oxygen vacancies, which act as the reaction sites for water splitting.

Highly efficient removal of organic pollutants by ultrahigh-surface-area-ethynylbenzene-based conjugated microporous polymers via adsorption–photocatalysis synergy

Conjugated microporous polymers with a high surface area and a narrow band gap exhibited efficient removal of organic pollutants via adsorption–photocatalysis synergy.

Photochemical Anti-Fouling Approach for Electrochemical Pollutant Degradation on Facet-Tailored TiO2 Single Crystals

Electrochemical degradation of refractory pollutants at low bias before oxygen evolution exhibits high current efficiency and low energy consumption, but its severe electrode fouling largely limits practical applications. In this work, a new antifouling strategy was developed and validated for electrochemical pollutant degradation by photochemical oxidation on facet-tailored {001}-exposed TiO₂ single crystals. Electrode fouling from anodic polymers at a low bias was greatly relieved by the free ·OH-mediated photocatalysis under UV irradiation, thus efficient and stable degradation of bisphenol A, a typical environmental endocrine disrupter, and treatment of landfill leachate were accomplished without remarkable oxygen evolution in synergistic photoassisted electrochemical system. Electrochemical and spectroscopic measurements indicated a clean electrode surface during cyclic pollutant degradation. Such a photochemical antifouling strategy for low-bias anodic pollutants degradation was mainly attributed to the improved electric conductivity and excellent electrochemical and photochemical activities of tailored TiO₂ anodic material, whose unique properties originated from the favorable surface atomic and electronic structures of high-energy {001} polar facet and single-crystalline structure. Our work opens up a brand new approach to develop catalytic systems for efficient degradation of refractory contaminants in water and wastewater.

A pM leveled photoelectrochemical sensor for microcystin-LR based on surface molecularly imprinted TiO2@CNTs nanostructure

A simple and highly sensitive photoelectrochemical (PEC) sensor towards Microcystin-LR (MC-LR), a kind of typical cyanobacterial toxin in water samples, was developed on a surface molecular imprinted TiO₂ coated multiwalled carbon nanotubes (MI-TiO₂@CNTs) hybrid nanostructure. It was synthesized using a feasible two-step sol-gel method combining with in situ surface molecular imprinting technique (MIT). With a controllable core-shell tube casing structure, the resultant MI-TiO₂@CNTs are enhanced greatly in visible-light driven response capacity. In comparison with the traditional TiO₂ (P25) and non-imprinted (NI-)TiO₂@CNTs, the MI-TiO₂@CNTs based PEC sensor showed a much higher photoelectric oxidation capacity towards MC-LR. Using this sensor, the determination of MC-LR was doable in a wide linear range from 1.0pM to 3.0nM with a high photocurrent response sensitivity. An outstanding selectivity towards MC-LR was further achieved with this sensor, proven by simultaneously monitoring 100-fold potential co-existing interferences. The superiority of the obtained MC-LR sensor in sensitivity and selectivity is mainly attributed to the high specific surface area and excellent photoelectric activity of TiO₂@CNTs heterojunction structure, as well as the abundant active recognition sites on its functionalized molecular imprinting surface. A promising PEC analysis platform with high sensitivity and selectivity for MC-LR has thus been provided.

Preparation and characterization of Nano-graphite/TiO2 composite photoelectrode for photoelectrocatalytic degradation of hazardous pollutant

Nano-graphite(Nano-G)/TiO2 composite photoelectrode was fabricated via sol-gel reaction, followed by the hot-press approach. The morphology, structure and light absorption capability of composite was characterized by various characterizations. The photoelectrochemical property and photoelectrocatalytic(PEC) activity of photoelectrode were also investigated. Results revealed that anatase TiO2 nanoparticles with an average diameter of 10nm were dispersed uniformly on the thickness of 2-3nm Nano-G, and TiOC bond was formed. The absorption edge of Nano-G/TiO2 photoelectrode was red-shifted towards low energy region and the enhanced visible light absorption was obtained. The charge transfer resistance of Nano-G/TiO2 photoelectrode was significantly decreased after the addition of Nano-G. And its transient photoinduced current was 10.5 times the value achieved using TiO2 electrode. Nano-G/TiO2 photoelectrode displayed greatly enhanced PEC activity of 99.2% towards the degradation of phenol, which was much higher than the 29.1% and 58.3% degradation seen on TiO2 and Nano-G electrode, respectively. The highly efficient and stable PEC activity of Nano-G/TiO2 photoelectrode was attributed to the synergy effect between photocatalysis and electrocatalysis, as well as enhanced light absorption ability and higher separation efficiency of photogenerated charge carriers. Moreover, contribution of series of reactive species to the PEC degradation of Nano-G/TiO2 photoelectrode was determined.

Synthesis of molecularly imprinted photocatalysts containing low TiO2 loading: Evaluation for the degradation of pharmaceuticals

A molecularly imprinted (MI) photocatalyst containing a low TiO2 loading (7.00-16.60mgL(-1) of TiO2) was prepared via an acid-catalyzed sol-gel route using different classes of pharmaceutical compounds (i.e., Atorvastatin, Diclofenac, Ibuprofen, Tioconazole, Valsartan, Ketoconazole and Gentamicine) as the template. Herein, our main goal was to test the hypothesis that photocatalysts based on molecular imprinting may improve the degradation performance of pharmaceutical compounds compared to that of a commercial sample (Degussa P25) due to presence of specific cavities in the silica domain. To elucidate certain trends between the performance of photocatalysts and their structural and textural properties, as well the effect of the structure of the drugs on molecular imprinting, the data were analyzed in terms of pore diameter, pore volume, surface area, zeta potential and six-membered ring percentage of silica. In comparison to the commercial sample (P25), we have shown that adsorption and degradation were enhanced from 48 to 752% and from 5 to 427%, respectively. A comparison with the control system (non-imprinted) indicates that the increased performance of the MI systems was due to the presence of specific cavities on the silica domain, and the textural and structural aspects also support this conclusion. The MI photocatalyst was reusable for seven cycles of reuse in which approximately 60% of its photocatalytic efficiency was preserved for the system containing Diclofenac as the template.

Energy-efficient degradation of rhodamine B in a LED illuminated photocatalytic fuel cell with anodic Ag/AgCl/GO and cathodic ZnIn2S4 catalysts

A PFC with anodic Ag/AgCl/GO and cathodic ZnIn₂S₄ catalysts was constructed for organic compound degradation and electricity generation.

AgBr nanoparticles decorated BiPO4 microrod: a novel p–n heterojunction with enhanced photocatalytic activities

AgBr nanoparticles were decorated on the surface of BiPO₄ micro-rod to fabricate a novel p–n heterojunction photocatalyst via a facile deposition–precipitation method.

Electrochemical degradation of chlortetracycline using N-doped Ti/TiO2 photoanode under sunlight irradiations

The appearance and the persistence of pharmaceutical products in the aquatic environment urgently call for the development of an innovative and practical water treatment technology. This study deals with the development of nanostructured nitrogen-doped TiO2 photoanodes and their subsequent use for chlortetracycline (CTC) photoelectrocatalytic oxidation under visible light. The N-doped TiO2 photoanodes with different nitrogen contents were prepared by means of a radiofrequency magnetron sputtering (RF-MS) process, with the objective to tune shift their optical absorption from the UV towards the visible. The N-doped TiO2 consist of nanostructured anatase phase with average TiO2 nanocrystallite size of 29 nm. The nitrogen doping is clearly shown to produce the desired red shift of the absorption onset of the TiO2 coatings (from ~380 nm to ~550 nm). Likewise, the N-doped TiO2 are found to be highly photo-electroactive not only under the UV light but most interestingly under the visible light as well. Using the optimal N-doped photoanodes, 99.6% of CTC (100 μg/L) was successfully degraded after 180 min of treatment time with a current intensity of 0.6 A. Under these conditions, a relatively high mineralization of CTC (92.5% ± 0.26% of TOC removal and 90.3% ± 1.1% of TN removal) was achieved.

Preparation and characterization of palladium nano-crystallite decorated TiO₂ nano-tubes photoelectrode and its enhanced photocatalytic efficiency for degradation of diclofenac

TiO2 has been considered as a versatile candidate for the photoelectrochemical (PECH) application. In this study, Pd nano-crystallite decorated TiO₂ nano-tubes (Pd/TNTs) photoelectrode was prepared through electrochemical deposition. The resulting Pd/TNTs samples were characterized by SEM, XRD, DRS and XPS. It was found that the decorated Pd nano-crystallite existed in the form of Pd(0) with an average diameter of 30 nm, and could improve the light absorption in visible region. In addition, PECH properties of Pd/TNTs photoanode were investigated through transient open circuit potential, photocurrent response, electro-chemical impedance spectroscopy (EIS) and Mott-Schottky analysis. Moreover, the generation rate of hydroxyl radicals (•OH) was detected by a photoluminescence (PL) spectra using terephthalic acid (TA) as a probe molecule. Results showed that Pd/TNTs photoelectrode exhibited high transient photoinduced current of 0.094 mA cm(-2), open circuit photovoltage of -0.339 mV cm(-2) and effective photoelectrocatalytic (PEC) efficiency of 67.7% (0.4V vs. SCE) for the degradation of diclofenac (DCF). The high PC and PEC efficiency could mainly be attributed to the decoration of Pd nano-crystallite which could provide pathway for the transfer of photoinduced charge carriers. Furthermore, the contribution of series of active species was applied to clarify the enhanced PC mechanism.