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First demonstration of photoelectrochemical water splitting by commercial W–Cu powder metallurgy parts converted to highly porous 3D WO3/W skeletons
, Article International Journal of Hydrogen Energy ; Volume 45, Issue 11 , 28 February , 2020 , Pages 6369-6379 ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Hydrogen evolution through photoelectrochemical (PEC) water splitting by tungsten oxide-based photoanodes, as a stable and environmental-friendly material with moderate band gap, has attracted significant interest in recent years. The performance of WO3 photoanode could be hindered by its poor oxygen evolution reaction kinetics and high charge carrier recombination rate. Additionally, scalable and cost-effective commercial procedure to prepare nanostructured electrodes is still challenging. We present, for the first time, a novel and scalable method to fabricate highly efficient self-supported WO3/W nanostructured photoanodes from commercial W–Cu powder metallurgy (P/M) parts for water...
Robust water splitting on staggered gap heterojunctions based on WO3∖WS2–MoS2 nanostructures
, Article Renewable Energy ; Volume 162 , December , 2020 , Pages 504-512 ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The high charge carrier recombination rate and weak oxygen evolution kinetics have impeded the efficiency of WO3 photoelectrodes for water splitting. We present a novel type II heterojunction semiconductor based on mixed WS2 and MoS2 nanosheets on WO3 nanoflakes hydrothermally grown on highly porous W skeletons. The chemically exfoliated transition metal dichalcogenide (TMD) sheets with submicrometric lateral sizes were deposited on the surface of WO3 nanoflakes by the electrophoretic technique to fabricate a staggered gap heterojunction. The photoanode exhibited an impressive current density of 14.9 mA cm−2 at 1.23 VRHE which comprised ∼1.7 mA cm−2 photocurrent under 100 mW cm−2 simulated...
Investigation of Photoelectrochemical Properties of Porous W\WO3 Nanoplates Sensitized with Transition Metal Dichalcogenides Nanolayers for Water Splitting
, Ph.D. Dissertation Sharif University of Technology ; Simchi, Abdolreza (Supervisor)
Abstract
Nowadays, storing solar renewable energy in hydrogen (as a clean fuel) is an attractive method for substitution of environmentally pollutant energy resources (fossil fuels) which is applicable through water splitting with the use of semiconductors. Among metal oxide photoanodes, WO3 as a moderate band gap semiconductor with high photo-stability, environmental compatibility, and low cost has attracted significant attention. However, photoelectron conversion efficiency of WO3 is still limited due to poor oxygen evolution reaction kinetics and charge carrier recombination. Herein, two strategies of nanostructuring and compositing with cocatalysts were applied to envisage with these limitations....
Improved efficiency of dye-sensitized solar cells based on a single layer deposition of skein-like TiO 2 nanotubes
, Article Journal of the American Ceramic Society ; Vol. 97, issue. 9 , 2014 , pp. 2873-2879 ; ISSN: 00027820 ; Mohammadi, M. R ; Madaah Hosseini, H. R ; Sharif University of Technology
2014
Abstract
We present a new TiO2 morphology, featuring high surface area and open structure, synthesized by a two-step chemical route for the manufacture of dye-sensitized solar cells (DSSCs). This construct is sets of intertwined one-dimensional (1D) nanostructures (i.e., nanotubes), so-called skein-like nanotubes (NTs). Such morphology is produced by a combination of TiC oxidation and hydrothermal processes. The mesoporous TiO2 nanoparticles, as the product of TiC oxidation operation, is used as the precursor of hydrothermal process to grow the skein-like NTs. The effect of processing parameters of TiC oxidation and hydrothermal processes is studied. The skein-like morphology enables to eliminate the...
3D self-supporting mixed transition metal oxysulfide nanowires on porous graphene networks for oxygen evolution reaction in alkaline solution
, Article Journal of Electroanalytical Chemistry ; Volume 893 , 2021 ; 15726657 (ISSN) ; Mohammadi, R ; Mojaddami, M ; Mohandes, F ; Simchi, A ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Precious metal-free electrocatalysts based on two-dimensional nanomaterials have efficiently been used for oxygen evolution reaction; however, the low activity and stability of these materials as compared with noble metals are still distractive. We present a novel and high-performance electrocatalyst based on nanowires of mixed transition metal oxysulfide supported by three-dimensional highly porous graphene networks. Electrochemical studies indicated that the high electron transport medium of nanowires and bilayer graphene nanosheets as well as their high active surface area promote the kinetics of oxygen evolution reaction (OER). A quite small overpotential of 260 mV at the current density...
Efficient dye-sensitized solar cells based on TiO2 nanoparticles and skein-like nanotubes: effect of arrangement modes of the layers and TiCl4 treatment
, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 61 , 2016 , Pages 138-146 ; 18761070 (ISSN) ; Andaji Garmaroudi, Z ; Mohammadi, M. R ; Madaah Hosseini, H. R ; Sharif University of Technology
2016
Abstract
Herein, we report a double-layer photoanode electrode composed of TiO2 nanoparticles active layer and a mixture of nanoparticles and newly proposed skein-like nanotubes (NTs) top layer. Such structure performs well in solar light harvesting due to first, the top layer exhibits superior light scattering and second, the active layer with high dye-loading can make better use of the back-scattered light. The results reveal that 30-40 nm nanoparticles have anatase structure, whereas 5-7 μm skein-like NTs show a mixture of anatase and rutile phases. Photovoltaic measurements demonstrate that by tuning mass ratio between nanoparticles and skein-like NTs, the cells based on single-layer photoanode...
In situ synthesis of quasi-needle-like bimetallic organic frameworks on highly porous graphene scaffolds for efficient electrocatalytic water oxidation
, Article Chemical Communications ; Volume 56, Issue 21 , 2020 , Pages 3135-3138 ; Hasanzadeh, M ; Mojaddami, M ; Shahriyar Far, H ; Simchi, A ; Sharif University of Technology
Royal Society of Chemistry
2020
Abstract
We present enhanced electrocatalytic activity of three-dimensional graphene scaffolds by decoration with one-dimensional CoxNi1-x MOF nanostructures (0 ≤ x ≤ 1). The decreased overpotential and fast kinetics of the oxygen evolution reaction as compared with the existing materials are shown. The developed bimetallic MOF/3DG composites have great potential to be used in electrocatalytic water oxidation. This journal is © The Royal Society of Chemistry
Efficient electrocatalytic oxidation of water and glucose on dendritic-shaped multicomponent transition metals/spongy graphene composites
, Article Electrochimica Acta ; Volume 386 , 2021 ; 00134686 (ISSN) ; Mohammadi, R ; Mojaddami, M ; Rahmati, R ; Hemmati, A ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
To improve the efficiency of electrochemical processes for environmental remediation, we present a new type of hybrid nanomaterials based on leaf-like copper-based quaternary transition metals and spongy monolayer graphene. To demonstrate the functionality of the hybrid electrocatalyst, fast and competent electrooxidation of water and glucose is shown. The mechanism of improved catalysis is ascribed to the synergetic catalytic effect of quaternary Cu-Ni-Fe-Co alloy with dendritic morphology along with the highly conductive and spongy structure of the graphene monolayer. It is shown that water oxidation can be performed at a low overpotential of 315 mV to reach a current denisty of 100 mA...
Synthesizing One-Dimensional TiO2 Nanostructure for Dye-Sensitized Solar Cell Application
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor) ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
Over the past several years, TiO2 has become a focus of considerable researches as it possesses unique optical, catalytic and electrical properties in different applications such as sensors, water purification and dye-sensitized solar cells (DSSC). The goal of this research was synthesis of 1-Dimentional TiO2 nanostructure with suitable properties for DSSC applications. Two different TiO2 powders including micron-size anatase and mesoporous powders (produced from reaction of TiC and HNO3) along with KOH or NaOH were employed in hydrothermal process. The process was performed in two different containers including autoclave and balloon-shaped flask. The products were characterized by X-Ray...