Highly photoactive SnO₂ nanostructures engineered by electrochemically active biofilm

Ansari, Sajid Ali,Khan, Mohammad Mansoob,Omaish Ansari, Mohd,Lee, Jintae,Cho, Moo Hwan The Royal Society of Chemistry 2014 NEW JOURNAL OF CHEMISTRY Vol.38 No.6

<P>This paper reports the defect-induced band gap narrowing of pure SnO<SUB>2</SUB> nanostructures (p-SnO<SUB>2</SUB>) using an electrochemically active biofilm (EAB). The proposed approach is biogenic, simple and green. The systematic characterization of the modified SnO<SUB>2</SUB> nanostructures (m-SnO<SUB>2</SUB>) revealed EAB-mediated defects in the pure SnO<SUB>2</SUB> nanostructures (p-SnO<SUB>2</SUB>). The modified SnO<SUB>2</SUB> (m-SnO<SUB>2</SUB>) nanostructures in visible light showed the enhanced photocatalytic degradation of <I>p</I>-nitrophenol and methylene blue compared to the p-SnO<SUB>2</SUB> nanostructures. The photoelectrochemical studies, such as the electrochemical impedance spectroscopy and linear scan voltammetry, also revealed a significant increase in the visible light response of the m-SnO<SUB>2</SUB> compared to the p-SnO<SUB>2</SUB> nanostructures. The enhanced activities of the m-SnO<SUB>2</SUB> in visible light was attributed to the high separation efficiency of the photoinduced electron–hole pairs due to surface defects mediated by an EAB, resulting in a band gap narrowing of the m-SnO<SUB>2</SUB> nanostructures. The tuned band gap of the m-SnO<SUB>2</SUB> nanostructures enables the harvesting of visible light to exploit the properties of the metal oxide towards photodegradation, which can in turn be used for environmental remediation applications.</P> <P>Graphic Abstract</P><P>This paper reports the defect-induced band gap narrowing of pure SnO<SUB>2</SUB> nanostructures (p-SnO<SUB>2</SUB>) using an electrochemically active biofilm (EAB). <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3nj01488f'> </P>

Mechanically exfoliated MoS₂ sheet coupled with conductive polyaniline as a superior supercapacitor electrode material

Ansari, Sajid Ali,Fouad, H.,Ansari, S.G.,Sk, Md Palashuddin,Cho, Moo Hwan Elsevier 2017 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.504 No.-

<P><B>Abstract</B></P> <P>The development of electrically conductive metal sulfide-based polymer nanocomposites for energy storage materials has been a major focus by researchers to solve the energy crisis. In this study, a simple and facile method was used to construct a nanocomposite by combining a mechanically exfoliated MoS<SUB>2</SUB> (M-MoS<SUB>2</SUB>) sheet with polyaniline (Pani) using a simple and scalable in-situ chemical oxidative polymerization method. The as-prepared nanocomposite (M-MoS<SUB>2</SUB>-Pani nanocomposite) was characterized further by usual basic spectroscopic techniques, such as X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller surface area analysis. The electrochemical supercapacitive characteristics of the M-MoS<SUB>2</SUB>-Pani nanocomposite was tested in a three-electrode assembly by obtaining cyclic voltammetric (CV) curves and galvanostatic charge-discharge (GCD) measurements. The results were compared with those of a C-MoS<SUB>2</SUB>-Pani nanocomposite that had been synthesized using bulk MoS<SUB>2</SUB>. The M-MoS<SUB>2</SUB>-Pani nanocomposite synthesized using exfoliated MoS<SUB>2</SUB> exhibited a higher specific capacitance of 510.12Fg<SUP>−1</SUP> at a current of 1Ag<SUP>−1</SUP> than the C-MoS<SUB>2</SUB>-Pani nanocomposite (225.15Fg<SUP>−1</SUP>), which was synthesized using bulk C-MoS<SUB>2</SUB> delivered. The enhanced electrochemical supercapacitive performance was correlated to the synergistic effect and chemical interactions between the Pani and MoS<SUB>2</SUB>, which provide high electrical conductivity and a sufficient empty state for electrode/electrolyte contact.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fibrous polyaniline@manganese oxide nanocomposites as supercapacitor electrode materials and cathode catalysts for improved power production in microbial fuel cells

Ansari, Sajid Ali,Parveen, Nazish,Han, Thi Hiep,Ansari, Mohammad Omaish,Cho, Moo Hwan The Royal Society of Chemistry 2016 Physical chemistry chemical physics Vol.18 No.13

<P>Fibrous Pani-MnO2 nanocomposite were prepared using a one-step and scalable in situ chemical oxidative polymerization method. The formation, structural and morphological properties were investigated using a range of characterization techniques. The electrochemical capacitive behavior of the fibrous Pani-MnO2 nanocomposite was examined by cyclic voltammetry and galvanostatic charge-discharge measurements using a three-electrode experimental setup in an aqueous electrolyte. The fibrous Pani-MnO2 nanocomposite achieved high capacitance (525 F g(-1) at a current density of 2 A g(-1)) and excellent cycling stability of 76.9% after 1000 cycles at 10 A g(-1). Furthermore, the microbial fuel cell constructed with the fibrous Pani-MnO2 cathode catalyst showed an improved power density of 0.0588 W m(-2), which was higher than that of pure Pani and carbon paper, respectively. The improved electrochemical supercapacitive performance and cathode catalyst performance in microbial fuel cells were attributed mainly to the synergistic effect of Pani and MnO2 in fibrous Pani-MnO2, which provides high surface area for the electrode/electrolyte contact as well as electronic conductive channels and exhibits pseudocapacitance behavior.</P>

Anion selective <i>p</i>TSA doped polyaniline@graphene oxide-multiwalled carbon nanotube composite for Cr(VI) and Congo red adsorption

Ansari, Mohammad Omaish,Kumar, Rajeev,Ansari, Sajid Ali,Ansari, Shahid Pervez,Barakat, M.A.,Alshahrie, Ahmed,Cho, Moo Hwan Elsevier 2017 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.496 No.-

<P><B>Abstract</B></P> <P>Multiwalled carbon nanotube (CNT)-graphene oxide (GO) composite was combined with polyaniline (Pani) using an oxidative polymerisation technique. The resulting Pani@GO-CNT was later doped with para toluene sulphonic acid (<I>p</I>TSA) to generate additional functionality. The functional groups exposed on the GO, Pani and <I>p</I>TSA were expected to impart a high degree of functionality to the <I>p</I>TSA-Pani@GO-CNT composite system. The composite was characterised by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The characterisation results revealed the characteristics of Pani, GO, CNT, and <I>p</I>TSA, and suggested the successful formation of the <I>p</I>TSA-Pani@GO-CNT composite system. The composite was utilised successfully for the adsorptive removal of Cr(IV) and Congo red (CR) dye and the adsorption of both pollutants was found to be strongly dependent on the solution pH, adsorbate concentration, contact time, and reaction temperature. The maximum adsorption of Cr(IV) and CR was observed in an acidic medium at 30°C. The kinetics for Cr(IV) and CR adsorption was studied using pseudo-first order, pseudo-second order, and intraparticle diffusion models. The adsorption equilibrium data were also fitted to the Langmuir and Freundlich isotherm models. The thermodynamic results showed that the adsorption process was exothermic in nature. The present study provides a new methodology for the preparation of a highly functionalised Pani-based nanocomposite system and its potential applications to the adsorptive removal of a multicomponent pollutant system from an aqueous solution.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Metal free earth abundant elemental red phosphorus: a new class of visible light photocatalyst and photoelectrode materials

Ansari, Sajid Ali,Ansari, Mohammad Shahnawaze,Cho, Moo Hwan The Royal Society of Chemistry 2016 Physical Chemistry Chemical Physics Vol.18 No.5

<P>Developing a high-performance photocatalyst and a photoelectrode with enhanced visible light harvesting properties is essential for practical visible light photocatalytic applications. Noble metal-free, highly visible light-active, elemental red phosphorus (RP) was prepared by a facile mechanical ball milling method, which is a reproducible, low cost and controllable synthesis process. The synthesis used inexpensive and abundant raw materials because most RP hybrids are based on expensive noble-metals. The novel milled RP showed significantly enhanced photocatalytic and photoelectrochemical performances with a lower charge transfer resistance compared to commercial RP under wide visible photoirradiation, making it a feasible alternative for photocatalytic applications.</P>

Highly visible light active Ag@ZnO nanocomposites synthesized by gel-combustion route

Sajid Ali Ansari,조무환,칸모하마드만숩,이진태 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

Highly visible light active 1% and 3% Ag@ZnO nanocomposites were synthesized via a gel combustion route using citric acid as a fuel. The formation of the nanocomposites with enhanced properties was confirmed using a range of characterization techniques, photocatalysis and photoelectrochemical studies. Compared to the pristine ZnO nanoparticles, the Ag@ZnO nanocomposites exhibited enhanced visible light photocatalytic activity for the degradation of methylene blue and photoelectrochemical response. A mechanism was proposed to account for the photocatalytic activities of the Ag@ZnO nanocomposite that showed the surface plasmon resonance (SPR) of Ag is an effective way of enhancing the visible light photocatalytic activities.

Simple and sustainable route for large scale fabrication of few layered molybdenum disulfide sheets towards superior adsorption of the hazardous organic pollutant

Ansari, Sajid Ali,Kumar, Rajeev,Barakat, M. A.,Cho, Moo Hwan Chapman and Hall 2018 Journal of materials science Materials in electron Vol. No.

Gold nanoparticles-sensitized wide and narrow band gap TiO₂ for visible light applications: a comparative study

Ansari, Sajid Ali,Khan, Mohammad Mansoob,Ansari, Mohd Omaish,Cho, Moo Hwan The Royal Society of Chemistry 2015 NEW JOURNAL OF CHEMISTRY Vol.39 No.6

<P>Gold nanoparticles (AuNPs)-sensitized wide band gap TiO<SUB>2</SUB> (Au/P-TiO<SUB>2</SUB>) and narrow band gap TiO<SUB>2</SUB> (Au/M-TiO<SUB>2</SUB>) nanocomposites were prepared using an electrochemically active biofilm. The optical and structural properties of the Au/P-TiO<SUB>2</SUB> and Au/M-TiO<SUB>2</SUB> nanocomposites were characterized using standard techniques. The surface plasmon resonance (SPR) absorption characteristics of the AuNPs on the TiO<SUB>2</SUB> surface extended the absorption edge of P-TiO<SUB>2</SUB> and M-TiO<SUB>2</SUB> to the visible light region. The photocatalytic activity of the Au/P-TiO<SUB>2</SUB> and Au/M-TiO<SUB>2</SUB> nanocomposites was evaluated by the photodegradation of methylene blue and methyl orange, and 2-chlorophenol under visible light irradiation, where Au/M-TiO<SUB>2</SUB> nanocomposite exhibited enhanced photocatalytic activity compared to the Au/P-TiO<SUB>2</SUB> nanocomposite and P-TiO<SUB>2</SUB> and M-TiO<SUB>2</SUB> nanoparticles. Furthermore, the higher photoelectrochemical performance of the Au/M-TiO<SUB>2</SUB> nanocomposite compared to the Au/P-TiO<SUB>2</SUB> nanocomposite and P-TiO<SUB>2</SUB> and M-TiO<SUB>2</SUB> nanoparticles further support its higher visible light active behavior under visible light irradiation. The pronounced photoactivities of the Au/M-TiO<SUB>2</SUB> nanocomposite in the visible region were attributed to the interfacial synergistic effects of the two phenomena, <I>i.e.</I> the SPR effect of AuNPs and the defect-induced band gap reduction of M-TiO<SUB>2</SUB> nanoparticles. The present work provides a newer insight into the development of nanocomposites of noble metals and defective metal oxides with high efficiency in the field of visible light-induced photoactivity.</P> <P>Graphic Abstract</P><P>Photocatalytic degradation of dyes and organic compounds by Au/P-TiO<SUB>2</SUB> and Au/M-TiO<SUB>2</SUB> nanocomposites under visible light irradiation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5nj00556f'> </P>

Electrically conductive polyaniline sensitized defective-TiO₂ for improved visible light photocatalytic and photoelectrochemical performance: a synergistic effect

Ansari, Mohd Omaish,Khan, Mohammad Mansoob,Ansari, Sajid Ali,Cho, Moo Hwan The Royal Society of Chemistry 2015 NEW JOURNAL OF CHEMISTRY Vol.39 No.11

<P>Sulfonated polyaniline@pure-TiO<SUB>2</SUB> (s-Pani@p-TiO<SUB>2</SUB>) and polyaniline@defective-TiO<SUB>2</SUB> (s-Pani@m-TiO<SUB>2</SUB>) nanocomposites were prepared by the <I>in situ</I> oxidative polymerization of aniline in the presence of TiO<SUB>2</SUB> (p-TiO<SUB>2</SUB> and m-TiO<SUB>2</SUB>) nanoparticles followed by sulfonation with fuming sulfuric acid. Defect-induced TiO<SUB>2</SUB> (m-TiO<SUB>2</SUB>) nanoparticles were obtained by an electron beam (EB) treatment of commercial TiO<SUB>2</SUB> (p-TiO<SUB>2</SUB>) nanoparticles. The resulting s-Pani@p-TiO<SUB>2</SUB> and s-Pani@m-TiO<SUB>2</SUB> nanocomposites were characterized by UV-visible diffuse absorbance spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Polyaniline (Pani) was dispersed uniformly over the defective m-TiO<SUB>2</SUB> surface with intimate contact on the interface to act cooperatively with the deliberately induced defects to achieve remarkably enhanced properties. The s-Pani@m-TiO<SUB>2</SUB> nanocomposite showed better photocatalytic activity and photoelectrochemical performance than s-Pani@p-TiO<SUB>2</SUB> under visible light irradiation, which was attributed partly to the sensitizing effect of Pani, the narrowed band gap of m-TiO<SUB>2</SUB> and the effective interfacial interaction between Pani and m-TiO<SUB>2</SUB>. The electrical conductivity measured using a four-point probe revealed s-Pani@m-TiO<SUB>2</SUB> to have much higher conductivity than s-Pani@p-TiO<SUB>2</SUB>. Therefore, s-Pani@m-TiO<SUB>2</SUB> may be used for a wide range of applications owing to its higher charge mobility and high photocatalytic activity. The proposed methodology can also be a potential route for the development of nanocomposites <I>via</I> EB treatment and can be commercialized.</P> <P>Graphic Abstract</P><P>A proposed scheme for the synthesis of s-Pani@m-TiO<SUB>2</SUB> nanocomposites. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5nj01127b'> </P>

Enhanced Thermal Stability under DC Electrical Conductivity Retention and Visible Light Activity of Ag/TiO₂@Polyaniline Nanocomposite Film

Ansari, Mohd Omaish,Khan, Mohammad Mansoob,Ansari, Sajid Ali,Raju, Kati,Lee, Jintae,Cho, Moo Hwan American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.11

<P>The development of organic–inorganic photoactive materials has resulted in significant advancements in heterogeneous visible light photocatalysis. This paper reports the synthesis of visible light-active Ag/TiO<SUB>2</SUB>@Pani nanocomposite film via a simple biogenic–chemical route. Electrically conducting Ag/TiO<SUB>2</SUB>@Pani nanocomposites were prepared by incorporating Ag/TiO<SUB>2</SUB> in <I>N</I>-methyl-2-pyrrolidone solution of polyaniline (Pani), followed by the preparation of Ag/TiO<SUB>2</SUB>@Pani nanocomposite film using solution casting technique. The synthesized Ag/TiO<SUB>2</SUB>@Pani nanocomposite was confirmed by UV–visible spectroscopy, photoluminescence spectroscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The Ag/TiO<SUB>2</SUB>@Pani nanocomposite film showed superior activity towards the photodegradation of methylene blue under visible light compared to Pani film, even after repeated use. Studies on the thermoelectrical behavior by DC electrical conductivity retention under cyclic aging techniques showed that the Ag/TiO<SUB>2</SUB>@Pani nanocomposite film possessed a high combination of electrical conductivity and thermal stability. Because of its better thermoelectric performance and photodegradation properties, such materials might be a suitable advancement in the field of smart materials in near future.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-11/am500488e/production/images/medium/am-2014-00488e_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am500488e'>ACS Electronic Supporting Info</A></P>