Mariam Barawi

Mariam Barawi
Madrid Institute for Advanced Studies | IMDEA · IMDEA-Energy

Chemistry

About

78
Publications
15,336
Reads
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2,603
Citations
Additional affiliations
January 2017 - present
Madrid Institute for Advanced Studies
Position
  • PostDoc Position
June 2015 - December 2016
Istituto Italiano di tecnologia, Lecce, Italy
Position
  • PostDoc Position
February 2012 - June 2015
Universidad Autónoma de Madrid
Position
  • PhD Student

Publications

Publications (78)
Article
Full-text available
Herein, the synthesis and characterization of two robust tungsten and rhenium carbonyl complexes integrated into an organic polymer (CPP‐Re, CPP‐W) are reported. These polymers are obtained by a Suzuki coupling reaction between the corresponding dibromo metal‐carbonyl substituted dipyrido[3,2‐a:2′,3′‐c]phenazine complex and 1,3,5‐triphenylbenzene‐4...
Article
Full-text available
The photocatalytic non-oxidative coupling of methane (NOCM) is a highly challenging and sustainable reaction to produce H2 and C2+ hydrocarbons under ambient conditions using sunlight. However, there is a lack of knowledge, particularly on how to achieve high photocatalytic yield in continuous-flow reactors. To address this, we have developed a nov...
Article
Full-text available
Transition metal chalcogenides have been identified as low-cost and efficient electrocatalysts to promote the hydrogen evolution reaction in alkaline media. However, the identification of active sites and the underlying catalytic mechanism remain elusive. In this work, we employ operando X-ray absorption spectroscopy and near-ambient pressure X-ray...
Article
Full-text available
Here, the use of high‐performance microfluidic techniques (HPMT) is reportedto afford conjugated porous polymer (CPPs) with smaller particle size and narrower particle size dispersion than the obtained by miniemulsion methodology. Specifically, polymers based on BODIPY or BOPHY dyes are synthesized by HPMT conditions and conventional miniemulsion c...
Article
Full-text available
Vanadium doped TiO2 NCs stand out as a promising candidate for energy storage applications due to its high electrical conductivity and redox properties. However, the thermodynamical behavior of the material under working conditions has not been explored and the reasons for its superior performance remain unlocked. This study explores the use of a c...
Article
Full-text available
Metal–organic frameworks (MOFs) are appealing candidate materials to design new photoelectrodes for use in solar energy conversion because of their modular nature and chemical versatility. However, to date there are few examples of MOFs that can be directly used as photoelectrodes, for which they must be able to afford charge separation upon light...
Article
One of the main challenges to expand the use of titanium dioxide (titania) as a photocatalyst is related to its large band gap energy and the lack of an atomic scale description of the reduction mechanisms that may tailor the photocatalytic properties. We show that rutile TiO2 single crystals annealed in the presence of atomic hydrogen experience a...
Article
CuBi 2 O 4 is one of the most studied potential candidates for photoelectrocatalytic solar fuel generation, from H 2 production, to CO 2 reduction, or even N 2 fixation. Hence, understanding its performance and catalytic behavior is key to use this material under real working conditions. Herein, Ag nanocorals are successfully deposited over CuBi 2...
Article
This work examines the role of polymer nanostructuration of phenylene vinylene (PV) conjugated porous polymers (PV‐CPPs) as highly active photocatalysts for both hydrogen production and CO 2 photoreduction reactions. It is found that nanostructured PV‐CPP hybrids with TiO 2 show a high increase in H 2 production being the most active example, the n...
Article
The versatile green ammonia is increasingly positioning itself as one of the key future energy carriers for the net-zero carbon landscape. Solar-driven nitrogen reduction reaction (NRR) offers a renewable, clean...
Article
Full-text available
In situ and operando X-ray techniques have emerged as powerful tools for unravelling the complex mechanisms underlying photoelectrochemical transformations. These techniques offer real-time insights into the dynamic processes occurring at...
Article
Solar energy conversion into fuels such as hydrogen through photoelectrochemical (PEC) cells is an attractive way to solve the problems present in the actual energetic system. ( 1 ) Despite the advances that have been made in this line, it is still necessary to develop new materials and cell configurations to take this technology to a higher scient...
Article
BiVO 4 has emerged as one of the most promising materials to fabricate efficient photoanodes for photoelectrochemical (PEC) solar water splitting. BiVO 4 is an n-type semiconductor, with a 2.4 eV bandgap and a theoretical solar to hydrogen (STH) efficiency of 9.2% with a maximum photocurrent of 7.5 mA cm ² under AM 1.5 G illumination, low overpoten...
Article
Full-text available
Herein, the design and synthesis of a couple of CPPs based on thienoacene units (named as IEP‐14 and IEP‐15, stand for IMDEA Energy Polymer numbers 14 and 15) are described, which show high BET surface areas, good photo(thermal) stabilities, and appropriate electronic alignment with TiO2 to prepare hybrids (named as IEP‐x@T‐10, X = 14 and 15, being...
Article
In this work we present the design, assembly and characterization of a tandem photoelectrochemical (PEC) cell based on two different crystallographic phases of sub-stoichiometric copper telluride nanocrystals (NCs). The first one, a pseudo-cubic phase, pc-Cu2-xTe, is characterized by positive photocurrents, while the second one, a hexagonal phase,...
Article
The conversion of sunlight into chemical energy to produce solar hydrogen, opens the door to one promising solution towards a sustainable alternative in the current energy crisis. Herein, we describe...
Article
Full-text available
Phenanthrenequinone (PhQ) based Conjugated Porous Polymers (CPPs) are synthetized without and with the presence of fluorine atoms in the trisubstituted core benzene unit (CPP‐FPA and CPP‐PA). Furthermore, organic‐inorganic hybrid heterojunctions based on these CPPs and TiO2 as inorganic semiconductor are prepared (CPP‐FPA@T‐10 and CPP‐PA@T‐10, with...
Article
Solar energy conversion through photoelectrochemical cells by organic semiconductors is a hot topic that continues to grow due to the promising optoelectronic properties of this class of materials. In this sense, conjugated polymers have raised the interest of researchers due to their interesting light‐harvesting properties. Besides, their extended...
Article
Full-text available
The immobilization of TiO2 nanoparticles on graphene acid (GA), a conductive graphene derivative densely functionalized with COOH groups, is presented. The interaction between the carboxyl groups of the surface and the titanium precursor leads to a controlled TiO2 heterogenization on the nanosheet according to microscopic and spectroscopic characte...
Article
The present study proposes a laser irradiation method to superficially reduce BiVO4 photoelectrodes and boost their water oxidation reaction performance. The origin of this enhanced performance toward oxygen evolution reaction (OER) was studied using a combination of a suite of structural, chemical, and mechanistic advanced characterization techniq...
Article
Nb doped TiO2 nanocrystals (NCs) are one of the most attractive candidates for energy-efficient smart window devices due to their ability to provide a selective modulation of the optical transmittance...
Article
Full-text available
We present a study of the effect of gold nanoparticles (Au NPs) on TiO2 on charge generation and trapping during illumination with photons of energy larger than the substrate band gap. We used a novel characterization technique, photoassisted Kelvin probe force microscopy, to study the process at the single Au NP level. We found that the photoinduc...
Article
Full-text available
Solar energy conversion plays a very important role in the transition to a more sustainable energy system. In this sense, so many systems have been proposed to drive artificial photosynthesis, most of them based on inorganic semiconductors, and the achievements performed continue every day. However, most of these systems present well‐known shortcom...
Article
Full-text available
In this work, the preparation of regular nanosized columnar structures of titanium dioxide by means of glancing angle deposition with magnetron sputtering (MS‐GLAD) followed by thermal annealing is reported. MS‐GLAD gives rise to metallic titanium columnar structures with regular width and length that after thermal treatment are fully oxidized to f...
Article
SnS and SnS2 are earth abundant layered semiconductors that owing to their optoelectronic properties have been proposed as materials for different photovoltaic, photosensing and photocatalytic applications. The intrinsic efficiency of...
Preprint
An attractive class of materials for photo(electro)chemical reactions are hybrids based on semiconducting metal oxides and nanocarbons (e.g. carbon nanotubes (CNT), graphene), where the nanocarbon acts as a highly-stable conductive scaffold onto which the nanostructured inorganic phase can be immobilised; an architecture that maximises surface area...
Article
Herein, the photocatalytic activity of four Conjugated Porous Polymers (CPPs) based on BOPHY moiety (named as IEP-x, x =7, 8, 9, and 10) and TiO2 hybrids thereof to produce hydrogen from water under UV-Vis irradiation is described. All the polymers show better performance than TiO2, and the hybrid materials (only 10 wt. % of polymer loading) show h...
Article
An attractive class of materials for photo(electro)chemical reactions are hybrids based on semiconducting metal oxides and nanocarbons (e.g. carbon nanotubes (CNT), graphene), where the nanocarbon acts as a highly-stable conductive scaffold onto which the nanostructured inorganic phase can be immobilised; an architecture that maximises surface area...
Article
This work describes a general method to obtain highly porous electrodes and their use as Dimensionally Stable Anodes for the O2 evolution (OER) and CO2 reduction reactions(CO2RR). By using a powder metallurgy based process, where metallic titanium and nickel powders are pressed and thermally treated to form “green compacts”, we obtain electrodes th...
Article
Truxene-based porous polymers synthesized through the simple “solvent knitting” strategy from hexamethyl or tribenzyl truxene-based monomers (TxPPs), and their corresponding [email protected] hybrids are used as photocatalysts for H2 production from water using methanol as sacrificial agent, under UV-Vis light. These polymers present higher hydroge...
Article
The hydrothermal synthesis of the perovskites NaNbO3, NaTaO3 and the intermediate composition NaNb0.5Ta0.5O3, as CO2 conversion photocatalysts is reported. Among them, the niobate shows the most promising performance under UV irradiation not only in terms of conversion and light utilization ability, but also regarding the selectivity towards CO2 re...
Article
Solar fuels production is a cornerstone in the development of emerging sustainable energy conversion and storage technologies. Light-induced H2 production from water represents one of the most crucial challenges to produce renewable fuel. Metal-organic frameworks (MOFs) are being investigated, due to the ability to assemble new structures with the...
Article
Photocatalysts provide a sustainable way to remove pollutants or store energy in the form of solar fuels by processes such as water splitting and CO2 photoreduction (artificial photosynthesis). Research in this topic is an expansive field evidenced by the large number of contributions published in the past few years. Hybrid photocatalysts based on...
Article
The chemistry of Metal-Organic Frameworks (MOFs) relies on the controlled linking of organic molecules and inorganic secondary building units to assemble an unlimited number of reticular frameworks. However, the design of porous solids with chemical stability remains still limited to carboxylate or azolate groups. There is a timely opportunity to d...
Article
Activation of ultraviolet (UV) energy-bandgap semiconductors for solar fuel production using visible light as energy source is one of the most challenging tasks in the artificial photosynthesis field. Triplet-triplet annihilation (TTA) based on photon upconversion (UC) generates frequently high energy (i.e. UV) from lower energy (visible). Thus, an...
Article
After 40 years of research on photocatalytic CO2 reduction, there are still many unknowns about its mechanistic aspects even for the most common TiO2-based photocatalytic systems. These uncertainties include the pathways inducing visible-light activity in wide-band-gap semiconductors; the charge transfer between semiconductors and plasmonic metal n...
Article
Full-text available
Sunlight plays a critical role in the development of emerging sustainable energy conversion and storage technologies. Light-induced CO2 reduction by artificial photosynthesis is one of the cornerstones to produce renewable fuels and environmentally friendly chemicals. Interface interactions between plasmonic metal nanoparticles and semiconductors e...
Article
Photoelectrochemical water splitting is one of the most interesting alternatives to produce hydrogen in a clean way by solar energy conversion.(1) Despite the huge potential and great advances, new materials need to be developed in order to take this technology to a commercial level. At present, different materials as oxides, oxisulfides and metal...
Article
The paper discloses a dual-band electrochromic device capable of selectively controlling the transmitted sunlight over the visible and the near-infrared regions. It exploits the peculiar spectro-electrochemical features of vanadium-modified titanium oxide colloidal nanocrystals, which exhibit a distinctive electrochromic response at visible wavelen...
Article
Full-text available
The isolation of graphene and transition metal dichalcongenides has opened a veritable world to a great number of layered materials which can be exfoliated, manipulated, and stacked or combined at will. With continued explorations expanding to include other layered materials with unique attributes, it is becoming clear that no one material will fil...
Article
A reliable exploitation of localized surface plasmon resonance in transparent conductive oxides is being prospected to push the blooming of a new class of advanced dynamic windows, which offer the unique opportunity to selectively, and dynamically, control the intensity of the incoming thermal radiation without affecting the transparency in the vis...
Article
The reliable exploitation of localized surface plasmon resonance in transparent conductive oxides is being prospected to push the blooming of an emerging class of advanced dynamic windows, which offer the opportunity to selectively, and dynamically, control the intensity of the incoming thermal radiation without affecting visible transparency. In t...
Article
We report the colloidal synthesis of ~5.5nm inverse spinel-type oxide Ga2FeO4 (GFO) nanocrystals (NCs) with control over the gallium and iron content. As recently theoretically predicted, some classes of spinel-type oxide materials can be intrinsically doped by means of structural disorder and/or change in stoichiometry. Here we show that, indeed,...
Article
Full-text available
We present characterizations of few-layer titanium trisulfide (TiS3) flakes which, due to their reduced in-plane structural symmetry, display strong anisotropy in their electrical and optical properties. Exfoliated few-layer flakes show marked anisotropy of their in-plane mobilities reaching ratios as high as 7.6 at low temperatures. Based on the p...
Article
We here report the fabrication of high-quality nanostructured electrodes based on surfactant-capped ITO colloidal nanocrystals and their implementation in self-powered bi-functional smart devices which are simultaneously capable of generating electric energy as a photovoltaic system as well as of controlling the intensity of incoming thermal radiat...
Article
A study of the electronic and optical bandgap is presented in layered TiS3, an almost unexplored semiconductor that has attracted recent attention because of its large carrier mobility and inplane anisotropic properties, to determine its exciton binding energy. Scanning tunneling spectroscopy and photoelectrochemical measurements are combined with...
Article
Full-text available
Nowadays, finding cheap and non-toxic materials able to reversibly store high amounts of hydrogen is a challenge in the renewable energy field. Metal sulfides seem to be promising candidates to this purpose. Titanium sulfides are reported to be particularly interesting but their ability to store hydrogen remains unclear. In this work, titanium base...
Article
Full-text available
First evidence of hydrogen evolution by using Titanium trisulphide (TiS3) as photoanode in a photoelectrochemical cell (PEC) is reported. Synthetized TiS3, composed by numerous nanoribbons, has been structural, morphological and photoelectrochemically characterized. Moreover, the value of its flat band potential has been estimated (Vfb=-0.68±0.05V...
Article
Full-text available
Control over the morphology of TiS3 is demonstrated by synthesizing 1D nanoribbons and 2D nanosheets. The nanosheets can be exfoliated down to a single layer. Through extensive characterization of the two morphologies, differences in the electronic properties are found and attributed to a higher density of sulphur vacancies in nanosheets which, acc...
Article
Full-text available
The potential of bulk black-phosphorus for thermoelectric applications has been experimentally studied. The Seebeck Coefficient (S) has been measured in the temperature range from 300 K to 385 K, finding a value of S = +335 +- 10 uV/K at room temperature (indicating a naturally occurring p-type conductivity). S increases with temperature, as expect...
Article
In this work, the growth of FeS2 by direct sulfuration of Fe thin films is examined with the purpose of elucidating the nature of the Fe to FeS2 transformation and to state some of its characteristics. To this aim, the film Seebeck coefficient (S) was measured during the whole sulfuration treatment. The S value changes from positive (ca. +8 μV K–1)...
Article
Palladium sulfide (PdS) nanostructures are proposed to be used as photoanode in photoelectrochemical cells (PEC) for hydrogen evolution due to its adequate transport and optical properties shown in previous works. Here, a complete morphological and electrochemical characterization of PdS films has been performed by different techniques. PdS flatban...
Article
Here, we isolate thin TiS3 ribbons, a layered direct band gap semiconductor (1.1 eV, well suited for detection all across the visible spectrum), thus far almost unexplored. We fabricate field effect transistors and study their electrical characteristics and optoelectronic properties. The measured FET characteristics show mobilities up to 2.6 cm^2/V...
Article
Nanocrystalline Mg films with thicknesses between 45 and 900 nm were prepared by e-beam on fused-SiO2 substrates and hydrogenated at 280 °C to investigate the H-absorption/desorption process. Films were characterized by XRD, RBS, Raman, FEG, “in situ” optical measurements and TPD-MS. Whereas practically full conversion into MgH2 is observed in thin...
Conference Paper
Interest in hydrogen solar production from water splitting is motivated by the need to find a green, renewable and environmentally safe fuel. Hydrogen is considered as a viable option sustainable development beyond fossil fuels, especially when it is produced from water by using only renewable energy sources. The identification of low cost material...
Article
Interest in hydrogen solar production from water splitting is motivated by the need to find a green, renewable and environmentally safe fuel. Hydrogen is considered as a viable option sustainable development beyond fossil fuels, especially when it is produced from water by using only renewable energy sources. The identification of low cost material...
Article
Titanium trisulphide thin films have been grown on quartz substrates by sulphuration of electron-beam evaporated Ti layers (d ~ 300 nm) in a vacuum sealed ampoule in the presence of sulphur powder at 550 °C for different periods of time (1 to 20 h). Thin films were characterized by X-ray diffraction, energy dispersive analyses of X-ray and scanning...

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