A new protocol for the distribution of MnO₂ nanoparticles on rGO sheets and the resulting electrochemical performance

Samdani, Jitendra,Samdani, Kunda,Kim, Nam Hoon,Lee, Joong Hee Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.399 No.-

<P><B>Abstract</B></P> <P>Herein, reduced graphene oxide (rGO)/MnO<SUB>2</SUB> hybrid materials were prepared via a direct redox reaction between MnCl<SUB>2</SUB> and KMnO<SUB>4</SUB> on reduced graphene oxide (rGO)<SUB>.</SUB> A systematic study was carried out to understand the role of KMnO<SUB>4</SUB>. The morphology and microstructure of the as-prepared composite was characterized using field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman Spectroscopy. Results indicate that the concentrations of KMnO<SUB>4</SUB> have a detrimental effect on the distribution of MnO<SUB>2</SUB> nanoparticles on rGO sheets and hence on electrochemical properties. The electrochemical capacitive behavior of the as-prepared composite was investigated using cyclic voltammetry (CV), galvanostatic charge discharge, and electrochemical impedance spectroscopy (EIS) in 1M Na<SUB>2</SUB>SO<SUB>4</SUB> aqueous electrolyte solution. At the optimum concentration of KMnO<SUB>4</SUB>, the as-prepared rGM-1 composite shows a high specific capacitance of 366F/g at a scan rate of 10mV/s. The composite also exhibits good electrocatalytic activity towards the oxidation of dopamine (DA), exhibiting a low detection limit of 2.3×10<SUP>−7</SUP> M with a wide linear range between 2.5×10<SUP>−7</SUP> M and 2.30×10<SUP>−4</SUP> M. Hence, the use of rGO/MnO<SUB>2</SUB> at an optimized concentration of KMnO<SUB>4</SUB> is a potential competitive candidate in supercapacitor and biosensor applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The role of KMnO<SUB>4</SUB> for the deposition of MnO<SUB>2</SUB> on rGO was studied. </LI> <LI> The as-synthesized rGM-1 shows good stability and a high specific capacitance value (366F/g). </LI> <LI> rGM-1 effectively detects dopamine with a detection limit of 2.3×10<SUP>−7</SUP> M. </LI> </UL> </P>

Molybdenum carbide nanoparticle-decorated 3D nitrogen-doped carbon flowers as an efficient electrode for high-performance, all-solid-state symmetric supercapacitors

Samdani, Kunda J.,Joh, Dong Woo,Lee, Kang Taek Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.748 No.-

<P><B>Abstract</B></P> <P>Electrode materials with high electro-catalytic activity and tailored nanostructures are of great importance for high performance energy storage devices. We develop a novel 3D nanostructured electrode with highly stable, and catalytically-active molybdenum carbide nanoparticles decorated on nitrogen-doped carbon flowers (Mo<SUB>2</SUB>C/NCF). The controlled synthesis of Mo<SUB>2</SUB>C/NCF provides a uniform distribution of Mo<SUB>2</SUB>C nanoparticles of ∼80 nm on carbon microflowers with a self-assembled petal-like structure. The Mo<SUB>2</SUB>C/NCF achieves excellent electrochemical performance, with a specific capacitance of 1250 F/g at the current density of 1 A/g in a liquid electrolyte. A device consisting of all-solid-state symmetric supercapacitors (SSC) that used this novel electrode exhibits a high energy density of 54 Wh/kg along with remarkable cycling stability (100% retention after 5000 cycles). We believe that these results provide a new way for carbide materials to be used in high-performance energy storage devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nanostructured Mo<SUB>2</SUB>C/NCF electrodes are developed via simple reflux reactions. </LI> <LI> The Mo<SUB>2</SUB>C/NCF achieves an excellent specific capacitance of 1250 F/g at 1 A/g. </LI> <LI> An all-solid-state symmetric supercapacitor exhibits an energy density of 54 Wh/kg. </LI> <LI> After 5000 cycles, the specific capacitance retention of the Mo<SUB>2</SUB>C/NCF is 100%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Consideration of Prestressed Tendons in Beam-truss Modeling of APR1400 Containment Building

Md Samdani Azad,Duy-Duan Nguyen,Bidhek Thusa,Tae-Hyung Lee 대한토목학회 2021 대한토목학회 학술대회 Vol.2021 No.10

Simplified Nonlinear FE Model for Reactor Containment Building

Md Samdani Azad,Duan Nguyen,Bidhek Thusa,Tae-Hyung Lee 대한토목학회 2020 대한토목학회 학술대회 Vol.2020 No.10

Morphology-controlled synthesis of Co3O4 composites with bio-inspired carbons as high-performance supercapacitor electrode materials

Kunda J. Samdani,김수희,박정화,홍순형,이강택 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.74 No.-

Herein, we developed a nanostructured Co3O4 and bio-inspired carbon (BIC) composite by a facilehydrothermal reaction as a supercapacitor electrode material. Microstructural analysis revealed that theBIC-Co3O4 composites possessed the hierarchical structure with a microflower shape consisting of thinnano-petals. Due to its characteristic nanostructure, the BIC-Co3O4 electrode exhibited a high specificcapacitance of 473 F/g at a current density of 1 A/g. Moreover, the all-solid-state symmetric device withthis electrode delivered the energy density of 17 Wh/kg at a power density of 184 W/kg with remarkablecycling stability over 10,000 cycles.

Customer Activity Recognition System using Image Processing

Waqas, Maria,Nasir, Mauizah,Samdani, Adeel Hussain,Naz, Habiba,Tanveer, Maheen International Journal of Computer ScienceNetwork S 2021 International journal of computer science and netw Vol.21 No.9

The technological advancement in computer vision has made system like grab-and-go grocery a reality. Now all the shoppers have to do now is to walk in grab the items and go out without having to wait in the long queues. This paper presents an intelligent retail environment system that is capable of monitoring and tracking customer's activity during shopping based on their interaction with the shelf. It aims to develop a system that is low cost, easy to mount and exhibit adequate performance in real environment.

일체형교대교량의 지진취약도 평가에 적합한 지진강도지표

응웬두이두안(Nguyen, Duy-Duan),삼다니아자드(Azad, Md Samdani),최병호(Choi Byung H.),이태형(Lee, Tae-Hyung) 한국방재학회 2020 한국방재학회논문집 Vol.20 No.6

본 논문의 목적은 일체형교대교량의 지진취약도를 평가하는데 적합한 지진강도지표(IM)를 판별하는 것이다. 90개의 지진가속도기록과 20가지 IM을 고려한 비선형시간이력해석을 수행하여 교각의 횡방향변위를 관찰하였다. 교량의 내진성능과 상관도가높은 IM을 판별하기 위해 결정계수, 표준편차, 상관계수 등 다양한 통계인자를 고려하였다. 수치해석결과 상관도가 높은IM은 고유주기에서의 스펙트럼가속도, 스펙트럼속도, 스펙트럼변위와 ASI, EPA, PGA, A95 등으로 나타났다. 상관도가 높은IM를 기준으로 한 교량의 지진취약도곡선을 도출하였다. The purpose of this study is to identify efficient earthquake intensity measures (IMs) for evaluating the seismic vulnerability of integral abutment bridges. A total of 90 ground motion records and 20 typical IMs were employed for the numerical analyses. A series of nonlinear time-history analyses was performed on the bridges to observe the lateral displacement of the bridge piers. Statistical parameters such as the coefficient of determination, standard deviation, and correlation coefficient were calculated to identify the strongly correlated IMs with the seismic performance of the bridges. The numerical results show that the efficient IMs are spectral acceleration, spectral velocity, spectral displacement at the fundamental period, acceleration spectrum intensity, effective peak acceleration, peak ground acceleration, and A95. Moreover, a set of fragility curves of the bridges was developed with respect to the efficient IMs.

A facile in-situ activation of protonated histidine-derived porous carbon for electrochemical capacitive energy storage

Tran, Thanh-Nhan,Jung Kim, Hwa,Samdani, Jitendra S.,Hwang, Jun Yeon,Ku, Bon-Cheol,Kwan Lee, Jae,Yu, Jong-Sung Elsevier 2019 Journal of industrial and engineering chemistry Vol.73 No.-

<P><B>Abstract</B></P> <P>A unique and effective synthesis approach to tune the structural and electrochemical properties of carbon materials (CMs) is demonstrated by template-free one-step pyrolysis of protonated histidine (His) containing each of different inorganic acids (HAs) such as HI, HBr, HCl, HNO<SUB>3</SUB>, H<SUB>2</SUB>SO<SUB>4</SUB>, and H<SUB>3</SUB>PO<SUB>4</SUB>. In particular, the (H<SUB>3</SUB>PO<SUB>4</SUB>)His-CM possesses high specific surface area, high capacitance, superior energy density and power density along with excellent cycle life. Such excellent electrochemical performance of (H<SUB>3</SUB>PO<SUB>4</SUB>)His-CM is attributed to the tunable structural properties of the precursor, where H<SUB>3</SUB>PO<SUB>4</SUB> plays dual roles of in-situ activation and additional P doping in the carbon skeleton.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Structural and electrochemical properties of carbon materials (CMs) is tuned by protonating histidine using different inorganic acids (HAs). </LI> <LI> The effects of each HA on the structural properties of respective (HA)His-CM and on its electrochemical behaviors are investigated. </LI> <LI> (H<SUB>3</SUB>PO<SUB>4</SUB>)His-CM possesses high specific surface area, high capacitance, superior energy density and power density along with excellent cycle life. </LI> <LI> H<SUB>3</SUB>PO<SUB>4</SUB> plays dual roles of in-situ activation and additional P doping in the carbon skeleton. </LI> <LI> A strategy of acid treatment of histidine and in-situ activation is unique and favorable for scalable production of novel carbon materials. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Unique synthesis method of protonating histidine with different inorganic acids is proposed as a novel efficient way to control the structural and surface properties of resulting carbon materials and eventually their electrochemical performance.</P> <P>[DISPLAY OMISSION]</P>

Optimal earthquake intensity measures for probabilistic seismic demand models of ARP1400 reactor containment building

Duy-Duan Nguyen,Bidhek Thusa,Md Samdani Azad,Viet-Linh Tran,이태형 한국원자력학회 2021 Nuclear Engineering and Technology Vol.53 No.12

This study identifies efficient earthquake intensity measures (IMs) for seismic performances and fragilityevaluations of the reactor containment building (RCB) in the advanced power reactor 1400 (APR1400)nuclear power plant (NPP). The computational model of RCB is constructed using the beam-truss model(BTM) for nonlinear analyses. A total of 90 ground motion records and 20 different IMs are employed fornumerical analyses. A series of nonlinear time-history analyses are performed to monitor maximum floordisplacements and accelerations of RCB. Then, probabilistic seismic demand models of RCB are developedfor each IM. Statistical parameters including coefficient of determination (R2), dispersion (i.e. standarddeviation), practicality, and proficiency are calculated to recognize strongly correlated IMs with theseismic performance of the NPP structure. The numerical results show that the optimal IMs are spectralacceleration, spectral velocity, spectral displacement at the fundamental period, acceleration spectrumintensity, effective peak acceleration, peak ground acceleration, A95, and sustained maximum acceleration. Moreover, weakly related IMs to the seismic performance of RCB are peak ground displacement,root-mean-square of displacement, specific energy density, root-mean-square of velocity, peak groundvelocity, Housner intensity, velocity spectrum intensity, and sustained maximum velocity. Finally, a set offragility curves of RCB are developed for optimal IMs.

A facile in-situ activation of protonated histidine-derived porous carbon for electrochemical capacitive energy storage

Thanh-Nhan Tran,김화정,Jitendra S. Samdani,황준연,구본철,이재관,유종성 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.73 No.-

A unique and effective synthesis approach to tune the structural and electrochemical properties of carbonmaterials (CMs) is demonstrated by template-free one-step pyrolysis of protonated histidine (His)containing each of different inorganic acids (HAs) such as HI, HBr, HCl, HNO3, H2SO4, and H3PO4. Inparticular, the (H3PO4)His-CM possesses high specific surface area, high capacitance, superior energydensity and power density along with excellent cycle life. Such excellent electrochemical performance of(H3PO4)His-CM is attributed to the tunable structural properties of the precursor, where H3PO4 plays dualroles of in-situ activation and additional P doping in the carbon skeleton.