High-performance nanofibrous LaCoO₃ perovskite cathode for solid oxide fuel cells fabricated <i>via</i> chemically assisted electrodeposition

Rehman, Saeed Ur,Song, Rak-Hyun,Lim, Tak-Hyoung,Park, Seok-Joo,Hong, Jong-Eun,Lee, Jong-Won,Lee, Seung-Bok Royal Society of Chemistry 2018 Journal of Materials Chemistry A Vol.6 No.16

<P>In this study, a new method is developed for the fabrication of nanofibrous LaCoO3 (LCO) perovskites as cathodes (oxygen electrodes) for solid oxide fuel cells (SOFCs). The proposed method involves chemically assisted electrodeposition (CAED) of mixed metal hydroxide onto a carbon nanotube (CNT) template, followed by a low-temperature heat-treatment process. The CNT template is first fabricated on porous zirconia-based ion-conducting scaffolds (ICS) by catalytic chemical vapor deposition (CCVD) of C2H4. Perovskite-type LCO is then fabricated on the CNT template by CAED process of mixed La-Co hydroxide combined with thermal conversion of hydroxide to perovskite oxide. The method proposed here allows for the fabrication of LCO perovskites with a unique nanofibrous structure at reduced temperatures (∼900 °C), while avoiding the formation of pyrochlore phases (<I>e.g.</I>, La2Zr2O7), which are typically observed during conventional high-temperature sintering processes of LaCoO3 with zirconia-based electrolytes. The new method also provides the precise control needed to achieve desired oxide loadings without the need for repeated deposition-annealing processes. The anode-supported SOFCs with nanofibrous LCO cathodes on zirconia and ceria scaffolds show high and stable electrochemical performance of 0.95 and 1.27 W cm<SUP>−2</SUP>, respectively, at 800 °C. In addition to the absence of insulating pyrochlore phases, the unique nanostructure of the LCO cathode is believed to play a beneficial role in improving the electrochemical properties by providing a large number of active reaction sites and by facilitating mass transport through the porous nanofibrous structure.</P>

Nano-fabrication of a high-performance LaNiO₃ cathode for solid oxide fuel cells using an electrochemical route

Rehman, Saeed Ur,Shaur, Ahmad,Song, Rak-Hyun,Lim, Tak-Hyoung,Hong, Jong-Eun,Park, Seok-Joo,Lee, Seung-Bok Elsevier 2019 Journal of Power Sources Vol.429 No.-

<P><B>Abstract</B></P> <P>The cost-effective fabrication of nanostructured cathodes for solid oxide fuel cells (SOFCs) that catalyze the oxygen reduction reaction effectively is a milestone to be achieved. Infiltration being the conventional method for the fabrication of nanostructured SOFC cathodes requires many infiltration and calcination cycles due to the low catalyst loading per infiltration cycle. Chemically assisted electrodeposition (CAED), a new means of fabricating nanostructured SOFC cathodes in a single loading step, provides the advantage of the simultaneous deposition of multiple cations while using dilute aqueous solutions of readily available salts. In this study, CAED is demonstrated by fabricating a cobalt-free LaNiO<SUB>3</SUB>/GDC composite cathode. The LaNiO<SUB>3</SUB>/GDC composite cathode prepared by CAED exhibits superior electrochemical properties compared to LaNiO<SUB>3</SUB>/GDC composite cathodes fabricated by sintering or self-assembly (a recently introduced low-temperature SOFC cathode fabrication method) approaches. An anode-supported SOFC with a LaNiO<SUB>3</SUB>/GDC composite cathode fabricated by CAED shows a high power density of 974 mW cm<SUP>−2</SUP> at an intermediate operating temperature of 750 °C. Low-temperature nano-fabrication by CAED, producing a cathode with a high surface area while avoiding the formation of insulating phases, is believed to play an important role in achieving better SOFC performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> LaNiO<SUB>3</SUB> was successfully nanofabricated by chemically assisted electrodeposition. </LI> <LI> Chemically assisted electrodeposition enabled LaNiO<SUB>3</SUB> incorporation in a single step. </LI> <LI> LaNiO<SUB>3</SUB> showed a uniform morphology throughout the body of the cathode layer. </LI> <LI> Nanofabricated LaNiO<SUB>3</SUB> cathode showed a performance of 974 mWcm<SUP>−2</SUP> at 750 °C. </LI> <LI> Chemically assisted electrodeposition shows promise for SOFC electrode fabrication. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication and characterization of La_0.65Sr_0.3MnO_3−δ/(Y₂O₃)_0.08(ZrO₂)_0.92/Gd_0.1Ce_0.9O_2−δ tri-composite cathode-suppo

Rehman, Saeed ur,Song, Rak-Hyun,Lee, Jong-Won,Lim, Tak-Hyoung,Park, Seok-Joo,Lee, Seung-Bok Elsevier 2017 Ceramics international Vol.43 No.1

<P><B>Abstract</B></P> <P>The purpose of this study was to fabricate a porous supporting cathode for direct carbon solid oxide fuel cells (DCFC). Therefore, the effect of Gd<SUB>0.1</SUB>Ce<SUB>0.9</SUB>O<SUB>2−δ</SUB> (GDC) addition on the phase stability, sintering behavior, thermal expansion, and porosity of La<SUB>0.65</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB> <SUB>−δ</SUB>/(Y<SUB>2</SUB>O<SUB>3</SUB>)<SUB>0.08</SUB>(ZrO<SUB>2</SUB>)<SUB>0.92</SUB> (LSM/YSZ) composite was evaluated. The sintering temperature and the porosity of the LSM/YSZ composite were observed to increase with increase in the amount of GDC. An LSM/YSZ/GDC tri-composite with optimized properties was selected to fabricate the tubular cathode-supported DCFCs (LSM/YSZ/GDC|YSZ|NiO/YSZ) through extrusion, slurry coating, and co-firing. A special chamber was designed for the DCFC operation of the tubular cell. Electrochemical characterization was performed by measuring the polarization curves and electrochemical impedance spectroscopy, using the syngas produced by in situ steam gasification of carbon black.</P>

Coupled transport of Tl3+ through triethanolamine–xylene–polypropylene supported liquid membranes

Saeed ur Rehman,Gul Akhtar,M. Ashraf Chaudry 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1

This study has been carried out for the uphill transport of Tl3+ across triethanolamine (TEA)–xylene based supported liquid membrane. The mechanism of transport of Tl3+ has been found to be based on the association of Tl3+ with six chloride ions to form anions, which associate with three protonated triethanolamine molecular cations (HOH4C2)3N+H at the feed side of the membrane face and form a complex. The complex is extracted into the liquid membrane organic phase, from where it diffuses towards the stripping side of membrane due to the concentration gradient and is dissociated due to alkaline conditions present in the stripping phase. It is also confirmed that proton addition to triethanolamine takes place at the N site and not at the –OH sites. 5.26 mol/dm3 of TEA in xylene in membrane phase, 1.0 mol/dm3 of HCl in feed and 1.0 mol/dm3 of NaOH in stripping phase have been found to be the optimum concentrations for the extraction of Tl3+. The method developed for transport of Tl3+ has been successfully applied to remove Tl3+ from coal ash acid leach liquors along with nickel,chromium and zinc ions.

GEGENBAUER WAVELETS OPERATIONAL MATRIX METHOD FOR FRACTIONAL DIFFERENTIAL EQUATIONS

UR REHMAN, MUJEEB,SAEED, UMER Korean Mathematical Society 2015 대한수학회지 Vol.52 No.5

In this article we introduce a numerical method, named Gegenbauer wavelets method, which is derived from conventional Gegenbauer polynomials, for solving fractional initial and boundary value problems. The operational matrices are derived and utilized to reduce the linear fractional differential equation to a system of algebraic equations. We perform the convergence analysis for the Gegenbauer wavelets method. We also combine Gegenbauer wavelets operational matrix method with quasilinearization technique for solving fractional nonlinear differential equation. Quasilinearization technique is used to discretize the nonlinear fractional ordinary differential equation and then the Gegenbauer wavelet method is applied to discretized fractional ordinary differential equations. In each iteration of quasilinearization technique, solution is updated by the Gegenbauer wavelet method. Numerical examples are provided to illustrate the efficiency and accuracy of the methods.

GEGENBAUER WAVELETS OPERATIONAL MATRIX METHOD FOR FRACTIONAL DIFFERENTIAL EQUATIONS

Mujeeb ur Rehman,Umer Saeed 대한수학회 2015 대한수학회지 Vol.52 No.5

In this article we introduce a numerical method, named Ge- genbauer wavelets method, which is derived from conventional Gegen- bauer polynomials, for solving fractional initial and boundary value prob- lems. The operational matrices are derived and utilized to reduce the lin- ear fractional differential equation to a system of algebraic equations. We perform the convergence analysis for the Gegenbauer wavelets method. We also combine Gegenbauer wavelets operational matrix method with quasilinearization technique for solving fractional nonlinear differential equation. Quasilinearization technique is used to discretize the nonlinear fractional ordinary differential equation and then the Gegenbauer wavelet method is applied to discretized fractional ordinary differential equations. In each iteration of quasilinearization technique, solution is updated by the Gegenbauer wavelet method. Numerical examples are provided to illustrate the efficiency and accuracy of the methods.

Synthesis of sulfadiazinyl acyl/aryl thiourea derivatives as calf intestinal alkaline phosphatase inhibitors, pharmacokinetic properties, lead optimization, Lineweaver-Burk plot evaluation and binding analysis

Sajid-ur-Rehman,Saeed, Aamer,Saddique, Gufran,Ali Channar, Pervaiz,Ali Larik, Fayaz,Abbas, Qamar,Hassan, Mubashir,Raza, Hussain,Fattah, Tanzeela Abdul,Seo, Sung-Yum Elsevier 2018 Bioorganic & medicinal chemistry Vol.26 No.12

<P><B>Abstract</B></P> <P>To seek the new medicinal potential of sulfadiazine drug, the free amino group of sulfadiazine was exploited to obtain acyl/aryl thioureas using simple and straightforward protocol. Acyl/aryl thioureas are well recognized bioactive pharmacophore containing moieties. A new series (<B>4a</B>–<B>4j</B>) of sulfadiazine derived acyl/aryl thioureas was synthesized and characterized through spectroscopic and elemental analysis. The synthesized derivatives <B>4a</B>–<B>4j</B> were subjected to calf intestinal alkaline phosphatase (CIAP) activity. The derivative <B>4a</B>–<B>4j</B> showed better inhibition potential compared to standard monopotassium phosphate (MKP). The compound <B>4c</B> exhibited higher potential in the series with IC<SUB>50</SUB> 0.251 ± 0.012 µM (standard KH<SUB>2</SUB>PO<SUB>4</SUB> 4.317 ± 0.201 µM). Lineweaver-Burk plots revealed that most potent derivative <B>4c</B> inhibition CIAP via mixed type pathway. Pharmacological investigations showed that synthesized compounds <B>4a</B>–<B>4j</B> obey Lipinsk’s rule. ADMET parameters evaluation predicted that these molecule show significant lead like properties with minimum possible toxicity and can serve as templates in drug designing. The synthetic compounds show none mutagenic and irritant behavior. Molecular docking analysis showed that compound <B>4c</B> interacts with Asp273, His317 and Arg166 amino acid residues.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sulfadiazine based acyl/aryl thioureas has been synthesized and were screen against calf intestinal alkaline phosphatase (CIAP). </LI> <LI> Compound <B>4c</B> was found to be potent derivative in the series. </LI> <LI> Lineweaver-Burk plots revealed mixed type of enzyme inhibition mechanism. </LI> <LI> All the derivatives <B>4a</B>–<B>4j</B> obey Lipinski’s Rule. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

An Efficient Synthesis of 2-Alkyl-4-hydroxy-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxides

Zia ur Rehman, Muhammad,Choudary, Jamil Anwar,Ahmad, Saeed Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.11

An efficient and environment friendly method has been described for the synthesis of various 2-alkyl-4-hydroxy-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxides starting from N-alkylation of sodium obenzosulfimide in an ionic liquid for the first time. Ring cleavage and ring closure of the resulting product were achieved in a single step in a cost effective solvent (methanol) followed by N-alkylation of resulting alkyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate in ionic liquid while boron triflouride was used as a catalyst along with molecular sieves in carboxamide formation step.

An Efficient Synthesis of 2-Alkyl-4-hydroxy-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxides

Muhammad Zia-ur-Rehman,Jamil Anwar Choudary,Saeed Ahmad 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.11

An efficient and environment friendly method has been described for the synthesis of various 2-alkyl-4-hydroxy-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxides starting from N-alkylation of sodium o-benzosulfimide in an ionic liquid for the first time. Ring cleavage and ring closure of the resulting product were achieved in a single step in a cost effective solvent (methanol) followed by N-alkylation of resulting alkyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate in ionic liquid while boron triflouride was used as a catalyst along with molecular sieves in carboxamide formation step.

A highly stable Co3O4-GDC nanocomposite cathode for intermediate temperature solid oxide fuel cells

Seung-Bok Lee(이승복),Saeed Ur Rehman 한국에너지학회 2023 한국에너지공학회 학술발표회 Vol.2023 No.4