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>

Effect of liquid phase plasma on photocatalysis of water for hydrogen evolution

Jeong, Sangmin,Chung, Kyong-Hwan,Lee, Heon,Park, Hyunwoong,Jeon, Ki-Joon,Park, Young-Kwon,Jung, Sang-Chul Elsevier 2017 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.42 No.27

<P><B>Abstract</B></P> <P>This study examined the effects of liquid phase plasma irradiation on the photocatalytic decomposition of water for hydrogen evolution. TiO<SUB>2</SUB> and metal-loaded TiO<SUB>2</SUB> nanocrystallites were introduced as photocatalysts. Na-Y zeolite was applied as a support for the TiO<SUB>2</SUB> nanocrystallites. The photocatalytic activities of the photocatalysts were estimated for hydrogen production from water. Hydrogen evolution appeared in the photodecomposition of water without photocatalysts. This was caused by the decomposition of water by plasma irradiation in water directly. The hydrogen evolution efficiency improved with increasing conductivity of water. The rate of hydrogen evolution was increased by the metal loading (Ni, Co, Fe) on the TiO<SUB>2</SUB> surface. Na-Y zeolite can be used as an efficient photocatalytic support for the fixation of TiO<SUB>2</SUB>. The TiO<SUB>2</SUB> nanocrystallites were incorporated above 40 wt% on Na-Y support.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effect of liquid phase plasma irradiation on water photolysis was studied for hydrogen evolution. </LI> <LI> TiO<SUB>2</SUB> and metal-loaded TiO<SUB>2</SUB> nanocrystallites were introduced as photocatalysts. </LI> <LI> Na-Y zeolite was applied as a support for the TiO<SUB>2</SUB> nanocrystallites. </LI> <LI> Hydrogen evolution appeared in the photodecomposition of water without photocatalysts. </LI> <LI> The rate of hydrogen evolution was increased by the metal loading on the TiO<SUB>2</SUB> surface. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</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>

알라네이트 계 수소 저장 물질의 수소 방출 특성

정헌도 한국수소및신에너지학회 2017 한국수소 및 신에너지학회논문집 Vol.28 No.4

Alanate-based materials, which were known to have high hydrogen storage capacity, were synthesized by mechanochemically metathesis reaction of metal chloride and sodium alanate without solvent. XRD patterns of synthesized materials showed that metathesis reaction of cations between metal chloride and sodium alanate was progressed favorably without any solvent. Magnesium alanate showed that 3.2 wt.% of hydrogen was evolved by the thermal decomposition. The addition of a small amount of Ti to the magnesium alanate greatly reduced hydrogen evolution temperature. Also, Ti doped magnesium alanate had a good regeneration property. Both the calcium and lithium-magnesium alanate showed the lower starting temperature of the two step hydrogen evolution and fast kinetics for the hydrogen evolution.

Electroactive P-Ani/core-shell/TiO2/TiO2-WO3 employed surface engineering of Ni-P electrodes for alkaline hydrogen evolution reaction

Athira Krishnan,Sheik Muhammadhu Aboobakar Shibli 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-

Ni-P coating (NPC) fabricated by electroless deposition has been widely accepted as an effective electrodefor alkaline hydrogen evolution reaction. Among the different strategies reported to improve the catalyticactivity of Ni-P electrode (NPE) further, incorporation of inorganic metal oxide composite is a provenmethod. Herein, we propose a modification of TiO2/TiO2-WO3 core-shell structured composite (a novelentity), by the application of conductive polyaniline (P-Ani), as a continuation of our earlier work on itssynthesis and characterization. The as-prepared polymer-metal oxide hybrid nanocomposite is thenemployed to modify the NPE by electroless deposition method. The improved surface characteristics ofthe modified NPE, after the incorporation of P-Ani/TiO2/TiO2-WO3 composite with reduced chargetransfer resistance and low overpotential for alkaline hydrogen evolution ( 65 mV at10 mA/cm2)corroborates its enhanced catalytic behavior. The increase in the number of catalytically active sites onthe NPE after modification through P-Ani composite is attributed to the enhanced characteristics foralkaline hydrogen evolution. Our strategy proposes a sustainable and low-cost electrode material,competent to the existing industrial electrocatalysts, for long term hydrogen evolution in alkalinemedium.

Experimental and Numerical Investigation of Hydrogen Embrittlement Effect on Microdamage Evolution of Advanced High-Strength Dual-Phase Steel

M. Asadipoor,J. Kadkhodapour,A. Pourkamali Anaraki,S. M. H. Sharifi,A. Ch. Darabi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

The efect of hydrogen on the microdamage evolution of 1200M advanced high-strength steel was evaluated by the combination of experimental and numerical approaches. In the experimental section, the tensile test was performed under diferent testing conditions, i.e., vacuum, in-situ hydrogen plasma charging (IHPC), ex-situ electrochemical hydrogen charging(EEHC), and ex-situ+in-situ hydrogen charging (EIHC) conditions. The post-mortem analysis was conducted on the fracturesurface of specimens to illuminate the impact of hydrogen on the microstructure and mechanical properties. The resultsshowed that under all of hydrogen charging conditions, the yield stress and ultimate tensile strength were slightly sensitive tohydrogen, while tensile elongation was profoundly afected. While only ductile dimple features were observed on the fracturesurfaces in vacuum condition, the results indicated a simultaneous action of the hydrogen-enhanced decohesion (HEDE)and hydrogen enhanced localized plasticity (HELP) mechanisms of HE, depending on the local concentration of hydrogenunder the IHPC and EEHC conditions. At the EIHC condition, the HEDE model was the dominant failure mechanism,which was manifested by the HE-induced large crack. In the numerical approach, a fnite-element analysis was developed toinclude the Gorson–Tvergaard–Needleman (GTN) damage model in Abaqus™ software. To numerically describe the damagemechanism, the GTN damage model was utilized in the 3D fnite-element model. After calibration of damage parameters, thepredicted damage mechanisms for two testing conditions, i.e., vacuum and EIHC, were compared with experimental results.

Hydrogen production from water electrolysis: role of catalysts

Wang Shan,Lu Aolin,Zhong Chuan-Jian 나노기술연구협의회 2021 Nano Convergence Vol.8 No.4

As a promising substitute for fossil fuels, hydrogen has emerged as a clean and renewable energy. A key challenge is the efficient production of hydrogen to meet the commercial-scale demand of hydrogen. Water splitting electrolysis is a promising pathway to achieve the efficient hydrogen production in terms of energy conversion and storage in which catalysis or electrocatalysis plays a critical role. The development of active, stable, and low-cost catalysts or electrocatalysts is an essential prerequisite for achieving the desired electrocatalytic hydrogen production from water splitting for practical use, which constitutes the central focus of this review. It will start with an introduction of the water splitting performance evaluation of various electrocatalysts in terms of activity, stability, and efficiency. This will be followed by outlining current knowledge on the two half-cell reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in terms of reaction mechanisms in alkaline and acidic media. Recent advances in the design and preparation of nanostructured noble-metal and non-noble metal-based electrocatalysts will be discussed. New strategies and insights in exploring the synergistic structure, morphology, composition, and active sites of the nanostructured electrocatalysts for increasing the electrocatalytic activity and stability in HER and OER will be highlighted. Finally, future challenges and perspectives in the design of active and robust electrocatalysts for HER and OER towards efficient production of hydrogen from water splitting electrolysis will also be outlined.

Novel NiCo2Se4/Mn0.5Cd0.5S photocatalyst for visible light-driven hydrogen evolution

Liu Chao,Zhang Feng-Jun,Wang Ying-Rui,Xie Wen-Jie,Ma Jie,Oh Won-Chun 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.4

The development of efficient and stable photocatalysts is one of the most important research directions to realize the practical application of photocatalytic hydrogen evolution. A series of novel visible light responsive NiCo 2Se4/Mn0.5Cd0.5S composites with different NiCo 2Se4 contents were prepared by hydrothermal method. The composites were characterized using different characterization techniques such as XRD, SEM, TEM, XPS, UV–Vis DRS, PL, and photoelectrochemistry. Photocatalytic hydrogen evolution reaction was also performed using visible light (λ > 420 nm) in an aqueous solution containing Na 2S·9H2O and Na 2SO3 as sacrificial reagents. The 4% NiCo 2Se4/ Mn 0.5Cd0.5S composites exhibited the highest photocatalytic hydrogen evolution capacity, producing 20 mmol  h −1  g−1 of hydrogen, higher than pure Mn0.5Cd0.50.5S (12.2mmol h-1g-1). The tight bonding of the two materials in the NiCo 2Se4/Mn0.5Cd0.5S composites may enhance the photocatalytic activity to some extent. The possible mechanism was suggested by UV–Vis DRS and photoelectrochemical measurements. The obtained NiCo 2Se4/ Mn0.5Cd0.5S composites have excellent photocatalytic activity and good stability in photocatalytic hydrogen evolution, and have potential applications in the photocatalytic hydrogen evolution from water using solar energy.

Design of active bifunctional electrocatalysts using single atom doped transition metal dichalcogenides

Hwang, Jeemin,Noh, Seung Hyo,Han, Byungchan Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.471 No.-

<P><B>Abstract</B></P> <P>Single atom catalyst is designed to achieve high catalytic activity while extremely minimizing precious metal loadings for electrochemical energy conversion and storage applications. Using first-principles density functional theory calculations, we screen 48 combinations of single atom catalysts anchored at defective monolayer transition metal dichalcogenides (A<SUB>1</SUB>/TMD; A = Ni, Cu, Pd, Ag, Pt and Au; TM = Mo, W, Nb and Ta; D = S and Se). With established methodologies, we identify five best catalysts for each of oxygen reduction/evolution and hydrogen evolution reactions among the stable candidates. A scaling relation between the Gibb’s free energy for intermediates is figured out to understand the governing mechanism of single atom catalysts with varying transition metal dichalcogenides supports and to introduce key descriptor. Pt<SUB>1</SUB>/MoS<SUB>2</SUB> is proposed as the best bifunctional catalyst for oxygen reduction/evolution reaction. In addition, Pt<SUB>1</SUB>/NbSe<SUB>2</SUB> and Pt<SUB>1</SUB>/TaS<SUB>2</SUB> are promising candidates for oxygen and hydrogen evolution reactions. Treating the support itself as an active site for hydrogen evolution reaction, Pd<SUB>1</SUB>/NbS<SUB>2</SUB> and Pt<SUB>1</SUB>/NbS<SUB>2</SUB> are proposed as potential bifunctional catalysts toward oxygen reduction and evolution reaction, respectively. Conceptual design principle via high-throughput screening of single atom catalyst is demonstrated as a great approach to determine active and durable bifunctional single atom catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single atom catalysts with transition metal dichalcogenides supports were screened. </LI> <LI> Five best catalysts were selected for redox reactions of oxygen and hydrogen. </LI> <LI> Pt<SUB>1</SUB>/MoS<SUB>2</SUB> was identified as a great bifunctional single atom catalyst. </LI> <LI> Scaling law was proposed as the key to understand catalytic mechanism. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

WS₂/CoSe₂ heterostructure: A designed structure as catalysts for enhanced hydrogen evolution performance

Hussain, Sajjad,Akbar, Kamran,Vikraman, Dhanasekaran,Liu, Hailiang,Chun, Seung-Hyun,Jung, Jongwan THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.65 No.-

<P><B>Abstract</B></P> <P>The development of hydrogen-evolving catalysts based on transition metal dichalchogenides (TMDs) is receiving a great attention for practical application of water-splitting devices and fuel cells due to their high electrocatalytic activity. Herein, we synthesized tungsten disulfide (WS<SUB>2</SUB>)/cobalt diselenide (CoSe<SUB>2</SUB>) hybrid catalyst for hydrogen evolution reaction (HER). CoSe<SUB>2</SUB> films were first deposited via electrodeposition of Co and followed by selenization process. And, the surface of the synthesized CoSe<SUB>2</SUB> films was covered with WS<SUB>2</SUB> via combined process of sputtering and sulfurization. In acidic media, the WS<SUB>2</SUB>/CoSe<SUB>2</SUB> heterostructure catalyst exhibited fast hydrogen evolution kinetics of onset potential and Tafel slope were at 95mV and 44mVdecade<SUP>−1</SUP>, respectively with the excellent electrocatalytic stability over 20h. WS<SUB>2</SUB>/CoSe<SUB>2</SUB> heterostructure electrode demonstrates an excellent HER activity and long-term stability owing to their abundant active edge sites, and the strong chemical and electronic coupling between the CoSe<SUB>2</SUB> and WS<SUB>2</SUB>.</P> <P><B>Graphical abstract</B></P> <P>WS<SUB>2</SUB>/CoSe<SUB>2</SUB> hybrid structure was implemented to enhance HER electrocatalytic activity. The WS<SUB>2</SUB>/CoSe<SUB>2</SUB> catalyst exhibited low overpotentials of 95mV (@1mAcm<SUP>−2</SUP>) and 160mV (@ 10mAcm<SUP>−2</SUP>), a high exchange current density of ∼1.0×10<SUP>−2</SUP> mAcm<SUP>−2</SUP>, and a small Tafel slope of 44mVdecade<SUP>−1</SUP>. In addition, WS<SUB>2</SUB>/CoSe<SUB>2</SUB> hybrid electrode was stable over 20h of sustained hydrogen production in 0.5M H<SUB>2</SUB>SO<SUB>4</SUB> acidic medium.</P> <P>[DISPLAY OMISSION]</P>