Fabrication of ZnS Hollow Spheres and RGO-ZnS Nanocomposite Using Cysteamine as Novel Sulfur Source: Photocatalytic Performance on Industrial Dyes and Effluent

Optimisation of Manganese Peroxidase (MnP) Activity of Enterobacter wuhouensis Using Response Surface Method and Evaluation of Its Maillard Reaction Products Along with Lignin Degradation Ability

Manganese peroxidase (MnP), a microbial ligninolytic enzyme which plays significant role in lignin and melanoidin degradation has gained much attention in the field of industry. In the present study, 15 ligninolytic bacteria were isolated from the soil sample of Similipal Biosphere Reserve (SBR) and screened for MnP activity. The most efficient MnP-producing bacterium HNB5 was evaluated for alkali lignin and maillard reaction products (MRPs) degradation and identified as Enterobacter wuhouensis using 16S rRNA sequencing. This bacterium exhibited the highest MnP activity of 2.6 U mL-1 min-1 in un-optimized conditions. Further, optimization using response surface methodology E. wuhouensis showed increased MnP activity of 4.11 U mL-1 min-1 at pH 6.3, temperature 37 °C, substrate concentration 1.05%, and time 144 h. In both FT-IR and UV-Vis spectrophotometry analyses of control and bacterium degraded MRPs, the reduction in Maillard product colour was correlated with shifting absorption peaks. Also, the GC-MS analysis data showing a change in functional group revealed the rise of novel peaks caused due to the degradation of MRPs complex. The phytotoxicity study was conducted for bacterial degraded MRPs medium revealed that toxicity of the medium decreased after bacterial treatment. The findings of the current study suggest that the manganese MnP produced by E. wuhouensis isolated from SBR soil sample may be employed for bioremediation purposes to degrade MRPs.

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Intriguing physicochemical properties and impact of co-dopants on N-doped graphene oxide based ZnS nanowires for photocatalytic application

Superparamagnetic N-doped graphene oxide (GO)- with ZnS nanowires was synthesized by a one-step hydrothermal method by doping dilute amounts of Ga, Cr, In, and Al ions for water treatment and biomedical applications. In these experiments, to enhance their properties, 2% of Ga³⁺, In³⁺, and or Al³⁺ were codoped along with 2% Cr ions in these ZnS nanowires. The nanocomposite with the composition, In_0.02Cr_0.02Zn_0.96S, has better photocatalytic efficiency than other co-doped nanocomposites. The In (metalloids) and Cr (transition metal ion) are the best combinations to increase the magnetic properties which are beneficial for photocatalytic activity. Synthesized nanocomposite materials were characterized by several techniques such as X-ray diffraction, Field emission-scanning electron microscope (FESEM) with EDAX, vibrating sample magnetometer (VSM), UV-Vis, X-ray photoelectron spectroscopy (XPS), and fluorescence spectroscopy. The correlation of intriguing magnetic properties with their photocatalytic properties is also discussed. XPS was employed for the detection of surface defects, phase transformation, and the nature of chemical components present in the nanocomposites. The Frankel and substitutional defects have a direct impact on photocatalytic activity that was determined from the fluorescence (FL) spectroscopy. FL and XPS reveal that the Cr and In codoped composite has a higher percentage of defects hence its photocatalytic efficiency reaches 94.21%.

Magnetic grinding synthesis of copper sulfide-based photocatalytic composites for the degradation of organic dyes under visible light

CuS based composites prepared by magnetic grinding method with metal and sulfur powder as raw materials have photocatalytic activity.

Transformation of CuS/ZnS nanomaterials to an efficient visible light photocatalyst by 'photosensitizer' graphene and the potential antimicrobial activities of the nanocomposites

We report the growth of CuS/ZnS (CZS) nanoparticles (NPs) on the graphene sheet by a facile green synthesis process. The CuS/ZnS-graphene (CZSG) nanocomposites exhibit enhanced visible light photocatalytic activity towards organic dye (methylene blue) degradation than that of CZS nanoparticles. To find the reason for the enhanced photo-activity, we propose a new photocatalytic mechanism where graphene in the CZSG nanocomposites acts as a 'photosensitizer' for CZS nanoparticles. This distinctive photocatalytic mechanism is noticeably different from all other previous research works on semiconductor-graphene hybrid photocatalysts where graphene behaves as an electron reservoir to capture the electrons from photo-excited semiconductor. This novel idea of the photocatalytic mechanism in semiconductor-graphene photocatalysts could draw a new track in thinking for designing of graphene-based photocatalysts for solving environmental pollution problems and they also show remarkable antimicrobial activities.

One-step synthesis of ZnS@MoS2 core–shell nanostructure for high efficiency photocatalytic degradation of tetracycline

Four kinds of ZnS@MoS₂ nanocomposite photocatalysts were successfully prepared via a facile hydrothermal method.

Tuning the Multifunctional Surface Chemistry of Reduced Graphene Oxide via Combined Elemental Doping and Chemical Modifications

The synthesis of graphene materials with multiple surface chemistries and functionalities is critical for further improving their properties and broadening their emerging applications. We present a simple chemical approach to obtain bulk quantities of multifunctionalized reduced graphene oxide (rGO) that combines chemical doping and functionalization using the thiol-ene click reaction. Controllable modulation of chemical multifunctionality was achieved by simultaneous nitrogen doping and gradual chemical reduction of graphene oxide (GO) using ammonia and hydrazine, followed by covalent attachment of amino-terminated thiol molecules using the thiol-ene click reaction. A series of N-doped rGO (N-rGO) precursors with different levels of oxygen groups were synthesized by adjusting the amount of reducing agent (hydrazine), followed by subsequent covalent attachment of cysteamine via the thermal thiol-ene click reaction to yield different ratios of mixed functional groups including N (pyrrolic N, graphitic N, and aminic N), S (thioether S, thiophene S, and S oxides), and O (hydroxyl O, carbonyl O, and carboxyl O) on the reduced GO surface. Detailed XPS analysis confirmed the disappearance of unstable pyridinic N in cys-N-rGO and the reduction degree threshold of N-rGO for effective cysteamine modification to take place. Our study establishes a strong correlation between different reduction degrees of N-rGO with several existing oxygen functional groups and addition of new tunable functionalities including covalently attached nitrogen (amino) and sulfur (C-S-C, C=S, and S-O). This simple and versatile approach provides a valuable contribution for practical designing and synthesis of a broad range of functionalized graphene materials with tailorable functionalities, doping levels, and interfacial properties for potential applications such as polymer composites, supercapacitors, electrocatalysis, adsorption, and sensors.

Carbon fibers coated with urchin-like copper sulfide for nonenzymatic voltammetric sensing of glucose

Urchin-like CuS was grown on xanthan gum-derived carbon nanofibers to obtain a sensor for enzyme-free electrochemical sensing of glucose. The unique nanostructure of the sensor provides a large specific surface, more electrocatalytically active sites, and high electrical conductivity. The voltammetric response to glucose, best measured at around 57 mV (vs. Ag/AgCl (E/V)) in 0.1 M NaOH solution, covers two linear ranges, one from 0.1-125 μM, another from 0.16 to 1.2 mM. The sensitivity is quite high (23.7 μA mM^-1 cm^-2), and the detection limit is low (19 nM at S/N = 3). The sensor has high selectivity against potentially interfering molecules such as fructose, appreciable operational stability, excellent durability, and good repeatability (with relative standard deviations of 2.3%). It was successfully applied to the determination of glucose in diluted serum samples. Graphical abstractSchematic representation of electrochemical detection of glucose based on the use of a screen printed carbon electrode (SPCE) modified with CuS and xanthan gum-derived carbon nanofibers (XGCNFs).

A. Visible-light-induced degradation of rhodamine B by nanosized Ag2S–ZnS loaded on cellulose

Visible-light-active nanosized Ag₂S–ZnS loaded on cellulose photocatalysts are used for RhB dye degradation to a maximum extent in a short period of time and the catalysts can be reused many times.

Multiple carrier-transfer pathways in a flower-like In2S3/CdIn2S4/In2O3 ternary heterostructure for enhanced photocatalytic hydrogen production

A novel flower-like In2S3/CdIn2S4/In2O3 (ICS) ternary heterostructure (HS) is rationally constructed for the first time by a series of carefully designed procedures. In2O3 nanoflakes are the main constituent units which assemble into a flower-like skeleton structure, and CdIn2S4 nanoparticles are in situ generated on the surface of In2O3 nanoflakes through the transformation of CdS quantum dots (QDs) while In2S3 nanoparticles are in situ produced at the region between CdIn2S4 nanoparticles and In2O3 nanoflakes resulting from a synchronous sulfuration procedure. As expected, the rationally designed ICS ternary HSs display significantly enhanced photocatalytic H2 production, especially ICS5 (sulfurized for 5 h) with the highest H2 evolution rate of 20.04 μmol h-1 (10 mg catalyst is used for photocatalytic reaction), which is 26.7 times and 2.6 times higher than that of pure In2O3 (0.75 μmol h-1) and In2S3/In2O3 binary HS (7.88 μmol h-1), respectively. The enhanced photocatalytic activity can be attributed to the multiple interfaces formed in the ICS HSs, including the CdIn2S4-In2O3 interface, the In2S3-In2O3 interface, and the CdIn2S4-In2O3-In2S3 interface, which construct multiple pathways for the transfer of photogenerated charge carriers, effectively promoting the photocatalytic hydrogen production.