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Hydrazine is a well-known carcinogen and can cause several other adverse effects on human health such as respiratory issues, irritation of the eyes, liver and kidney problems, and dermal corrosion. An effective method is needed to detect the carcinogenic reagent like hydrazine. Tin oxide (SnO2)-modified graphitic carbon nitride (g-C3N4) decorated with well-crystallized silver (Ag) nanoparticles (denoted as Ag@SO-gCN) was fabricated by a biogenic/green approach and characterized by standard techniques. A fluorine-doped tin oxide (FTO) support/substrate was coated with Ag@SO-gCN by the doctor-blade technique, and employed as the working electrode (denoted as Ag@SO-gCN/FTO) for the electrochemical detection of carcinogenic hydrazine (Hz) as a model analyte at room temperature. The dual electrochemical techniques of linear sweep voltammetry (LSV) and cyclic voltammetry (CV) were used for the detection of hydrazine (denoted as Hz). The Ag@SO-gCN/FTO sensor shows an effective current response in the detection of Hz in solutions. The concentration of Hz was very efficiently monitored using LSV and CV under different conditions. The sensor shows a low limit of detection (LOD), high sensitivity and selectivity, and good linear range. The sensitivity and LOD of this sensor using LSV are 2.01 μA μM−1 cm−2 and 0.164 ± 0.013 μM, respectively. However, the fabricated Hz sensor using CV showed a sensitivity of 2.305 μA μM−1 cm−2 and LOD of 0.143 ± 0.011 μM. This study thus provides an innovative Ag@SnO2-g-C3N4-based electrochemical sensor as an effective device for the successful detection of hazardous chemicals.

Antibiotics and organic dyes are both significant causes of water pollution, and their removal from, or degradation in, water systems can be difficult. To address this issue, SnO2-modified TiO2 nanocomposites (STOs) were fabricated using a sonication-impregnation method. The prepared STOs (STO-1, STO-2, and STO-3) were characterized through various techniques including powder X-ray diffraction, Fourier-transform infrared spectroscopy, UV–vis diffuse reflectance spectroscopy, photoluminescence, high resolution-transmission electron microscopy, and X-ray photoelectron spectroscopy. The fabricated STOs exhibited narrowing of their bandgap and enhanced absorption in the UV and visible region. The STOs were further tested for their use in the photocatalytic degradation of tetracycline hydrochloride (TC) under visible light irradiation and were found to be very suitable for this application. The adsorption of TC on the STOs reached nearly 56%–62% after 15 min in the dark, while the vast majority degraded (81%–95%) within 20 min of visible light exposure. The narrowed band-gap and surface-based properties played a significant role in improving the adsorption-degradation efficiency of TC by extending the absorption spectrum and enhancing the separation efficiency of charge carriers. Moreover, the degradation of MB and CR was performed using STO-1 and displayed over 97% and 90% degradation, respectively. Thus, an effective method to utilize a non-noble photocatalyst to efficiently degrade antibiotics and organic dyes was achieved.

The influence of cobalt doping in SnO2 crystal lattice tailored the optical, structural, and surface properties of SnO2. Co2+ was successfully doped in SnO2 (Co-SnO2) via green synthesis using Tradescantia spathacea aqueous leaf extract. Powder X-ray diffraction patterns of the synthesized nanoparticles showed a rutile structure with no impurities. As Co-doping was increased, the average crystallite size increased from 13.25 nm to 32.32 nm and BET results showed reduced surface area. The presence of organic compounds of the aqueous leaf extract was confirmed by Fourier-transform infrared spectroscopy. UV-visible diffuse reflectance spectroscopy showed a red shift suggesting a band gap reduction with Co-doping. The photoluminescence study showed a peak quenching with the increase in Co-doping. Spherical and smaller particles were observed by scanning electron microscopy. The density of states was proposed using X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectroscopy data. A novel antioxidant study of SnO2 and Co-SnO2 nanoparticles was done under visible light irradiation using 2,2-diphenyl-1-picrylhydrazyl free radicals and was compared to conventional antioxidant method in the dark. Photocatalytic 4-nitrophenol conversion was also conducted in the dark and under visible light irradiation. The enhancement in the photoantioxidant activities and photocatalytic conversion of 4-nitrophenol to 4-nitrophenolate using SnO2 and Co-SnO2 was observed under visible light irradiation.

This paper reports the simultaneous synthesis of gold nanoparticles (AuNPs) with a spherical and stable structure using microbial fuel cell (MFC) biofilms. The green, facile, chemical stabilizers and capping-agent free AuNPs synthesis allow the binder-free in situ decoration of AuNPs on MFC anode electrode with the help of special interactions of biofilm. The MFC with AuNPs decorated carbon foam anode electrode produced 62.5% higher (46.37 Wm-3) power density than that of the MFC equipped with plain carbon foam anode (control). The AuNPs facilitated the good adhesion of bacteria, amplified the conductivity, and reduced the internal resistance, resulting in improved overall MFC performance. In addition, the peroxide-mimicking activity was evaluated and the MFC-synthesized AuNPs exhibited significantly higher peroxidase mimicking activity than the chemically synthesized AuNPs, thereby, allowing the easy and rapid colorimetric detection of hydrogen peroxide with a detection limit of 20 uM.

Molybdenum-based compounds are considered as a potential replacement for expensive precious-metal electrocatalysts for the hydrogen evolution reaction (HER) in acid electrolytes. However, coating of thin films of molybdenum nitride or carbide on a large-area self-standing substrate with high precision is still challenging. Here, MoNx is uniformly coated on carbon cloth (CC) and nitrogen-doped carbon (NC)-modified CC (NCCC) substrates by atomic layer deposition (ALD). The as-deposited film has a nanocrystalline character close to amorphous and a composition of approximately Mo2 N with significant oxygen contamination, mainly at the surface. Among the as-prepared ALD-MoNx electrodes, the MoNx /NCCC has the highest HER activity (overpotential η≈236 mV to achieve 10 mA cm-2 ) owing to the high surface area and porosity of the NCCC substrate. However, the durability of the electrode is poor, owing to the poor adhesion of NC powder on CC. Annealing MoNx /NCCC in H2 atmosphere at 400 °C improves both the activity and durability of the electrode without significant change in the phase or porosity. Annealing at an elevated temperature of 600 °C results in formation of a Mo2 C phase that further enhances the activity (η≈196 mV to achieve 10 mA cm-2 ), although there is a huge reduction in the porosity of the electrode as a consequence of the annealing. The structure of the electrode is also systematically investigated by electrochemical impedance spectroscopy (EIS). A deviation in the conventional Warburg impedance is observed in EIS of the NCCC-based electrode and is ascribed to the change in the H+ ion diffusion characteristics, owing to the geometry of the pores. The change in porous nature with annealing and the loss in porosity are reflected in the EIS of H+ ion diffusion observed at high-frequency. The current work establishes a better understanding of the importance of various parameters for a highly active HER electrode and will help the development of a commercial electrode for HER using the ALD technique.

In this study, highly graphitic nitrogen-doped carbon nano-onions (N-CNOs) were prepared by a one-step, direct, in situ flame synthesis technique and their potential applications as catalysts for oxygen reduction reaction (ORR) in a microbial fuel cell (MFC) were evaluated for the first time. The ORR activity of the CNO, N-CNO, and the commercial Pt/C were measured using a rotating ring-disk electrode (RRDE). The reaction mechanism for the N-CNO was found to follow a four-electron transfer pathway and possess a higher onset potential in RRDE measurement than CNOs. The ORR activity of N-CNO was 5.4 times better than that of CNO, which was attributed to the introduction of nitrogen to the carbon faramework. The MFC fabricated with the N-CNO cathode produced a maximum power density of 49.6 mW m–2, which was approximately double the performance of the CNO-based MFC. The performance of N-CNO was low compared to Pt/C but the cost per power was only 1/310th. These results confirmed that N-CNOs could be used as a low-cost alternative and an energy-efficient metal-free ORR catalyst for practical MFC applications.

Development of advanced materials with a benign environmentally friendly approach for heterogeneous visible light photocatalysis is always preferable. An environmentally favorable approach was used to anchor silver nanoparticles (Ag NPs) to tin oxide-decorated-graphitic carbon nitride (SnO2-g-C3N4) using a biofilm as a green reducing tool for the biogenic synthesis of 1–6 mM Ag@SnO2-g-C3N4 nanostructures (NSs). The fabricated NSs were characterized using sophisticated techniques. The developed Ag@SnO2-g-C3N4 NSs showed a well-defined spherical-shaped Ag NPs anchored to SnO2-g-C3N4 NSs. The synthesized NSs were applied for photocatalytic degradation of hazardous dyes and photoelectrochemical studies. A comparative investigation of Ag@SnO2-g-C3N4 NSs for the visible light-assisted photocatalytic degradation of Methylene blue (MB), Congo red (CR), and Rhodamine B (RhB) was performed. The photocatalytic degradation of MB, CR, and RhB reached ∼99% in 90 min, ∼98% in 60 min, and ∼94% in 240 min, respectively. T...

Narrow band gap zinc oxide (ZnO) nanoparticles (NPs) were synthesized using unboiled and boiled leaf extracts of Costus woodsonii. The as-synthesized NPs were characterized using a range of techniques. The as-synthesized ZnO NPs were crystalline with a hexagonal wurtzite structure similar to the commercial ZnO (ZnO-C). The maximum absorbance was observed at ~390 nm for ZnO-C and the as-synthesized ZnO NPs (ZnO-UL and ZnO-BL) showed a red shift, i.e. ~448 nm to ~462 nm, hence, a lower band gap of ~2.68–2.77 eV. The band gap energy of the as-synthesized ZnO NPs was lower than that of commercial ZnO. The surface of ZnO was coated/modified with the components of the leaf extract. The as-synthesized ZnO NPs showed similar particle sizes and were spherical in shape. These studies confirmed the green synthesis of ZnO NPs using Costus woodsonii and the significantly reduced band gap (Eg = ~2.68 eV to ~2.77 eV) of the as-synthesized ZnO NPs compared to the ZnO-C (Eg = 3.18 eV).

Synthesis of the strongly anisotropic materials, such as highly porous hollow double walled cubes are considered excellent approach to maximize the diffusion of electrolytes. Herein, hollow doubled walled (HDW) Mn2O3 nanocubes (NCs) were synthesized by facile hydrothermal method followed by calcination method. The growth of nanocubes were studied by performing hydrothermal reaction at different times ranging from 3 to 9 h. Thereafter, the feasibility of prepared HDW NCs as air cathode in hybrid Na-air battery was systematically investigated. Among all, the sample prepared by 9 h hydrothermal treatment showed superior performance than 3 and 6 h samples. The fabricated hybrid Na-air cell using HDW Mn2O3 NCs displayed 330 mV overpotential gap and 90% electrical energy efficiency at 5 mA g−1 current density, maximum of 0.2 W g−1 power density and good cyclic stability up to 75 cycles which is attributed to the highly porous nature of material that allows efficient diffusion of electrolyte ions and oxygen from air. Thus, present investigation suggests that HDW Mn2O3 NCs can be a potential air cathode and can be utilized in other metal-air battery systems.

The use of biomass for functional nanomaterial is fascinating. Costus woodsonii was used as a green approach to synthesize zinc oxide (ZnO) nanoparticles from its bulb (flower). The as-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), and transmission electron microscopy (TEM). XRD showed that the commercial ZnO (C-ZnO) and as-synthesized ZnO nanoparticles were of high purity and displayed a hexagonal wurtzite and well crystalline structure. XPS confirms that Zn was in the + 2 chemical state. FT-IR spectroscopy showed some additional peaks on the as-synthesized ZnO only due to a surface coating of the components of the bulb extract. TEM revealed the morphology, particle size, and high purity of the ZnO nanoparticles. The UV-Vis DRS of the as-synthesized ZnO showed a red shift compared to C-ZnO, which was attributed to the surface coating of the as-synthesized ZnO nanoparticles. These studies confirmed the synthesis of ZnO nanoparticles with a lower band gap, i.e., Eg = 2.66–2.79 eV. Therefore, phytogenic synthesis could be a new or alternate pathway for the synthesis of different types of novel nanomaterials with unique characteristics without altering the basic and fundamental structure.

Ag nanoparticles (NPs) grafted on TiO2 nanorods (NRs) using electroactive biofilms (EABs) were assessed as photoanodes for water splitting under solar light irradiance. EABs-assisted bio-reduction leads to the uniform decoration of spherical Ag NPs (10–40 nm) and stronger attachment to the Ag–TiO2 interface due to the prior adsorption of Ag+ ions. Plasmonic interaction of Ag NPs with TiO2 NRs showed stronger adsorption in visible range due to surface plasmon resonance. Compared to TiO2 NRs, Ag–TiO2 NRs/FTO exhibited 8 times higher current density under solar light irradiation due to enhanced visible light absorption, SPR effect, and efficient electron-hole separation.

The aerogels are porous with low density structures and have been explored in the range of applications including catalysis, thermal insulators, solar energy uses, piezoelectric, energy conversions-storage, low-temperature glass formation, sensors, adsorption, and photocatalysis. A variety of aerogels with unusual architect have been developed such as organic aerogels, nonsilica oxide aerogels, chalcogenide aerogels, carbon aerogels, and others. In the present chapter, we have tried to compile a brief research associated with the development of aerogels and their composites and used in the various applications of present need of water pollution and its remediation. Additionally, we have discussed the problems with the different examples of aerogels as sensors, adsorbents, and photocatalysts.

Molybdenum-based compounds are considered as a potential replacement for expensive precious-metal electrocatalysts for the hydrogen evolution reaction (HER) in acid electrolytes. However, coating of thin films of molybdenum nitride or carbide on a large-area self-standing substrate with high precision is still challenging. Here, MoN

The development of nanoparticle-based drugs has provided many opportunities to diagnose, treat and cure challenging diseases. Through the manipulation of size, morphology, surface modification, surface characteristics, and materials used, a variety of nanostructures can be developed into smart systems, encasing therapeutic and imaging agents with stealth properties. These nanostructures can deliver drugs to specific tissues or sites and provide controlled release therapy. This targeted and sustained drug delivery decreases the drug-related toxicity and increases the patient's compliance with less frequent dosing. Nanotechnology employing nanostructures as a tool has provided advances in the diagnostic testing of diseases and cure. This technology has proven beneficial in the treatment of cancer, AIDS, and many other diseases. This review article highlights the recent advances in nanostructures and nanotechnology for drug delivery, nanomedicine and cures.

The hazardous effects of current nanoparticle synthesis methods have steered researchers to focus on the development of newer environmentally friendly and green methods for synthesizing nanoparticles using nontoxic chemicals. The development of environmentally friendly methods of nanoparticle synthesis with different sizes and shapes is one of the pressing challenges for the current nanotechnology. Several novel green approaches for the synthesis of AuNPs have been explored using different natural sources, such as plants, algae, bacteria, and fungi. Among organisms, algae and blue-green algae are of particular interest for nanoparticle synthesis. Gold nanoparticles (AuNPs) have a range of applications in medicine, diagnostics, catalysis, and sensors because of their significant key roles in important fields. AuNPs have attracted a significant interest for use in a variety of applications. The widespread use of AuNPs can be accredited to a combination of optical, physical, and chemical properties as well as the miscellany of size, shape, and surface composition that has been adopted through green synthesis methods.

The effect of Gallium (Ga) doping on CdS thin film properties and the performance of the corresponding Cu(InGa)Se2/CdS heterojunction solar cell has been investigated. The CdS thin films were deposited using a conventional chemical bath deposition (CBD) process. For a source of Ga dopant, a gallium nitrate (Ga(NO3)3) aqueous solution with Ga concentration from 5×10−4 to 2×10−3 M has been used. Ga doping was carried out by adding gallium nitrate aqueous solution directly to the main CBD solution that contained all the other reactants (i.e., Cd2+, S2−, and NH3). It was found that Ga doping is effective for improving the optical transmittance of CdS films and, thus, increasing the photoelectric current density of the films and the short-circuit current density (JSC) of CIGS cells. With the use of a Ga-doped CdS buffer layer, the photovoltaic performance of CIGS cells was improved, primarily because of enhanced JSC and fill factor.

Super activated carbon (SAC) with a high surface area and pore volume of 3095 m2/g and 2.11 cm3/g, respectively, was produced from raw petroleum coke using a chemical activation method on a pilot-scale basis and assessed as an adsorbent for the removal of metanil yellow. A detailed study, including the influence of pH, contact time, temperature, amount of SAC, and concentration of metanil yellow, was carried out to optimize the operating conditions. The results showed that the SAC obtained had a maximum adsorption capacity for metanil yellow of 937 mg/g at pH 3 and 303 K. The metanil yellow uptake capacity of SAC was highest among the carbon-based adsorbents reported owing to its high surface area, porous texture, and surface functionality, which was sufficient for the 100% decolorization of highly metanil yellow contaminated water (500 mg/g) using 1 g/L of SAC at 303 K and a neutral pH. The thermodynamic and kinetics study showed that the adsorption of metanil yellow on SAC was a spontaneous and exothermic process that was controlled by pseudo-second-order kinetics. The SAC and metanil yellow were both regenerated using methanol as the desorption medium, and the SAC could be reused for the next processes.

Noble-metal silver (Ag) nanoparticles (NPs) anchored/decorated onto polymeric graphitic carbon nitride (g-C3N4) as nanostructures (NSs) were prepared using modest and environment-friendly synthesis method with a developed-single-strain biofilm as a reducing implement. The as-fabricated NSs were characterized using standard characterization techniques. The nanosized and uniform AgNPs were well deposited onto the sheet-like matrix of g-C3N4 and exhibited good antimicrobial activity and superior photodegradation of dyes methylene blue (MB) and rhodamine B (RhB) dyes under visible-light illumination. The Ag@g-C3N4 NSs exhibited active and effective bactericidal performance and a survival test in counter to Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The as-fabricated NSs also exhibited superior visible-light photodegradation of MB and RhB in much less time as compared to other reports. Ag@g-C3N4 NSs (3 mM) showed superior photocatalytic measurements under visible-light irradiation: ∼1...

Microbial fuel cells (MFCs) are a potential sustainable energy resource by converting organic pollutants in wastewater to clean energy. The performance of MFCs is influenced directly by the electrode material. In this study, a ternary PANI-TiO2-GN nanocomposite was used successfully to improve the performance of both the cathode and anode MFC. The PANI-TiO2-GN catalyst exhibited better oxygen reduction reaction activity in the cathode, particularly as a superior catalyst for improved extracellular electron transfer to the anode. This behavior was attributed to the good electronic conductivity, long-term stability, and durability of the composite. The immobilization of bacteria and catalyst matrix in the anode facilitated more extracellular electron transfer (EET) to the anode, which further improved the performance of the MFCs. The application of PANI-TiO2-GN as a bifunctional catalyst in both the cathode and anode helped decrease the cost of MFCs, making it more practical.

The development of energy storage materials with high capacity and rapid charging and discharging ability have become the most important and major issues of concern in recent years. In this study, a mesoporous nickel sulfide (NiS) hierarchical framework was synthesized using a simple solvothermal method under optimized experimental conditions, including the amount of sulfur and experimental time, and characterized using a range of spectroscopic and microscopic techniques. The resulting materials were tested further as electrode materials in an electrochemical half-cell assembly and full cell solid-state symmetric assembly cell. The optimized mesoporous nickel sulfide hierarchical showed excellent specific capacitance performance with outstanding cycling stability (∼88.57%) after 5000 consecutive charge discharge cycles. A prototype symmetric supercapacitor device was also assembled using hierarchical flower-like NiS and the measured device performance showed a high capacitance of 11.15 F/g, high energy density of 0.991 Wh/kg at a power density of 132 W/kg, and at power density of 261.11 W/kg at an energy density of 0.329 Wh/kg, and excellent cycling stability (83.8% with 92.9% coulombic efficiency after 2000 cycles at 0.26 A/g). The potential applications of the above device were demonstrated by powering a light emitting diode and commercially available fan for more than 30s discharging time.

This paper reports the synthesis of N-doped carbon foams (NCFs) using simple, environment-friendly, and self-developed freezing method. A robust structure of NCFs along with high surface area, hierarchical pore structure, and nitrogen/oxygen functionalities allows their application as free-standing electrode. Microbial fuel cell equipped with differently prepared NCFs as free-standing anode and metal-free cathode generates significantly higher power density, 35.74 W m−3 than conventional electrodes. Furthermore, NCF with an optimized resorcinol-formaldehyde content shows significantly high-charge storage capacity, 799 F g−1, at 0.25 A g−1 and also delivers a high energy density, 111 Wh kg−1, equivalent to that of a Li-ion battery.

SnS2 is an emerging candidate for an electrode material because of the considerable interlayer spaces in its crystal structures and the large surface area. SnS2 as a photocatalyst and in lithium ion batteries has been reported. On the other hand, there are only a few reports of their supercapacitor applications. In this study, sheetlike SnS2 (SL-SnS2), flowerlike SnS2 (FL-SnS2), and ellipsoid-like SnS2 (EL-SnS2) were fabricated via a facile solvothermal route using different types of solvents. The results suggested that the FL-SnS2 exhibited better capacitive performance than the SL-SnS2 and EL-SnS2, which means that the morphology has a significant effect on the electrochemical reaction. The FL-SnS2 displayed higher supercapacitor performance with a high capacity of approximately similar to 431.82 F/g at a current density of 1 A/g. The remarkable electrochemical performance of the FL-SnS2 could be attributed to the large specific surface area and better average pore size. These results suggest that a suitable solvent is appropriate for the large-scale construction of SnS2 with different morphologies and also has huge potential in the practical applications of high-performance supercapacitors. Funding Agencies|Priority Research Centers Program through the National Research Foundation of Korea - Ministry of Education in South Korea [2014R1A6A1031189]

This paper reports the synthesis of positively charged gold nanoparticles [(+)AuNPs] for the colorimetric detection of hydrogen peroxide (H2O2). (+)AuNPs were synthesized using an electrochemically active biofilm in an aqueous solution, which is a novel, simple, and green approach. The as-synthesized (+)AuNPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). UV-Vis spectroscopy confirmed the synthesis of AuNPs and DLS showed that the as-synthesized AuNPs had a charge of +32.72 mV. XRD confirmed the formation of AuNPs as well as the purity, crystallinity, and fcc structure. TEM and HRTEM showed that (+)AuNPs were 15–21 nm in size and spherical in shape. The as-synthesized (+)AuNPs were used for the colorimetric detection of H2O2 using 3,3,5,5-tetramethylbenzidine dihydrochoride. This study provides a simple, fast, and sensitive colorimetric method for the detection of H2O2 in the linear range from 1.0 × 10−3 to 2.5 × 10−3 M. The (+)AuNPs possessed extraordinary intrinsic peroxidase-like activity (peroxidase mimic) compared to citrate-capped negatively charged AuNPs. This approach to the colorimetric detection of H2O2 is novel and simple because it uses positively charged gold nanoparticles, which may provide new areas for further research.

Noble-metal gold (Au) nanoparticles (NPs) anchored/decorated on polymeric graphitic carbon nitride (g-C3N4), as a nanostructure, was fabricated by a simple, single step, and an environmentally friendly synthesis approach using single-strain-developed biofilm as a reducing tool. The well deposited/anchored AuNPs on the sheet-like structure of g-C3N4 exhibited high photoelectrochemical performance under visible-light irradiation. The Au-g-C3N4 nanostructures behaved as a plasmonic material. The nanostructures were analyzed using standard characterization techniques. The effect of AuNPs deposition on the photoelectrochemical performance of the Au-g-C3N4 nanostructures was examined by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), incident photon-to-current efficiency (IPCE) and cyclic voltammetry (CV) in the dark and under visible-light irradiation. The optimal charge transfer resistance for Au-g-C3N4 nanostructures (6 mM) recorded at 18.21 ± 1.00 Ω cm−2 and high electron transfer efficiency, as determined by EIS. The improved photoelectrochemical performance of the Au-g-C3N4 nanostructures was attributed to the synergistic effects between the conduction band minimum of g-C3N4 and the plasmonic band of AuNPs, including high optical absorption, uniform distribution, and nanoscale particle size. This simple, biogenic approach opens up new ways of producing photoactive Au-g-C3N4 nanostructures for potential practical applications, such as visible light-induced photonic materials for real device development.

Colonies of electrochemically active microorganisms called electroactive biofilms (EABs) have potential applications in bioenergy and chemical production. In the present study, an EAB was used as a reducing tool to synthesize Ag-decorated ZnO@C core–shell (Ag–ZnO@C) ternary plasmonic photocatalysts. A simple thermal decomposition route was followed to synthesize ZnO@C nanoparticles using a zinc aniline nitrate complex. The simultaneous adsorption of Ag+ in the carbon shell of the ZnO@C particles during reduction using an EAB allowed the direct contact among Ag nanoparticles, the ZnO core, and the carbon shell. Therefore, the synthesized Ag–ZnO@C ternary photocatalysts showed a stronger interconnection among all the components, which allowed the easy transfer of photogenerated charges and provided enhanced charge carrier separation. Optical characterization showed that the enhanced absorption of visible light along with a decrease in the band gap and a red shift in the valence band maximum occurred due to the decoration of Ag-nanoparticles on ZnO@C. Ag–ZnO@C exhibited higher photocatalytic activity for the degradation of rhodamine blue and 4-nitrophenol under visible light irradiation than ZnO@C and bare ZnO without any significant loss after five successive cycles. Finally, a possible photocatalytic mechanism for charge transfer was proposed to explain the enhanced photocatalytic performance of the Ag–ZnO@C ternary photocatalyst. This study provides insights into the ternary photocatalytic system with a core–shell material and offers a biogenic route for the facile fabrication of Ag–ZnO@C photocatalysts.

Although tungsten disulfide (WS2), an analogue of graphite, has long been pursued as a promising energy storage material due to its unique layered structure, structural changes, volumetric expansion and poor electronic conductivity have limited its practical use. Here, we report the synthesis of porous WS2 composed of a few layered nanosheets (P-WS2) using a simple and scalable hydrothermal method, as well as its electrochemical properties when used for a lithium storage electrode, a supercapacitor electrode, and a visible light active photocatalytic material. P-WS2 as an anode for lithium-ion batteries showed a high specific capacity of 292 mA h g−1 at a current density of 0.2C with excellent cycling stability over 100 cycles. The half-cell electrochemical assembly test demonstrated that P-WS2 delivered 241.5 F g−1 at a current density of 0.75 A g−1 and showed excellent stability over 2000 consecutive charge–discharge cycles. P-WS2 nanosheets exhibited 10 times higher photocatalytic activity than bulk commercial WS2 (C-WS2) for the degradation of Rhodamine B dye under visible light irradiation. The excellent performance of P-WS2 is due to its sheet-like structure, porous characteristics, and high surface area.

Metal-graphene nanostructures (NSs) as photocatalysts, prepared using simple and scalable synthesis methods, are gaining heightened attention as novel materials for water treatment and environmental remediation applications. Graphene, the unique few layers sheet-like arrangement of sp2 hybridized carbon atoms, has an inimitable two-dimensional (2D) structure. The material is highly conductive, has high electron mobility and an extremely high surface area, and can be produced on a large scale at low cost. Accordingly, it has been considered as an essential base component for producing various metal-based NSs. In particular, metal-graphene NSs as photocatalysts have attracted considerable attention because of their special surface plasmon resonance (SPR) effect that can improve their performance for the removal of toxic dyes and other pollutants. This review summarizes the recent and advanced progress for the easy fabrication and design of graphene-based NSs as photocatalysts, as a novel tool, using a range of approaches, including green and biogenic approaches.

Organic–inorganic functional hybrid polymeric materials are well known for the efficient removal of contaminants from wastewater. Herein, mechanical exfoliation of bulk MoS2 and its composite with polyaniline (Pani@MoS2) via facile in situ oxidative polymerization has been reported. The application of the Pani@MoS2 hybrid adsorbent to the scavenging of the organic pollutant dye Congo red (CR) from an aquatic environment in batch experiments has been investigated. The adsorption and removal of CR using Pani/MoS2 was much higher than the bulk and exfoliated MoS2 nanosheets. The effects of varying experimental conditions, such as pH, temperature, CR concentration, and interaction time between the adsorbent and CR at which optimal removal occurs, were examined. The highest adsorption of 70.921 mg g−1 was recorded at 120 min, pH 5, and 50 °C and was due to the π–π and electrostatic interactions between the nitrogen containing groups of the adsorbent and CR molecules. The adsorption equilibrium data were well fitted to the Langmuir adsorption isotherm model, revealing monolayer coverage of the CR molecules on the Pani@MoS2 nanohybrid adsorbent. The CR adsorption kinetics and thermodynamics were also studied to gain a better understanding of the adsorption mechanism and the interaction between the CR molecules and the active sites present on the Pani@MoS2 nanohybrid. The results show that Pani/MoS2 is an efficient adsorbent for the removal of CR dye from wastewater.

Citrus are one of the most widely cultivated fruit crops. Citrus fruits are rich source of essential vitamins, minerals, fibers and bioactive phytochemicals, such as alkaloids, carotenoids, nitrogenous compounds and polyphenolics. The by-products derived from citrus wastes are considered to be an economic and renewable source for valuable compounds which can be used in pharmaceutical, nutraceutical, food and cosmetic industries. The review presents a detailed description on the recent advances with emphasis on the citrus derived nutraceuticals as potential source for various biological properties and physiological roles, such as anti-carcinogenicity, anti-mutagenicity, anti-allergenicity, anti-ageingactivitiy, and natural as well as important constituent in synthetic antioxidants. A comprehensive description on the citrus derived food and drinks as well as nutritious feed for animals has also been included.

In this study, a SnO2/CeO2 nanostructured oxide was prepared by a sonication-based approach. The prepared SnO2/CeO2 nanostructured oxide was examined for its structural and morphological characteristics using powder X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray electron microscopy, and Brunauer–Emmett–Teller analysis. An electrochemical sensor was fabricated by deposition of the SnO2/CeO2 nanostructured oxide on a glassy carbon electrode (GCE) using a binder (SnO2/CeO2/GCE). The fabricated SnO2/CeO2/GCE, as an efficient electrochemical sensor, was employed for detection of hydrazine using the electrochemical technique viz. linear sweep voltammetry (LSV). The voltammetric detection of hydrazine at the SnO2/CeO2/GCE sensor exhibits a rapid increase in the oxidation peak current upon addition of hydrazine. The electrochemical response of the SnO2/CeO2/GCE shows excellent sensitivity for hydrazine. The sensitivity, limit of detection (LOD), and limit of quantification (LOQ) of the sensor using LSV technique are estimated to be 81 μA μM−1 cm−2, 0.179 μM, and 0.52 μM, respectively. The SnO2/CeO2/GCE as a sensor shows a mostly linear relationship between current and concentration of hydrazine over the concentration range of 3–26 μM (R2 = 0.975). Overall, our proposed SnO2/CeO2/GCE sensor shows significant stability, selectivity, sensitivity, repeatability, and reproducibility.

Increasing environmental concerns related to the use of antibiotics and organic dyes has resulted in a serious demand for effective methods to remove these compounds from industrial wastewater. To address this issue, there remains a need for advanced semiconductor photocatalysts with cost-effectiveness and better performance. Tuned properties (optical and surface) were achieved for the fabricated tin oxide/cerium oxide nanostructured photocatalysts and used for visible-light-induced photocatalytic degradation of antibiotic and dyes for wastewater decontamination. The visible-light-induced degradation performance of tin oxide/cerium oxides was tested in aqueous solution using the antibiotic tetracycline hydrochloride (TC) as a model pollutant. The best result among the studied photocatalysts showed the TC removal efficiency of ~97% in 120 min under visible-light irradiation with more than 50% of adsorption of TC. Furthermore, the photocatalytic activity was also tested towards organic dyes (Methylene blue; MB and Congo red; CR) and exhibited excellent performance for the degradation of both the dyes with the degradation efficiency of around ~90 and ~97% for CR and MB, respectively. Moreover, the photocatalyst also showed the stability towards the degradation of a pollutant, thus can be also explored for other emerging pollutants.

To enhance the activities of advanced semiconductor photocatalysts, the charge carriers must be separated effectively. One strategy for achieving this is the use of heterogeneous structures, which can be prepared by hydrothermal synthesis and post-synthetic thermal and ultrasonic treatment. Herein, we report a mixed-phase composite of basic bismuth nitrate/pentabismuth heptaoxide nitrate (PC) prepared by hydrothermal synthesis under basic conditions and post-synthetic thermal treatment. In addition, sulfur-doped-graphitic carbon nitride (S-g-C3N4) was prepared and combined with PC in different ratios, denoted as PC-1, PC-2, and PC-3, using sonication-assisted treatment. The characterization of these catalysts confirmed the formation of mixed basic bismuth nitrate/pentabismuth heptaoxide nitrate phases and the composite nanostructure. The developed nanostructure showed interesting morphological features, for example, layered sheets of S-g-C3N4. The prepared PCs were tested for their visible light responsiveness for the photocatalytic degradation of a representative organic dye (Rhodamine B). We found that the modified photocatalysts showed superior activity to that of pristine PC. The optimal photocatalyst (PC-3) was also used to degrade methylene blue and Congo red, achieving 99% degradation. Thus, we present not only an efficient photocatalyst but also insights into the post-synthetic modification of basic bismuth nitrate/pentabismuth heptaoxide nitrate with stable carbon-based nanostructures.

Nutrient removal from artificial wastewater in autotrophic condition by the co-culture consortium of Scenedesmus dimorphus and nitrifiers was investigated. The batch experiments of co-culture, S. dimorphus- and nitrifiers-only treatments were conducted and compared for 9 days. As a result, the co-culture system showed enhancement in both nitrogen (N) and phosphorous (P) removal compared to each single culture. Especially, total N removal efficiency and P removal efficiency in co-culture reactor were enhanced 3.4 and 6.5 times compared to nitrifiers-only reactor, respectively. This result implies that post-treatment systems such as denitrification of nitrate and luxury uptake of P can be deducted by using the co-culture consortium of Scenedesmus dimorphus and nitrifiers. In addition, unlike nitrifiers-only reactor, the co-culture maintained high Dissolved Oxygen (DO) without external aeration. Thus it is suggested that co-culture of Scenedesmus dimorphus and nitrifiers is an efficient and economic method to removal nutrient from wastewater.

N-doped carbon cubes (NCCs) with varying nitrogen contents and different densities were fabricated using a simple and binder-free method that involved the curing of resorcinol-formaldehyde (RF) gel with different RF contents in the framework of a melamine sponge. In addition to the robust structure and nitrogen doping, the porosity of the NCCs could be tailored easily within the mesopores and ultra-micropores with a unique combination of macro, meso, and micropores. The prepared NCCs exhibited excellent uptake capacity, ranging from 32.1 to 39.3 mg/g Pb2+ ions, owing to their high surface area (up to 675 m2/g) and nitrogen doping (max. 4.9 wt. %). The Pb2+ adsorption property of NCC-10 was also compared with that of widely used commercial 3D carbon adsorbents. The weight and surface area-normalized Pb2+ adsorption capacity of NCC-10 was found to be 3.7 and 6.6 times higher, respectively than the commercial activated carbon granules. The continuous mode model data fitted with experimental fixed-bed results well, and showed 8.95 mg/g loading capacity, proving that NCC-10 is an effective 3D adsorbent. The prepared NCCs could be used as a practical adsorbent for the removal of Pb2+ ions because of their high adsorption capacity, easy regeneration, and exceptional stability maintained after longer reuse.

Na-air batteries are regarded as a potential alternate to Li-air batteries due to the abundant sodium source and high theoretical energy density. However, non-aqueous Na-air battery suffers from the electrode polarization owing to the formation of insoluble discharge product, which severely limits its cyclability and performance. Herein, a high performance hybrid Na-air cell is demonstrated using a dual electrolyte (mixed aqueous and non-aqueous electrolyte) system and three dimensionally (3D) grown tin sulfide (SnS 2 ) nanopetals based air electrode. 3D SnS 2 nanopetals are synthesized by a facile solvothermal method and used as an air electrode material for hybrid Na-air battery. The vertically-grown and self-assembled ultra-thin nanosheets of 3D SnS 2 nanopetals provide exposed active sites for the efficient air and electrolyte diffusion to air electrodes, resulting in high performance hybrid Na-air cell. The fabricated hybrid Na-air cell displays low overpotential gap (0.52 V), high round trip efficiency (83%), high power density (300 mW g −1 ) and good rechargeability up to 40 cycles. The proposed 3D SnS 2 nanopetals as air electrodes can provide a robust platform for the future development of Na-air batteries and other energy storage devices.