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곽철환,김민일,허윤석,임지선 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Titanium dioxide (TiO<sub>2</sub>) is one of highly promising photocatalysts because of its biological and chemical inertness, nontoxicity, low cost, and high photocatalytic activity. However, generally anatase TiO<sub>2</sub> shows a large band gap (3.2 eV) corresponding to UV light (λ < 380 nm), which only accounts 5% of the solar energy spectrum. Over few decades, transition metal doping and organic-inorganic hybridization are proposed to enhance photocatalytic performance of TiO<sub>2</sub>. These two approaches, however, have shown disadvantages such as limited visible light absorption due to inhomogeneous distribution of doped heteroatom in TiO<sub>2</sub> and lowered mobility of carriers in the localized states, respectively. In this work, TiO<sub>2</sub> nanoparticles with enriched oxygen vacancy were synthesized using polyvinyl alcohol and consequently, TiO<sub>2</sub>/activated carbon substrate was fabricated for the detection and reduction of NOx gas with enhanced visible-light photocatalytic activity.
곽철환,김진운,허남수,오서영,( A. T. Ezhil Vilian ),허윤석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Localized surface plasmon resonance (LSPR) gives many advantages in biosensor applications such as the short analysis time and the cost-effectiveness. However, previous LSPR sensor are low sensitivity due to a reproducibility issue. In this study, a LSPR chip based on gold nanoparticles (Au NPs) for detection of hepatitis B virus marker (HBsAg) with high reproducibility. The LSPR chips were simply nano-patterned with AuNPs and showed sufficient sensitivity to detect HBsAg at concentrations of 1 pg/mL. In addition, an enhancing receptor was used to obtain lower limit of detection (LOD) The enhancing receptor was prepared with three different sizes of Au NPs modified with secondary antibody to enhance LSPR signal. The LSPR chip showed hundredfolded sensitivity by using enhancing receptor and consequently LOD was 100 fg/mL.
곽철환,강성민,정의영,Yuvaraj Haldorai,한영규,김우식,유태경,허윤석 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-
A customized droplet-based microfluidic reactor was fabricated for the synthesis of silver nanoparticles (Ag NPs) using silver nitrate (AgNO3) and branched polyethyleneimine (BPEI) as a precursor and a reducing agent, respectively. The effects of static mixing, temperature, and the volumetric flow rates of AgNO3 and BPEI on the particle size were investigated. The use of a static mixer and the optimization of the reaction temperature enhanced the monodispersity of the Ag NPs. In addition, the size of the Ag NPs was manipulated by changing the flow rate ratio of AgNO3 to BPEI at 60 °C for 60 min.
곽철환,김민일,서상완,허윤석,임지선 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
In this study, the effect of the activation reagent on the pore structure of pitch-based activated carbon (AC) was investigated. The pitch based on petroleum residue was used as a raw material. The AC was prepared using CO<sub>2</sub> or steam with N<sub>2</sub> carrier under 900 °C. The activation time was 1 h with steam and varied from 1 to 5 h with carbon dioxide. It is noted that the pitch was oxidized by air before activation process. The pre-oxidation of pitch has a key factor to prepare microporous AC using CO<sub>2</sub> as the activation reagent. It is strongly assumed that the surface chemical structure of carbon material affects the degree of activation due to the weak activation nature of CO<sub>2</sub> activation. Finally highly microporous AC with high specific surface area was obtained from physical activation of pitch.
SERS-based biosensor using novel structure of gold nanocubes
곽철환,( Joseph Dickson ),오서영,( A. T. Ezhil Vilian ),김진운,주상우,허윤석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Melamine is widely used in chemical industry. Several food products are adulterated with melamine to increase the apparent protein content, which is usually evaluated by Kjeldahl method, although it is prohibited to add melamine in food. In a decade, melamine has received increasing attentions due to melamine-contamination event in China. Melamine-contaminated powder milk caused several health problems and even death to infants. Due to this incident, the melamine levels in food are strictly regulated for public health in worldwide. Here, we present a method for detection of melamine based on surface-enhanced Raman spectroscopy (SERS). Au nanocubes (Au NCs) were prepared with novel structure to use as SERS substrates to detect melamine with high sensitivity.