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Maarten Roeffaers

Maarten Roeffaers
KU Leuven | ku leuven · Department of Microbial and Molecular Systems (M²S)

Ph.D.

About

263
Publications
45,044
Reads
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8,514
Citations
Additional affiliations
October 2010 - present
KU Leuven
Position
  • Research Assistant
August 2009 - August 2010
Harvard University
August 2008 - July 2009
KU Leuven
Position
  • KU Leuven Post Doc

Publications

Publications (263)
Article
Organic solar cells (OSCs) have experienced rapid progress with the innovation of near‐infrared (NIR)‐absorbing small‐molecular acceptors (SMAs), while the unique electronic properties of the SMAs raise new challenges in relation to cathode engineering for effective electron collection. To address this issue, we synthesized two fluorinated perylene...
Article
We demonstrate a new case of materials‐gene engineering to precisely design photocatalysts with the prescribed properties. Based on theoretical calculations, a phase‐doping strategy was proposed to regulate the pathways of CO2 conversion over Au nanoparticles (NPs) loaded TiO2 photocatalysts. As a result, the thermodynamic bottleneck of CO2‐to‐CO c...
Article
We demonstrate a new case of materials‐gene engineering to precisely design photocatalysts with the prescribed properties. Based on theoretical calculations, a phase‐doping strategy was proposed to regulate the pathways of CO2 conversion over Au nanoparticles (NPs) loaded TiO2 photocatalysts. As a result, the thermodynamic bottleneck of CO2‐to‐CO c...
Article
Cd1−xZnxS solid solutions with strong light absorption are promising materials for solar-driven CO2 reduction; however, their relatively weak redox ability and intrinsic photo-corrosion limit their further development as a photocatalyst. The addition of a second photocatalyst with a suitable band structure to construct a S-scheme photocatalytic sys...
Article
With fascinating photophysical properties and strong potential to utilize solar energy, metal halide perovskites (MHPs) have become a prominent feature within photocatalysis research. However, the effectiveness of single MHP photocatalysts is relatively poor. The introduction of a second component to form a heterojunction represents a well‐establis...
Article
Full-text available
Metal halide perovskites (MHPs) have been widely investigated for various photocatalytic applications. However, the dual-functional reaction system integrated selective organic oxidation with H2 production over MHPs is rarely reported. Here, we demonstrate for the first time the selective oxidation of aromatic alcohols to aldehydes integrated with...
Article
With fascinating photophysical properties and strong potential to utilize solar energy, metal halide perovskites (MHPs) have become a prominent feature within photocatalysis research. However, the effectiveness of single MHP photocatalysts is relatively poor. The introduction of a second component to form a heterojunction represents a well‐establis...
Article
Due to the high stability and chemical inertia of methane, CH4, its selective conversion into value-added organic chemicals under mild conditions has been widely regarded as an important reaction for the chemical industry. Here, we develop a RuOx decorated ZnO/CeO2 photocatalyst for the highly efficient and selective transformation of CH4 into CH3O...
Article
We report on < 2 μm spatial resolution investigations of structural and morphological uniformity of aligned high-performance gel-spun ultrahigh-molecular-weight polyethylene (UHMWPE) fibers (thicknesses ranging from 60 μm to 300 μm) whose processing includes draw and quench. The degree of orientation of PE crystallites were found to increase near t...
Article
The cover image depicts self-assembled highly luminescent silver nanoclusters confined into the cavities of zeolites. These materials have garnered the interest of fundamental and applied nanomaterials research due to the fascinating properties they exhibit once stabilized into small, molecule-like nanoclusters displaying tunable optical emission a...
Article
Full-text available
Micelle formation inside faujasite (FAU) zeolite, a critical step in the introduction of mesoporosity in zeolites by surfactant templating, has been confirmed by both ¹³C NMR and Raman spectroscopy. Here we provide unambiguous evidence of the incorporation of surfactant molecules inside zeolites during the first step of the surfactant-templating pr...
Article
Full-text available
Stable emissive carbon nanodots were generated in zeolite crystals using near infrared photon irradiation gradually converting the occluded organic template, originally used to synthesize the zeolite crystals, into discrete luminescent species consisting of nano-sized carbogenic fluorophores, as ascertained using Raman microscopy, and steady-state...
Article
The excellent optoelectronic properties of metal halide perovskites (MHPs) have been employed in various photocatalytic applications, but their poor water stability is considered as the main bottleneck for further development. Herein, we protect the light-absorbing CsPbBr3 MHP with a NiOx and TiO2 hole and electron extracting layer. This planar NiO...
Article
Full-text available
Exposure to combustion-derived particles (CDPs), such as carbonaceous particulate matter (PM), has adverse effects on human health. Hence, selective detection of these particles in biological environments is required to understand their toxicity. The optical detection of carbonaceous PM is possible in biological samples based on white light (WL) em...
Article
Full-text available
Molecular additives are widely utilized to minimize non-radiative recombination in metal halide perovskite emitters due to their passivation effects from chemical bonds with ionic defects. However, a general and puzzling observation that can hardly be rationalized by passivation alone is that most of the molecular additives enabling high-efficiency...
Article
Following the rapid increase of organic metal halide perovskites toward commercial application in thin-film solar cells, inorganic alternatives attracted great interest with their potential of longer device lifetime due to the stability improvement under increased temperatures and moisture ingress. Among them, cesium lead iodide (CsPbI3) has gained...
Article
Full-text available
Amines are widely employed as additives for improving the performance of metal halide perovskite optoelectronic devices. However, amines are well-known for their high chemical reactivity, the impact of which has yet to receive enough attention from the perovskite light-emitting diode community. Here, by investigating an unusual positive aging effec...
Article
Full-text available
Metal-halide perovskites have rapidly emerged as one of the most promising materials of the 21st century, with many exciting properties and great potential for a broad range of applications, from photovoltaics to optoelectronics and photocatalysis. The ease with which metal-halide perovskites can be synthesized in the form of brightly luminescent c...
Article
The study of luminescent silver nanoclusters confined inside porous zeolite crystal has garnered the interest of fundamental and applied nanomaterials research owing to the fascinating properties they exhibit once stabilized into small, molecule‐like clusters. Notably, such systems display a tunable optical emission (spanning nearly the entire visi...
Article
Full-text available
Background Pregnant women and developing fetuses comprise a particularly vulnerable population as multiple studies have shown associations between prenatal air pollution exposure and adverse pregnancy outcomes. However, the mechanisms underlying the observed developmental toxicity are mostly unknown, in particular, if pollution particles can cross...
Article
Zeolite catalysts often display highly intergrown structures, yielding a zeolite “flower” or “sun” at the microscale. Using small‐angle X‐ray scattering and in‐situ fluorescence microscopy, Bert M. Weckhuysen et al. show in their Communication (DOI: 10.1002/anie.202101747) that porosity is developed only in specific segments of zeolites, which migh...
Article
Full-text available
Lead halide perovskites have attracted tremendous attention in photovoltaics due to their impressive optoelectronic properties. However, the poor stability of perovskite-based devices remains a bottleneck for further commercial development. Two-dimensional perovskites have great potential in optoelectronic devices, as they are much more stable than...
Article
Full-text available
Photocatalytic selective organic transformations provide an efficient synthetic alternative for several industrially relevant chemicals, using solar rather than thermal energy. However, in most cases, photocatalytic organic reaction systems involve only reductive or oxidative pathways with the aid of sacrificial reagents as efficient electron accep...
Article
Full-text available
Controlling grain orientations within polycrystalline all‐inorganic halide perovskite solar cells can help increase conversion efficiencies toward their thermodynamic limits; however, the forces governing texture formation are ambiguous. Using synchrotron X‐ray diffraction, mesostructure formation within polycrystalline CsPbI2.85Br0.15 powders as t...
Article
Research into organic–inorganic lead halide perovskites as photoactive material in solar cells and other electro‐optical devices has made immense progress in recent years. However, efficiency losses resulting from deep traps associated with framework defects, still limit the performance of perovskite semiconductors. Defect passivation by the incorp...
Article
Zeolith‐Katalysatoren zeigen oft stark verwachsene Strukturen, die auf der Mikroskala als „Blume“ oder „Sonne“ erscheinen. Mithilfe von Röntgenkleinwinkelstreuung und In‐situ‐Fluoreszenzmikroskopie zeigen Bert M. Weckhuysen et al. in ihrer Zuschrift (DOI: 10.1002/ange.202101747), dass sich die Porosität nur in bestimmten Segmenten der Zeolithe ausb...
Article
Full-text available
This work reported the rational design of single‐atom metal‐insulator‐semiconductor (SMIS) heterojunctions based on earth‐abundant Sn‐doped hematite nanorods (SF NRs) for high‐rate, efficient CO 2 ‐to‐syngas conversion and unveiled the details of dielectric field‐assisted hole‐tunneling dynamics at the SMIS heterojunctions. The results showed that...
Article
Full-text available
Hole-tunneling heterojunctions of atomically dispersed RuOx-Al2O3-Sn-Fe2O3 photoanodes were designed rationally to achieve an overall quantum efficiency of 5.7 % in the all-solar-driven APS cells equipped with a Ni-SNG catalyst cathode for CO2 conversion into syngas with excellent stability for 30 h under 450 nm LED irradation. Abstract Single-ato...
Article
The selective oxidation of benzyl alcohol to benzaldehyde using oxygen (O2) as the oxidant is a reaction of critical importance in the organic industry. In this study, CsPbX3/W18O49 composites with varying band gap energies were synthesized using an in situ solvothermal method. The abundant oxygen vacancies in W18O49 extend the light response of th...
Article
Full-text available
Introducing hierarchical porosity to zeolites is vital for providing molecular access to microporous domains. Yet, the dynamics of meso‐ and macropore formation has remained elusive and pore space ill‐characterized by a lack of ( in‐situ ) microscopic tools sensitive to nanoporosity. Here, we probe hierarchical porosity formation within a zeolite Z...
Article
Full-text available
Semiconductor-based light detection finds widespread application in everyday devices. Since the fabrication of commercial photodetectors requires complex and capital-intensive equipment, a search for semiconductors with low-cost processing is essential. To this end, hybrid organic–inorganic metal halide perovskites (MHPs) have gained interest due t...
Article
Full-text available
Hierarchical porosity within a zeolite crystal is visualized by X‐ray scattering microscopy to probe nanoporosity within the inorganic zeolite phase. In complement, in situ fluorescence microscopy allows to monitor pore hierarchization in real‐time via organic fluorescent stains, which fill the meso‐ and macropore space. Abstract Introducing hiera...
Article
Full-text available
Ultrasmall gold (Au) clusters have been regarded as one of the prototypes materials for solar energy conversion due to their unique strong molecular-like light absorption properties. However, the light-induced aggregation of Au clusters into nanoparticles is one of the most important factors that restricts its application in photocatalysis. Althoug...
Article
Full-text available
A novel fluorinated soft thermoplastic elastomer (sTPE) for microfluidics is presented. It allows the rapid fabrication of microfluidic devices through a 30‐second hot embossing cycle at 220°C followed by self‐sealing through simple conformal contact at room temperature, or with baking. The material shows high chemical resistance, particularly in c...
Article
Controlled chemical functionalization of graphite’s outer surface layers into photocatalytically oxidized graphite (POG) is reported. POG can be easily prepared via a UV-driven process using titanium dioxide photocatalyst in molecular oxygen and water vapor at relatively low temperature. The photo-oxidation offers a mild and highly controllable pro...
Article
Full-text available
We report the band-like transport of photogenerated charge carriers within all-inorganic black γ-phase CsPbI3 (γ-CsPbI3) thin films, with local mobilities up to 270 ± 44 cm²V–1s–1 recorded using terahertz (THz) spectroscopy at room temperature. Temperature-dependent, high-frequency photoconductivity measurements indicate that large polaron formatio...
Article
Full-text available
Bromide-based metal halide perovskites (MHPs) are promising photocatalysts with strong blue-green light absorption. Composite photocatalysts of MHPs with MIL-100(Fe), as a powerful photocatalyst itself, have been investigated to extend the responsiveness towards red light. The composites, with a high specific surface area, display an enhanced solar...
Article
Full-text available
Zeolites are widely used acid catalysts in research and in industrial processes. The catalytic performance of these materials is affected by the nature and concentration of Brønsted and Lewis acid sites. The balance between these types of active sites—and thus the activity and selectivity of the zeolite—can be altered by the introduction of metal s...
Preprint
Controlling grain orientations within polycrystalline all-inorganic halide perovskite solar cells can help increase conversion efficiencies toward their thermodynamic limits, however the forces governing texture formation are ambiguous. Using synchrotron X-ray diffraction, we report meso-structure formation within polycrystalline CsPbI2.85Br0.15 po...
Article
A new generation of semiconducting materials based on metal halide perovskites has recently been launched into the scientific spotlight, exhibiting outstanding optoelectronic properties and providing promise for the development of efficient optical devices. As a vivid example, solar cells made from these materials have quickly reached conversion ef...
Article
Full-text available
Lead‐free double perovskites have great potential as stable and nontoxic optoelectronic materials. Recently, Cs2AgBiBr6 has emerged as a promising material, with suboptimal photon‐to‐charge carrier conversion efficiency, yet well suited for high‐energy photon‐detection applications. Here, the optoelectronic and structural properties of pure Cs2AgBi...
Article
CsPbBr3 perovskite-based composites so far have been synthesized by postdeposition of CsPbBr3 on a parent material. However, in situ construction offers enhanced surface contact, better activity, and improved stability. Instead of applying a typical thermal condensation at highly elevated temperatures, we report for the first time CsPb(Br x Cl1-x...
Chapter
The synthesis of functional metal clusters has attracted the attention of scientists from diverse fields over the past decades, due to promising optical properties associated with such structures, particularly their luminescence properties. However, the synthesis of sub-nanometer metal clusters consisting of few atoms is not straightforward due to...
Article
Indoor plants can be used to monitor atmospheric particulates. Here, we report the label-free detection of combustion-derived particles (CDPs) on plants as a monitoring tool for indoor pollution. First, we measured the indoor CDP deposition on Atlantic ivy leaves (Hedera hibernica) using two-photon femtosecond microscopy. Subsequently, to prove its...
Article
During sprouting angiogenesis – the growth of blood vessels from the existing vasculature ‐ endothelial cells adopt an elongated invasive form and exert forces at cell–cell and cell‐matrix interaction sites. These cell shape changes and cellular tractions require extensive reorganizations of the acto‐myosin network. However, the respective roles of...
Article
Metal halide perovskites with direct bandgap and strong light absorption are promising materials for harvesting solar energy, however, their relatively narrow bandgap limits their redox ability when used as a photocatalyst. Adding a second semiconductor component with the appropriate band structure offsets can generate a Z-scheme photocatalytic sys...
Article
Herein, AlKα X‐rays are used to drive the growth of luminescent silver clusters in zeolites. The growth of the silver species is tracked using Auger spectroscopy and fluorescence microscopy, by monitoring the evolution from their ions to luminescent clusters and then metallic, dark nanoparticles. It is shown that the growth rate in different zeolit...
Article
Full-text available
The development of green, sustainable and economical chemical processes represents a cornerstone challenge within chemistry today. Semiconductor heterogeneous photocatalysis is currently utilized within a wide variety of societally impactful processes, spanning reactions like hydrogen production and CO2 conversion, to the organic transformation of...
Article
Angiogenesis is the formation of new blood vessels from the pre-existing vasculature. It is essential for normal tissue growth and regeneration, and also plays a key role in many diseases [Carmeliet in Nat Med 9:653–660, 2003]. Cytoskeletal components have been shown to be important for angiogenic sprout initiation and maintenance [Kniazeva and Put...
Article
Metal clusters confined inside zeolite materials display remarkable luminescent properties, making them very suitable as potential alternative phosphors in white LED applications. However, up to date, only single-color emitters have been reported for luminescent metal-exchanged zeolites. In this study, we synthesized and characterized white emittin...
Article
Full-text available
Reduced-dimensional perovskites are attractive light-emitting materials due to their efficient luminescence, color purity, tunable bandgap, and structural diversity. A major limitation in perovskite light-emitting diodes is their limited operational stability. Here we demonstrate that rapid photodegradation arises from edge-initiated photooxidation...
Article
Full-text available
The transition to solid-state Li-ion batteries will enable progress toward energy densities of 1000 W·hour/liter and beyond. Composites of a mesoporous oxide matrix filled with nonvolatile ionic liquid electrolyte fillers have been explored as a solid electrolyte option. However, the simple confinement of electrolyte solutions inside nanometer-size...
Article
Full-text available
In order to unravel rapid mechano-chemical feedback mechanisms in sprouting angiogenesis, we combine selective plane illumination microscopy (SPIM) and tailored image registration algorithms — further referred to as SPIM-based displacement microscopy — with an in vitro model of angiogenesis. SPIM successfully tackles the problem of imaging large vo...
Article
Defect engineering in photocatalysts represents a fundamental method toward tailoring their solar-to-chemical energy conversion performance, although determining the nature and impact of subsurface defects remains challenging. Single-unit-cell Bi2WO6 monolayers – forming a sandwich-like structure; [BiO]⁺–[WO4]²−–[BiO]⁺ – exhibit promising photocata...
Article
A novel metal‐insulator‐semiconductor (MIS) photosystem based on covalent orga