Enhancement of photocatalytic hydrogen production by liquid phase plasma irradiation on metal-loaded TiO₂/carbon nanofiber photocatalysts

Chung, Kyong-Hwan,Jeong, Sangmin,Kim, Byung-Joo,An, Kay-Hyeok,Park, Young-Kwon,Jung, Sang-Chul Elsevier 2018 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.43 No.24

<P><B>Abstract</B></P> <P>Enhanced hydrogen production by photocatalytic decomposition was assessed using liquid phase plasma over metal-loaded photocatalysts. Effects of irradiation of the liquid phase plasma were evaluated in the photocatalytic hydrogen production of hydrogen. Carbon nanofiber was introduced as photocatalytic support for the Ni-loaded TiO<SUB>2</SUB> photocatalyst. The influence of addition of organic reagents into water on hydrogen evolution was also evaluated. The photocatalytic decomposition by irradiation of the liquid phase plasma without photocatalyst produced some hydrogen evolution. The rate of hydrogen evolution was improved by the metal loading on the TiO<SUB>2</SUB> surface. The carbon nanofiber acted as a useful photocatalytic support for the fixation of TiO<SUB>2</SUB>. Hydrogen evolution was enhanced by the Ni loading on the TiO<SUB>2</SUB> nanocrystallites supported on the carbon nanofiber support. Hydrogen evolution was increased significantly by the addition of organic reagents, which acted as a type of sacrificial reagent promoting photocatalysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen evolution was estimated from water photocatalysis by liquid phase plasma. </LI> <LI> Enhancement of hydrogen evolution was evaluated by liquid phase plasma irradiation. </LI> <LI> Carbon nanofiber was applied as a support for a fixation of TiO<SUB>2</SUB> nanocrystallites. </LI> <LI> Rate of hydrogen evolution was improved by the metal loading on the TiO<SUB>2</SUB> surface. </LI> <LI> Hydrogen evolution was increased significantly by adding of organic reagent into water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Investigation of the Physical Properties of Plasma Enhanced Atomic Layer Deposited Silicon Nitride as Etch Stopper

Kim, Harrison Sejoon,Meng, Xin,Kim, Si Joon,Lucero, Antonio T.,Cheng, Lanxia,Byun, Young-Chul,Lee, Joy S.,Hwang, Su Min,Kondusamy, Aswin L. N.,Wallace, Robert M.,Goodman, Gary,Wan, Alan S.,Telgenhoff, American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.51

<P>Correlations between physical properties linking film quality with wet etch rate (WER), one of the leading figures of merit, in plasma-enhanced atomic layer deposition (PEALD) grown silicon nitride (SiN<SUB><I>x</I></SUB>) films remain largely unresearched. Achieving a low WER of a SiN<SUB><I>x</I></SUB> film is especially significant in its use as an etch stopper for technology beyond 7 nm node semiconductor processing. Herein, we explore the correlation between the hydrogen concentration, hydrogen bonding states, bulk film density, residual impurity concentration, and the WERs of PEALD SiN<SUB><I>x</I></SUB> using Fourier transform infrared spectrometry, X-ray reflectivity, and spectroscopic ellipsometry, etc. PEALD SiN<SUB><I>x</I></SUB> films for this study were deposited using hexachlorodisilane and hollow cathode plasma source under a range of process temperatures (270-360 °C) and plasma gas compositions (N<SUB>2</SUB>/NH<SUB>3</SUB> or Ar/NH<SUB>3</SUB>) to understand the influence of hydrogen concentration, hydrogen bonding states, bulk film density, and residual impurity concentration on the WER. Varying hydrogen concentration and differences in the hydrogen bonding states resulted in different bulk film densities and, accordingly, a variation in WER. We observe a linear relationship between hydrogen bonding concentration and WER as well as a reciprocal relationship between bulk film density and WER. Analogous to the PECVD SiN<SUB><I>x</I></SUB> processes, a reduction in hydrogen bonding concentration arises from either (1) thermal activation or (2) plasma excited species. However, unlike the case with silane (SiH<SUB>4</SUB>)-based PECVD SiN<SUB><I>x</I></SUB>, PEALD SiN<SUB><I>x</I></SUB> WERs are affected by residual impurities of Si precursors (i.e., chlorine impurity). Thus, possible wet etching mechanisms in HF in which the WER is affected by hydrogen bonding states or residual impurities are proposed. The shifts of amine basicity in SiN<SUB><I>x</I></SUB> due to different hydrogen bonding states and the changes in Si electrophilicity due to Cl impurity content are suggested as the main mechanisms that influence WER in the PEALD processes.</P> [FIG OMISSION]</BR>

A Study on the Safe Hydrogen Exhaust Method in the Semiconductor Industry

서성민,송용원 사단법인 미래융합기술연구학회 2021 아시아태평양융합연구교류논문지 Vol.7 No.6

This study proposed a solution to prevent explosion accidents that may occur in the process of exhausting hydrogen in the semiconductor industry. Furthermore, it developed a hydrogen plasma treatment unit (HPTU) that converts exhausted hydrogen gas into safe water vapor using function-oriented search (FOS), which is one of the TRIZ tools. Also, the core technology of the renewable energy industry was applided to convert a greenhouse gas into clean energy using a plasma carbon conversion unit (PCCU). The correlation between the decomposition rate and each factor was found through the experiment of plasma decomposition and chemical reaction by mixing oxygen with exhausted hydrogen. The decomposition rate is higher as the amount of hydrogen decreases or both oxygen and RF power increases. Based on the experiment, the optimal combination of degradation rates was determined. With 9.17slm of hydrogen, 20slm of oxygen and 4.93kW of RF power, the decomposition rate is 100%. Data was collected through the design of experimental using the split-plot design, and the data was optimized using the JMP statistical program provided by SAS. A hydrogen exhaust safety system was constructed by combining HPTU ans hydrogen dilution unit (NDU), ang the system operation experiment was conducted. Using 40slm of hydrogen, which is 4 times that of the existing system, the result was obtained that the concentration in the non-explosive range could bo controlled. The construction of hydrogen exhaust safety system suggested a new method to prevent serious industrial accidents by using a large amount of hydrogen used in semiconductor process development and then discharging it in a safe state.

Co-application of liquid phase plasma process for hydrogen production and degradation of acetaldehyde over NiTiO₂ supported on porous materials

Chung, Kyong-Hwan,Jeong, Sangmin,Lee, Heon,Kim, Sun-Jae,Jeon, Ki-Joon,Park, Young-Kwon,Jung, Sang-Chul Elsevier 2017 International journal of hydrogen energy Vol.42 No.38

<P><B>Abstract</B></P> <P>Photocatalytic decomposition of acetaldehyde-contained wastewater was assessed for the degradation of pollutants and the production of hydrogen. Liquid phase plasma was applied in the photoreaction as a light source. The evolution of hydrogen and acetaldehyde degradation were characterized by the photocatalytic decomposition system. Ni-loaded TiO<SUB>2</SUB> photocatalysts and various porous materials were introduced to the photocatalytic reaction. The photochemical decomposition by irradiation of the liquid phase plasma without photocatalysts produced some hydrogen evolution with the degradation of acetaldehyde, which was attributed to the decomposition of the reactant by active species generated by the irradiation of liquid phase plasma. The Ni loading on TiO<SUB>2</SUB> brought out an enhancement of acetaldehyde degradation and hydrogen evolution. In the photocatalysis of acetaldehyde-contained wastewater using the liquid phase plasma, hydrogen evolution was accelerated due to the additional hydrogen production by the photocatalytic decomposition of acetaldehyde. The porous materials could be used as an effective photocatalytic support. MCM-41 mesoporous material has acted as a highly efficient photocatalytic support to the TiO<SUB>2</SUB> photocatalyst.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The decomposition using liquid phase plasma was assessed in acetaldehyde-containing wastewater. </LI> <LI> The effects of irradiation of the liquid phase plasma were evaluated over Ni-loaded TiO<SUB>2</SUB>. </LI> <LI> The acetaldehyde was degraded gradually with the progress of the photochemical reaction. </LI> <LI> The Ni/TiO<SUB>2</SUB> brought out an enhancement of acetaldehyde degradation and hydrogen evolution. </LI> <LI> Hydrogen evolution was increased not only from the photocatalytic decomposition of acetaldehyde. </LI> </UL> </P>

Irradiation of liquid phase plasma on photocatalytic decomposition of acetic acid-containing wastewater over metal oxide photocatalysts

Chung, Kyong-Hwan,Park, Hyunwoong,Jeon, Ki-Joon,Park, Young-Kwon,Jung, Sang-Chul Elsevier 2018 CATALYSIS TODAY - Vol.307 No.-

<P><B>Abstract</B></P> <P>The photocatalytic decomposition of acetic acid-containing wastewater was assessed for the removal of pollutants and the production of hydrogen. The effects of irradiation of the liquid phase plasma were evaluated in the photocatalytic decomposition reaction. The evolution of hydrogen was also characterized by the photocatalytic decomposition of wastewater. Ni-loaded TiO<SUB>2</SUB> photocatalysts were introduced to the photocatalytic reaction. With the Ni loading to the TiO<SUB>2</SUB>, the adsorption wavelength was enlarged to the visible range. The photochemical decomposition by irradiation of the liquid phase plasma without photocatalysts produced some hydrogen evolution with the degradation of acetic acid, which was attributed to the decomposition of the reactant by active species generated by the irradiation of liquid phase plasma. The rate of hydrogen evolution from water on the photocatalyst was ca. 1.6mmol/min at 1h of process time. The photocatalytic decomposition of acetic acid was improved by the addition of Ni-loaded TiO<SUB>2</SUB> photocatalysts by the irradiation of liquid phase plasma. The Ni loading on TiO<SUB>2</SUB> brought out an enhancement of acetic acid degradation and hydrogen evolution. Hydrogen evolution was accelerated significantly due to the additional hydrogen production by the photocatalytic decomposition of acetic acid.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The photocatalytic decomposition using liquid phase plasma was assessed in acetic acid-containing wastewater. </LI> <LI> The effects of irradiation of the liquid phase plasma were evaluated over Ni-loaded TiO<SUB>2</SUB> photocatalysts. </LI> <LI> The acetic acid was degraded gradually with the progress of the photochemical reaction. </LI> <LI> The Ni loading on TiO<SUB>2</SUB> brought out an enhancement of acetic acid degradation and hydrogen evolution. </LI> <LI> Hydrogen evolution was increased in the photocatalytic reaction due to the decomposition of acetic acid. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced Electrical and Optical Properties of Atmospheric-Plasma-Treated Al-Doped ZnO Thin Films with Hydrogen Gas

정예술,이현욱,Kyun Ahn,Je-Hoon Jeon,정세영,이원재,Chae-Ryong Cho 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2

Al-doped zinc oxide (AZO) thin films were grown on glass substrates by radio-frequency (rf) magnetron sputtering at 250℃. The surface of the AZO films was treated with hydrogen gas by using an atmospheric plasma (AP) system. The resistivity of the hydrogen-plasma treated films was improved by approximately 40 % compared with that of the untreated film. However, the crystal structure of the films was unchanged by the plasma treatment. The optical transmission of the AZO films was 80 % in the visible range and the band gap of the AZO film treated with a hydrogen plasma was higher than that of the untreated AZO film. The chemical bonding states of oxygen, aluminum and zinc elements in the AZO films were examined by using X-ray photoelectron spectroscopy (XPS). XPS showed a decrease in the metallic Zn content of the AZO films and an increase in the bonds with oxide functional groups, such as Al-O and Zn-O, in the films after the hydrogen plasma treatment. Al-doped zinc oxide (AZO) thin films were grown on glass substrates by radio-frequency (rf) magnetron sputtering at 250℃. The surface of the AZO films was treated with hydrogen gas by using an atmospheric plasma (AP) system. The resistivity of the hydrogen-plasma treated films was improved by approximately 40 % compared with that of the untreated film. However, the crystal structure of the films was unchanged by the plasma treatment. The optical transmission of the AZO films was 80 % in the visible range and the band gap of the AZO film treated with a hydrogen plasma was higher than that of the untreated AZO film. The chemical bonding states of oxygen, aluminum and zinc elements in the AZO films were examined by using X-ray photoelectron spectroscopy (XPS). XPS showed a decrease in the metallic Zn content of the AZO films and an increase in the bonds with oxide functional groups, such as Al-O and Zn-O, in the films after the hydrogen plasma treatment.

Hydrogen plasma-enhanced atomic layer deposition of hydrogenated amorphous carbon thin films

Choi, Taejin,Yeo, Seungmin,Song, Jeong-Gyu,Seo, Seunggi,Jang, Byeonghyeon,Kim, Soo-Hyun,Kim, Hyungjun Elsevier 2018 Surface & coatings technology Vol.344 No.-

<P><B>Abstract</B></P> <P>Hydrogenated amorphous carbon (a-C:H) thin films were prepared by hydrogen plasma-enhanced atomic layer deposition (PE-ALD). The a-C:H thin films were grown at low temperatures in the range of 150–350 °C using CBr<SUB>4</SUB> as the precursor and hydrogen plasma as the reactant. Raman spectroscopy, secondary ion mass spectrometry, X-ray photoelectron spectroscopy and Fourier transform infrared measurements showed that the a-C:H films consist of hydrogenated nanocrystalline sp<SUP>3</SUP> diamond, disordered sp<SUP>3</SUP> carbon and sp<SUP>2</SUP>-hybridized graphitic carbon incorporated with oxygen as a main contaminant. Moreover, the incorporation of bromine and oxygen in the a-C:H films was significantly reduced upon increasing the growth temperature from 200 to 300 °C. Surface hydroxylation and precursor exposure pretreatments were employed to saturate the adsorption of CBr<SUB>4</SUB> precursors and enhance the initial nucleation of carbon during the deposition of the a-C:H thin film by the PE-ALD process. In addition, the conformal growth of a-C:H thin films on three-dimensional structures was confirmed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrogen plasma-enhanced atomic layer deposition of hydrogenated amorphous carbon (a-C:H) thin films was developed. </LI> <LI> Substrate pretreatments by plasma hydroxylation and CBr<SUB>4</SUB> exposure are helpful for the uniform deposition of a-C:H films. </LI> <LI> a-C:H thin films can be deposited on three-dimensional structures in a conformal manner. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A comparative study on electrogeneration of hydrogen peroxide through oxygen reduction over various plasma-treated graphite electrodes

Khataee, Alireza,Sajjadi, Saeed,Pouran, Shima Rahim,Hasanzadeh, Aliyeh,Joo, Sang Woo Elsevier 2017 ELECTROCHIMICA ACTA Vol.244 No.-

<P><B>Abstract</B></P> <P>The present study reports a simple modified method that enhanced the surface characteristics of graphite electrode towards greater hydrogen peroxide production. In this method, the plasmas of various gases vis. air, argon and nitrogen were used in alternating current glow discharge plasma (AC-GDP) technique to treat graphite surface. The morphology, microstructure, roughness, disorder degree, surface chemical composition and carbon state of the graphite samples were determined before and after plasma treatments. The formation of 3D nanostructures and enhancement in surface characteristics resulted in effective H<SUB>2</SUB>O<SUB>2</SUB> generation over the plasma-treated electrodes. Particularly, air plasma-treated electrode showed higher efficiencies by producing 119μmol/L H<SUB>2</SUB>O<SUB>2</SUB>, owing to etching effect of oxygen-content and improved wettability. Furthermore, the pH, applied current and electrolyte concentration had distinct effects on the H<SUB>2</SUB>O<SUB>2</SUB> yield. The results indicated that AC-GDP using air plasma can be a promising technique for developing high efficient graphite electrodes for facile electro-generation of hydrogen peroxide.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Air, Ar and N<SUB>2</SUB> gases were used in alternating current glow discharge plasma method. </LI> <LI> The employed plasmas resulted in 3D nanostructured-surface of graphite electrodes. </LI> <LI> The plasma-treated electrodes gave rise to greater H<SUB>2</SUB>O<SUB>2</SUB> electro-production. </LI> <LI> Air-GDP was the most effective. owing to etching effect of the oxygen-content. </LI> <LI> pH, current and electrolyte concentration had distinct effects on accumulated H<SUB>2</SUB>O<SUB>2</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic illustration of the preparation of nanostructured graphite samples by treatment under air, N<SUB>2</SUB> and Ar plasmas.</P> <P>[DISPLAY OMISSION]</P>

공기 플라즈마와 산소 플라즈마 공정에서 과산화수소 생성량 비교

곽은지 ( Eun Ji Kwak ),박영식 ( Young Seek Park ),김동석 ( Dong Seog Kim ) 대구가톨릭대학교 자연과학연구소 2012 자연과학연구논문집 Vol.10 No.1

The purpose of this study is to investigate the operating parameters to impact of operating parameters in plasma reactors. in order to increased products of hydrogen peroxide in this system. The dielectric barrier discharge(DBD) plasma reactors was used in this study. the influent gas was divided into air and oxygen. the produced hydrogen peroxide concentration was analyzed and compared the operating condition of the parameter(Primary voltage, flow rate, secondary voltage, NaCl concentration, pH). In the same operating conditions, the produce amounts of hydrogen peroxide in oxygen plasma was higher than that in air plasma. the production of Hydrogen peroxide increased rapidly in the early 1minutes. the production of Hydrogen peroxide was increased with increasing NaCl concentration, primary voltage and secondary voltage. the production of Hydrogen peroxide was increased with increasing more acidic pH.

Development of hydrogen production by liquid phase plasma process of water with NiTiO₂/carbon nanotube photocatalysts

Chung, Kyong-Hwan,Jeong, Sangmin,Kim, Byung-Joo,Kim, Jung-Sik,Park, Young-Kwon,Jung, Sang-Chul Elsevier 2018 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.43 No.11

<P><B>Abstract</B></P> <P>Hydrogen evolution by water photocatalysis using liquid phase plasma system was disserted over metal-loaded TiO<SUB>2</SUB> photocatalysts. Carbon nanotube was applied as a support for the metal-loaded TiO<SUB>2</SUB> nanocrystallites. Photocatalytic activities of the photocatalysts were estimated for hydrogen production from water. Hydrogen was produced from the photodecomposition of water by liquid phase plasma irradiation. The rate of hydrogen evolution was improved by the metal loading on the TiO<SUB>2</SUB> surface. TiO<SUB>2</SUB> nanocrystallites were incorporated above 40 wt% onto the carbon nanotube support. The carbon nanotubes could be applied as a useful photocatalytic support for the fixation of TiO<SUB>2</SUB>. Hydrogen evolution was enhanced by the Ni loading on the TiO<SUB>2</SUB> nanocrystallites supported on the carbon nanotube. Hydrogen evolution was increased apparently with addition of the alcohols which contributes as a kind of sacrificial reagent promoting the photocatalysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Rate of hydrogen evolution was estimated by water photocatalysis using liquid phase plasma. </LI> <LI> Photocatalytic activity was investigated to Ni-loaded TiO<SUB>2</SUB> photocatalysts. </LI> <LI> Carbon nanotube was evaluated as a photocatalytic support for the TiO<SUB>2</SUB> nanocrystallites. </LI> <LI> The rate of hydrogen evolution was improved by metal loading on the TiO<SUB>2</SUB> surface. </LI> <LI> Hydrogen evolution was increased apparently with addition of alcohols into water. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>