Carbonaceous Materials-Based Photothermal Process in Water Treatment: From Originals to Frontier Applications.

The photothermal process has attracted considerable attention in water treatment due to its advantages of low energy consumption and high efficiency. In this respect, photothermal materials play a crucial role in the photothermal process. Particularly, carbonaceous materials have emerged as promising candidates for this process because of exceptional photothermal performance. While previous research on carbonaceous materials has primarily focused on photothermal evaporation and sterilization, there is now a growing interest in exploring the potential of photothermal effect-assisted advanced oxidation processes (AOPs). However, the underlying mechanism of the photothermal effect assisted by carbonaceous materials remains unclear. This review aims to provide a comprehensive review of the photothermal process of carbonaceous materials in water treatment. It begins by introducing the photothermal properties of carbonaceous materials, followed by a discussion on strategies for enhancing these properties. Then, the application of carbonaceous materials-based photothermal process for water treatment is summarized. This includes both direct photothermal processes such as photothermal evaporation and sterilization, as well as indirect photothermal processes that assisted AOPs. Meanwhile, various mechanisms assisted by the photothermal effect are summarized. Finally, the challenges and opportunities of using carbonaceous materials-based photothermal processes for water treatment are proposed.

Strategies for Enhancing the Photocatalytic and Electrocatalytic Efficiency of Covalent Triazine Frameworks for CO2 Reduction.

Converting carbon dioxide (CO2) into fuel and high-value-added chemicals is considered a green and effective way to solve global energy and environmental problems. Covalent triazine frameworks (CTFs) are extensively utilized as an emerging catalyst for photo/electrocatalytic CO2 reduction reaction (CO2RR) recently recognized for their distinctive qualities, including excellent thermal and chemical stability, π-conjugated structure, rich nitrogen content, and a strong affinity for CO2, etc. Nevertheless, single-component CTFs have the problems of accelerated recombination of photoexcited electron-hole pairs and restricted conductivity, which limit their application for photo/electrocatalytic CO2RR. Therefore, emphasis will then summarize the strategies for enhancing the photocatalytic and electrocatalytic efficiency of CTFs for CO2RR in this paper, including atom doping, constructing a heterojunction structure, etc. This review first illustrates the synthesis strategies of CTFs and the advantages of CTFs in the field of photo/electrocatalytic CO2RR. Subsequently, the mechanism of CTF-based materials in photo/electrocatalytic CO2RR is described. Lastly, the challenges and future prospects of CTFs in photo/electrocatalytic CO2RR are addressed, which offers a fresh perspective for the future development of CTFs in photo/electrocatalytic CO2RR.

Copper Single-Atom Catalysts-A Rising Star for Energy Conversion and Environmental Purification: Synthesis, Modification, and Advanced Applications.

Future renewable energy supply and green, sustainable environmental development rely on various types of catalytic reactions. Copper single-atom catalysts (Cu SACs) are attractive due to their distinctive electronic structure (3d orbitals are not filled with valence electrons), high atomic utilization, and excellent catalytic performance and selectivity. Despite numerous optimization studies are conducted on Cu SACs in terms of energy conversion and environmental purification, the coupling among Cu atoms-support interactions, active sites, and catalytic performance remains unclear, and a systematic review of Cu SACs is lacking. To this end, this work summarizes the recent advances of Cu SACs. The synthesis strategies of Cu SACs, metal-support interactions between Cu single atoms and different supports, modification methods including modification for carriers, coordination environment regulating, site distance effect utilizing, and dual metal active center catalysts constructing, as well as their applications in energy conversion and environmental purification are emphatically introduced. Finally, the opportunities and challenges for the future Cu SACs development are discussed. This review aims to provide insight into Cu SACs and a reference for their optimal design and wide application.

The Collision between g-C3 N4 and QDs in the Fields of Energy and Environment: Synergistic Effects for Efficient Photocatalysis.

Recently, graphitic carbon nitride (g-C3 N4 ) has attracted increasing interest due to its visible light absorption, suitable energy band structure, and excellent stability. However, low specific surface area, finite visible light response range (<460 nm), and rapid photogenerated electron-hole (e- -h+ ) pairs recombination of the pristine g-C3 N4 limit its practical applications. The small size of quantum dots (QDs) endows the properties of abundant active sites, wide absorption spectrum, and adjustable bandgap, but inevitable aggregation. Studies have confirmed that the integration of g-C3 N4 and QDs not only overcomes these limitations of individual component, but also successfully inherits each advantage. Encouraged by these advantages, the synthetic strategies and the fundamental of QDs/g-C3 N4 composites are briefly elaborated in this review. Particularly, the synergistic effects of QDs/g-C3 N4 composites are analyzed comprehensively, including the enhancement of the photocatalytic performance and the avoidance of aggregation. Then, the photocatalytic applications of QDs/g-C3 N4 composites in the fields of environment and energy are described and further combined with DFT calculation to further reveal the reaction mechanisms. Moreover, the stability and reusability of QDs/g-C3 N4 composites are analyzed. Finally, the future development of these composites and the solution of existing problems are prospected.

Ultrahigh Performance H2 O2 Generation by Single-Atom Fe Catalysts with N/O Bidentate Ligand via Oxalic Acid and Oxygen Molecules Activation.

Single-atom catalysts (SACs) for photocatalytic hydrogen peroxide (H2 O2 ) generation are researched but it is still challenging to obtain high H2 O2 yields. Herein, graphite carbon nitride (FeSA /CN) confined single Fe atoms with N/O coordination is prepared, and FeSA /CN shows high H2 O2 production via oxalic acid and O2 activation. Under visible light illumination, the concentration of H2 O2 generated by FeSA /CN can achieve 40.19 mM g-1 h-1 , which is 10.44 times higher than that of g-C3 N4 . The enhanced H2 O2 generation can be attributed to the formation of metal-organic complexes and rapid electron transfer. Moreover, the O2 activation of photocatalysts is revealed by 3,3',5,5'-tetramethylbenzidine oxidation. The results display that the O2 activation capacity of FeSA /CN is higher than that of g-C3 N4 , which facilitates the formation of H2 O2 . Finally, density functional theory calculation demonstrates that O2 is chemically adsorbed on Fe atomic sites. The adsorption energy of O2 is enhanced from -0.555 to -1.497 eV, and the bond length of OO is extended from 1.235 to 1.292 Å. These results exhibit that the confinement of single Fe atoms can promote O2 adsorption and activation. Finally, the photocatalytic mechanism is elaborated, which provides a deep understanding for SACs-catalyzed H2 O2 generation.

How Do Enzymes 'Meet' Nanoparticles and Nanomaterials?

Enzymes are fundamental biological catalysts responsible for biological regulation and metabolism. The opportunity for enzymes to 'meet' nanoparticles and nanomaterials is rapidly increasing due to growing demands for applications in nanomaterial design, environmental monitoring, biochemical engineering, and biomedicine. Therefore, understanding the nature of nanomaterial-enzyme interactions is becoming important. Since 2014, enzymes have been used to modify, degrade, or make nanoparticles/nanomaterials, while numerous nanoparticles/nanomaterials have been used as materials for enzymatic immobilization and biosensors and as enzyme mimicry. Among the various nanoparticles and nanomaterials, metal nanoparticles and carbon nanomaterials have received extensive attention due to their fascinating properties. This review provides an overview about how enzymes meet nanoparticles and nanomaterials.

MXenes as Superexcellent Support for Confining Single Atom: Properties, Synthesis, and Electrocatalytic Applications.

Single atom catalysts (SACs) have shown their noticeable potential and gradually become a new favorite in catalytic field due to the particular selectivity, high catalytic performance, and strong durability. The most important factor in the synthesis of SACs is the selection of appropriate support and formation of metal-support interaction. Among a large number of nanomaterials, MXenes can be utilized as benign supports for fixing SACs because of their expansive specific surface area, regulable bandgap, superior electronic conductivity, and strong mechanical stability. The structure and property of MXenes can be manipulated by changing transition metal elements and surface termination. Here, the uniqueness and superiority of MXenes as superexcellent supports for confining SACs are analyzed from structure and property. The synthetic strategy of MXene-supported SACs is also summarized, especially emphasizing the immobilization of isolated atom against aggregation by utilizing the formidable metal-support covalent coordination interaction. In addition, the applications of MXene-supported SACs in electrocatalytic field are highlighted, including hydrogen evolution reaction, oxygen evolution reaction, overall water splitting, oxygen reduction reaction, and nitrogen reduction reaction. Finally, the challenges and prospects are pointed out for the further understanding and practical application of MXene-supported SACs in electrocatalysis.

Recent development of advanced biotechnology for wastewater treatment.

The importance of highly efficient wastewater treatment is evident from aggravated water crises. With the development of green technology, wastewater treatment is required in an eco-friendly manner. Biotechnology is a promising solution to address this problem, including treatment and monitoring processes. The main directions and differences in biotreatment process are related to the surrounding environmental conditions, biological processes, and the type of microorganisms. It is significant to find suitable biotreatment methods to meet the specific requirements for practical situations. In this review, we first provide a comprehensive overview of optimized biotreatment processes for treating wastewater during different conditions. Both the advantages and disadvantages of these biotechnologies are discussed at length, along with their application scope. Then, we elaborated on recent developments of advanced biosensors (i.e. optical, electrochemical, and other biosensors) for monitoring processes. Finally, we discuss the limitations and perspectives of biological methods and biosensors applied in wastewater treatment. Overall, this review aims to project a rapid developmental path showing a broad vision of recent biotechnologies, applications, challenges, and opportunities for scholars in biotechnological fields for "green" wastewater treatment.

Recent advances in covalent organic frameworks (COFs) as a smart sensing material.

As a newly emerging kind of porous material, covalent organic frameworks (COFs) have drawn much attention because of their fascinating structural features (e.g., divinable structure, adjustable porosity and total organic backbone). Since the seminal work of Yaghi and co-workers reported in 2005, the COF materials have shown superior potential in diverse applications, such as gas storage, adsorption, optoelectronics, catalysis, etc. Recently, COF materials have shown a new trend in sensing fields. This critical review briefly describes the synthesis routes for COF powders and thin films. What's more, the most fascinating and significant applications of COFs in sensing fields including explosive sensing, humidity sensing, pH detection, biosensing, gas sensing, metal ion sensing, and other substance sensing are summarized and highlighted. Finally, the major challenges and future trends of COFs with respect to their preparation and sensing applications are discussed.

Recent progress in covalent organic framework thin films: fabrications, applications and perspectives.

As a newly emerging class of porous materials, covalent organic frameworks (COFs) have attracted much attention due to their intriguing structural merits (e.g., total organic backbone, tunable porosity and predictable structure). However, the insoluble and unprocessable features of bulk COF powder limit their applications. To overcome these limitations, considerable efforts have been devoted to exploring the fabrication of COF thin films with controllable architectures, which open the door for their novel applications. In this critical review, we aim to provide the recent advances in the fabrication of COF thin films not only supported on substrates but also as free-standing nanosheets via both bottom-up and top-down strategies. The bottom-up strategy involves solvothermal synthesis, interfacial polymerization, room temperature vapor-assisted conversion, and synthesis under continuous flow conditions; whereas, the top-down strategy involves solvent-assisted exfoliation, self-exfoliation, mechanical delamination, and chemical exfoliation. In addition, the applications of COF thin films including energy storage, semiconductor devices, membrane-separation, sensors, and drug delivery are summarized. Finally, to accelerate further research, a personal perspective covering their synthetic strategies, mechanisms and applications is presented.

Peroxidase-Like Activity of Smart Nanomaterials and Their Advanced Application in Colorimetric Glucose Biosensors.

Diabetes is a dominating health issue with 425 million people suffering from the disease worldwide and 4 million deaths each year. To avoid further complications, the diabetic patient blood glucose level should be strictly monitored despite there being no cure for diabetes. Colorimetric biosensing has attracted significant attention because of its low cost, simplicity, and practicality. Recently, some nanomaterials have been found that possess unexpected peroxidase-like activity, and great advances have been made in fabricating colorimetric glucose biosensors based on the peroxidase-like activity of these nanomaterials using glucose oxidase. Compared with natural horseradish peroxidase, the nanomaterials exhibit flexibility in structure design and composition, and have easy separation and storage, high stability, simple preparation, and tunable catalytic activity. To highlight the significant progress in the field of nanomaterial-based peroxidase-like activity, this work discusses the various smart nanomaterials that mimic horseradish peroxidase and its mechanism and development history, and the applications in colorimetric glucose biosensors. Different approaches for tunable peroxidase-like activity of nanomaterials are summarized, such as size, morphology, and shape; surface modification and coating; and metal doping and alloy. Finally, the conclusion and challenges facing peroxidase-like activity of nanomaterials and future directions are discussed.

Black Phosphorus, a Rising Star 2D Nanomaterial in the Post-Graphene Era: Synthesis, Properties, Modifications, and Photocatalysis Applications.

Semiconductor photocatalysis, a sustainable and renewable technology, is deemed to be a new path to resolve environmental pollution and energy shortage. The development of effective photocatalysts, especially the metal-free photocatalysts, is a critical determinant of this technique. The recently emerged 2D material of black phosphorus with distinctive properties of tunable direct bandgap, ultrahigh charge mobility, fortified optical absorption, large specific surface area, and anisotropic structure has captured enormous attention since the first exfoliation of bulk black phosphorus into mono- or few layered phosphorene in 2014. In this article, the state-of-the-art preparation methods are first summarized for bulk black phosphorus, phosphorene, and black phosphorus quantum dot and then the fundamental structure and electronic and optical properties are analyzed to evaluate its feasibility as a metal-free photocatalyst. Various modifications on black phosphorus are also summarized to enhance its photocatalytic performance. Furthermore, the multifarious applications such as solar to energy conversion, organic removal, disinfection, nitrogen fixation, and photodynamic therapy are discussed and some of the future challenges and opportunities for black phosphorus research are proposed. This review reveals that the rising star of black phosphorus will be a multifunctional material in the postgraphene era.

Electrochemical biosensor for amplified detection of Pb2+ based on perfect match of reduced graphene oxide-gold nanoparticles and single-stranded DNAzyme.

In this study, a sensitive amplification strategy for Pb2+ detection using reduced graphene oxide (RGO) and gold nanoparticles (AuNPs) was proposed. Thiol-modified DNAzyme is specific for Pb2+ self-assembly on RGO-AuNPs-modified electrode surface. Ferrocene labeled single-stranded DNAzyme (Fc-ssDNAzyme) self-hybridizes to form a DNA hairpin structure. The amount of Fc adsorbed on the electrode surface changes after the appearance of Pb2+, leading to a change of electrical signal. This change can be sensitively identified by differential pulse voltammetry (DPV) assisted by ferricyanide ([Fe(CN)6]3-/4-) in the electrolyte. The high conductivity and specific surface area of RGO and the strong chemical bond adsorption effect between DNAzyme and AuNPs are responsible for the amplified detection of Pb2+, which realize a detection range of 0.05-400,000.0 nM and a minimum detection limit of 0.015 nM. Moreover, the selectivity test results indicated that the biosensor had specificity for Pb2+, even if there was interference from other high-concentration metal ions. This simple biosensor also exhibited good responsiveness in actual sample detection, which provides a good application prospect for field detection of Pb2+ in water. Graphical abstract.

Tween 80 surfactant-enhanced bioremediation: toward a solution to the soil contamination by hydrophobic organic compounds.

The occurrence of hydrophobic organic compounds (HOCs) in the soil has become a highly significant environmental issue. This problem has been exacerbated by the strong sorption of HOCs to the soils, which makes them unavailable for most remediation processes. More and more works show that surfactant-enhanced biological technologies offer a great potential to clear up HOCs-contaminated soils. This article is a critical review of HOCs removal from soils using Tween 80 (one of the mostly used nonionic surfactants) aided biological remediation technologies. The review begins with a discussion of the fundamentals of Tween 80-enhanced desorption of HOCs from contaminated soils, with special emphasis on the biotoxicity of Tween 80. Successful results obtained by Tween 80-enhanced microbial degradation and phytoremediation are documented and discussed in section 3 and section 4, respectively. Results show Tween 80-enhanced biotechnologies are promising for treating HOCs-contaminated soils. However, considering the fact that most of these scientific studies have only been conducted at the laboratory-scale, many improvements are required before these technologies can be scaled up to the full-scale level. Moreover, further research on mechanisms related to the interaction of Tween 80 with degrading microorganisms and the plants is in high demand.

Colorimetric determination of mercury(II) using gold nanoparticles and double ligand exchange.

A colorimetric assay is described for highly selective and sensitive determination of Hg(II) ions by using gold nanoparticles (AuNPs) functionalized with dithioerythritol (DETL). This method relies on the unique optical properties of DETL-functionalized AuNPs as well as the thiophilicity of both AuNPs and Hg(II). In the presence of DETL, the AuNPs aggregate due to ligand exchange between thiol groups of DETL and the citrate ions on the surface of AuNPs. This induces a color change from red to blue. On addition of Hg(II), the thiol groups preferably interact with Hg(II) rather than with AuNPs. Thus, the DETL is released from the surface of the AuNPs and binds to Hg(II). This triggers the redispersion of the AuNPs. The ratio of absorbances at 650 and 525 nm drops linearly in two Hg(II) concentration ranges (viz. from 0.1 to 0.5 µM, and from 0.5 to 5 µM). The ions Cu(II), Pb(II), and Cd(II) do not interfere even in the absence of masking agents. The detection limit is as low as 24 nM. Graphical abstract A highly selective colorimetric method based on gold nanoparticles via double ligand exchange reaction is described for determination of Hg2+. This assay can selective detect Hg2+ with no response to major interfering metal ions such as Cu2+, Pb2+, and Cd2+ in the absence of masking agents compared with previous works.

Molecular docking simulation on the interactions of laccase from Trametes versicolor with nonylphenol and octylphenol isomers.

The biodegradation of nonylphenol (NP) and octylphenol (OP) isomers by laccase has attracted increasing concerns. However, the interaction mechanism between these isomers and laccase remains unclear, especially for fungal laccase. In this work, molecular docking was employed to study this issue. The results indicated that the structural characteristic of alkyl chain (position and branching degree) affected the interactions between Trametes versicolor (T. versicolor) laccase and isomers. The binding affinity between them was closely related to the position and branching degree of alkyl chain in isomers. The binding affinities between linear isomers and T. versicolor laccase were para-position < meta-position < ortho-position. For selected branched 4-NP, the isomers with bulky α-substituent in alkyl chain had higher binding affinities. In addition, hydrophobic contacts between T. versicolor laccase and NP or OP isomers were necessary, while H-bonds were optional. The isomers with similar structure may have more common residues involved in hydrophobic contacts. The H-bonds of selected NPs and OPs were all connected with phenolic hydroxyl. These findings provide an insight into detailed interaction mechanism between T. versicolor laccase and isomers of NP and OP. It is helpful to broaden the knowledge of degradation technology of NPs and OPs and provide theoretical basis on biological remediation of these contaminants.

Effects of calcium at toxic concentrations of cadmium in plants.

MAIN CONCLUSION: This review provides new insight that calcium plays important roles in plant growth, heavy metal accumulation and translocation, photosynthesis, oxidative damage and signal transduction under cadmium stress. Increasing heavy metal pollution problems have raised word-wide concerns. Cadmium (Cd), being a highly toxic metal, poses potential risks both to ecosystems and human health. Compared with conventional technologies, phytoremediation, being cost-efficient, highly stable and environment-friendly, is believed to be a promising green technology for Cd decontamination. However, Cd can be easily taken up by plants and may cause severe phytotoxicity to plants, thus limiting the efficiency of phytoremediation. Various researches are being done to investigate the effects of exogenous substances on the mitigation of Cd toxicity to plants. Calcium (Ca) is an essential plant macronutrient that involved in various plant physiological processes, such as plant growth and development, cell division, cytoplasmic streaming, photosynthesis and intracellular signaling transduction. Due to the chemical similarity between Ca and Cd, Ca may mediate Cd-induced physiological or metabolic changes in plants. Recent studies have shown that Ca could be used as an exogenous substance to protect plants against Cd stress by the alleviation of growth inhibition, regulation of metal uptake and translocation, improvement of photosynthesis, mitigation of oxidative damages and the control of signal transduction in the plants. The effects of Ca on toxic concentrations of Cd in plants are reviewed. This review also provides new insight that plants with enhanced Ca level have improved resistance to Cd stress.

The interactions of composting and biochar and their implications for soil amendment and pollution remediation: a review.

Compost and biochar, used for the remediation of soil, are seen as attractive waste management options for the increasing volume of organic wastes being produced. This paper reviews the interaction of biochar and composting and its implication for soil amendment and pollution remediation. The interaction of biochar and composting affect each other's properties. Biochar could change the physico-chemical properties, microorganisms, degradation, humification and gas emission of composting, such as the increase of nutrients, cation exchange capacity (CEC), organic matter and microbial activities. The composting could also change the physico-chemical properties and facial functional groups of biochar, such as the improvement of nutrients, CEC, functional groups and organic matter. These changes would potentially improve the efficiency of the biochar and composting for soil amendment and pollution remediation. Based on the above review, this paper also discusses the future research required in this field.

Manganese-enhanced degradation of lignocellulosic waste by Phanerochaete chrysosporium: evidence of enzyme activity and gene transcription.

Lignolytic fungi initiate lignocellulose decay by producing extracellular oxidative enzymes. For better understanding the enzymatic degradation of lignocellulose by white-rot fungi, we investigated the effect of manganese on the organic matter loss, manganese peroxidase (MnP) activity, and manganese peroxidase gene (mnp) transcription levels during solid-state fermentation of rice straw with Phanerochaete chrysosporium. The results showed that the addition of manganese improved MnP activity and made it reach the peak earlier, promoted fungal growth at the early period (0-9 days), and enhanced the degradation of lignocellulosic waste. The total organic matter loss had a good correlation with fungal biomass during 30 days of cultivation, and manganese amendment promoted the ability of P. chrysosporium to degrade lignocellulose. Quantitative real-time RT-PCR revealed the differential expression of mnp1, mnp2, and mnp3: manganese amendment increased the transcription of mnp1 and mnp2 but not mnp3. The results indicated that manganese stimulated mnp transcription levels and played a post-transcriptional role in MnP production. These findings provide opportunity of development in enzymatic degradation of lignocellulosic waste by P. chrysosporium amended with manganese.

The rapid degradation of bisphenol A induced by the response of indigenous bacterial communities in sediment.

In the present study, sediment was spiked with bisphenol A (BPA) solution to explore the interaction between indigenous bacterial communities and BPA biodegradation in sediment. Results showed that BPA could be adsorbed to the sediment and then biodegraded rapidly. Biodegradation efficiency of BPA in treatments with 10 and 50 mg/L BPA reached 64.3 and 61.8% on the first day, respectively. Quantitative polymerase chain reaction and denaturing gradient gel electrophoresis analysis indicated that BPA affected the densities, species, and diversities of bacteria significantly. The response of bacterial community to BPA favored BPA biodegradation by promoting the growth of BPA-reducing bacteria and inhibiting other competitors. According to the results of sequencing, Pseudomonas and Sphingomonas played vital roles in the degradation of BPA. They presented over 73% of the original bacterial community, and both of them were promoted by BPA comparing with controls. Laccase and polyphenol oxidase contributed to the degradation of BPA and metabolic intermediates, respectively. This paper illustrates the rapid biodegradation of BPA induced by the response of indigenous bacterial communities to the BPA stress, which will improve the understandings of BPA degradation in sediment.