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>

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>

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>

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>

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>

Efficacy and safety of sequential neoadjuvant chemotherapy and short-course radiation therapy followed by delayed surgery in locally advanced rectal cancer: a single-arm phase II clinical trial with subgroup analysis between the older and young patients

Ali Mohammad Bananzadeh,Ali Akbar Hafezi,NamPhong Nguyen,Shapour Omidvari,Ahmad Mosalaei,Niloofar Ahmadloo,Mansour Ansari,Mohammad Mohammadianpanah 대한방사선종양학회 2021 Radiation Oncology Journal Vol.39 No.4

Purpose: This study was performed to investigate the efficacy and safety of short-course radiation therapy (SCRT) and sequential chemotherapy followed by delayed surgery in locally advancer rectal cancer with subgroup analysis between the older and young patients.Materials and Methods: In this single-arm phase II clinical trial, eligible patients with locally advanced rectal cancer (T3–4 and/or N1–2) were enrolled. All the patients received a median three sequential cycles of neoadjuvant CAPEOX (capecitabine + oxaliplatin) chemotherapy. A total dose of 25 Gy in five fractions during 1 week was prescribed to the gross tumor and regional lymph nodes. Surgery was performed about 8 weeks following radiotherapy. Pathologic complete response rate (pCR) and grade 3–4 toxicity were compared between older patients (≥65 years) and younger patients (<65 years).Results: Ninety-six patients with locally advanced rectal cancer were enrolled. There were 32 older patients and 64 younger patients. Overall pCR was 20.8% for all the patients. Older patients achieved similar pCR rate (18.7% vs. 21.8; p = 0.795) compared to younger patients. There was no statistically significance in terms of the tumor and the node downstaging or treatment-related toxicity between older patients and younger ones; however, the rate of sphincter-saving surgery was significantly more frequent in younger patients (73% vs. 53%; p=0.047) compared to older ones. All treatment-related toxicities were manageable and tolerable among older patients.Conclusion: Neoadjuvant SCRT and sequential chemotherapy followed by delayed surgery was safe and effective in older patients compared to young patients with locally advanced rectal cancer.

Lithium ion storage ability, supercapacitor electrode performance, and photocatalytic performance of tungsten disulfide nanosheets

Ansari, Mohd Zahid,Ansari, Sajid Ali,Parveen, Nazish,Cho, Moo Hwan,Song, Taeseup The Royal Society of Chemistry 2018 New Journal of Chemistry Vol.42 No.8

<P>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<SUP>−1</SUP> 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<SUP>−1</SUP> at a current density of 0.75 A g<SUP>−1</SUP> 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.</P>

Low-Temperature Atomic Layer Deposition of Highly Conformal Tin Nitride Thin Films for Energy Storage Devices

Ansari, Mohd Zahid,Nandi, Dip K.,Janicek, Petr,Ansari, Sajid Ali,Ramesh, Rahul,Cheon, Taehoon,Shong, Bonggeun,Kim, Soo-Hyun American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.46

<P>We present an atomic layer deposition (ALD) process for the synthesis of tin nitride (SnN<SUB><I>x</I></SUB>) thin films using tetrakis(dimethylamino) tin (TDMASn, Sn(NMe<SUB>2</SUB>)<SUB>4</SUB>) and ammonia (NH<SUB>3</SUB>) as the precursors at low deposition temperatures (70-200 °C). This newly developed ALD scheme exhibits ideal ALD features such as self-limited film growth at 150 °C. The growth per cycle (GPC) was found to be ∼0.21 nm/cycle at 70 °C, which decreased with increasing deposition temperature. Interestingly, when the deposition temperature was between 125 and 180 °C, the GPC remained almost constant at ∼0.10 nm/cycle, which suggests an ALD temperature window, whereas upon further increasing the temperature to 200 °C, the GPC considerably decreased to ∼0.04 nm/cycle. Thermodynamic analysis via density functional theory calculations showed that the self-saturation of TDMASn would occur on an NH<SUB>2</SUB>-terminated surface. Moreover, it also suggests that the condensation of a molecular precursor and the desorption of surface *NH<SUB>2</SUB> moieties would occur at lower and higher temperatures outside the ALD window, respectively. Thanks to the characteristics of ALD, this process could be used to conformally and uniformly deposit SnN<SUB><I>x</I></SUB> onto an ultranarrow dual-trench Si structure (minimum width: 15 nm; aspect ratio: ∼6.3) with ∼100% step coverage. Several analysis tools such as transmission electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, and secondary-ion mass spectrometry were used to characterize the film properties under different deposition conditions. XRD showed that a hexagonal SnN phase was obtained at a relatively low deposition temperature (100-150 °C), whereas cubic Sn<SUB>3</SUB>N<SUB>4</SUB> was formed at a higher deposition temperature (175-200 °C). The stoichiometry of these thermally grown ALD-SnN<SUB><I>x</I></SUB> films (Sn-to-N ratio) deposited at 150 °C was determined to be ∼1:0.93 with negligible impurities. The optoelectronic properties of the SnN<SUB><I>x</I></SUB> films, such as the band gap, wavelength-dependent refractive index, extinction coefficient, carrier concentration, and mobility, were further evaluated via spectroscopic ellipsometry analysis. Finally, ALD-SnN<SUB><I>x</I></SUB>-coated Ni-foam (NF) and hollow carbon nanofibers were successfully used as free-standing electrodes in electrochemical supercapacitors and in Li-ion batteries, which showed a higher charge-storage time (about eight times greater than that of the uncoated NF) and a specific capacity of ∼520 mAh/g after 100 cycles at 0.1 A/g, respectively. This enhanced performance might be due to the uniform coverage of these substrates by ALD-SnN<SUB><I>x</I></SUB>, which ensures good electric contact and mechanical stability during electrochemical reactions.</P> [FIG OMISSION]</BR>

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>

Nano Structured Potentiometric Sensors Based on Polyaniline Conducting Polymer for Determination of Cr (VI)

Ali, Mohammad-Khah,Ansari, Reza,Delavar, Ali Fallah,Mosayebzadeh, Zahra Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.4

In this paper, a potentiometric sensor based on polyaniline conducting polymer for potentiometric determination of Cr (VI) ions is reported. Polyaniline was synthesized electrochemically (cyclic voltammetry method) onto a micro pencil graphite electrode (0.7 mm diameter) in the presence of HCl and diphenylcarbazide (termed as (PGE/PAni/DPC). Some initial experiments were performed in order to find out the optimized conditions for preparation of the introduced Cr (VI) sensor electrode. The plot of E vs. log [Cr (VI)], showed a linear response in the range from $1.0{\times}10^{-6}$ to $1.0{\times}10^{-1}$ M. High repeatability with the detection limit of $8.0{\times}10^{-7}$ M was obtained.