Facile photohydroxylation of ZnS nanobelts for enhanced photocatalytic activity

Ham, Sooho,Jang, Du-Jeon Elsevier 2018 Journal of environmental chemical engineering Vol.6 No.1

<P><B>Abstract</B></P> <P>The photocatalytic performances of ZnS photocatalysts have been extensively enhanced by treating ZnS nanobelts for 10min with hydrogen peroxide under Xe-lamp irradiation. The photocatalytic degradation reaction of 4-nitrophenol via photohydroxylated ZnS nanobelts takes place faster six times than that via pristine ZnS nanobelts, demonstrating that the simple and facile photohydroxylation process increases the photocatalytic activity of ZnS nanobelts extensively. Photoluminescence spectra and kinetic profiles have suggested that surface hydroxyl groups as well as surface defects increase the separation rate of photogenerated charges, enhancing the photocatalytic activity of 4-nitrophenol degradation. Radical species tests have indicated that the photocatalytic performance of ZnS nanobelts is mainly contributed by hydroxyl radicals generated by the photooxidation of surface-adsorbed hydroxyl groups. Because hydroxyl groups are adsorbed on the surfaces of photocatalysts, diffusion is not necessary when hydroxyl radicals are formed by photoexcited holes. Thus, the photocatalytic degradation of 4-nitrophenol via ZnS nanobelts follows the zero-order kinetics. The generation of hydroxyl radicals is promoted by the retarded recombination of photoexcited charges, leading to the enhancement of the photocatalytic activity of ZnS nanobelts. Overall, a simple and facile photohydroxylation process increases the photocatalytic performances of ZnS photocatalytsts enormously via forming reactive hydroxyl radicals, which are readily generated by the photooxidation of surface-adsorbed hydroxyl groups. Overall, our facile and eco-friendly photohydroxylation method is suggested to have great potential for industrial applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZnS nanobelts have been hydroxylated with hydrogen peroxide under UV irradiation. </LI> <LI> Facile photohydroxlation has enhanced the photocatalytic activity of ZnS nanobelts. </LI> <LI> Surface OH groups and surface defects block the recombination of excited charges. </LI> <LI> Surface-adsorbed hydroxyl groups enhance the generation of hydroxyl radicals highly. </LI> <LI> The efficient generation of hydroxyl radicals enhances photocatalytic activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Hydroxyl Group-Solvent and Carbonyl Group-Solvent Specific Interactions for Some Selected Solutes Including Positional Isomers in Acetonitrile/Water Mixed Solvents Monitored by HPLC

Cheong, Won-Jo,Keum, Young-Ik,Ko, Joung-Ho Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.1

We have evaluated the specific hydroxyl group-solvent and carbonyl group-solvent interactions by using an Alltima C18 stationary phase and by measuring the retention data of carefully selected solutes in 60/40, 70/30, and 80/20(v/v%) acetonitrile/water eluents at 25, 30, 35, 40, 45, and 50 oC. The selected solutes are phenol, acetophenone, alkylbenznes(benzene to hexylbenznene), 4 positional isomers of phenylbutanol, 5-phenyl-1-pentanol, 3 positional isomers of alkylarylketone derived from butylbenzene, and 1-phenyl-2-hexanone. The magnitudes of hydroxyl group-acetonitrile/water specific interaction enthalpies are larger than those of carbonyl group-acetonitrile/water specific interaction enthalpies in general while the magnitudes of carbonyl group-methanol/water specific interaction enthalpies are larger than those of hydroxyl group-methanol/water specific interactions. We observed clear discrepancies in functional group-solvent specific interaction among positional isomers. The variation trends of solute transfer enthalpies and entropies with mobile phase composition in the acetonitrile/water system are much different from those in the methanol/water system. The well-known pocket formation of acetonitrile in aqueous acetonitrile mixtures has proven to be useful to explain such phenomena.

Inverted Polymer Solar Cells Based on Small molecular electrolyte with Hydroxyl Groups as the Cathode Buffer Layer

정미진,김주현,진호철,이준호,( Sabrina Aufar Salma ),( Ratna Dewi Maduwu ) 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

Novel organic electrolytes were synthesized and applied to a cathode buffer layer in inverted polymer solar cells (iPSCs). The prepared electrolytes consist of polar quaternary ammonium bromide and hydroxyl groups, which are C4-OH and C4-3OH. A favorable interface dipole is generated due to the quaternary ammonium bromid. Furthemore, the interface dipole magnitude is increased through the polar hydroxyl groups. Thus, the number of hydroxyl groups have an influence on the power conversion efficiencies (PCEs) of iPSCs. The PCE of device based on C4-3OH was higher than the PCE of device based on C4-OH. The best PCE of device with C4-3OH was reached up to 9.20%.

2LO-21 Cathode interfacial process using small molecules with multiple hydroxyl groups for high Efficiency organic solar cells

김윤환,김동근,진호철,김주현 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

Bulkheterojunction organic solar cells (OSCs) have attracted attention because of low cost manufacturing process, promising transparency, and capability for application in lightweight devices. In order to improve the power conversion efficiencty (PCE) of OSCs, new conjugated polymers have been synthesized as the electron donor or accpetor. Furthermore, introducing interlayers between electrode and active layer can improve the PCE. In this work, we design and synthesize several cathode buffer layer (CBL) materials which have multiple hydroxyl groups on their carbon backbone and introduce between ZnO layer and active layer. These CBL materials enhance interfacial properties since induce the favorable interface dipole from hydroxyl group. Herein we show the effect of interfacial process with hydroxyl groups on photovoltaic performances.

Gas Permeation Properties of Hydroxyl-Group Containing Polyimide Membranes

이영무,정철호 한국고분자학회 2008 Macromolecular Research Vol.16 No.6

A series of hydroxyl-group containing polyimides (HPIs) were prepared in order to investigate the structure-gas permeation property relationship. Each polymer membrane had structural characteristics that varied according to the dianhydride monomers. The imidization processes were monitored using spectroscopic and thermog-ravimetric analyses. The single gas permeability of He, H2, CO2, O2, N2 and CH4 were measured and compared in order to determine the effect of the polymer structure and functional -OH groups on the gas transport properties. Surprisingly, the ideal selectivity of CO2/CH4 and H2/CH4 increased with increasing level of -OH incorporation, which affected the diffusion of H2 or the solubility of CO2 in HPIs. For H2/CH4 separation, the difference in the diffusion coefficients of H2 and CH4 was the main factor for improving the performance without showing any changes in the solubility coefficients. However, the solubility coefficient of CO2 in the HPIs increased at least four fold compared with the conventional polyimide membranes depending on the polymer structures. Based on these results, the polymer membranes modified with -OH groups in the polymer backbone showed favorable gas permeation and separation performance.

Gas Permeation Properties of Hydroxyl-Group Containing Polyimide Membranes

Jung, Chul-Ho,Lee, Young-Moo The Polymer Society of Korea 2008 Macromolecular Research Vol.16 No.6

A series of hydroxyl-group containing polyimides (HPIs) were prepared in order to investigate the structure-gas permeation property relationship. Each polymer membrane had structural characteristics that varied according to the dianhydride monomers. The imidization processes were monitored using spectroscopic and thermog-ravimetric analyses. The single gas permeability of He, $H_2$, $CO_2$, $O_2$, $N_2$ and $CH_4$ were measured and compared in order to determine the effect of the polymer structure and functional -OH groups on the gas transport properties. Surprisingly, the ideal selectivity of $CO_2/CH_4$ and $H_2/CH_4$ increased with increasing level of -OH incorporation, which affected the diffusion of $H_2$ or the solubility of $CO_2$ in HPIs. For $H_2/CH_4$ separation, the difference in the diffusion coefficients of $H_2$ and $CH_4$ was the main factor for improving the performance without showing any changes in the solubility coefficients. However, the solubility coefficient of $CO_2$ in the HPIs increased at least four fold compared with the conventional polyimide membranes depending on the polymer structures. Based on these results, the polymer membranes modified with -OH groups in the polymer backbone showed favorable gas permeation and separation performance.

Adsorption of pharmaceuticals and personal care products over metal-organic frameworks functionalized with hydroxyl groups: Quantitative analyses of H-bonding in adsorption

Song, Ji Yoon,Jhung, Sung Hwa Elsevier 2017 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.322 No.-

<P><B>Abstract</B></P> <P>The removal of pharmaceuticals and personal care products (PPCPs) from water is important for ensuring a clean aquatic environment. In this work, the adsorptive removal of five PPCPs such as p-chloro-m-xylenol, bisphenol-A, triclosan, ketoprofen, and naproxen was carried out using metal-organic framework (MOF, here MIL-101) with or without modifications, i.e., introduction of hydroxyl groups. Quantitative investigations were conducted in order to understand the major mechanisms for adsorption. H-bonding is suggested as the principal mechanism for the adsorption of PPCPs over MOFs, where the PPCPs and MOFs can be H-acceptors and H-donors, respectively. This conclusion is drawn based on the fact that the quantity of adsorbed PPCPs increased monotonously with (i) increase in the number of H-acceptors (O in PPCPs) and (ii) increase in the number of –OH groups in the MOFs. The effect of solution pH on the amount of adsorbed triclosan also supports the suggested mechanism. Additionally, MIL-101-(OH)<SUB>3</SUB> appears to be a useful adsorbent for PPCPs, especially for p-chloro-m-xylenol and ketoprofen.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Adsorptive removal of five PPCPs was done with MOFs having ample –OH groups. </LI> <LI> The adsorption can be explained quantitatively with hydrogen bonding. </LI> <LI> The five PPCPs and MOFs can be H-acceptors and H-donors, respectively. </LI> <LI> Adsorption can be increased with increasing –OH of MOF or O of PPCPs. </LI> <LI> MIL-101-(OH)<SUB>3</SUB> was highly effective in adsorption and reusable by solvent washing. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Gas hydrate inhibition by 3-hydroxytetrahydrofuran: Spectroscopic identifications and hydrate phase equilibria

Ahn, Y.H.,Kang, H.,Koh, D.Y.,Park, Y.,Lee, H. Elsevier Scientific Pub. Co 2016 Fluid phase equilibria Vol.413 No.-

<P>Large organic guest molecules (LOGMs) have been reported to form clathrate hydrates with help gas molecules. Specific LOGMs with a hydroxyl group show an 'inhibition effect' on the thermodynamic equilibria of clathrate hydrates, forcing the phase equilibrium curve to shift to a relatively unstable region of lower temperature and higher pressure conditions. Here, we introduce a potential candidate, 3hydroxytetrahydrofuran (3-OH THF), which has a sole different functional group from tetrahydrofuran (THF), a powerful thermodynamic promoter, to examine the effect of the hydroxyl group on the phase equilibria of clathrate hydrates. The powder X-ray diffraction patterns and Raman spectra reveal that both sI and sII clathrate hydrates can be formed depending on the type of help gas molecules (methane, nitrogen, oxygen, and carbon dioxide). Additionally, the phase equilibria of binary (3-OH THF + help gases) clathrate hydrates are measured to check the degree of inhibition due to the substituted hydroxyl group. The carbon dioxide, unlike other gaseous guest molecules, prevented LOGMs of 3-OH THF from occupying sII large cages, and thus we only observed the appearance of pure carbon dioxide hydrate. (C) 2015 Elsevier B.V. All rights reserved.</P>

Accelerated degradation of lignin by lignin peroxidase isozyme H8 (LiPH8) from Phanerochaete chrysosporium with engineered 4-O-methyltransferase from Clarkia breweri

Pham, L.T.M.,Kim, Y.H. IPC Science and Technology Press ; Elsevier Scienc 2014 Enzyme and microbial technology Vol.66 No.-

Free-hydroxyl phenolic units can decrease or even abort the catalytic activity of lignin peroxidase H8 during oxidation of veratryl alcohol and model lignin dimers, resulting in slow and inefficient lignin degradation. In this study we applied engineered 4-O-methyltransferase from Clarkia breweri to detoxify the inhibiting free-hydroxyl phenolic groups by converting them to methylated phenolic groups. The multistep, enzyme-catalyzed process that combines 4-O-methyltransferase and lignin peroxidase H8 suggested in this work can increase the efficiency of lignin-degradation. This study also suggests approaching the field of multi-enzyme in vitro systems to improve the understanding and development of plant biomass in biorefinery operations.

The Positional Effect of Solute Functional Group among Positional Isomers of Phenylpropanol in Hydroxyl Group-Solvent Specific Interactions in Methanol/Water Mixed Solvents Monitored by HPLC

Won Jo Cheong,Joung Ho Ko,Gyoung Won Kang 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.8

We have evaluated the hydroxyl group-solvent specific interactions by using a Lichrosorb RP18 stationary phase and by measuring the retention data of carefully selected solutes in 50/50, 60/40, 70/30, 80/20, and 90/10(v/v%) methanol/water eluents at 25, 30, 35, 40, 45, and 50 oC. The selected solutes are 3 positional isomers of phenylpropanol, that is, 1-phenyl-1-propanol, 1-phenyl-2-propanol, and 3-phenyl-1-propanol. There exist clear discrepancies in Ho (solute transfer enthalpy from the mobile to the stationary phase) and TSo (solute transfer entropy) among positional isomers. The difference in Ho and TSo between secondary alcohols (1-phenyl-1-propanol and 1-phenyl-2-propanol)is negligible compared to the difference between the primary alcohol (1-phenyl-3-propanol) and secondary alcohols. The TSo values of 3-phenyl-1-propanol are close to those of butylbenzene while the TSo values of secondary alcohols are close to those of propylbenzene. The difference in Ho (specific solute-mobile phase interaction enthalpy) between the primary alcohol and the secondary alcohol decreases with increase of methanol content in the mobile phase. A unique observation is an extremum for 1-phenyl-3-propanol in the plot of TSo vs. methanol volume %. The positive sign of TSo of 3-phenyl-1-propanol implies that the entropy of 3-phenyl-1-propanol is greater than that of the hypothetical alkylbenzene (the same size and shape as phenylpropanol) in the mobile phase.