Can supervise: YES
Majeed, I, Manzoor, U, Kanodarwala, FK, Nadeem, MA, Nadeem, MA, Hussain, E, Ali, H, Badshah, A & Stride, JA 2018, 'Pd-Ag decorated g-C3N4 as an efficient photocatalyst for hydrogen production from water under direct solar light irradiation', Catalysis Science and Technology, vol. 8, no. 4, pp. 1183-1193.View/Download from: UTS OPUS or Publisher's site
© The Royal Society of Chemistry. A low visible light absorption efficiency and high recombination rate of photogenerated charge carriers are two major problems encountered in graphitic carbon nitride (g-C3N4) based photocatalysts for water splitting applications. In this work, Pd-Ag bimetallic and monometallic nanoparticles were decorated on graphitic carbon nitride by a simple chemical reduction method and evaluated for their ability to produce H2 during water splitting reactions. The physical and photophysical characteristics of the as-prepared Pd-Ag/g-C3N4 photocatalysts were studied by powder X-ray diffraction (PXRD), UV-visible diffuse reflection spectroscopy (DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and steady state photoluminescence (PL). The Pd0.7-Ag0.3/g-C3N4 photocatalyst with an overall metal loading of 1 wt% showed a very high H2 generation rate of 1250 mol h-1 g-1, which is 1.5 and 5.7 times higher than those of the Pd/g-C3N4 and Ag/g-C3N4 photocatalysts, respectively. The high activity of the Pd-Ag/g-C3N4 photocatalyst was attributed to the inherent property of palladium metal to quench photogenerated electrons by the Schottky barrier formation mechanism and strong visible light absorption due to the characteristic surface plasmon resonance (SPR) of silver nanoparticles along with the absorption of g-C3N4.
Ali, H, Zaman, S, Majeed, I, Kanodarwala, FK, Nadeem, MA, Stride, JA & Nadeem, MA 2017, 'Porous Carbon/rGO Composite: An Ideal Support Material of Highly Efficient Palladium Electrocatalysts for the Formic Acid Oxidation Reaction', ChemElectroChem, vol. 4, no. 12, pp. 3126-3133.View/Download from: UTS OPUS or Publisher's site
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Catalyst support materials play an important role in the electrochemical performance of the catalyst in fuel cells. Herein, we present a synergistic effect of surface area and electronic conductivity on the efficiency of a carbon support material towards its application in direct formic acid fuel cells. A composite of reduced graphene oxide (rGO) and metal organic framework (MOF-5) derived porous carbon (PC) was used as a novel support material for a high dispersion of palladium nanoparticles. The rGO 1 -C 1 electrocatalyst, which consists of an equal ratio of PC and rGO, was found to be the most effective for the formic acid electro-oxidation reaction. The obtained mass specific activity for Pd/rGO 1 -C 1 (969.76 mA mg 1 ) is 1.52 times higher than for Pd/rGO (639.5 mA mg 1 ) and 2.63 times higher than Pd/C (368.73 mA mg 1 ) synthesized under the same conditions and at given onset peak potentials. The Pd/rGO 1 -C 1 electrocatalyst was also found to be much more stable than other catalysts as evidenced by chronoamperometric measurements for up to 3000 s. The high activity and stability of the catalyst fabricated over the composite carbon support is due to a synergism between the Pd metal and the composite support toward charge transfer, where highly porous carbon provides a high surface area and the rGO is highly conductive, thereby boosting the electrical properties of the catalyst.
Majeed, I, Nadeem, MA, Badshah, A, Kanodarwala, FK, Ali, H, Khan, MA, Stride, JA & Nadeem, MA 2017, 'Titania supported MOF-199 derived Cu-Cu 2 O nanoparticles: Highly efficient non-noble metal photocatalysts for hydrogen production from alcohol-water mixtures', Catalysis Science and Technology, vol. 7, no. 3, pp. 677-686.View/Download from: UTS OPUS or Publisher's site
© The Royal Society of Chemistry 2017. Fabrication of cheap and efficient photocatalysts is pivotal for practical applications of solar energy devices. Here, we illustrate a novel trend in generating Cu-Cu 2 O nanoparticles over TiO 2 for water splitting systems. Titanium(IV) isopropoxide was hydrolysed in the presence of various wt% of MOF-199 ([Cu 3 (BTC) 2 (H 2 O) 3 ] n ) to obtain TiO 2 -MOF-199 composite materials. These composite materials are then calcined at various temperatures in air to produce highly dispersed Cu-Cu 2 O nanoparticles over TiO 2 ; these nanoparticles were tested as photocatalyts for hydrogen generation from alcohol-water mixtures. The photocatalyst 1 wt% Cu/TiO 2 -400 was found to exhibit a hydrogen production rate some 2.5 times higher than that of CuO prepared by conventional precipitation methods. The calcination temperature of the TiO 2 -MOF composite was found to affect the oxidation state of Cu and the photocatalytic activity, with an optimum performance achieved at 400°C. Calcination beyond this temperature led to oxidation and agglomeration of Cu-Cu 2 O nanoparticles into larger CuO deposits, which reduce the H 2 production activity (ca. 80%).
Majeed, I, Nadeem, MA, Kanodarwala, FK, Hussain, E, Badshah, A, Hussain, I, Stride, JA & Nadeem, MA 2017, 'Controlled Synthesis of TiO2Nanostructures: Exceptional Hydrogen Production in Alcohol-Water Mixtures over Cu(OH)2–Ni(OH)2/TiO2Nanorods', ChemistrySelect, vol. 2, no. 25, pp. 7497-7507.View/Download from: UTS OPUS or Publisher's site
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Development of non-noble metal photocatalysts for hydrogen (H 2 ) generation from renewables is important towards cost effective technology. Titania nanorods with different phase compositions and surface areas were fabricated by calcination of hydrogen titanate (H 2 Ti 3 O 7 ) precursors obtained by treating P25 (TiO 2 ) hydrothermally in 10 M NaOH and followed by HCl washing. Subsequently the copper and nickel hydroxides were co-deposited over TiO 2 nanorods and used to generate H 2 from alcohol-water mixtures under UV light. Among the synthesized materials, the optimized photocatalyst 0.8Cu(OH) 2 -0.2Ni(OH) 2 /TNR 130 -400 showed very high H 2 production rates that are 26.6 mmol h 1 g 1 in 20 vol.% ethanol-water mixture and 35.1 mmol h 1 g 1 in 5 vol.% glycerol-water mixtures. The amount of this H 2 production is even higher than obtained from noble metal supported TiO 2 photocatalysts. This exceptional photocatalytic H 2 production is attributed to the high synergism among nanords mophology of support and in situ formation of Cu and Ni exclusively in metallic states during photoreactions.
Ali, H, Kanodarwala, FK, Majeed, I, Stride, JA & Nadeem, MA 2016, 'La 2 O 3 promoted Pd/rGO electro-catalysts for formic acid oxidation', ACS Applied Materials and Interfaces, vol. 8, no. 47, pp. 32581-32590.View/Download from: Publisher's site
© 2016 American Chemical Society. High activity, a low rate of CO poisoning, and long-term stability of Pd electro-catalysts are necessary for practical use as an anode material in direct formic acid fuel cells. Achieving a high degree of Pd nanoparticle dispersion on a carbon support, without agglomeration, while maintaining a facile electron transfer through the catalyst surface are two challenging tasks to be overcome in fulfilling this aim. Herein, we report the effect of addition of La/La-oxides on the efficiency of Pd nanoparticles supported on reduced graphene oxide (rGO) for formic acid electro-oxidation reaction. A series of electro-catalysts with different Pd-La molar ratios were successfully synthesized and characterized using a range of techniques including PXRD, XPS, TEM, FTIR, and Raman spectroscopy and then tested as anode materials for direct formic acid fuel cells. We explore that the lanthanum species (La/La-oxide) significantly promote the activity and stability of Pd catalyst toward electrocatalytic oxidation of formic acid. The metallic ratio is found to be critical, and the activity order of various catalysts is observed as follows; Pd 30 La 70 /rGO > Pd 80 La 20 /rGO > Pd 70 La 30 rGO. The obtained mass specific activity for Pd 30 La 70 /rGO (986.42 A/g) is 2.18 times higher than that for Pd/rGO (451 A/g) and 16 times higher than that for Pd/C (61.5 A/g) at given onset peak potentials. The high activity and stability of the electro-catalysts are attributed to the uniform dispersion of Pd nanoparticles over the rGO support, as evidenced from TEM images. It is believed that the role of La species in promoting the catalyst activity is to disperse the catalyst particles during synthesis and to facilitate the electron transfer via providing a suitable pathway during electrochemical testing.
Gonçalves, LFFF, Silva, CJR, Kanodarwala, FK, Stride, JA & Pereira, MR 2015, 'Effect of acid or alkaline catalyst and of different capping agents on the optical properties of CdS nanoparticles incorporated within a diureasil hybrid matrix', Optical Materials, vol. 49, pp. 171-181.View/Download from: Publisher's site
© 2015 Elsevier B.V. All rights reserved. CdS nanoparticles (NPs) were synthesized using colloidal methods and incorporated within a diureasil hybrid matrix. The surface capping of the CdS NPs by 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APTMS) organic ligands during the incorporation of the NPs within the hybrid matrix has been investigated. The matrix is based on poly(ethylene oxide)/poly(propylene oxide) chains grafted to a siliceous skeleton through urea bonds and was produced by sol-gel process. Both alkaline and acidic catalysis of the sol-gel reaction were used to evaluate the effect of each organic ligand on the optical properties of the CdS NPs. The hybrid materials were characterized by absorption, steady-state and time-resolved photoluminescence spectroscopy and High Resolution Transmission Electron Microscopy (HR-TEM). The preservation of the optical properties of the CdS NPs within the diureasil hybrids was dependent on the experimental conditions used. Both organic ligands (APTMS and MPTMS) demonstrated to be crucial in avoiding the increase of size distribution and clustering of the NPs within the hybrid matrix. The use of organic ligands was also shown to influence the level of interaction between the hybrid host and the CdS NPs. The CdS NPs showed large Stokes shifts and long average lifetimes, both in colloidal solution and in the xerogels, due to the origin of the PL emission in surface states. The CdS NPs capped with MPTMS have lower PL lifetimes compared to the other xerogel samples but still larger than the CdS NPs in the original colloidal solution. An increase in PL lifetimes of the NPs after their incorporation within the hybrid matrix is related to interaction between the NPs and the hybrid host matrix.
Kanodarwala, FK, Wang, F, Reece, PJ & Stride, JA 2015, 'Phase transformations in CdSe quantum dots induced by reaction time', MATERIALS LETTERS, vol. 141, pp. 67-69.View/Download from: UTS OPUS or Publisher's site
Gonçalves, LFFF, Silva, CJR, Kanodarwala, FK, Stride, JA, Pereira, MR & Gomes, MJM 2014, 'Influence of Cd 2+ /S 2- molar ratio and of different capping environments in the optical properties of CdS nanoparticles incorporated within a hybrid diureasil matrix', Applied Surface Science, vol. 314, pp. 877-887.View/Download from: Publisher's site
The incorporation of CdS nanoparticles (NPs), as prepared through colloidal methods using reverse micelles, within diureasil hybrid organic-inorganic sol-gel matrices was investigated. Several experimental conditions, namely the influence of capping agent 3-mercaptopropyltrimethoxysilane (MPTMS) or the use of tetraethoxysilane (TEOS), were studied in order to assure the preservation of the original optical properties of colloidal CdS NPs after the incorporation of the NPs within the solid diureasil hybrid matrix. The diureasil matrix is based on a siliceous network cross linked through urea bonds to poly(oxyethylene)/ poly(oxypropylene) (PEO/PPO) chains. The influence of the Cd 2+ /S 2- molar ratio of the NPs in the stability and dispersion of the NPs within the diureasil matrix was also investigated. The obtained CdS doped hybrid matrix was characterized by absorption, steady-state and time-resolved photoluminescence (PL) spectroscopy and by transmission electron microscopy (TEM). The stability of the CdS NPs within the hybrid matrix showed to be dependent on the Cd 2+ /S 2- molar ratio used in the synthesis of the NPs. The use of MPTMS proved to be crucial in the preservation of the original optical properties of the colloidal CdS NPs after the incorporation of the NPs within the hybrid matrix. The effect of MPTMS was in turn influenced by the Cd 2+ /S 2- molar ratio employed in the synthesis of the CdS NPs. The use of MPTMS was less effective when Cd 2+ /S 2- molar ratio equal to 0.5 was used. In the absence of MPTMS or TEOS larger NPs size distribution and clustering of the CdS NPs were obtained after the transfer of the NPs into the hybrid matrix. © 2014 Elsevier B.V.
Gonçalves, LFFF, Silva, CJR, Kanodarwala, FK, Stride, JA & Gomes, MJM 2014, 'Synthesis and characterization of organic-inorganic hybrid materials prepared by sol-gel and containing CdS nanoparticles prepared by a colloidal method using poly(N-vinyl-2-pyrrolidone)', Journal of Sol-Gel Science and Technology, vol. 71, no. 1, pp. 69-78.View/Download from: Publisher's site
This paper describes the synthesis and characterization of CdS nanoparticles (NPs) stabilized with poly(N-vinyl-2-pyrrolidone) and their further immobilization on a hybrid organic-inorganic matrix produced by the sol-gel process. The production of the hybrid matrix doped with CdS NPs was carried out in two steps. In the first step a precursor, designated diureasil precursor, was synthesized from the reaction between the terminal amine groups of ,-diamine-poly(oxyethylene-co-oxypropylene) and the isocyanate group of 3-isocyanatopropyltriethoxysilane. The next step involved the hydrolysis and condensation reactions of ethoxy groups attached to silicon, this step resulting in the formation of a crosslinked siliceous network linked through urea bonds to a poly(oxyethylene)/poly(oxypropylene) chain. The NPs were added to the diureasil precursor before the gelation process to allow a homogeneous dispersion of the NPs within the matrix. The developed method allowed the transfer of colloidal NPs to a solid matrix without the need of exchange the capping agents or the solvent. The materials were characterized by absorption, steady-state photoluminescence spectroscopy and by TEM. The results obtained showed the presence of CdS NPs with quantum size effect dispersed within the diureasil matrix. The obtained nanocomposites show a high transparency in the visible range accounting for the good dispersion of the NPs within the matrix. The TEM analysis confirmed that the NPs are uniformly dispersed within the diureasil matrix. © 2014 Springer Science+Business Media New York.
Gonçalves, LFFF, Silva, CJR, Kanodarwala, FK, Stride, JA, Pereira, MR & Gomes, MJM 2014, 'Synthesis of an optically clear, flexible and stable hybrid ureasilicate matrix doped with CdSe nanoparticles produced by reverse micelles', Materials Chemistry and Physics, vol. 147, no. 1-2, pp. 86-94.View/Download from: Publisher's site
Optically clear and flexible organic-inorganic hybrid materials doped with CdSe nanoparticles (NPs) were synthesized by a sol-gel method based on the hydrolysis and condensation reactions of ureasilicate precursors. The CdSe NPs were produced by a colloidal method using reverse micelles and were then transferred to the ureasilicate precursor solution followed by gelation of the mixture using ammonia/water vapours as catalyst for the sol-gel process. The influence of the NPs surface in the dispersion of the NPs within the matrix was investigated by the addition of a capping agent with both thiol and siloxane groups (3-mercaptopropyltrimethoxysilane, MPTMS). This capping agent was used in order to improve compatibility and avoid aggregation of the NPs within the matrix and to increase the preservation of the original optical properties of the NPs. The nanocomposites obtained were characterized by absorption spectroscopy, steady-state photoluminescence, time resolved photoluminescence, HRTEM and FTIR spectroscopy. The results obtained showed the influence of the use of MPTMS in the preservation of the original optical properties of the CdSe NPs after their transfer into the ureasilicate matrix. The HRTEM analysis showed the presence of well-dispersed spherical NPs with well-defined lattice fringes. The obtained nanocomposites exhibit high transparency in the visible range as a result of the good dispersion of the NPs within the matrix, showing the potentials of the developed method in the production of composite materials in which the optical properties of the NPs incorporated are crucial to the desired application. © 2014 Elsevier B.V. All rights reserved.
Gonçalves, LFFF, Kanodarwala, FK, Stride, JA, Silva, CJR, Pereira, MR & Gomes, MJM 2014, 'One-pot synthesis of CdSe nanoparticles exhibiting quantum size effect within a sol-gel derived ureasilicate matrix', Journal of Photochemistry and Photobiology A: Chemistry, vol. 285, pp. 21-29.View/Download from: Publisher's site
This paper describes the one-pot synthesis of CdSe nanoparticles (NPs) exhibiting quantum size effect, by the reaction between cadmium and selenosulfate ions in the presence of 3-mercaptopropyltrimethoxysilane (MPTMS), within a hybrid organic-inorganic xerogel material produced by sol-gel. The highly transparent, homogeneous and flexible xerogel matrix doped with the CdSe NPs was prepared using an organically modified silicon alkoxide (3-isocyanatepropyltriethoxysilane) and a di-amine functionalized poly(ethylene oxide)/poly(propylene oxide) (Jeffamine ED-600), as precursors, which by subsequent hydrolysis and condensation reaction formed a solid network. The influence of the molar ratio between cadmium and selenosulfate ions and between cadmium ion and MPTMS in the optical properties of the nanocomposites was investigated. The materials were characterized by absorption, steady-state and time-resolved photoluminescence (PL) spectroscopy and by TEM. The absorption spectrum showed the presence of CdSe NPs with quantum size effect. The PL studies showed the presence of CdSe NPs with near band-edge emission. The developed method allows in a simple manner, at ambient temperature, using inexpensive reagents and without the need of the previous synthesis of the NPs by colloidal methods, the production of hybrid materials doped with semiconductor NPs showing quantum size effect. The developed sol-gel process allows also the control of the optical properties of the obtained CdSe NPs embedded within the network by adjusting the molar ratio between cadmium ion and MPTMS and between cadmium and selenium ions. The presence of NPs with near band-edge emission stabilized within a solid matrix opens the perspective of practical applications that take advantage of the optical properties of NPs, in particular photophysical applications such as photoluminescent devices. © 2014 Elsevier B.V.
Kanodarwala, FK, Wang, F, Reece, PJ & Stride, JA 2014, 'Deposition of CdSe quantum dots on graphene sheets', JOURNAL OF LUMINESCENCE, vol. 146, pp. 46-52.View/Download from: UTS OPUS or Publisher's site
Gonçalves, LFFF, Kanodarwala, FK, Stride, JA, Silva, CJR & Gomes, MJM 2013, 'One-pot synthesis of CdS nanoparticles exhibiting quantum size effect prepared within a sol-gel derived ureasilicate matrix', Optical Materials, vol. 36, no. 2, pp. 186-190.View/Download from: Publisher's site
This paper describes a novel single-pot synthesis process based on sol-gel for the production of a highly transparent hybrid matrix containing CdS nanoparticles (NPs). The reaction between cadmium and sulphide ions in the presence of 3-mercaptopropyltrimethoxysilane (MPTMS) that originates the formation of quantum confined CdS NPs occurs simultaneously with the condensation and polymerization of the gel precursors that evolves to a macromolecular hybrid organic-inorganic network. The obtained xerogel matrix is based on the reaction of organically modified alkoxysilane (3- isocyanatepropyltriethoxysilane) and a di-amine functionalized oligopolyoxyethylene (Jeffamine ED-600). The final material is characterized as highly transparent, homogeneous and flexible xerogel incorporating stabilized and high crystalline CdS NPs that exhibit size-dependent optical properties due to quantum confinement of photogenerated e-h pairs as observed from UV-visible and photoluminescence spectroscopy and HRTEM microscopy measurements. The developed approach has obvious advantages comparatively to the alternative and more complex routes of production of composite materials with embedded semiconductor NPs because of the simplified one-pot preparative procedure used. The developed sol-gel process allows the control of the optical characteristics of the obtained CdS NPs embedded within the network by adjusting the molar ratio between cadmium ion and MPTMS and between cadmium and sulphide ions. © 2013 Elsevier B.V. All rights reserved.
Gonçalves, LFFF, Silva, CJR, Kanodarwala, FK, Stride, JA, Pereira, MR & Gomes, MJM 2013, 'Synthesis and characterization of organic-inorganic hybrid materials prepared by sol-gel and containing ZnxCd1-xS nanoparticles prepared by a colloidal method', Journal of Luminescence, vol. 144, pp. 203-211.View/Download from: Publisher's site
Nanocomposite materials based on a hybrid organic-inorganic ureasilicate matrix doped with ZnxCd1-xS nanoparticles were prepared. ZnxCd1-xS nanoparticles with different compositions (Zn/Cd mole ratio) were prepared through a colloidal method using reverse micelles. Previously to dispersion within the matrix precursors used to prepare the hybrid gel composite, the nanoparticles surface was modified in order to improve compatibility and stability with the matrix and to assure the preservation of the original optical properties of the nanoparticles. The matrix was obtained by the reaction between a silicon alkoxide modified by an isocyanate group and a di-amine functionalized oligopolyoxyethylene (Jeffamine ED-600), which by subsequent hydrolysis and condensation reactions formed a mechanically stable and highly transparent solid network containing the ZnxCd 1-xS nanoparticles. The materials were characterized by absorption, steady-state and time-resolved photoluminescence spectroscopy and by HRTEM. The obtained nanocomposites show a high transparency in the visible range accounting for the good dispersion of the nanoparticles within the matrix. The results obtained confirmed the preservation of the original optical properties of the nanoparticles after their incorporation into the ureasilicate matrix, showing that the developed method is suitable for the production of materials with potential applications in which it is necessary to take advantage of the optical properties of the nanoparticles incorporated. The HRTEM analysis confirmed that the dispersed nanoparticles show a high level of crystallinization. © 2013 Elsevier B.V.
Kanodarwala, FK & Stride, JA 2016, 'Phase transition in CdSe quantum dots and deposition of cdse quantum dots on graphene sheets' in Nanomaterials: Science and Applications, pp. 203-230.View/Download from: Publisher's site
© 2016 Pan Stanford Publishing Pte. Ltd. To date, quantum dots (QDs) have been synthesized through a number of different processes ranging from colloidal synthesis and electrochemical methods to chemical vapor deposition (CVD). This chapter focuses on the synthesis of high-quality CdSe nanocrystals through a bench-top colloidal synthesis, paying particular attention to the effects on the size and crystallinity of the QDs of varying the reaction temperature and reagent concentrations. Powder X-ray diffraction (PXRD) analysis and high-resolution transmission electron microscopy (HRTEM) have been used to highlight a transition of the crystallite phases obtained, from cubic zinc blende to hexagonal wurtzite and back again to the cubic phase as a function of reaction time. The nature of this phase shift is believed to be due to the rapid growth along the (111) crystallite facets, with the facial facets then "catching up," to restore the cubic symmetry. High-quality trioctylphosphine/trioctylphosphine oxide (TOP/ TOPO)-capped CdSe QDs displaying a narrow emission band were then grafted onto graphene nanosheets through a simple wetchemical procedure. A significant red shift of both the broad absorption and the narrow emission spectrum of the QDs was observed upon attachment to graphene, as determined by UV-Vis absorption and photoluminescence spectroscopies, whilst HRTEM data clearly show the successful decoration of the graphene sheets with CdSe QDs. This type of nanocomposite may have potential applications in the fields of optics, biological imaging, and sensing.