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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>
Khan, Mohammad Mansoob,Kalathil, Shafeer,Lee, Jin-Tae,Cho, Moo-Hwan Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.8
Cysteine capped silver nanoparticles (Cys-AgNPs) have been synthesized by employing electrochemically active biofilm (EAB), $AgNO_3$ as precursor and sodium acetate as electron donor in aqueous solution at $30^{\circ}C$. Cys-AgNPs of 5-10 nm were synthesized and characterized by UV-Vis, FT-IR, XRD and TEM. Capping of the silver nanoparticles with cysteine provides stability to nanoparticles by a thiolate bond between the amino acid and the nanoparticle surface and hydrogen bonding among the Cys-AgNPs. In addition, the antibacterial effects of as-synthesized Cys-AgNPs have been tested against two pathogenic bacteria Escherichia coli (O157:H7) and Pseudomonas aeruginosa (PAO1). The results demonstrate that the as-synthesized Cys-AgNPs can proficiently inhibit the growth and multiplication of E. coli and P. aeruginosa.
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>
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>
Mohammad Mansoob Khan,Shafeer Kalathil,이진태,조무환 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.8
Cysteine capped silver nanoparticles (Cys-AgNPs) have been synthesized by employing electrochemically active biofilm (EAB), AgNO3 as precursor and sodium acetate as electron donor in aqueous solution at 30 oC. Cys-AgNPs of 5-10 nm were synthesized and characterized by UV-Vis, FT-IR, XRD and TEM. Capping of the silver nanoparticles with cysteine provides stability to nanoparticles by a thiolate bond between the amino acid and the nanoparticle surface and hydrogen bonding among the Cys-AgNPs. In addition, the antibacterial effects of as-synthesized Cys-AgNPs have been tested against two pathogenic bacteria Escherichia coli (O157:H7) and Pseudomonas aeruginosa (PAO1). The results demonstrate that the as-synthesized Cys-AgNPs can proficiently inhibit the growth and multiplication of E. coli and P. aeruginosa.
Mohammad Mansoob Khan,Shafeer Kalathil,이진태,조무환 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.5
A novel, efficient and controlled protocol for the synthesis and enhanced photocatalytic activity of Au@TiO2 nanocomposite is developed. TiO2 (P25) was pretreated by employing UV light (λ = 254 nm) and the pretreated TiO2 was uniformly decorated by gold nanoparticles (AuNPs) in presence of sodium citrate and UV light. UV pretreatment makes the TiO2 activated, as electrons were accumulated within the TiO2 in the conduction band. These accumulated electrons facilitate the formation of AuNPs which were of very small size (2-5 nm), similar morphology and uniformly deposited at TiO2 surface. It leads to formation of stable and crystalline Au@TiO2 nanocomposites. The rapidity (13 hours), monodispersity, smaller nanocomposites and easy separation make this protocol highly significant in the area of nanocomposites syntheses. As-synthesized nanocomposites were characterized by TEM, HRTEM, TEM-EDX, SAED, XRD, UV-visible spectrophotometer and zeta potential. Dye degradation experiments of methyl orange show that type I (Au@TiO2 nanocomposites in which TiO2 was pretreated with UV light) has enhanced photocatalytic activity in comparison to type II (Au@TiO2 nanocomposites in which TiO2 was not pretreated with UV light) and TiO2 (P25). This shows that pretreatment of TiO2 provides type I a better catalytic activity.
Mohammad Mansoob Khan,조무환,이진태 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Au@TiO2 nanocomposites were used for the catalytic degradation of methyl orange and methylene blue by NaBH4. A detail pathway for step by step reduction, oxidation and complete mineralization of intermediates into the respective end-products was established by UV–vis spectroscopy, chemical oxygen demand, ion chromatography and cyclic voltammetry (CV). CV studies confirmed that the dyes were reduced and oxidized to the end-products by NaBH4 in the presence of Au@TiO2 nanocomposites and O2, OH and HO2 radicals generated in situ. Results suggest that Au@TiO2 nanocomposites not only assist in the decolorization of dyes, but also promote their complete mineralization into harmless endproducts.
Biogenic Fabrication of Au@CeO<sub>2</sub> Nanocomposite with Enhanced Visible Light Activity
Khan, Mohammad Mansoob,Ansari, Sajid Ali,Ansari, Mohd Omaish,Min, B. K.,Lee, Jintae,Cho, Moo Hwan American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.18
<P>This study reports a biogenic approach to the synthesis of Au@CeO<SUB>2</SUB> nanocomposite using electrochemically active biofilms (EABs) in water under normal pressure and 30 °C. This work presents the results of extensive morphological, structural, optical, visible light photoelectrochemical and photocatalytic studies of Au@CeO<SUB>2</SUB> nanocomposite. The presence of a large number of interfaces between Au nanoparticles and CeO<SUB>2</SUB> for charge transfer is believed to play a key role in enhancing the optical and visible light photoelectrochemical and photocatalytic performance of Au@CeO<SUB>2</SUB> nanocomposite. The enhanced visible light degradation of methyl orange and methylene blue by Au@CeO<SUB>2</SUB> nanocomposite was much higher than that by pure CeO<SUB>2</SUB>. The reusability, stability, and other results suggests that the Au@CeO<SUB>2</SUB> nanocomposite could be exploited as potential candidates for visible light photocatalysis, photovoltaic, and photoelectrochemical devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-18/jp500933t/production/images/medium/jp-2014-00933t_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp500933t'>ACS Electronic Supporting Info</A></P>