Synergetic effect of CQD and oxygen vacancy to TiO2 photocatalyst for boosting visible photocatalytic NO removal

Epitaxial growth of Bi4Ti3O12-BiPO4 Z-scheme heterojunction to promote carrier transfer for photocatalytic oxidation of NO

The lack of compactness in heterojunction interfaces and poor charge separation is a great challenge in developing high-efficiency heterojunction photocatalysts. Herein, a novel Bi4Ti3O12-BiPO4 heterojunction was successfully prepared for the first time by epitaxial growth of BiPO4 on the surface of Bi4Ti3O12 nanosheets. The optimized Bi4Ti3O12-BiPO4-0.5 increased the NO oxidation efficiency to 73.05%, surpassing pure Bi4Ti3O12 (63.45%) and BiPO4 (8.35%). Experiments and theoretical calculations indicated that the closely contacted heterointerface between BTO and BPO promoted the generation of the built-in electric field, which led to the formation of the Z- scheme transfer pathway for the photogenerated carriers. Therefore, the separation of photogenerated carriers was facilitated while retaining high redox potential, generating more ·O2- and ·OH to participate in NO oxidation. Furthermore, the adsorption of NO and O2 was enhanced by introducing BiPO4, further improving the photocatalytic NO oxidation performance. This work emphasizes the critical role of heterointerface in accelerating charge transfer, providing a basis for the design and construction of tightly contacted heterojunction photocatalysts.

A Review of Synthesis Methods, Modifications, and Mechanisms of ZnO/TiO2-Based Photocatalysts for Photodegradation of Contaminants

The environment being surrounded by accumulated durable waste organic compounds has become a critical crisis for human societies. Generally, organic effluents of industrial plants released into the water source and air are removed by some physical and chemical processes. Utilizing photocatalysts as cost-effective, accessible, thermally/mechanically stable, nontoxic, reusable, and powerful UV-absorber compounds creates a new gateway toward the removal of dissolved, suspended, and gaseous pollutants even in trace amounts. TiO2 and ZnO are two prevalent photocatalysts in the field of removing contaminants from wastewater and air. Structural modification of the photocatalysts with metals, nonmetals, metal ions, and other semiconductors reduces the band gap energy and agglomeration and increases the affinity toward organic compounds in the composite structures to expand their usability on an industrial scale. This increases the extent of light absorbance and improves the photocatalytic efficiency. Selecting a suitable synthesis method is necessary to prepare a target photocatalyst with distinct properties such as high specific surface area, numerous surface functional groups, and an appropriate crystalline phase. In this Review, significant parameters for the synthesis and modification of TiO2- and ZnO-based photocatalysts are discussed in detail. Several proposed mechanistic routes according to photocatalytic composite structures are provided. Some electrochemical analyses using charge carrier trapping agents and delayed recombination help to plot mechanistic routes according to the direction of photoexcited species (electron-hole pairs) and design more effective photocatalytic processes in terms of cost-effective photocatalysts, saving time and increasing productivity.

One-step in-situ construction engineering of ZnO-Zn2SnO4 heterojunction for deeply photocatalytic oxidation of nitric oxide

The generation of hazardous intermediates during the process of photocatalytic nitric oxide (NO) oxidation presents a tough issue. Herein, a one-step microwave strategy was employed to introduce oxygen vacancies (OVs) into zinc oxide-zinc stannate (ZnO-Zn2SnO4) heterojunction, resulting in an improvement in the photocatalytic efficiency for NO removal. The construction ZnO-Zn2SnO4 heterojunction with the OVs (ZSO-3) owns a significant contribution towards highly efficient electron transfer efficiency (99.7%), which renders ZSO-3 to exert a deep oxidation of NO-to-nitrate (NO3-) rather than NO-to-nitrite (NO2-) or NO-to-nitrogen dioxide (NO2). Based on the solid supports of experimental and simulated calculations, it can be found that OVs play an irreplaceable role in activating small molecules such as NO and O2. Moreover, the enhanced adsorption capacity of small molecules, which guarantees the high yield of active radical due to the formation of S-scheme heterojunction. This work illuminates a novel viewpoint on one-step in-situ route to prepare Zn2SnO4-based heterojunction photocatalyst with deep oxidation ability of NO-to-NO3-.

Visible Light Enhancement of Biocarbon Quantum-Dot-Decorated TiO2 for Naphthalene Removal

In this study, carbon-quantum-dot (CQD)-decorated TiO2 was prepared using an ultrasonic doping method and applied in the photocatalytic degradation of naphthalene under sunlight irradiation. The CQDs were synthesized from a typical macroalgae via diluted sulfuric acid pretreatment and hydrothermal synthesis using an optimal design, i.e., 3 wt% and 200 °C, respectively. The CQD/TiO2 composite remarkably enhanced the photocatalytic activity. The degradation of naphthalene under a visible light environment indicated that there is a synergistic mechanism between the CQDs and TiO2, in which the generation of reactive oxygen species is significantly triggered; in addition, the N that originated from the macroalgae accelerated the photocatalytic efficiency. Kinetic analysis showed that the photocatalytic behavior of the CQD/TiO2 composite followed a pseudo-first-order equation. Consequently, our combined experimental approach not only provides a facile pretreatment process for bio-CQDs synthesis, but also delivers a suitable TiO2 photocatalyst for the visible environment along with critical insights into the development of harmful macroalgae resources.

Recent progress in defect-engineered metal oxides for photocatalytic environmental remediation

Rapid industrial advancement over the last few decades has led to an alarming increase in pollution levels in the ecosystem. Among the primary pollutants, harmful organic dyes and pharmaceutical drugs are directly released by industries into the water bodies which serves as a major cause of environmental deterioration. This warns of a severe need to find some sustainable strategies to overcome these increasing levels of water pollution and eliminate the pollutants before being exposed to the environment. Photocatalysis is a well-established strategy in the field of pollutant degradation and various metal oxides have been proven to exhibit excellent physicochemical properties which makes them a potential candidate for environmental remediation. Further, with the aim of rapid industrialization of photocatalytic pollutant degradation technology, constant efforts have been made to increase the photocatalytic activity of various metal oxides. One such strategy is the introduction of defects into the lattice of the parent catalyst through doping or vacancy which plays a major role in enhancing the catalytic activity and achieving excellent degradation rates. This review provides a comprehensive analysis of defects and their role in altering the photocatalytic activity of the material. Various defect-rich metal oxides like binary oxides, perovskite oxides, and spinel oxides have been summarized for their application in pollutant degradation. Finally, a summary of existing research, followed by the existing challenges along with the potential countermeasures has been provided to pave a path for the future studies and industrialization of this promising field.

Facile fabrication of Ag decorated MnFeO3 catalyst: Comparative analysis of visible light driven antibiotic reduction and antibacterial performance

Photocatalysis is an effective method with the potential to eliminate pharmaceutical compounds from water sources. Manganese ferrite (MnFeO3), a type of multiferroic perovskite catalyst, has attracted significant attention due to its small band gap, however its application was limited due to its high recombination rate and low quantum efficiency. It was therefore aimed to improve the properties of MnFeO3 by doping silver (Ag)-particles. In this study, Ag-MnFeO3 photocatalysts with different Ag content (1-3 mmol%) were synthesized by performing a facile hydrothermal method. The as-prepared samples were characterized using x-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (DRS), photoluminescence spectroscopy (PL), electrochemical impedance spectroscopy (EIS) and Brunauer-Emmett-Teller (BET) method, showing successful addition of Ag-particles with the MnFeO3 structure. Then, the as-synthesized materials were investigated as: (i) photocatalysts for degradation tetracycline (TC) antibiotic and (ii) antibacterial agents for bacteria. The Ag-MnFeO3 catalyst demonstrated superior catalytic performance (95.7%), which was 1.6 times higher than that of pristine MnFeO3 (59.7%). The positive effect was ascribed to oxygen vacancies, enhanced light absorption ability, and lower recombination rate. The Ag-MnFeO3 catalyst also showed satisfactory removal performances in real water matrices. Furthermore, radical trapping tests depicted that the superoxide radicals played a dominant role in the photodegradation system. In addition, Box-Behnken design (BBD) was performed to determine the optimum conditions, which were determined as catalyst dosage of 0.45 g/L, initial TC concentration of 5.10 mg/L, and initial solution pH value of 3.69. In terms of antibacterial tests, the incorporation of Ag into the MnFeO3 structure greatly increased the antimicrobial resistance against bacteria. Our findings disclose that the incorporation of Ag into the MnFeO3 structure can be regarded as a feasible and promising approach to improve both photocatalytic degradation and antibacterial performances.

Efficient visible light-driven photodegradation of glyphosate utilizing Bi2WO6 with oxygen vacancies: Performance, mechanism, and toxicity assessment

Global environmental deterioration poses a major risk to ecological security and human health, and emerging technologies are urgently needed to deal with it. Therefore, the exploitation of photocatalysts with favorable activity for efficient degradation of pesticide contaminants is one of the strategies to achieve environmental remediation. Herein, oxygen vacancy-rich Bi2WO6 (Ov-BWO) was prepared through a solvothermal method utilizing ethylene glycol (EG), which exhibited excellent photocatalytic efficiency in photodegradation of glyphosate. The formation of oxygen vacancies (Ovs) in Ov-BWO was demonstrated utilizing XPS and EPR. PL, TRPL, photocurrent tests, and EIS analyses revealed that Ovs accelerated effective transfer of photogenerated charge, extended lifetime of charge carriers, promoted production of active species and significantly improved the photocatalytic performance. Compared with the low-activity Bi2WO6 (BWO, 59.6%), Ov-BWO showed outstanding photocatalytic activity, achieving a degradation efficiency of 91% for glyphosate at 120 min of visible light irradiation. Moreover, Ov-BWO also displayed outstanding recyclable stability after four repeated uses. Based on the characterization of photoelectric properties, a feasible photocatalytic reaction was put forth, along with glyphosate degradation pathways. Furthermore, the degradation intermediates of glyphosate were analyzed in detail employing HPLC-MS. The toxicity assessment indicated that degraded products had been proven to be non-toxic to the ecological system. This work presents the potential of photocatalysts with Ovs for the photodegradation of pesticides, providing a viable strategy for environmental renovation.

Enhanced metal-free photocatalyst performance by synergistic Coupling of internal magnetic field and piezoelectric field

Graphitic carbon nitride (g-C3N4) is a promising metal-free photocatalyst; however, its high carrier recombination rate and insufficient redox capacity limit its degradation effect on antibiotics. In order to overcome these shortcomings, the photocatalytic activity is improved by regulating the spin polarization state, constructing the internal electric field, and applying the external piezoelectric field. In this paper, the chlorine-doped and nitrogen-deficient porous carbon nitride composite carbon quantum dots (Nv-Cl/UPCN@CQD) has been synthesized successfully. The doping position of chlorine and spin polarization properties are verified by DFT calculation. The key intermediates *O2- and *OOH for the synthesis of reactive oxygen species were detected by in-situ infrared testing, which promotes the production of •O2- and H2O2. The degradation rate constant of Nv-Cl/UPCN@CQD for removal of tetracycline is 8.45 times higher than that of g-C3N4. The active oxygen production and degradation efficiency of piezoelectric photocatalysis under the synergistic effect of intense stirring and vis-light irradiation are much higher than those of photocatalysis and piezoelectric catalysis, and the conversion of H2O2 to •OH is promoted by piezoelectric field. This paper provides a reliable way to improve the performance of piezoelectric photocatalysts by adjusting their energy band, electronic structure and piezoelectric force.

Efficient photocatalytic NO removal with inhibited NO2 formation and catalyst loss over sponge-supported and functionalized g-C3N4

Though photocatalytic purification of NO has been widely studied, how to avoid secondary pollution during gas-solid reaction is still a challenge, especially in inhibiting the formation of toxic intermediates (NO2) and avoiding the blow away of powdery photocatalyst. Herein, we proposed a one-step solvothermal method to prepare melamine sponge (MS) supported and functionalized g-C3N4 (CN), which simultaneously realizes the inhibition of NO2 formation and catalyst loss. Sodium hydroxide, which plays a dual role, has been introduced during the preparation of supported photocatalyst. Specifically, sodium atom, as the modifier of performance, could facilitate the randomly distributed charge of pristine CN to be converged, which accelerates the adsorption/activation of reactants for efficient and deep NO oxidation. Hydroxyl group, as the binder between CN and MS, induces the interaction by forming hydrogen bonds, which contributes to the firm immobilization of powdery photocatalyst. The supported sample exhibits outstanding NO removal rate (58.90%) and extremely low NO2 generation rate (1.41%), and the mass loss rate of photocatalyst before and after reaction is less than 1%. The promotion mechanism of performance also has been elaborated. This work takes environmental risks as a prerequisite to propose a feasible strategy for perfecting the practical application of photocatalytic technology.

Designing Z-scheme In2O3 @ZnIn2S4 core-shell heterojunctions for enhanced photocatalytic multi-pollutant removal

In water bodies, the coexistence of and interaction between multiple pollutants complicate remediation. In this study, the In2O3 @ZnIn2S4 Z-scheme heterojunction with a stratified core-shell structure was constructed and used to remove multiple pollutants (tetracycline hydrochloride and Cr(VI)). The large number of active sites and the mechanism of photogenerated charge separation ensured the substantially enhanced catalytic activity of this photocatalyst, making it superior to In2O3 nanospheres and pure ZnIn2S4. The optimised In2O3 @ZnIn2S4 nano-flowers (In2O3 @ZnIn2S4 NFs) realised 99.8% removal of tetracycline hydrochloride and 100% removal of Cr(VI) within 60 min under visible-light. The material's high stability was demonstrated by five experiment cycles. Effects of organics, inorganics, and pH about the photocatalytic performance of the optimised In2O3 @ZnIn2S4 NFs when tetracycline hydrochloride and Cr(VI) coexist were also explored. Finally, the intermediates and degradation pathways were analysed, and the possible photocatalytic mechanism was also investigated by performing density functional theory calculations.

A systematic review on Nb2O5-based photocatalysts: Crystallography, synthetic methods, design strategies, and photocatalytic mechanisms

With the increasing popularity of photocatalytic technology and the highly growing issues of energy scarcity and environmental pollution, there is an increasing interest in extremely efficient photocatalytic systems. The widespread immense attention and applicability of Nb2O5 photocatalysts can be attributed to their multiple benefits, including strong redox potentials, non-toxicity, earth abundance, corrosion resistance, and efficient thermal and chemical stability. However, the large-scale application of Nb2O5 is currently impeded by the barriers of rapid recombination loss of photo-activated electron/hole pairs and the inadequacy of visible light absorption. To overcome these constraints, plentiful design strategies have been directed at modulating the morphology, electronic band structure, and optical properties of Nb2O5. The current review offers an extensive analysis of Nb2O5-based photocatalysts, with a particular emphasis on crystallography, synthetic methods, design strategies, and photocatalytic mechanisms. Finally, an outline of future research directions and challenges in developing Nb2O5-based materials with excellent photocatalytic performance is presented.

Facile synthesis of multi-layer Co(OH)2/CeO2-g-C3N4 ternary synergistic heterostructure for efficient photocatalytic oxidation of NO under visible light

In this work, we report a one-step synthesis of ternary Z-scheme Co(OH)2/CeO2-g-C3N4 (CoCe-CN) heterostructure via hydrothermal method. Owing to the modification of Co(OH)2 and CeO2, the existence of Co(OH)2 as an electron acceptor-donor center between CeO2 and g-C3N4 accelerates the electron transfer and provides extra OH- reaction pathway for photocatalytic oxidation of NO. As a result, 50CoCe-CN (Co and Ce accounting for 25% mass ratio separately) achieved a 53.5% conversion efficiency of NO at 600 ppb concentration, which is 1.82 times that of g-C3N4 under visible light. The results of the DFT analysis and element distribution of cobalt and ceria provide convincing evidence supporting the existence of a novel multi-layer structure in the CoCe-CN photocatalyst. This structure involves the loading of CeO2 and Co(OH)2 on the g-C3N4 surface, and Co(OH)2 as a co-catalyst introduced between CeO2 and g-C3N4 realizes the synergy between CeO2 and Co(OH)2 which further improve the photocatalytic properties. The higher photocatalytic efficiencies observed in the CoCe-CN photocatalysts compared to those containing only cobalt (Co-CN) or ceria (Ce-CN) provide further evidence of the synergistic effect of these two elements. This work demonstrates a more efficient and effective ternary photocatalytic system, with greater practical potential for photocatalytic oxidation of NO.

Unraveling the potential of sonochemically achieved DyMnO3/Dy2O3 nanocomposites as highly efficient visible-light-driven photocatalysts in decolorization of organic contamination

In the present day, the widespread presence of lingering contaminants in ecosystems has prompted scientists to develop novel semiconductor nanoarchitectures that assist in photocatalytic reactions mediated by visible light. As a result, we propose to prepare a series of Dy-Mn-O based nano-catalysts using a sonochemical approach utilizing various ionic phases of surfactants as structure-directing agents. In this study, X-ray diffraction (XRD) and Rietveld refinement techniques were used to explore the fundamental effects of surfactants on the compositional-structural features of the materials. In terms of morphological profiles, DyMnO3/Dy2O3 (DM) nanostructures fabricated with Triton X-80 as a structure-directing agent showed the best uniformity with an acceptable size range between 14.14 and 52.35 nm. In the visible-light-driven photocatalytic domain, these nanocomposites provide high responsiveness based on their optical band gap value of 2.0 eV. According to our findings, two individual factors affect dye activity, namely dye type and concentration, which is why a high decomposition efficiency of 78.8% was obtained for 10 ppm Acid violet (AV) using DyMnO3/Dy2O3 nanocomposites after 120 min of exposure to visible light. Furthermore, radical quenching test confirmation confirmed the mechanistic behind the degradation process. This indicates that active species of O2•- and •OH may play a significant role in photocatalysis. As a result of repeated processes over three consecutive cycles, binary DyMnO3/Dy2O3 nanocomposites had an efficiency of 64.4% in removing dyes from the environment, indicating their high stability.

Digital health utilities in acute kidney injury management

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a highly prevalent clinical syndrome that substantially impacts patient outcomes. It is accepted by the clinical communities that the management of AKI is time-sensitive. Unfortunately, despite growing proof of its preventability, AKI management remains suboptimal in community, acute care, and postacute care settings. Digital health solutions comprise various tools and models to improve care processes and patient outcomes in multiple medical fields. AKI development, progression, recovery, or lack thereof, offers tremendous opportunities for developing, validating, and implementing digital health solutions in multiple settings. This article will review the definitions and components of digital health, the characteristics of AKI that allow digital health solutions to be considered, and the opportunities and threats in implementing these solutions.

RECENT FINDINGS

Over the past two decades, the academic output related to the use of digital health solutions in AKI has exponentially grown. While this indicates the growing interest in the topic, most topics are primarily related to clinical decision support by detecting AKI within hospitals or using artificial intelligence or machine learning technologies to predict AKI within acute care settings. However, recently, projects to assess the impact of digital health solutions in more complex scenarios, for example, managing nephrotoxins among adults of pediatric patients who already have AKI, is increasing. Depending on the type of patients, chosen digital health solution intervention, comparator groups, and selected outcomes, some of these studies showed benefits, while some did not indicate additional gain in care processes or clinical outcomes.

SUMMARY

Careful needs assessment, selection of the correct digital health solution, and appropriate clinical validation of the benefits while avoiding additional health disparities are moral, professional, and ethical obligations for all individuals using these healthcare tools, including clinicians, data scientists, and administrators.

Vacancy pairs regulate BiOBr microstructure for efficient dimethyl phthalate removal under visible light irradiation

Developing new photocatalysts to achieve efficient removal of phthalate esters (PAEs) in water is an important research task in environmental science. However, existing modification strategies for photocatalysts often focus on enhancing the efficiency of material photogenerated charge separation, neglecting the degradation characteristics of PAEs. In this work, we proposed an effective strategy for the photodegradation process of PAEs: introducing vacancy pair defects. We developed a BiOBr photocatalyst containing "Bi-Br" vacancy pairs, and confirmed that it has an excellent photocatalytic activity in removing phthalate esters (PAEs). Through a combination of experimental and theoretical calculations, it is proved that "Bi-Br" vacancy pairs can not only improve the charge separation efficiency, but also alter the adsorption configuration of O₂, thus accelerating the formation and transformation of reactive oxygen species. Moreover, "Bi-Br" vacancy pairs can effectively improve the adsorption and activation of PAEs on the surface of samples, surpassing the effect of O vacancies. This work enriches the design concept of constructing highly active photocatalysts based on defect engineering, and provides a new idea for the treatment of PAEs in water.