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Optical gas sensing selectivity property of ruthenium (II)-metalloporphyrins Langmuir?Blodgett films
Akrajas Ali Umar,Muhamad Mat Salleh,Muhammad Yahaya 한국물리학회 2008 Current Applied Physics Vol.8 No.1
This paper reports the study of the selectivity property of a metalloporphyrins derivative LangmuirBlodgett thin lm,n-octaethylporphine ruthenium (II) carbonyl (RuOEPCO), to several organic gas samples, namely the saturated vapor of acetone, 2-propanol, eth-anol and cyclohexane. The sensing sensitivity was based on the change in the optical property of the lm upon exposure to the gas sam-k = 514 nm, of the light source. It was observed that the thin lm exhibited excellentselectivity property to the gas samples by presenting clear dierences amongst its responses. The selectivity property of the thin lm wasfound to depend on the structure of the gaseous molecules of which the highest sensitivity was shown for the gaseous molecules withplanar structure, such as cyclohexane. The mechanism for the thin lms-gas interaction that promotes the selectivity characteristic is proposed.
Erman Taer,Mohamad Deraman,Ibrahim Abu Talib,Akrajas Ali Umar,Munetaka Oyama,Rozan Mohamad Yunus 한국물리학회 2010 Current Applied Physics Vol.10 No.4
The physical and electrochemical properties of the activated carbon pellet electrodes have been investigated. Activated carbon pellets were prepared from single step carbonization process of pre-carbonized rubber wood sawdust at a temperature of 800 ℃ that followed with a CO2 activation process at temperature in the range of 700–1000 ℃. The BET characterization on the sample found that the surface area of the carbon pellet increased with the increasing of the activation temperature. The optimum value was as high as 683.63 ㎡ g-1. The electrical conductivity was also found to increase linearly with the increasing of the activation temperature, namely from 0.0075 S cm-1 to 0.0687 S cm-1 for the activation temperature in the range of 700–1000 ℃. The cyclic voltammetry characterization of the samples in aqueous solution of 1 M H2SO4 also found that the specific capacitance increased with the increasing of the activation temperature. Typical optimum value was shown by the sample activated at 900 ℃ with the specific capacitance was as high as 33.74 Fg-1 (scan rate 1 mV s-1). The retained ratio was as high as 32.72%. The activated carbon pellet prepared from the rubber wood sawdust may found used in supercapacitor applications.
Airul Azha Abd Rahman,Wan Adil Wan Jamil,Akrajas Ali Umar 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.4
Multivariate energy harvesting system, solar and thermalenergies, with configurable impedance matching features ispresented. The system consists of a tuneable mechanism forpeak performance tracking. The inputs are voltages rangingfrom 20 mV to 3.1 V. The matching load is individually tunedfor photovoltaic and thermoelectric power efficiency not lessthan 80% and 50% of the open circuit voltage respectively. Ofexperimentation and analysis has been done, the time it takesto fully charge up to 3.4 V is 23 minutes with the rate ofcharging is 1.8 mV/sec. Empirical data is presented.
Nanocomposite design of graphene modified TiO2 for electrochemical sensing in phenol detection
Muhammad Nurdin,Maulidiyah Maulidiyah,Abdul Haris Watoni,Armawansa Armawansa,La Ode Agus Salim,Zul Arham,Dwiprayogo Wibowo,Irwan Irwan,Akrajas Ali Umar 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.1
This study is the stage of developing a phenol detection electrochemical sensor. Phenol is one of the organic pollutants harmful to human life and ecosystems. The development of this sensor was carried out by studying the use of TiO2 anatase as a modifier of graphene electrodes. The mass of TiO2 anatase was varied, while the mass of graphene and paraffin was fixed. The results showed that the TiO2 mass of 1.0 g was the best mass as a graphene electrode modifier. The use of this mass increases the oxidation current (Ipa) of phenol by 450 A, which is observed at an oxidation potential (Epa) of −0.30 V. The presence of interfering ions such as K+, Fe2+, and OH− can decrease the measurement current. However, based on the %RSD value, it shows that the performance of TiO2-graphene is in a good category, where the %RSD value obtained is 0.6%. TiO2-graphene electrodes can be used repeatedly for 12 days. Overall, this work demonstrates the potential of TiO2-graphene electrodes as electrode candidates for electrochemical-based phenol sensors.
Nurdin Muhammad,Watoni Abdul Haris,Natsir Muhammad,Rahmatilah Sarifa,Maulidiyah Maulidiyah,Wibowo Dwiprayogo,Salim La Ode Agus,Sadikin Siti Naqiyah,Bijang Catherina Manukpadang,Umar Akrajas Ali 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.9
The modification of ternary metal oxide to improve the photoelectrocatalysis (PEC) properties of TiO2 photocatalyst is a hot issue in environmental and resource applications. Herein, we present a novel photoelectrocatalytst of Se doped-TiO2/Ti nanotube arrays (Se@TiO2/Ti-NTAs) for high-efficiency degradation of diazinon pesticide. The Se@TiO2/Ti-NTAs were prepared to treat the TiO2-NTAs in Se-TiO2 sol-gel for 10 min, which was followed by calcination in air at 200 °C for 1 h. Optical absorption spectroscopy of the Se@TiO2/Ti-NTAs indicated that there is a red-shift in the optical energy gap to 2.95 eV if compared to the pristine TiO2/Ti NTAs, which suggests that the new photoelectrocatalyst is photoactive under visible light irradiation. We evaluated the photoactivity of the sample by using it as the photoelectrocatalyst in the degradation of diazinon pesticides under the PEC process. The results showed that the Se@TiO2/Ti-NTAs can degrade 95.62% for 1 h under visible light irradiation, which is equivalent to the degradation rate constant of 0.0183 s−1. For comparison, the pristine TiO2/Ti NTAs only degrades the diazinon as high as 87.65%, even then under UV light irradiation. Our result also indicated that the Se@TiO2/Ti-NTAs promote active photoelectron transfer and active radical formation, such as •OH and •O − 2 , for rapid diazinon pesticide degradation. The Se@TiO2/Ti-NTAs photoelectrode should be a potential platform for environmental pollution treatment.