Role of Transition Metal-Hydroxide (M-OHx , M=Mn, Fe, Ni, Co) Co-catalyst Loading : Efficiency and Stability of CdS Photoanode

2015 ◽  
Vol 1776 ◽  
pp. 1-6 ◽  
Author(s):  
Alka Pareek ◽  
Pradip Paik ◽  
Pramod H. Borse
Keyword(s):  
Transition Metal ◽  
Water Oxidation ◽  
Photocurrent Density ◽  
Chemical Precipitation ◽  
Metal Hydroxide ◽  
Photoelectrochemical Cell ◽  
Precipitation Method ◽  
Catalyst Loading ◽  
Co Catalyst

ABSTRACTIn this work we have synthesized the colloidal particles of transition metal-hydroxide (M= Ni, Co, Mn, Fe) by a simple chemical precipitation method. The surface of spray deposited CdS thin films were modified using nano-colloids to utlize them as water oxidation catalysts (WOC) for the photoelectrochemical cell (PEC). A systematic comparison of the PEC performance of modified and unmodified film is carried out to understand the role of co-catalyst. Ni(OH)2 modification yields 3.4 times higher photocurrent density than bare CdS photoanode, and exhibits hydrogen-evolution rate of 600 μmol/hr. Fe(OH)2 modified film shows best stability of 8 hours as compared to the others.

scholarly journals How ab initio Molecular Dynamics Can Change the Understanding on Transition Metal Catalysed Water Oxidation

2021 ◽  
Vol 75 (3) ◽  
pp. 195-201
Author(s):  
Mauro Schilling ◽  
Rangsiman Ketkaew ◽  
Sandra Luber
Keyword(s):  
Transition Metal ◽  
Ab Initio ◽  
Water Oxidation ◽  
Ab Initio Molecular Dynamics ◽  
Computational Studies ◽  
Chemical Complexity ◽  
Oxygen Oxygen ◽  
Wide Range ◽  
Solvent Environment

Artificial water splitting is a promising technology that allows the storage of renewable energy in the form of energy-rich compounds. This mini-review showcases how theoretical studies contribute to the under-standing of existing water oxidation catalysts (WOCs) as well as inspiring the development of novel WOCs. In order to understand the chemical complexity of transition metal complexes and their interaction with the solvent environment, the use of sophisticated simulation protocols is necessary. As an illustration, a family of ruthe- nium-based WOCs is presented which were investigated employing a wide range of forefront computational methods with emphasis on ab initiomolecular dynamic based approaches. In those studies a base assisted oxygen–oxygen bond formation was identified as the energetically most favourable reaction mechanism. By examining the role of local environmental effects at ambient temperature and the effect of modifications in the ligand framework, a comprehensible picture of the WOCs can be given, where the latter can serve as a guideline for further experimental and computational studies. In this mini-review, we provide a description of the methods, and the findings of our previous computational studies in compacted form, aimed at scientists with a theoretical as well as experimental background.

scholarly journals A stable dye-sensitized photoelectrosynthesis cell mediated by a NiO overlayer for water oxidation

2019 ◽  
Vol 117 (23) ◽  
pp. 12564-12571 ◽  
Author(s):  
Degao Wang ◽  
Fujun Niu ◽  
Michael J. Mortelliti ◽  
Matthew V. Sheridan ◽  
Benjamin D. Sherman ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Photocurrent Density ◽  
Oxidation Catalysis ◽  
Oxidation Catalyst ◽  
Photoelectrochemical Cells ◽  
Half Cell ◽  
Dye Sensitized ◽  
Light Absorber ◽  
Water Oxidation Catalysis

In the development of photoelectrochemical cells for water splitting or CO2reduction, a major challenge is O2evolution at photoelectrodes that, in behavior, mimic photosystem II. At an appropriate semiconductor electrode, a water oxidation catalyst must be integrated with a visible light absorber in a stable half-cell configuration. Here, we describe an electrode consisting of a light absorber, an intermediate electron donor layer, and a water oxidation catalyst for sustained light driven water oxidation catalysis. In assembling the electrode on nanoparticle SnO2/TiO2electrodes, a Ru(II) polypyridyl complex was used as the light absorber, NiO was deposited as an overlayer, and a Ru(II) 2,2′-bipyridine-6,6′-dicarboxylate complex as the water oxidation catalyst. In the final electrode, addition of the NiO overlayer enhanced performance toward water oxidation with the final electrode operating with a 1.1 mA/cm2photocurrent density for 2 h without decomposition under one sun illumination in a pH 4.65 solution. We attribute the enhanced performance to the role of NiO as an electron transfer mediator between the light absorber and the catalyst.

Sintering of Hydroxyapatite Ceramic Produced by Wet Chemical Method

2011 ◽  
Vol 264-265 ◽  
pp. 1856-1861 ◽  
Author(s):  
Ramesh Singh ◽  
R. Tolouei ◽  
Chou Yong Tan ◽  
K.L. Aw ◽  
Wei Hong Yeo ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Maximum Hardness ◽  
Wet Chemical Method ◽  
Hydroxyapatite Ceramic ◽  
Maximum Value ◽  
Wet Chemical ◽  
Increasing Temperature

In the present work, densification of synthesised hydroxyapatite (HA) bioceramic prepared via chemical precipitation method was investigated. HA samples was prepared by compaction at 200 MPa and sintered at temperatures ranging from 800°C to 1400°C. The results revealed that the HA phase was stable for up to sintering temperature of 1250°C. However, decomposition of HA was observed in samples sintered at 1300°C with the formation of tetra-calcium phosphate (TTCP) and CaO. Samples sintered above 1400°C were found to melt into glassy phases. The bulk density increases with increasing temperature and attained a maximum value of 3.14 gcm-3 at 1150°C whereas maximum hardness value of 6.64 GPa was measured in HA sintered at 1050°C. These results are discussed in terms of the role of grain size.

Tuning Complex Transition Metal Hydroxide Nanostructures as Active Catalysts for Water Oxidation by a Laser–Chemical Route

Nano Letters ◽  
2015 ◽  
Vol 15 (4) ◽  
pp. 2498-2503 ◽  
Author(s):  
Kai-Yang Niu ◽  
Feng Lin ◽  
Suho Jung ◽  
Liang Fang ◽  
Dennis Nordlund ◽  
...  
Keyword(s):  
Transition Metal ◽  
Water Oxidation ◽  
Metal Hydroxide ◽  
Chemical Route

Synthesize and Characterization of Hollow Hydroxyapatite Nanopowders with Different Morphologies: Role of Cationic and Non-Ionic Surfactants

2013 ◽  
Vol 829 ◽  
pp. 268-273 ◽  
Author(s):  
Amir Seyfoori ◽  
Hamideh Mahmoodzadeh Hosseini ◽  
Abbas Ali Imani Fooladi ◽  
Mohammad Reza Nourani
Keyword(s):  
Protein Delivery ◽  
Nitrogen Adsorption ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Live Cells ◽  
X Ray Diffraction ◽  
Hollow Structures ◽  
Average Surface Area

Today, hydroxyapatite hollow nanopowders have attracted the attention of researchers as a reliable option for drug and protein delivery systems. In this study, nanohydroxyapatite powders with different morphologies were successfully synthesized via wet chemical precipitation method. Elongated rice-shape and semi-spherical nanopowders with hollow structures were synthesized using CTAB and the mixture of cetyltrimethylammonium bromide (CTAB) and polyethylene glycol (PEG) as surfactants respectively. The properties of these nanopowders were charecterized by means of scanning electron microscopy, x-ray diffraction, fourier transform infrared spectroscopy and nitrogen adsorption experiments. The results showed that using CTAB as a surfactant not only can alter the morphology of the HAp nanopowders but also it can have a significant effect on the structure of them, so that by using CTAB and mixture of CTAB and PEG, nanoporous HAp nanopowders were acquired. Moreover, the analysis of nitrogen adsorption showed a higher average surface area for CTAB synthesized HAp in comparison to CTAB/PEG synthesized nanopowder. The amount of live cells adjacent to the HAp suspensions in PBS (50, 100, 200 mg/L) was evaluated by MTT experiment. The results of MTT assay showed the ascending cell proliferation trend for spherical nanopowders by an increment in suspension concentration, while this trend was descending for rice-shape nanopwders.

scholarly journals Adsorption of U(VI) ions from aqueous solution using nanogoethite powder

2018 ◽  
Vol 37 (1-2) ◽  
pp. 113-126 ◽  
Author(s):  
Lijiang Zhang ◽  
Xiaowen Zhang ◽  
Qian Lu ◽  
Xiaoyan Wu ◽  
Tianjiao Jiang ◽  
...  
Keyword(s):  
Contact Time ◽  
Adsorption Process ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Small Particles ◽  
Order Model ◽  
X Ray ◽  
Pseudo Second Order ◽  
Adsorption Desorption

Goethite is a stable and widespread mineral present in soil with many uses, and it affects the transportation and immobilization of heavy metals in solution. Nanogoethite was synthesized by a chemical precipitation method and used to batch adsorb U(VI) in solution. Adsorption experiments were used to understand the role of nanogoethite in controlling the U(VI) adsorption behavior in soil. The morphology and the crystallinity of nanogoethite were characterized by scanning electron microscopy and wide-angle X-ray powder diffractometry, respectively. The results showed that the crystallinity of nanogoethite after the adsorption of uranium did not change, but small particles appeared on the surface of the scales. The surface area was determined from N2 adsorption–desorption experiments using the Brunauer–Emmett–Teller to be 81.86 m2/g. The effects of factors such as the contact time, pH, adsorbent dosage, and the initial concentration of uranium on the adsorption of U(VI) were investigated. The experimental results showed that nanogoethite removed over 85% of the U(VI) in an aqueous 5.0 mg/L U(VI) solution at pH 4.0 and at 298 K. The pseudo-second-order model was used to simulate the adsorption process. The results show that chemisorption plays a major role in the adsorption process. The results of this study suggest that nanogoethite may play a significant role in controlling the migration and transfer of U(VI) in the soil, thus controlling the presence of U(VI) in soil.

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