Dragos Neagu

Dragos Neagu
University of Strathclyde · Department of Chemical and Process Engineering

PhD

About

52
Publications
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2,854
Citations

Publications

Publications (52)
Article
Full-text available
Photoelectrochemical Water Splitting In article number 2201106, Athanasios Chatzitakis and co‐workers combine in situ metal exsolution and the galvanic replacement reaction for the synthesis of advanced catalysts for diverse energy conversion applications. Exsolved Ni nanoparticles are galvanically restructured and a wealth of bimetallic nanostruct...
Article
Full-text available
There is a growing need to control and tune nanoparticles (NPs) to increase their stability and effectiveness, especially for photo‐ and electrochemical energy conversion applications. Exsolved particles are well anchored and can be re‐shaped without changing their initial location and structural arrangement. However, this usually involves lengthy...
Article
Full-text available
Surplus renewable electricity used to convert CO2 into CO, the building block of liquid fuels, advances the energy transition by enabling large-scale, long-term energy storage and the synthesis of fuel for long-haul transportation. Among the various technologies developed, renewable electricity driven conversion of CO2 by high-temperature electroly...
Article
Controlling the geometric shape of nano-catalysts plays a key role in maximizing unique properties of the materials. Although shape control of nanoparticles is well known by various preparation methods, still there is no clear case for exsolution. Here we show that the shape of embedded Ni nanoparticles can be changed on exsolution process, by cont...
Article
Perovskite oxides with dispersed nanoparticles on their surface are considered instrumental in energy conversion and catalytic processes. Redox exsolution is an alternative method to the conventional deposition techniques for directly growing well‐dispersed and anchored nanoarchitectures from the oxide support through thermochemical or electrochemi...
Article
Inorganic perovskites exhibit many important physical properties such as ferroelectricity, magnetoresistance and superconductivity as well their importance as energy materials. Many of the most important energy materials are inorganic perovskites and find application in batteries, fuel cells, photocatalysts, catalysis, thermoelectrics and solar the...
Article
Exsolution is a relatively new research hotspot which can be traced back to 2002. In the Minireview on page 6666, C. Tang, K. Kousi, D. Neagu, and I. S. Metcalfe review the, approximately, 70 studies published so far, on bimetallic exsolution and identified research trends in this area. It has been demonstrated that exsolution can endow bimetallic...
Article
Full-text available
Supported nanoparticle systems have received increased attention over the last decades because of their potential for high activity levels when applied to chemical conversions, although, because of their nanoscale nature, they tend to exhibit problems with long‐term durability. Over the last decade, the discovery of the so‐called exsolution concept...
Article
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Please cite this article as: Umar A., Neagu D., Irvine J.T.S. Alkaline modified A-site deficient perovskite catalyst surface with exsolved nanoparticles and functionality in biomass valorisation. Environmental problems associated with the use of fossil fuels and increase in energy demands due to rise in population and rapid industrialisation, are t...
Article
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Perovskite oxides displaying mixed ionic and electronic conductivity have attracted a lot of interest for application in oxygen separation membranes. Such membranes could be used for a range of processes, including the conversion of natural gas to hydrogen or syngas. A major limitation of these materials is their tendency to segregate into simpler...
Article
Full-text available
Supported bimetallic nanoparticles used for various chemical transformations appear to be more appealing than their monometallic counterparts, because of their unique properties mainly originating from the synergistic effects between the two different metals. Exsolution, a relatively new preparation method for supported nanoparticles, has earned in...
Article
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Most of exsolved metallic nanoparticles can only be applied as catalysts in a reducing atmosphere, which limits their enhancement on electrochemical activity under oxidizing conditions. In article number 2000828 by Jun Zhou, Kai Wu, and co‐workers, through a simple, low‐cost and environmental method, to synthesize Ru/RuO2 core‐shell catalytical nan...
Article
Cu-based electrodes could advance solid oxide fuel cells (SOFC) technology due to good electric conductivity and relatively high electrochemical activity among transition metals. However, one of the main challenges for designing anode materials is thermal stability in SOFC operation condition. Herein, a promising anode material decorated with Cu na...
Article
Although numerous perovskite oxides can enhance the electrochemical activity via exsolved metallic nanoparticles on the surface, most of them can only be applied as catalysts in a reducing atmosphere. These nanoparticles cause serious performance degradation in oxidizing conditions due to the formation of low‐conductive metal oxides. This poses a b...
Article
The search for new functional materials that combine high stability and efficiency with reasonable cost and ease of synthesis is critical for their use in renewable energy applications. Specifically in catalysis, nanoparticles, with their high surface-to-volume ratio, can overcome the cost implications associated with otherwise having to use large...
Article
Lowering the temperature at which CH4 is converted to useful products has been long-sought in energy conversion applications. Selective conversion to syngas is additionally desirable. Generally, most of the current CH4 activation processes operate at temperatures between 600 and 900 °C when non-noble metal systems are used. These temperatures can b...
Article
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Membranes for CO2 capture should offer high permeant fluxes to keep membrane surface area small and material requirements low. Ag-supported, dual-phase, molten-carbonate membranes routinely demonstrate the highest CO2 fluxes in this class of membrane. However, using Ag as a support incurs high cost. Here, the non-equilibrium conditions of permeatio...
Article
Full-text available
Exsolution of surface and bulk nanoparticles in perovskites has been recently employed in chemical looping methane partial oxidation because of the emergent materials’ properties such as oxygen capacity, redox stability, durability, coke resistance and enhanced activity. Here we attempt to further lower the temperature of methane conversion by comp...
Article
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Composite materials consisting of metal and metal oxide phases are being researched intensively for various energy conversion applications where they are often expected to operate under redox conditions at elevated temperature. Understanding of the dynamics of composite evolution during redox cycling is still very limited, yet critical to maximisin...
Article
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Membranes are a critical technology for energy-efficient separation processes. The routine method of evaluating membrane performance is a permeation measurement. However, such measurements can be limited in terms of their utility: membrane microstructure is often poorly characterised, membranes or sealants leak, and conditions in the gas phase are...
Article
Carbon dioxide and steam solid oxide co-electrolysis is a key technology for exploiting renewable electricity to generate syngas feedstock for the Fischer-Tropsch synthesis. The integration of this process with methane partial oxidation in a single cell can eliminate or even reverse the electrical power demands of co-electrolysis, while simultaneou...
Article
Particles dispersed on the surface of oxide supports have enabled a wealth of applications in electro- photo- and heterogeneous catalysis. Dispersing nanoparticles within the bulk of oxides is, however, synthetically much more challenging and therefore less explored, but could open new dimensions to control material properties analogous to substitu...
Article
Full-text available
Metallic nanoparticles exsolved at the surface of perovskite oxides have been recently shown to unlock superior catalytic activity and durability towards various chemical reactions of practical importance. For example, for the CO oxidation reaction, exsolved Ni nanoparticles in oxidised form exhibit site activities approaching those of noble metals...
Article
Understanding and controlling the formation of nanoparticles at the surface of functional oxide supports is critical for tuning activity and stability for catalytic and energy conversion applications. Here we use a latest generation environmental transmission electron microscope to follow the exsolution of individual nanoparticles at the surface of...
Article
The growing demand for H2 and syngas requires the development of new, more efficient processes and materials for their production, especially from CH4 that is a widely available resource. One process that has recently received increased attention is chemical looping CH4 partial oxidation, which however, poses stringent requirements on material desi...
Article
Many catalysts and in particular automotive exhaust catalysts usually consist of noble metal nanoparticles dispersed on metal oxide supports. While highly active, such catalysts are expensive and prone to deactivation by sintering and thus alternative methods for their production are being sought to ensure more efficient use of noble metals. Exsolu...
Article
Syngas (CO+H2) is a key-intermediate for the production of liquid fuels via the Fischer-Tropsch process. An emerging technology for generating syngas is the co-electrolysis of H2O/CO2 in solid oxide cells powered by renewable electricity. An application of this technology, however, is still challenging because the Ni-based cermet fuel electrodes ar...
Chapter
This chapter provides an overview of the considerations that must be made regarding new materials development for improved durability and robustness in solid oxide fuel cells (SOFCs). A number of recent development concepts are outlined for the core cell materials of anode, electrolyte, and cathode, in particular new catalytic approaches such as ca...
Article
Enhancing the stability of introduced metal catalysts on oxide surfaces is a major issue for infiltrated anodes in Solid Oxide Cells (SOC) and other related catalysis field. Stoichiometric SrTiO3 (STO) and A-site cation deficient LaxSr1-3x/2TiO3 (LST) were compared to investigate the influence of stoichiometry upon the contact between metal and oxi...
Article
Full-text available
Metal nanoparticles prepared by exsolution at the surface of perovskite oxides have been recently shown to enable new dimensions in catalysis and energy conversion and storage technologies owing to their socketed, well-anchored structure. Here we show that contrary to general belief, exsolved particles do not necessarily re-dissolve back into the u...
Article
The potential of MS-SOFCs was demonstrated through the previous EU METSOFC project, which concluded that the development of oxidation resistant novel metal-supported solid oxide fule cell (MS-SOFC) design and stack is the requirement to advance this technology to the next level. The following EU METSAPP project has been executed with an overall aim...
Article
Metal supports and metal supported half cells developed at DTU are used for the study of a solution infiltration approach to form protective coatings on porous metal scaffolds. The metal particles in the anode layer, and sometimes even in the support may undergo oxidation in realistic operating conditions leading to severe cell degradation. Here, a...
Article
Solid oxide cells (SOCs) can operate with high efficiency in two ways-as fuel cells, oxidizing a fuel to produce electricity, and as electrolysis cells, electrolysing water to produce hydrogen and oxygen gases. Ideally, SOCs should perform well, be durable and be inexpensive, but there are often competitive tensions, meaning that, for example, perf...
Article
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The critical region determining the performance and lifetime of solid oxide electrochemical systems is normally at the electrode side of the electrode/electrolyte interface. Typically this electrochemically active region only extends a few micrometres and for best performance involves intricate structures and nanocomposites. Much of the most exciti...
Article
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The evolution of the surface morphology during exsolution of Ni from the perovskite, La0.4Sr0.4Ti0.97Ni0.03O3-δ, under reducing conditions was determined using atomic force microscopy (AFM). The exsolution process was found to initially induce the formation of a 20-30 nm deep pit on the oxide surface followed by the emergence of a Ni particle at th...
Article
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Metal particles supported on oxide surfaces are used as catalysts for a wide variety of processes in the chemical and energy conversion industries. For catalytic applications, metal particles are generally formed on an oxide support by physical or chemical deposition, or less commonly by exsolution from it. Although fundamentally different, both me...
Article
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Conventional Ni cermet anodes suffer from carbon deposition when they are directly used with hydrocarbon fuels due to the negative effects of pyrolysis and Boudouard reactions. In this work, the use of a non-stoichiometric perovskite, La0.8Ce0.1Ni0.4Ti0.6O3, as a reforming layer in reducing atmospheres led to the surface being highly populated with...
Conference Paper
Full-text available
Metal supported fuel cells show great promise for cost effective scaling-up due to lower potential material costs, increased tolerance to mechanical and thermal stresses and lower operational temperatures. However, the metal particles in the anode layer, and sometimes even in the support may undergo oxidation in realistic operating conditions leadi...
Article
A standard reformed biogas composition, based on a 63% CH4 37% CO2 input biogas, was defined by calculation. It is designed to resemble the composition of biogas that would enter a real SOFC stack, assuming 80% fuel utilization, and 25% recirculation of the anode off-gas. It is thermodynamically impervious to coking above 720°C. This gas compositio...
Article
Surfaces decorated with uniformly dispersed catalytically active nanoparticles play a key role in many fields, including renewable energy and catalysis. Typically, these structures are prepared by deposition techniques, but alternatively they could be made by growing the nanoparticles in situ directly from the (porous) backbone support. Here we dem...
Chapter
This chapter explores various aspects of perovskite nonstoichiometry and defect chemistry, including the means through which different defects are accommodated by the perovskite crystal structure and the effect they exert on properties. The chapter also demonstrates that defect chemistry not only can serve as an additional tool for tailoring well-e...
Article
B-site doped, A-site deficient perovskite oxide titanates with formula La0.4Sr0.4Mn+xTi1−xO3−γ−δ (M = Fe3+ or Ni2+; x = 0.06; γ = (4 − n)x/2) were employed as solid oxide electrolysis cell (SOEC) cathodes for hydrogen production via high temperature steam electrolysis at 900 °C. A-site deficiency provided additional driving force for the exsolution...
Article
A doping strategy aimed at improving n-type conductivity in perovskite oxides by enhancing bulk oxide ion mobility is proposed and discussed. To justify and further assess this premise, the oxygen deficiency (δ) and conductivity (σ) of reduced La0.4Sr0.4GaxTi1−xO3−x/2−δ (0 ≤ x ≤ 0.15) samples were studied as a function of Ga doping (x). Both δ and...
Article
Full-text available
High quality, single phase c-axis oriented YBa2Cu3O7-δ thin films with superconducting properties were grown by laser ablation on (001) SrTiO3 substrates. The surface morphology of the films has been investigated by means of high-pressure reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), and scanning electron micro...
Article
In this work, La0.4Sr0.4TiO3-based ceramics intended for use as anode materials in solid oxide fuel cells were investigated. The material was found to preserve its cubic structure throughout testing across a range of conditions, although slight signs of phase segregation were also identified under extreme conditions. The thermal expansion coefficie...
Article
Ce1-xGdx/SmxO2-δ(x=0.1, 0.2) powders were prepared by combustion method using corresponding metallic nitrates and different fuels (α-alanine, oxamic hydrazide and tartaric acid). Ce1-xGdx/SmxO2-δ powders were formed direct from combustion reaction in one single step when oxamic hydrazide or α-alanine is used as fuel. In the case of tartarate-based...

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