Geopolymer is a ceramic material, most often amorphous; finds applications in fire- and heat-resistant coatings and adhesives, medicines, refractory ceramics and binders, and manufacturing of ...radioactive waste container. Over the last decade, new cement based on geopolymers has been developed. Most relevant to this review is the fact that its porous nature and chemical similarity to zeolites is being employed for applications pertaining to wastewater treatment. Most of the work has been on the adsorptive treatment of water. However, using chemical reasoning and literature available we show that geopolymers have relevance for further activity on additional areas of relevance to waste water treatment such as photocatalysis, disinfection, and H2-energy production from waste water etc. These applications would depend strongly on the properties of geopolymers, which in turn would rely on the precursors employed and the synthetic methods used. The relevance of geopolymers for cleaner production is also highlighted. The use of fly ashes and metakaolin composites for the fabrication and surface tailoring of geopolymers (perhaps using relevant surfactants) is suggested as a plausible step in the right direction. Given the critical analysis of the state of the art, and the plausible directions identified, this article will benefit environmental scientists, engineers and chemists interested in deploying geopolymers for environmental remediation purposes. However moving forward, barriers are to be anticipated for the large scale implementation of geopolymers. Several barriers (e.g. legal, economical, technocrats and synthetic challenges) that are likely to hinder future research and translation are highlighted.
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•(i) Raw materials, and (ii) synthetic/process parameters influence geopolymer properties.•Properties relevant for H2-production and photodegradation are elaborated.•Filler-materials from wastes relevant for catalytic-enhancement are identified.•Heavy-metal removal using geopolymers: methods and mechanisms are elucidated.•Technology barriers of relevance to all stake holders are projected.
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•Lignin based antimicrobial hydrogel was synthesized for antimicrobial application.•Silver nanoparticles were incorporated to enhance the antimicrobial effect.•The hydrogel shows good ...antibacterial properties towards both S. aureus and E. coli.•The hydrogel displays low toxicity to cells.
Although antibiotics have been widely used, the problem of bacterial infection in the medical field still faces many challenges. In this study, we designed a new lignin based antimicrobial hydrogel for antimicrobial application. First, we grafted the amino group onto sodium lignin sulfonate through Mannich reaction to obtain lignin amine (LA), which can cross-link with poly(vinyl alcohol) (PVA) to form hydrogel. Then, silver nitrate solution is added to the formed gel pre-solution to be in situ reduced to silver nanoparticles. The enhanced effect of antibacterial properties due to lignin and silver nanoparticles endows the hydrogel enhanced antibacterial properties. The modification of sodium lignosulfonate and the crosslinking reaction between LA and PVA are confirmed by FTIR, while the content of nitrogen in LA is characterized by XPS. The SEM image of the hydrogel after lyophilization illustrates its internal porous network structure. The rheological test of hydrogel demonstrates its good strength and elasticity. The hydrogel exhibits good antibacterial properties in in vitro antibacterial experiments towards both S. aureus and E. coli, while toxicity tests using L929 cells demonstrated good biocompatibility of the hydrogel.
Electrocatalysis is an efficient and promising means of energy conversion, with minimal environmental footprint. To enhance reaction rates, catalysts are required to minimize overpotential. ...Alternatives to noble metal electrocatalysts are essential to address these needs on a large scale. In this context, transition metal nitride (TMN) nanoparticles have attracted much attention owing to their high catalytic activity, distinctive electronic structures, and enhanced surface morphologies. Nickel‐based materials are an ideal choice for electrocatalysts given nickel's abundance and low cost in comparison to noble metals. In this Minireview, advancements made specifically in Ni‐based binary and ternary TMNs as electrocatalysts for the oxygen evolution reaction (OER) are critically evaluated. When used as OER electrocatalysts, Ni‐based nanomaterials with 3 D architectures on a suitable support (e.g., a foam support) speed up electron transfer as a result of well‐oriented crystal structures and also assist intermediate diffusion, during reaction, of evolved gases. 2 D Ni‐based nitride sheet materials synthesized without supports usually perform better than 3 D supported electrocatalysts. The focus of this Minireview is a systematic description of OER activity for state‐of‐the‐art Ni‐based nitrides as nanostructured electrocatalysts.
A revolution in evolution: The electrocatalytic oxygen evolution reaction is a promising means of efficient energy conversion, with minimal environmental footprint. Transition metal nitride nanoparticles have attracted much attention owing to their high electrocatalytic activities, distinctive electronic structures, and enhanced surface morphologies. Nickel‐based electrocatalysts are of particular interest, given their abundance and low cost.
Photocatalysis is a promising and convenient strategy to convert solar energy into chemical energy for various fields. However, photocatalysis still suffers from low solar energy conversion ...efficiency. Developing state of the art photocatalysts with high efficiency and low cost is a huge challenge. Transition metal nitrides (TMNs) as a class of metallic interstitial compounds have attracted significant attention in photocatalytic applications. In fact, TMNs exhibit multifunctional properties in various photocatalytic systems. This review is the first attempt that summarizes recent research on TMNs‐based materials in various photocatalytic applications. Different roles of TMNs materials in photocatalytic systems including semiconductor active components, co‐catalysts, inter‐band excitation, and surface plasmon resonance components are systematically discussed and summarized. The fundamentals, latest progress, and emerging opportunities for further improving the performances of TMNs‐based materials for photocatalysis are also discussed. Finally, some challenges facing TMNs, and perspectives on their future that are relevant for furthering research in the area of photocatalysis are also proposed.
This review summarizes recent research on TMNs‐based materials in various photocatalytic applications including water splitting, CO2 reduction, and dye degradation. Different roles of TMNs materials in photocatalytic systems such as semiconductor active components, co‐catalysts, inter‐band excitation, and surface plasmon resonance components are systematically discussed and summarized.
Abstract
The sluggish kinetics of Oxygen Reduction Reaction (ORR) at the cathode in proton exchange membrane fuel cells or metal-air batteries requires highly effective and stable electrocatalysts to ...boost the reaction. The low abundance and high price of Pt-based electrocatalysts hamper the widespread application of proton exchange membrane fuel cells and metal-air batteries. As promising alternatives, metal-free carbon materials, especially upon doping heteroatoms or creating defects demonstrated excellent ORR activity, which is as efficient as or even superior to commercial platinum on carbon. Significant progress on the development of advanced carbon materials as highly stable and durable catalysts has been achieved, but the catalytic mechanisms of these materials still remain undistinguished. In present review, we summarized the up-to-date progress in the studies of carbon materials, and emphasized on the combination of experiment and theory to clarify the underlying mechanisms of these materials. At last, we proposed the perspectives on the proper strategies of elucidating the mechanisms of carbon materials as electrocatalysts towards ORR.
•Xiamen Island’s ecological quality has remained stable and even improved slightly during 1995 to 2016.•Xiamen Island’s ecological quality is closely correlated with its urban planning policy.•Kinmen ...Island has suffered different levels of reduction of the ecological quality during 1995 to 2016.•For Kinmen Island, Xiamen's ecological environment governance experiences are worth learning.•RSEI values are positively correlated with greenness and humidity and negatively correlated with heat and dryness.
Island ecosystems are increasingly threatened by pressures from both climate change and intensifying human activity, especially in developing countries. Evaluation of ecological quality is essential to implementation of interventions for adapting to climate change and alleviating human–nature land-use conflicts in the Anthropocene era. However, the temporal and spatial characteristics of island ecological quality, including variation arising from anthropogenic perturbations, climate change effects, and spatiotemporal heterogeneity, are rarely given serious attention. This study compares Xiamen Island and Kinmen Island, two neighboring islands with pronounced differences in urban density, adopting a Remote Sensing Ecological Index (RSEI) to describe the spatiotemporal differences in island ecological quality. The results show that the RSEI was positively correlated with greenness and humidity and negatively correlated with heat and dryness. Despite the fact that Xiamen Island has experienced extensive urban expansion and rapid population growth, its ecological quality has remained stable and even improved slightly, which mainly due to scientific urban planning. Despite the ecological advantages of its less urban setting, Kinmen Island has suffered reduced ecological quality due to deterioration of natural conditions, climate warming, and increasing human activity. These research findings provide empirical evidence for the need for scientific and systematic urban planning in high-density urban areas and serves as an important reference for planners and decision-makers for effective improvement in the ecological quality of Kinmen Island.
Bimetallic Pd–Au cluster was synthesized through a direct chemical reduction method and utilized for the fabrication of electrochemical sensing platform. Scanning electron microscopy (SEM) ...characterization indicated the obtained Pd–Au cluster displays branch-type structure that composed of nanowires. As a demonstration of the application of the sensing platform, the performance of the platform toward non-enzymatic electrochemical detection of glucose was studied. Analytical results show improved activity of the Pd–Au cluster toward glucose oxidation with high sensitivity, wide linear range and good stability. When the electrode was used for the detection of glucose in blood samples, the glucose contents detected by the electrode was in good agreement with those from the hospital. The proposed electrochemical sensing platform can certainly be expanded to the fabrication of other kinds of electrochemical sensors and biosensors.
The development of Pt‐free catalysts for the alkaline hydrogen evolution reaction (HER), which is widely used in industrial scale water‐alkali electrolyzers, remains a contemporary and pressing ...challenge. Ruthenium (Ru) has excellent water‐dissociation abilities and could be an alternative water splitting catalyst. However, its large hydrogen binding energy limits HER activity. Here, a new approach is proposed to boost the HER activity of Ru through uniform loading of Ru nanoparticles on triazine‐ring (C3N3)‐doped carbon (triNC). The composite (Ru/triNC) exhibits outstanding HER activity with an ultralow overpotential of ≈2 mV at 10 mA cm−2; thereby making it the best performing electrocatalyst hitherto reported for alkaline HER. The calculated metal mass activity of Ru/triNC is >10 and 15 times higher than that of Pt/C and Pt/triNC. Both theoretical and experimental studies reveal that the triazine‐ring is a good match for Ru to weaken the hydrogen binding on Ru through interfacial charge transfer via increased contact electrification. Therefore, Ru/triNC can provide the optimal hydrogen adsorption free energy (approaching zero), while maintaining the strong water‐dissociation activity. This study provides a new avenue for designing highly efficient and stable electrocatalysts for water splitting.
A triazine‐ring as an active “electron acceptor” is a good match for ruthenium to weaken hydrogen's binding to ruthenium through interfacial charge transfer via increased contact electrification. This is confirmed by both theoretical and experimental results. The resulting ruthenium triazine composites exhibit outstanding hydrogen evolution reaction activity when compared to commercial Pt/C in alkaline solution.
There is currently an outbreak of respiratory disease caused by a novel coronavirus. The virus has been named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the disease it causes ...has been named coronavirus disease 2019 (COVID-19). More than 16% of patients developed acute respiratory distress syndrome, and the fatality ratio was 1%–2%. No specific treatment has been reported. Herein, we examined the effects of favipiravir (FPV) versus lopinavir (LPV)/ritonavir (RTV) for the treatment of COVID-19. Patients with laboratory-confirmed COVID-19 who received oral FPV (Day 1: 1600 mg twice daily; Days 2–14: 600 mg twice daily) plus interferon (IFN)-α by aerosol inhalation (5 million international unit (IU) twice daily) were included in the FPV arm of this study, whereas patients who were treated with LPV/RTV (Days 1–14: 400 mg/100 mg twice daily) plus IFN-α by aerosol inhalation (5 million IU twice daily) were included in the control arm. Changes in chest computed tomography (CT), viral clearance, and drug safety were compared between the two groups. For the 35 patients enrolled in the FPV arm and the 45 patients in the control arm, all baseline characteristics were comparable between the two arms. A shorter viral clearance median time was found for the FPV arm versus the control arm (4 d (interquartile range (IQR): 2.5–9) versus 11 d (IQR: 8–13), P < 0.001). The FPV arm also showed significant improvement in chest CT compared with the control arm, with an improvement rate of 91.43% versus 62.22% (P = 0.004). After adjustment for potential confounders, the FPV arm also showed a significantly higher improvement rate in chest CT. Multivariable Cox regression showed that FPV was independently associated with faster viral clearance. In addition, fewer adverse events were found in the FPV arm than in the control arm. In this open-label before-after controlled study, FPV showed better therapeutic responses on COVID-19 in terms of disease progression and viral clearance. These preliminary clinical results provide useful information of treatments for SARS-CoV-2 infection.
Protein kinase (PKA) and alkaline phosphatase (ALP) are clinically relevant enzymes for a number of diseases. In this work, we developed a new simple electrochemical biosensor for the detection of ...the activity and inhibition of both PKA and ALP. One common feature of the PKA and ALP catalyzing process is that PKA can hydrolysis adenosine-5′-triphosphate (ATP) and ALP can hydrolysis pyrophosphate, both reactions produce phosphate ions, and the amount of phosphate ion produced is proportional to enzyme activity. Our assay is based on the principle that phosphate ions react with molybdate to form redox molybdophosphate precipitates on the electrode surface, thus generating electrochemical current. The detection limit for PKA and ALP were much lower than existing assays. The biosensor has good specificity and was used to measure drug-stimulated PKA from lysates of HeLa cells. We also evaluated the use of the biosensor as a screening tool for enzyme inhibitors. To the best of our knowledge, this is the first report of a biosensor capable of detecting the activity of both PKA and ALP. This tool has the potential to simplify PKA and ALP clinical measurement, thereby improving diagnostics of relevant diseases. It also may serve as the basis for a simple screening method for new enzyme inhibitors for disease treatment.
•Protein kinase (PKA) and alkaline phosphatase (ALP) are clinically relevant enzymes.•Electrochemical biosensor for assay the activity and inhibition of both PKA and ALP was reported.•The assay is based on reaction of phosphate ions with molybdate to form redox precipitates.•The biosensor was applied for screening enzyme inhibitors.•The biosensor was also used to measure drug-stimulated PKA from lysates of HeLa cells.
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