Defected graphene nano-platelets for enhanced hydrophilic nature and visible light-induced photoelectrochemical performances

Khan, Mohammad Ehtisham,Khan, Mohammad Mansoob,Cho, Moo Hwan Elsevier 2017 The Journal of physics and chemistry of solids Vol.104 No.-

<P><B>Abstract</B></P> <P>This paper reports an optimized electron beam irradiation (60kGy and 90kGy) approach for defects-related engineering of graphene nano-platelets for optical and structural properties dependent photoelectrochemical performances. The defects in the electron beam irradiated pristine graphene nano-platelets were studied, analyzed and confirmed using standard characterization techniques such as, diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), high resolution-transmission electron microscopy (HR-TEM) and contact angle measurements. DRS clearly revealed the increment in the absorption band using electron beam irradiation doses of 60kGy and 90kGy. Contact angle measurements confirm the additional hydrophilic nature of the defects engineered graphene nano-platelets in comparison with pristine graphene. The photoelectrochemical performances such as linear sweep voltammetry and electrochemical impedance spectroscopy further confirms the enhancement in the optical, spectroscopic, and photoelectrochemical properties of the 90kGy defected graphene in comparison to pristine graphene nano-platelets. Therefore, the proposed method is a reliable way of fine-tuning the properties (optical, spectroscopic and photoelectrochemical) of pristine graphene nano-platelets using electron beam irradiation for enhanced photoelectrochemical performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electron beam irradiated (60 kGy and 90 kGy) pristine graphene. </LI> <LI> Defects engineered graphene for visible light induced photoelectrochemical performances. </LI> <LI> Detailed analysis of defects engineered graphene with standard characterization techniques. </LI> <LI> Defects engineered pristine graphene used as a photoelectrode. </LI> <LI> Defects engineered graphene as an enhanced hydrophilic in nature. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Proposed electron transfer mechanism of defect engineered graphene nano-platelets under visible light irradiation.</P> <P>[DISPLAY OMISSION]</P>

Recent progress of metal-graphene nanostructures in photocatalysis

Khan, Mohammad Ehtisham,Khan, Mohammad Mansoob,Cho, Moo Hwan The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.20

<P>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 sp<SUP>2</SUP> 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.</P>

Visible light-induced enhanced photoelectrochemical and photocatalytic studies of gold decorated SnO₂ nanostructures

Khan, Mohammad Mansoob,Ansari, Sajid Ali,Khan, Mohammad Ehtisham,Ansari, Mohd Omaish,Min, Bong-Ki,Cho, Moo Hwan The Royal Society of Chemistry 2015 NEW JOURNAL OF CHEMISTRY Vol.39 No.4

<P>This paper reports a novel one-pot biogenic synthesis of Au–SnO<SUB>2</SUB> nanocomposite using electrochemically active biofilm. The synthesis, morphology and structure of the as-synthesized Au–SnO<SUB>2</SUB> nanocomposite were in-depth studied and confirmed by UV-vis spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. It was observed that the SnO<SUB>2</SUB> surface was decorated homogeneously with Au nanoparticles. The photoelectrochemical behavior of the Au–SnO<SUB>2</SUB> nanocomposite was examined by cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectroscopy, and linear sweep voltammetry in the dark and under visible light irradiation. Visible light-induced photoelectrochemical studies confirmed that the Au–SnO<SUB>2</SUB> nanocomposite had enhanced activities compared to the P–SnO<SUB>2</SUB> nanoparticles. The Au–SnO<SUB>2</SUB> nanocomposite was also tested for the visible light-induced photocatalytic degradation of Congo red and methylene blue, and showed approximately 10 and 6-fold higher photocatalytic degradation activity, respectively, compared to P–SnO<SUB>2</SUB>. These results showed that the Au–SnO<SUB>2</SUB> nanocomposite exhibits excellent and higher visible light-induced photoelectrochemical and photocatalytic activities than the P–SnO<SUB>2</SUB> nanoparticles, and can be used for a wide range of applications.</P> <P>Graphic Abstract</P><P>Visible light-induced photocatalytic degradation of colored dyes using Au–SnO<SUB>2</SUB> nanocomposite. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4nj02245a'> </P>

Biogenic synthesis of a Ag–graphene nanocomposite with efficient photocatalytic degradation, electrical conductivity and photoelectrochemical performance

Khan, Mohammad Ehtisham,Khan, Mohammad Mansoob,Cho, Moo Hwan The Royal Society of Chemistry 2015 New journal of chemistry Vol.39 No.10

<P>This paper reports an environmentally benign, simple, cost efficient, one-step, surfactant free, and biogenic synthesis of a silver–graphene (Ag–graphene) nanocomposite using an electrochemically active biofilm (EAB). The EAB was used for the reduction of Ag<SUP>+</SUP> to Ag<SUP>0</SUP> onto the graphene sheets. The morphology, structure, composition, and optical properties and contact angle of the Ag–graphene were obtained using a range of techniques which confirmed the anchoring/presence of silver nanoparticles (AgNPs) onto the graphene sheets. The photocatalytic activity of Ag–graphene was evaluated by the degradation of methylene blue and Congo red dye in aqueous solution at an ambient temperature in the dark and under visible-light irradiation. The results showed that the photocatalytic activity of the Ag–graphene nanocomposite was enhanced significantly by the loading of AgNPs in the graphene sheets. Contact angle measurements confirm the hydrophilic nature of the Ag–graphene nanocomposite which is very helpful in photocatalysis. The electrical conductivity and photocurrent measurements of the Ag–graphene nanocomposite exhibited a much better performance than P–graphene. This study highlights the design of a novel facile synthetic route for a new photocatalyst using the SPR of Ag and graphene as a support. The as-synthesized Ag–graphene nanocomposite has potential applications in photocatalytic degradation, photoelectrodes and optoelectronic devices.</P> <P>Graphic Abstract</P><P>Visible light-driven photocatalytic degradation of organic pollutants using the Ag–graphene nanocomposite. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5nj01320h'> </P>

Spatially-offset Fluorescence Spectroscopy (SOFS) Using Ring Illumination and Point Collection for Sub-surface Measurements in Layered Tissue

Khan Mohammad Khan,Ragesh Kumar,Hemant Krishna,Nirmalya Ghosh,Shovan Kumar Majumder 대한의용생체공학회 2016 Biomedical Engineering Letters (BMEL) Vol.6 No.4

Purpose To report development of a depth-sensitivefluorescence spectroscopy system based on the configurationof point collection fixed at the centre of an illumination ringon the surface of a target sample. Methods The system makes use of an axicon for convertingthe collimated laser beam into ring shaped illumination andachieves the ability of subsurface interrogation by varyingthe radii of the illumination rings thereby introducing spatialoffsets between collection and illumination. The system wasvalidated on a non-biological phantom comprising a thin tissuepaper overlaying a thick dye card and also on a biologicaltissue sample that was a chicken leg tissue consisting of athin epithelial membrane on the top of a much thicker muscletissue. Results It was found that while the fluorescence spectracorresponding to zero spatial offset are dominated by thefluorescence emission bands associated with the top layer ofthe layered samples, the fluorescence spectra measured withspatial offsets contain higher contribution of fluorescencesignatures characteristics of the bottom layer as compared tothe spectrum measured with the zero offset. Conclusions The SOFS based system is able to interrogatesubsurface depths beyond the reach of the conventionalconfocal fluorescence by simply varying the position ofthe axicon in the excitation arm. Due to the simplicity inits instrumentation, the approach has the potential to bedeveloped into a portable system for in situ measurement ina tissue.

pH 감응성 NIPAM-co-MAA 고분자 마이크로젤의 제조 및 분석과 염 종류에 따른 부피상 변화

Mohammad Saleem Khan,Gul Tiaz Khan,Abbas Khan,Sabiha Sultana 한국고분자학회 2013 폴리머 Vol.37 No.6

Novel microgels of N-isopropylacrylamide (NIPAM)-co-methacrylic acid (MAA) (NIPAM-co-MAA) with different contents of N,N-methylene bis acrylamide (MBA) were prepared by emulsion polymerization technique and were studied by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and zeta potential measurement. Effect of pH, temperature and different salts concentration on the microgel particles was investigated. DLS results have shown that the hydrodynamic radius of the microgel increased upon increasing pH and decreased upon increasing temperature. The swelling/deswelling behaviors as determined by DLS showed the ionic repulsions of the carboxyl group of the methacrylic acid and hydrophobic interaction of NIPAM. The effect of various salts on volume phase transition temperature (VPTT) was also investigated. Upon increasing salt concentration, VPTT became broad and shifted to a lower temperature. Electrophoretic mobility measurements showed an increase with increasing pH and temperature at a constant ionic strength.

Potentials of <i>Costus woodsonii</i> leaf extract in producing narrow band gap ZnO nanoparticles

Khan, Mohammad Mansoob,Saadah, Nurin Hayatus,Khan, Mohammad Ehtisham,Harunsani, Mohammad Hilni,Tan, Ai Ling,Cho, Moo Hwan Elsevier 2019 Materials science in semiconductor processing Vol.91 No.-

<P><B>Abstract</B></P> <P>Narrow band gap zinc oxide (ZnO) nanoparticles (NPs) were synthesized using unboiled and boiled leaf extracts of <I>Costus woodsonii</I>. 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 <I>Costus woodsonii</I> and the significantly reduced band gap (E<SUB> <I>g</I> </SUB> = ~2.68 eV to ~2.77 eV) of the as-synthesized ZnO NPs compared to the ZnO-C (E<SUB> <I>g</I> </SUB> = 3.18 eV).</P>

Occupational Therapy Intervention for Malunion of Distal Radial Fracture: A Case Report

Noor Mohammad(Noor Mohammad ),Nahid Khan(Nahid Khan ) 셀메드 세포교정의약학회 2023 셀메드 (CellMed) Vol.13 No.6

Objective: Malunion of distal radial fracture can result in pain, stiffness, and decreased function of the affected limb. Occupational therapy intervention can improve outcomes in these patients, but there is limited research on the effectiveness of such interventions. Case Description: This case report describes the occupational therapy intervention and outcomes for a 44-year-old female patient with malunion of left distal radial fracture. The patient received 8 weeks of occupational therapy intervention consisting of therapeutic exercises, joint mobilization, and fine motor activities. The patient demonstrated significant improvements in range of motion, grip strength, and activities of daily living (ADL) in her left hand. The patient also reported less pain and greater ease in performing activities of daily living. Conclusion: Occupational therapy intervention can be effective in improving outcomes for patients with malunion of distal radial fracture. This case report highlights the importance of early intervention and interdisciplinary collaboration among healthcare professionals to optimize patient outcomes. Further research is needed to explore the effectiveness of occupational therapy interventions for patients with malunion of distal radial fracture.

PROLONGATIONS OF G-STRUCTURES IMMERSED IN GENERALIZED ALMOST r-CONTACT STRUCTURE TO TANGENT BUNDLE OF ORDER 2

Khan, Mohammad Nazrul Islam,Jun, Jae-Bok Chungcheong Mathematical Society 2018 충청수학회지 Vol.31 No.4

The aim of this study is to investigate the prolongations of G-structures immersed in the generalized almost r-contact structure on a manifold M to its tangent bundle T(M) of order 2. Moreover, theorems on Hsu structure, integrability and (${F\limits^{\circ}},\;{{\xi}\limits^{\circ}}{{\omega}\limits^{\circ}}_p,\;a,\;{\epsilon}$)-structure have been established.

Fungi-assisted silver nanoparticle synthesis and their applications

Khan, Azhar U.,Malik, Nazia,Khan, Masudulla,Cho, Moo Hwan,Khan, Mohammad Mansoob Springer-Verlag 2018 Bioprocess and biosystems engineering Vol.41 No.1

<P>Nanotechnology is a rapidly developing field because of its wide range of applications in science, nanoscience and biotechnology. Nanobiotechnology deals with nanomaterials synthesised or modified using biotechnology. Fungi are used to synthesise metal nanoparticles and they have vast applications in wound healing, pathogen detection and control, food preservation, textiles, fabrics, etc. The present review describes the different types of fungi used for the biosyntheses of silver nanoparticles (AgNPs), along with their characterisation and possible biological applications. AgNPs synthesised by other physical and chemical methods are expensive and have toxic substances adsorbed onto them. Therefore, green, simple and effective approaches have been chosen for the biosynthesis of AgNPs, which are very important because of their lower toxicity and environmentally friendly behaviour. AgNPs synthesised using fungi have high monodispersity, specific composition and a narrow size range. In this regard, among the different biological methods used for metal nanoparticle synthesis, fungi are considered to be a superior biogenic method owing to their diversity and better size control. To further understand the biosynthesis of AgNPs using various fungi and evaluate their potential applications, this review discusses the antimicrobial, antibacterial, antifungal, antiviral, antidermatophytic, anti-inflammatory, antitumor, hepatoprotective, cytotoxic, hypotensive, and immunomodulatory activities of these AgNPs. The synthesis of AgNPs using fungi is a clean, green, inexpensive, eco-friendly, reliable, and safe method that can be used for a range of applications in real life for the benefit of human beings.</P>