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A new benign aqueous route towards bismuth-containing photoelectrodes is proposed to eliminate the need for harmful organic solvents and/or acids. A CuBi2O4 photocathode was prepared by stabilizing the metal ions through complexation in pH neutral aqueous solutions. Merits of the proposed approach are elemental homogeneity (with unique doping possibilities) and ease of fabrication (e.g. high scalability). The prepared aqueous CuBi2O4 precursor forms a nearly phase-pure kusachiite crystalline phase free of organics residuals and capable of water reduction due to its sufficiently negatively positioned conduction band at -0.4 V vs. RHE. Deposition on FTO/glass substrates and thermal treatment leads to uniform but granular films of CuBi2O4 with excellent control over stoichiometry and thickness, owing to the facile and non-destructive synthesis conditions. Ultimately, the optimized CuBi2O4 photocathodes produced AM1.5G photocurrent densities of up to -1.02 mA∙cm-2 at 0.4 V vs. RHE with H2O2 as an electron scavenger, competing with bare CuBi2O4 prepared through less benign non-aqueous organic synthesis routes.

This work received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement 101015960 (SPOTLIGHT). This work received financial support from the VLAIO network through the Catalisti Moonshot project D2M.

Co-free Li-rich layered oxides are gaining interest as feasible positive electrode materials in lithium-ion batteries (LIBs) in terms of energy density, cost reduction, and alleviating safety concerns. Unfortunately, their commercialization is hindered by the severe structural degradation that occurs during electrochemical operation. The study at hand demonstrates advanced structural engineering of a Li-rich Co-free oxide with composition Li1.1Ni0.35Mn0.55O2 by spray-pyrolysis and subsequent calcination of an aqueous precursor, creating a segregated structure of two distinct layered phases with space groups 𝑅3̅𝑚 (rhombohedral) and 𝐶2/𝑚 (monoclinic) . This particular structure was investigated with powder neutron diffraction, high-resolution analytical transmission electron microscopy imaging, and electron energy loss spectroscopic characterization. This complex structure contributes to the high electrochemical stability and good rate capability observed for this compound (160 mAh/g at C/3 and 100 mAh/g at 1C). These results provide new insights into the feasibility of developing and commercializing of cobalt-free positive electrode materials for LIBs.

Transport is the only sector to have increased its CO2 emissions since 1990, and regular passenger cars make up the largest part of these transport emissions. Thus, a growing need for sustainable mobility is clear, leading to an expanding electric vehicle market. Lithium-ion batteries are considered most suitable for these vehicles owing to their large volumetric and gravimetric capacities. The need for increased battery performance as well as improved safety makes solid-state batteries the main contender for next-generation Lithium-ion batteries in all battery development roadmaps. Among solid-state electrolytes, sulfide-based materials such as LGPS (Li10GeP2S12), lithium thiophosphates (Li3PS4 and related compounds), and lithium argyrodite-type (generally Li6PS5X, X being Cl, Br, or I) materials are attracting much attention because of their high ionic conductivity, which is comparable in magnitude to that of known liquid electrolytes, potential for improved safety, and potential for more sustainable production. Synthesis of both lithium thiophosphates and their derived products, lithium argyrodites, can be performed in several ways: solid-state methods offer proven ways to achieve these materials, although they come at significant cost in both reaction time as well as energy consumption. Solution-based methods have been shown to produce these materials with lower reaction times, requiring a smaller energy investment, and offering access to metastable phases. A solution-based route starting from the precursor P4S10 towards the final Li6PS5Br argyrodite-type product has been described in literature by Yubuchi et al., whereby P4S10 and Li2S are first reacted in a tetrahydrofuran (THF) solvent to form Li3PS4, followed by addition of Li2S and LiBr in ethanol to form the Li6PS5Br product in a mixed-solvent solution. This work examines the presence of intermediate compounds in the first step of this synthesis (performed in THF), and the formation of ethanolic degradation products over time in the second step of the synthesis (performed in the THF-ethanol mixed solvent system) by a combination of analytical techniques including MAS-31P-NMR, liquid 31P-NMR and ICP-OES. This project receives financial support from Flanders Innovation & Entrepreneurship (VLAIO) and Umicore as part of Baekeland-mandate HBC.2020.2822. Bjorn Joos receives financial support from FWO (G053519N).

Batteries are ubiquitous in our society and can be used in many applications, such as electric vehicles and stationary energy storage. Further progress in the development of batteries relies on the synergy between concepts from chemistry, physics and engineering. Creative chemical synthesis processes for the electrodes and electrolyte are a key factor in improving the functionality of battery technologies and pave the way toward a more sustainable future. This presentation will showcase a number of selected examples, where chemical approaches were used to improve the electrochemical performance and/or sustainability of current and upcoming battery chemistries. Although commonly used in lithium-ion batteries (LIBs), the mining, refining, and processing of cobalt causes a range of detrimental societal and environmental impacts. Therefore, extensive research was performed within the Horizon 2020 COBRA project to produce a positive electrode material for LIBs that does not contain any cobalt but still reaches a high energy/power density and cycle life at a competitive cost. In a different research path, core particles of positive electrode materials were coated with a shell of a material with high conductivity, thereby enhancing their energy and power density. The synthesis of core-shell particles can also enable an improved battery cycle life.1,2 Creative chemical approaches were also used to synthesize durable negative electrode materials for sodium-ion batteries (SIBs), making use of a carbothermal reduction reaction to form a phase which can otherwise only be formed in a cumbersome synthesis method.3 The electrolyte component of batteries should have a high conductivity for ions. Conventional electrolytes are highly flammable, limiting the safety of battery operation. To improve the safety, a nonflammable class of liquid electrolyte was developed for SIBs. The combination of experimental and computational studies allowed the optimization of the coordination structure of deep eutectic solvents (DESs) as viable electrolyte alternatives. They can offer a more durable electrochemical performance compared to conventional electrolytes.4 The development of solid electrolytes for battery applications may enable the safe use of metallic anodes, thereby offering the possibility to drastically improve the energy density. Therefore, DESs were incorporated into inorganic and polymeric backbone structures, compatible with high-energy density electrode materials. This new class of solid electrolyte for battery applications was termed eutectogel and consists of inexpensive and mechanically optimized electrolytes for next-generation solid-state batteries.5,6 This work was supported by Horizon 2020 LCBAT-5 COBRA project 875568 and by Research Foundation Flanders in several projects and mandates. Furthermore, the work received the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg (project 936). (1) Ulu Okudur, F. et al. Ti surface doping of LiNi0.5Mn1.5O4-δ positive electrodes for lithium ion batteries. RSC Adv. 8, p7287–7300 (2018). (2) Mylavarapu, S. K. et al. Effect of TiOx Surface Modification on the Electrochemical Performances of Ni-Rich (NMC-622) Cathode Material for Lithium-Ion Batteries. ACS Appl. Energy Mater. 4, p10493–10504 (2021). (3) De Sloovere, D. et al. Reduced Na2+xTi4O9/C Composite: A Durable Anode for Sodium-Ion Batteries. Chem. Mater. 30, p8521–8527 (2018). (4) De Sloovere, D. et al. Deep Eutectic Solvents as Nonflammable Electrolytes for Durable Sodium‐Ion Batteries. Adv. Energy Sustain. Res. 3, p2100159 (2022). (5) Joos, B. et al. Eutectogels: A New Class of Solid Composite Electrolytes for Li/Li-Ion Batteries. Chem. Mater. 30, p655–662 (2018). (6) Joos, B. et al. Polymeric Backbone Eutectogels as a New Generation of Hybrid Solid-State Electrolytes. Chem. Mater. 32, p3783–3793 (2020). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 875568. The complete DESINe group Technical personnel at UH All coauthors

Plasmon catalysis for endothermic reverse water-gas shift (rWGS) reaction making use of sunlight and renewable hydrogen is a low temperature alternative to the conventional thermal process. 1 A plasmonic catalyst consists of plasmonic nanoparticles dispersed on a supporting oxide, which can be semiconducting or insulating. The plasmonic nanoparticles exhibits localised surface plasmon resonance (LSPR) upon illumination. This results in the catalyst exhibiting following pathways to catalyse reactions: 2-Local heat generation (fig. A)-Near field enhancement (fig. B)-Hot electron injection (fig. C)-Charge separation over Schottky barrier (if semiconducting support) (fig. D)-Band gap activity of semiconductor (if semiconducting support) (Fig. E) To investigate which catalytic effects contribute to rWGS reaction: Au was chosen as plasmonic nanoparticle for a high selectivity towards CO production and strong plasmonic resonance. P25 TiO 2 was chosen as semiconducting oxide with a band gap in the near UV and good photocatalytic properties. In order to investigate the catalytic effects at play, as well as the impact of plasmonic nanoparticle size, smaller (5.5 nm) and larger (16 nm) particles were synthesised on the TiO 2 support and tested for catalytic activity in both light and dark conditions.

Lithium-ion batteries (LIBs) are considered an important technology for the mobility sector’s green energy transition by enabling the breakthrough of electric vehicles (EVs). The forecasted explosive growth of the EV market implies that the demand for LIB materials will show a steep increase over the following years. This will put considerable strain on the sourcing of the critical raw materials needed for LIB production. The mining, refining, and processing of cobalt pose a number of challenges, ranging from social and environmental impacts to supply shortages. One way to tackle these challenges is to use battery active materials which contain (almost) no cobalt. This again requires extensive research to ensure high cycle life and thermal stability. In the Horizon 2020 COBRA project, we aim to completely eliminate cobalt from the positive electrode, while reaching an adequate energy density (750 Wh/L) and cycle life (>2000 cycles) with fast charging (3 C). COBRA aims to reach competitive cost targets (< 90 €/kWh at pack level). Here, an overview will be given of our recent studies on Co-free and Co-poor materials for LIBs. Our research relies on the use of wet chemical routes, either to synthesize the active materials, or to form a shell on pre-existing active material core particles. The developed wet chemical synthesis routes allow a careful control over the synthesis parameters, and enable us to accurately control the particle size/morphology of cobalt-free LiNi0.5Mn1.5O4 (LNMO) particles.[1] The electrochemical performance of LNMO core particles could be further improved by coating them with shells of TiOx or amorphous Li4Ti5O12.[2] Cores of LiNi0.6Mn0.2Co0.2O2 (NMC-622, a nickel-rich, cobalt-poor layered oxide) were similarly modified with TiOx shells, improving its rate capability and energy density.[3] Wet chemical routes are ideal for inserting dopants into materials. For instance, the replacement of Mn4+ by Sn4+ in lithium- and manganese-rich (and cobalt-poor) NMC was studied in an effort to mitigate the voltage fade which is typically observed in such materials.[4] Whereas cobalt is ubiquitous in today’s LIBs, current research efforts strive toward a reduction and even elimination of cobalt in future LIBs. As shown here, our research contributes to the improvements required to make these novel materials competitive with the materials that are currently used in LIBs. [1] F. Ulu Okudur, S. K. Mylavarapu, M. Safari, D. De Sloovere, J. D’Haen, B. Joos, P. Kaliyappan, A. S. Kelchtermans, P. Samyn, M. K. Van Bael, A. Hardy, J. Alloys Compd. 892 (2022) 162175. [2] F. Ulu Okudur, J. D’Haen, T. Vranken, D. De Sloovere, M. Verheijen, O. M. Karakulina, A. M. Abakumov, J. Hadermann, M. K. Van Bael, A. Hardy, RSC Adv. 8 (2018) 7287-7300. [3] S. K. Mylavarapu, F. Ulu Okudur, S. Yari, D. De Sloovere, J. D’Haen, A. Shafique, M. K. Van Bael, M. Safari, A. Hardy, ACS Appl. Energy Mater. 4 (2021) 10493-10504. [4] A. Paulus, M. Hendrickx, M. Bercx, O. M. Karakulina, M. A. Kirsanova, D. Lamoen, J. Hadermann, A. M. Abakumov, M. K. Van Bael, A. Hardy, Dalt. Trans. 49 (2020) 10486-10497. The Horizon 2020 LCBAT-5 COBRA project 875568 is acknowledged for financial support.

This study reports the low temperature and low pressure conversion (up to 160 °C, p = 3.5 bar) of CO2 and H2 to CO using plasmonic Au/TiO2 nanocatalysts and mildly concentrated artificial sunlight as the sole energy source (up to 13.9 kW·m-2 = 13.9 suns). To distinguish between photothermal and non-thermal contributors, we investigated the impact of the Au nanoparticle size and light intensity on the activity and selectivity of the catalyst. A comparative study between P25 TiO2-supported Au nanocatalysts of a size of 6 nm and 16 nm displayed a 15 times higher activity for the smaller particles, which can only partially be attributed to the higher Au surface area. Other factors that may play a role are e.g., the electronic contact between Au and TiO2 and the ratio between plasmonic absorption and scattering. Both catalysts displayed ≥84% selectivity for CO (side product is CH4). Furthermore, we demonstrated that the catalytic activity of Au/TiO2 increases exponentially with increasing light intensity, which indicated the presence of a photothermal contributor. In dark, however, both Au/TiO2 catalysts solely produced CH4 at the same catalyst bed temperature (160 °C). We propose that the difference in selectivity is caused by the promotion of CO desorption through charge transfer of plasmon generated charges (as a non-thermal contributor).

Batteries are a major base for today’s society and will play an even larger role due to the further electrification. Besides increasing their energy and power density, several challenges exist for the next generation batteries such as designing more sustainable and safer batteries. In this regard, solid-state electrolytes are of high importance because of their higher stability. In this poster, silica-based ionogels for sodium-ion batteries (SIBs) are investigated. SIBs are considered more sustainable than their lithium counterparts due to the high abundance of sodium in the earth’s crust. On the other hand, the quasi-solid silica-based ionogels are very attractive due to their desired electrolyte properties such as high thermal stability, high electrochemical stability, and high ionic conductivity. Unfortunately, silica-based ionogels are in general brittle, which may induce cracking when in contact with electrodes. In this poster silica-based ionogels are organically modified to investigate the effect on the desired electrolyte properties.

Photocatalysis is a valuable method for the degradation of polluting organic dyes present in the wastewater. Therefore, in this study, undoped and Al-doped ZnO nanoparticles were synthesised via a solvothermal route, characterised and tested as photocatalysts for the photodegradation of Rhodamine B under UV-Visible light illumination. The amount of dopant incorporated into the final solid was quantified by inductively coupled plasma-optical emission spectrometry (ICP-OES). It showed that the experimental Al content represents about 65% of the nominal value. Transmission electron microscopy (TEM) investigation performed on both undoped and Al-doped ZnO revealed the presence of quasi-spherical nanoparticles with a diameter ranging between 10 and 60 nm. The structural features of the catalysts were investigated employing X-ray Powder Diffraction (XRPD). The patterns of the nanomaterials matched with the hexagonal wurtzite crystal phase. A secondary crystalline phase was also detected. In the Fourier transform infrared (FT-IR) spectra, a pronounced absorption between 800 and 3000 cm-1 is observed for all the Al-doped ZnO semiconductors while it is absent for the undoped material. The appearance of this absorption in the MID infrared can be attributed to plasmon absorption in the case of Al-doped ZnO nanoparticles. Furthermore, solid-state 27Al Magic Angle Spinning (MAS) NMR can provide information on the local environment of the aluminium ions inserted into the ZnO structure. The NMR results display that Al is occupying both octahedral and tetrahedral sites, and that higher Al contents result in decreasing fractions of Al occupying tetrahedral sites. The preliminary photocatalytic tests evinced that both undoped and Al-doped ZnO materials are active under UV-C, UV-A and visible-light irradiation, demonstrating their ability to remove the organic dye in aqueous solution.

Plasma catalysis, a promising technology for conversion of CO2 into value-added chemicals near room temperature, is gaining increasing interest. A dielectric barrier discharge (DBD) plasma has attracted attention due to its simple design and operation at near ambient conditions, ease to implement catalysts in the plasma zone and upscaling ability to industrial applications. To improve its main drawbacks, being relatively low conversion and energy efficiency, a packing material is used in the plasma discharge zone of the reactor, sometimes decorated by a catalytic material. Nevertheless, the extent to which different properties of the packing material influence plasma performance is still largely unexplored and unknown. In this study, the particular effect of synthesis induced differences in the morphology of a TiO2 shell covering a SiO2 core packing material on the plasma conversion of CO2 is studied. TiO2 has been successfully deposited around 1.6–1.8 mm sized SiO2 spheres by means of spray coating, starting from aqueous citratoperoxotitanate(IV) precursors. Parameters such as concentration of the Ti(IV) precursor solutions and addition of a binder were found to affect the shells’ properties and surface morphology and to have a major impact on the CO2 conversion in a packed bed DBD plasma reactor. Core-shell SiO2@TiO2 obtained from 0.25 M citratoperoxotitante(IV) precursors with the addition of a LUDOX binder showed the highest CO2 conversion 37.7% (at a space time of 70 s corresponding to an energy efficiency of 2%) and the highest energy efficiency of 4.8% (at a space time of 2.5 s corresponding to a conversion of 3%).

In the layered Li2MnO3 cathode material for Li-ion batteries manganese is exclusively present in a 4+ oxidation state. The high theoretical capacity of 460 mAh/g can be explained by the contribution of anionic redox chemistry from the oxygen sublattice as the Mn5+/Mn4+ redox couple is situated below the top of the O-2p band. The gradual layered to spinel structural transition upon galvanostatic cycling causing voltage fade is originates from a lack of Mn-O covalency, resulting in irreversible O_h→T_h migration of Mn3+ and oxygen release upon charging.1 Here, we present the partial substitution of Mn4+ for Ti4+ as a promising way to enhance the reversible discharge capacity upon extended galvanostatic cycling. Ti substituted Li2MnO3 has been synthesized via a facile solution-gel method. The structure of pristine Li2Mn1-xTixO3 (x=0-0.2) has been comparatively investigated by PXRD, Raman spectroscopy, 7Li NMR and advanced TEM. Galvanostatic charge/discharge measurements performed at C/10 show a significant improvement of discharge capacities up to 30 galvanostatic charge/discharge cycles as compared to unsubstituted Li2MnO3. The ameliorated reversible discharge capacities are correlated with the structure of the pristine samples and the structure of post mortem samples analyzed by ex situ advanced TEM.

Li2MnO3 is extensively investigated as a cathode material for Li-ion batteries. However, oxygen loss (oxygen will oxidize prior to Mn4+ to Mn5+) resulting in irreversible structural changes decreases the electrochemical performance. The layered disordered NaFeO2 type structured cathode material Li2MoO3 has several advantages over Li2MnO3. This includes the accessibility of the Mo4+/Mo6+ redox couple, improved kinetics due to the higher electronic conductivity and lower oxygen evolution from the cathode’s active material oxygen sublattice. Most commonly, Li2MoO3 is prepared by reducing Li2MoO4 under Ar/H2 flow1 or N2/H2 flow 2. However, the use of H2 comprises severe safety issues. As an alternative, Li2MoO3/C has been obtained in literature via a solid state reaction between Li2CO3 and MoO2 with acetylene black as an additive under inert Argon atmosphere, excluding the use of H2.3 The major limitation of the proposed synthesis method is the extended anneal period of 24 hours at 900°C or 1000°C. Here, we report the synthesis of LixMoyOz/C composite materials via a carbothermal reduction method with organic ligands serving as the carbon source, requiring an anneal period of less or equal to 12 hours at 900°C or less. Molybdenum is present in a 6+ oxidation state in the aqueous precursor. The end products are characterized by Raman spectroscopy, XRD and SEM. The XRD patterns indicate Li2MoO3 and Li4Mo5O24 as major phases, hinting the ability to effectively reduce Mo6+ to Mo4+ by our method. The composite end product has been electrochemically characterized vs. Li metal as an anode in a coin cell configuration. The initial galvanostatic charging curve has at first glance a similar shape as compared to literature for Li2MoO3, including the prominent potential plateau around 3.5V. In order to gain understanding of the mechanisms behind initial charge/discharge of our LixMoyOz /C composite material, with focus on the contribution of the individual compounds of which the composite is composed of, in situ Raman spectroscopy has been applied.

International audience

Several applications related to energy harvesting (e.g. photovoltaics) or energy efficient lighting (EL, OLEDs, …) strongly rely on effective transparent electrodes. Recently, metal nanowire networks are put forward as a promising concept for replacing transparent conducting oxides, such as Indium Tin Oxide (ITO). In such networks, the nanowires conduct charge carriers, while the open areas allow the transmission of light. Metal nanowires are both printable and achieve a performance equivalent to ITO upon thermal processing at moderate temperatures below 150°C, making them ideal for printing (flexible) transparent electrodes on plastic substrates. Various formulations containing Ag NWs were prepared and their rheological behavior was assessed in view of screen printing on PET. The opto-electrical properties of the printed features are characterized by a Van der Pauw method and UV-Vis spectroscopy and analyzed by a semi-empirical model, relating the transparency and conductivity of the electrodes. Depending on the concentration and dimensions of the nanowires, the features have a transparency ranging from 50% up to 90% and a sheet resistance down to 20 Ohm/sq, fulfilling the requirements for a wide range of optoelectronic devices. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 641864.

High energy and power density lithium ion batteries are extensively being studied for their potential applications in portable electronics and hybrid/full electric vehicles as well as for their ability to store solar, wind and other renewable energies with high efficiency [1]. LiNi 0.5 Mn 1.5 O 4-δ (LNMO) is a high voltage lithium ion battery cathode material with potential for high power applications requiring good rate capability, such as hybrid/full electric vehicles [2]. The cyclic stability of LNMO remains an issue since all cathode materials containing Mn are challenged with a capacity fade problem due to Mn leaching into commercial electrolytes, during cycling or storage [1, 3]. One of the mechanisms causing Mn leaching is by hydrofluoric acid corrosion. HF forms by hydrolysis of LiPF 6 salt in electrolyte in presence of traces of water [3]. One way to prevent the Mn loss is to modify the surface of the cathode particles by coating or doping the surface with a chemically stable material. Zr 4+ /ZrO 2 is a good canditate to be used as a surface modification material since Zr-O has a high bond-dissociation energy (766.1±10.6 kJ/mol [4]). Zr-O presence at the surface can make the particle more stable against leaching compared to Mn-O (362±25 kJ/mol) or Ni-O (366±30 kJ/mol) presence at the surface. Purpose of this study is therefore to coat or dope the LNMO particle surfaces with ZrO 2 shell or Zr 4+ cation, respectively, to obtain batteries having better cycle life and rate performance than the LNMO without any surface modification.

Average LNMO diameter ± std. error (nm) SEM TEM Smaller LNMO particles N/A 34 ± 2 Larger LNMO particles 575 ± 73 N/A • Using an anneal at 500°C; Ti atoms were found to dope at the LNMO surface. Increasing the annealing temperature to 800 o C caused these Ti atoms to diffuse towards the core. Above 750°C, a slight amounts of secondary LiNi 0.5 Mn 1.5-x Ti x O 4 spinel phase were formed. • A surface modification followed by an anneal at 500°C improves cycle life, CE% and rate performance. This is probably due to incorporation of stronger Ti-O bonds within the spinel LNMO surface structure, which reduces the Mn dissolution into the electrolyte upon cycling. Introduction Conclusions References Results LiNi 0.5 Mn 1.5 O 4 is surface modified with TiO 2 (LNMO@TiO 2). The effects of annealing under oxygen atmosphere between temperatures of 500 to 850°C on Ti 4+ positions, morphology, crystal structure and electrochemical performance are investigated. A sol-gel approach is used to homogeneously modify the surface of ~30-500 nm diameter LNMO core particles with TiO 2. Metal oxide shell synthesis on LNMO through wet-chemical routes usually results in amorphous deposits [1-3]. The shell is then crystallized by high temperature anneals; ranging from 500 to 800°C [1-4]. The annealing temperature and atmosphere deserve, however, special attention, since these can cause Ti diffusion from the shell towards the surface or bulk of the LNMO particles, as well as causing changes in cation ordering inside the LNMO. Ti surface doping is useful in increasing the LNMO's structural stability, while excess Ti doping may cause capacity drops [5]. In this study, we aimed to increase the cycle life of LNMO, by modifying the LNMO surface with titanium oxide, while at the same time, avoiding bulk doping. Region Ni (at%) Mn (at%) Ti (at%) Mn/Ni S1 28.9 63.1 7.9 2.2 C1 29.0 70.0 1.0 2.4 S2 26.2 68.5 5.2 2.6 C2 27.0 69.3 3.7 2.6 Cycle 10

High energy and power density lithium ion batteries (LIB) are extensively being studied for their potential applications in portable electronics and hybrid/full electric vehicles as well as for their ability to store solar, wind and other renewable energies with high efficiency [1]. LiNi 0.5 Mn 1.5 O 4 (LNMO) attracts attention as a high voltage cathode material (4.7 V vs. Li/Li +) with good capacity (147 mAh/g); having potential for high power applications [2]. However, cyclic stability of LNMO still remains an issue since all cathode materials containing Mn are challenged with capacity fade problem due to Mn leaching within commercial electrolytes [1]. Introducing a shell layer on LNMO that is stable at high voltages can prevent Mn dissolution and increase cycle life; while also enabling good conductivity, if ionically and electronically conductive [3]. Materials such as Li 4 Ti 5 O 12 [4] , Li 2 TiO 3 [5] and TiO 2 [4] attract attention as shell material candidates in literature, owing to their structural stability within organic electrolytes at high voltages, as well as their 3D Li + diffusion paths allowing good ionic conductivity. TiO 2 is used as the surface modification material in this work; synthesized using a sol-gel approach. Different from previous studies; effect of different annealing temperatures (500 to 850 o C) on Ti 4+ diffusion from surface towards the core of LNMO is investigated. Electrochemical performances are compared while also considering the ordering/disordering changes within the LNMO crystal structure.

The transparent conductive aluminum-doped zinc oxide (AZO) attracts attention as an alternative for indium tin oxide. Still, it is unclear how different point defects affect its properties. Here, we explore which defects contribute to the conductivity of AZO nanospheres and how they can be tuned by solvolysis synthesis and annealing. Using a combination of NMR, Infrared and Raman spectroscopy, the occurrence and position of the Al dopant was determined in these samples. Moreover, the microwave cavity perturbation technique (MCPT) was used to qualitatively compare the conductivity of the powders. From the results of MCPT we can conclude that, a combination of annealingand prolonged refluxing leads to an increased conductivity. Also a significant rise of an NMR Knight Shift and a broad and intense FTIR band attributed to surface plasmon resonance, both indicate free charge carriers. This is in agreement with Raman spectra showing the presence of clusters of Zn interstitials in all samples. Our first-principles calculations corroborate these findings, that annealing of Al interstitials leads to the formation of zinc interstitials in combination with substitutional Al, which results in an increased conductivity in AZO. FWO

While using Li4Ti5O12 as the anode material in lithium ion batteries greatly enhances their operation safety and avoids the formation of a solid electrolyte interface, the synthesis of this material often comes at a high time and energy cost. A typical solid-state synthesis method requires the reagents to be kept at temperatures up to 900 °C for several hours. Both synthesis temperature and processing time were reduced by applying the concept of solution combustion synthesis, where a sol-gel precursor is synthesized which generates the energy needed for complete sample conversion and crystallization by itself when it is heated to a relatively low process temperature. The large amount of parameters inherent to this concept, such as fuel and oxidizer amount, heating rate and atmosphere were studied and the physical properties of both precursor gels and thermally processed powders were characterized by thermogravimetric analysis (TGA) coupled with differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR) and mass spectrometry (MS), Raman spectroscopy and X-ray diffraction (XRD). By using the concept of solution combustion synthesis, the synthesis temperature was reduced to a temperature as low as 250 °C, while the processing time required was in the order of seconds. The oxidizer amount, NH4NO3 in this case, is of great importance, since while it is necessary for a balanced combustion reaction, an excess also decomposes endothermically, thereby preventing the necessary accumulation of heat within the sample. Solution combustion synthesis can considerably lower the temperature and time required for the synthesis of ceramic materials, but careful optimization of the precursor gel is necessary, since the mechanism of thermal degradation is complex and dependent on a large amount of parameters.

Inkjet printing is a fast, cheap and flexible method to deposit thin and structured layers. In this work precursor based Ag inks were developed instead of the commercially available particle based ones that usually have to be sintered at temperatures of at least 200 °C. It is proven that inkjet printed Ag layers can be sintered at temperatures as low as 60 °C reaching a resistance of less than 5 Ohms/cm with these home-made precursor inks. The author would like to thank the financial contribution from the CORNET project POLEOT (IWT-TETRA-120629) and the support from BOF (Bijzonder OnderzoeksFonds) of Hasselt University.

Lithium Manganese Oxide (LiMn2O4, LMO) (4.1 V, 148 mAh/g) and Lithium Nickel Manganese Oxide (Li2NiMn3O8, LMNO) (4.7 V, 148 mAh/g) are high voltage cathode materials aiming at high energy density battery applications like electric vehicles [1]. However, their applicability in actual devices is limited due to their low electrochemical stability with most of the commercial electrolytes at high potentials. The purpose of this research is to introduce a core-shell structure for the battery cathode using LM(N)O as the core and TiO2 as the shell material to prevent the electrolyte decomposition on the surface of the LM(N)O particles. A kinetics controlled coating technique [2] mainly based on hydrolysis and condensation reactions of titanium butoxide (TBOT) was used to initiate heterogenous nucleation and growth of TiO2 on commercial LM(N)O particles in an ethanol based environment. The effect of different synthesis parameters; such as the LM(N)O amount, the TBOT amount and the reaction time on the shell formation was examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). SEM images revealed changes in surface morphology when compared to the bare, commercial LMO powders. Titanium and oxygen signals revealed by EDS also pointed out possible formation of a thin TiO2 layer on LMO particles. However, powder agglomeration was observed via SEM after coating process. To avoid agglomeration, studies were focused on increasing the zeta-potential value of the core particles by surface functionalization. Citric acid functionalized [3] LMNO particles revealed stable dispersions at a pH of 10 with a zeta-potential value of about -54 mV in aqueous medium while the non-functionalized LMNO particles revealed about -16 mV at the same pH. Effect of using the citric acid functionalized starting powders in the ethanol based actual shell synthesis medium is further to be investigated. 1. C. M. Julien, A. Mauger, K. Zaghib and H. Groult, Inorganics 2 (2014) 132. 2. W. Li, J. Yang, Z. Wu, J. Wang, B. Li, S. Feng, Y. Deng, F. Zhang, D. Zhao, J. Am. Chem. Soc. 29 (2012) 11864. 3. S. Mornet, C. Elissalde, V. Hornebecq, O. Bidault, E. Duguet, A. Brisson, M. Maglione Chem. Mater. 17 (2005) 4530.

FWO project G014913, BOF Uhasselt

FWO project G014913, BOF Uhasselt

Extended Abstract In the food packaging industry there is a gaining interest in bioplastics to replace conventional plastics, such as PET, PP, etc., as packaging material. Although these new polymers show the advantages of being bio-based and/or biodegradable, it is still a challenge to produce bioplastics with similar properties to the conventional plastics. For food packaging material for example, it is important to maintain food quality. Therefore it is essential to enhance the gas barrier properties of these bioplastics. Recent studies show that gas barrier properties of polymers can be improved through use of polymer nanocomposites, a two-phase system of a polymeric matrix and dispersed inorganic nanoparticles. A limiting factor, however, is the dispersion of the nanoparticles into the polymer. A solution is to deposit the nanoparticles on the polymer surface instead. Here, nanoparticles were deposited at temperatures below 95°C on the surface of the bioplastic PHBV through chemical bath method, which allows low-cost and low deposition temperatures, to study the effect of ZnO nanolayers on the gas barrier properties. By means of XRD the formation of (002) oriented ZnO was confirmed, while Raman spectroscopy confirmed the chemical structure of the ZnO nanolayer. The influence of the deposition of ZnO layers on the properties of the PHBV bioplastic was investigated by means of differential scanning calorimetry and transmission spectrometry in the wavelength ranging from 200 nm to 800 nm and. The O 2 , CO 2 and water vapour permeability were measured at a controlled temperature of 10°C, 23°C and 38°C to determine the influence of temperature on the barrier properties. For the O 2 permeability these experiments were performed at a relative humidity of 0%, 40% and 80% to also determine the influence of humidity on the oxygen barrier, while for CO 2 and water vapour permeability the relative humidity was kept constant at 0% and 100% respectively. The temperature study showed an increase of the oxygen, carbon dioxide and water vapour permeability with increasing temperature. This is mostly due to an increased free volume in the polymer matrix, improved motion of the polymer segments and a higher energy level of the permeating molecules. It was observed that the deposition of ZnO nanoparticles decreases oxygen, carbon dioxide and water vapour permeability. Temperature dependent measurements show that the activation energy for permeability of pure PHBV is lower than that of PHBV with a ZnO nanolayer on top. The humidity study of the oxygen barrier showed that for pure PHBV the permeability is stable until 40% RH and then increases with 20% at 23°C and even with 45% at 38°C. This is due to the fact that PHBV will absorb moisture from the humid air, which will lead to an increase in free volume and higher permeability values. For the PHBV with ZnO nanolayer an opposite effect is observed. In the region of 0%RH to 40%RH the oxygen permeability increases with 15% at 23°C and 23% at 38°C while afterwards, in the

Ligands provide physicochemical functionality to colloidal nanoparticles (NPs). Used during synthesis to control nucleation and growth, they end up as a monolayer covering the NP surface and stabilizing the NP colloidal suspension [1]. After synthesis, they can be exchanged by others to change the properties of the suspension or to improve certain characteristics [2]. In the last few years NMR techniques have been developed that can give a molecular view on the NPs from the ligands’ point of view, both in a qualitative and quantitative way. Using this ‘NMR toolbox’ different NPs and ligands have already been investigated [2-5]. In current research, two new types of NP materials are being investigated: Aluminium-Zinc-Oxide NPs (AZO-NPs) surrounded with oleic acid ligands, and Cupper-Indium-Gallium-Sulfide NPs (CIGS) surrounded by non-hydrogen containing tin-sulfide ligands. Preliminary results of these studies will be presented.

In deze thesis staan de synthese en de eigenschappen van de supergeleider YBa2Cll40s (Y-124) centraal. We beschrijven de bereiding van deze fase bij 1 atmosfeer via een chemische pre~ursorroute, met name de sol-gelroute. De geoptimaliseerde solgelbereiding wordt vervolgens aangewend om varianten van de Y-124-fase te bereiden waarin respectievelijk Y door Ca, Ba door Sr en Cu door Co of Ni gesubstitueerd worden. De invloed van deze substituties op de eigenschappen van de Y-124-fase wordt geevalueerd en vergeleken met in de literatuur beschreven resultaten. ...

[EN] The metastability impediment which usually prevents the obtaining of a phase-pure BiFeO3 material can be dramatically stressed when taking the system to the thin film configuration. In order to preserve the stoichiometry, the films need to be processed at low temperatures and hence the solid-state diffusion processes which usually govern the microstructural evolution in bulk cannot be expected to also rule the development of the functional films. All these circumstances were presumed when exploring the possibilities of an aqueous solution–gel process plus spin-coating deposition method to reproduce, in thin film dimensions, the excellent multiferroic properties that have been previously observed with an optimized rare-earth and Ti4+-codoped BiFeO3 bulk composition. The experiments indicate high reliability for the tested methodology, allowing for the obtaining of homogeneous dense films at temperatures as low as 600 1C and with a tunable multiferroic response depending on the formulated rare-earth (Sm or Nd). Thorough structural characterization of the films reveals that despite the low temperature processing restrictions, effective microstructural control is achieved at the nanoscale, which is attributed to effective retention (pinning) of the dopants inside the perovskite structure of BiFeO3., his work was supported by the Spanish Ministry of Science, Innovation and Universities (MICINN) under projects MAT2016-80182-R, MAT2017-87134-c2-2-R and partially by the project MAT2016-76851-R. It was also supported by the Research Foundation Flanders (FWO-Vlaanderen), project number G039414N. Dr T. Jardiel acknowledges the European Science Foundation (ESF) and the Ramon y Cajal Program of MICINN for the financial support. Work by Dr Calatayud was also supported by Fundación General CSIC (COMFUTURO Program). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

The switching performance of W/VO2 nanoparticles in thermochromic glass laminates was investigated. W/VO2 powder was prepared, and displayed a phase transition temperature and switching enthalpy of 20.9 degrees C and 37.5 +/- 0.2 J g- 1, respectively. Using wet bead milling, the particle size was reduced from 24 +/- 2 mu m to 120 +/- 10 nm. In the same process, the switching enthalpy decreased to 18.2 +/- 0.6 J g-1 due to partial loss of crystallinity. The kinetics of the structural phase transition were studied using Friedman's differential isoconversional method. This demonstrated that the activation energy |E alpha| was inversely proportional to the square of the difference between the material's temperature and the critical switching temperature T0, pointing out that nucleation kinetics were determining the rate. Furthermore, |E alpha| decreased upon milling, and kinetic asymmetry was induced. The milled nanoparticles were compounded with PVB to produce thermo-chromic films, which were applied for laminating glass plates. The impact of nanoparticle size and concentration on the resulting optical properties of the laminate, viz. solar transmission and solar modulation, was studied in detail. The highest solar modulation obtained was 9.4%. The results obtained in this study are of direct importance for the application in smart windows, showing that (i) the W/VO2 particle size needs to be

Sulfur particles coated by activation of metal alkoxide precursors, aluminum-sulfur (Alu-S) and vanadium-sulfur (Van-S), were produced by dielectric barrier discharge (DBD) plasma technology under low temperature and ambient pressure conditions. We report a safe, solvent-free, low-cost, and low-energy consumption coating process that is compatible for sustainable technology up-scaling. NMR, XPS, SEM, and XRD characterization methods were used to determine the chemical characteristics and the superior behavior of Li-S cells using metal oxide-based coated sulfur materials. The chemical composition of the coatings is a mixture of the different elements present in the metal alkoxide precursor. The presence of alumina Al 2 O 3 within the coating was confirmed. Multi-C rate and long-term galvanostatic cycling at rate C/10 showed that the rate capability losses and capacity fade could be highly mitigated for the Li-S cells containing the coated sulfur materials in comparison to the references uncoated (raw) sulfur. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirm the lower charge-transfer resistance and potential hysteresis in the electrodes containing the coated sulfur particles. Our results show that the electro-chemical performance of the Li-S cells based on the different coating materials can be ranked as Alu-S > VanS > Raw sulfur.

Quasi-spherical undoped ZnO and Al-doped ZnO nanoparticles with different aluminum content, ranging from 0.5 to 5 at% of Al with respect to Zn, were synthesized. These nanoparticles were evaluated as photocatalysts in the photodegradation of the Rhodamine B (RhB) dye aqueous solution under UV-visible light irradiation. The undoped ZnO nanopowder annealed at 400 °C resulted in the highest degradation efficiency of ca. 81% after 4 h under green light irradiation (525 nm), in the presence of 5 mg of catalyst. The samples were characterized using ICP-OES, PXRD, TEM, FT-IR, 27Al-MAS NMR, UV-Vis and steady-state PL. The effect of Al-doping on the phase structure, shape and particle size was also investigated. Additional information arose from the annealed nanomaterials under dynamic N2 at different temperatures (400 and 550 °C). The position of aluminum in the ZnO lattice was identified by means of 27Al-MAS NMR. FT-IR gave further information about the type of tetrahedral sites occupied by aluminum. Photoluminescence showed that the insertion of dopant increases the oxygen vacancies reducing the peroxide-like species responsible for photocatalysis. The annealing temperature helps increase the number of red-emitting centers up to 400 °C, while at 550 °C, the photocatalytic performance drops due to the aggregation tendency. Funding: This research was co-funded by Hasselt University and Namur University through the BOF programme (Project R-9087) and the Fonds spécial de recherche. This work is also supported by the Research Foundation Flanders (FWO) and Hasselt University via the Hercules project AUHL/15/2-GOH3816N. This research used resources of the PC2 and the MORPH-IM platforms located at the University of Namur Acknowledgments: The authors acknowledge C. Charlier for his assistance with TEM and N. Billiet with N. Debusschere for the PXRD measurements.

The preparation of Ru nanoparticles supported on gamma-Al2O3 followed by chemical reduction using RuCl3 as a precursor is demonstrated, and their properties are compared to Ru nanoparticles supported on gamma-Al2O3 prepared by impregnation of gamma-Al2O3 with Ru-3(CO)(12) and subsequent thermal decomposition. The Ru nanoparticles resulting from chemical reduction of RuCl3 are slightly larger (1.2 vs. 0.8 nm). In addition, Ru nanoparticles were deposited on Stober SiO2 using both deposition techniques. These particles were larger than the ones deposited on gamma-Al2O3 (2.5 and 3.4 nm for chemical reduction and thermal decomposition, respectively). Taking into account the size differences between the Ru nanoparticles, all catalysts display similar activity (0.14-0.63 mol center dot g(Ru)(-1)center dot h(-1)) and selectivity (>= 99%) in the sunlight-powered Sabatier reaction. Ergo, the use of toxic and volatile Ru-3(CO)(12) can be avoided, since catalysts prepared by chemical reduction of RuCl3 display similar catalytic performance. This research was funded by the European Commission (H2020 project SPOTLIGHT, grant no. 722788).

This study reports the low temperature and low pressure conversion (up to 160 degrees C, p = 3.5 bar) of CO2 and H-2 to CO using plasmonic Au/TiO2 nanocatalysts and mildly concentrated artificial sunlight as the sole energy source (up to 13.9 kW center dot m(-2) = 13.9 suns). To distinguish between photothermal and non-thermal contributors, we investigated the impact of the Au nanoparticle size and light intensity on the activity and selectivity of the catalyst. A comparative study between P25 TiO2-supported Au nanocatalysts of a size of 6 nm and 16 nm displayed a 15 times higher activity for the smaller particles, which can only partially be attributed to the higher Au surface area. Other factors that may play a role are e.g., the electronic contact between Au and TiO2 and the ratio between plasmonic absorption and scattering. Both catalysts displayed >= 84% selectivity for CO (side product is CH4). Furthermore, we demonstrated that the catalytic activity of Au/TiO2 increases exponentially with increasing light intensity, which indicated the presence of a photothermal contributor. In dark, however, both Au/TiO2 catalysts solely produced CH4 at the same catalyst bed temperature (160 degrees C). We propose that the difference in selectivity is caused by the promotion of CO desorption through charge transfer of plasmon generated charges (as a non-thermal contributor). We acknowledge financial support from the Flanders Innovation & Entrepeneurship (Vlaio) network through the Moonshot project D2M. We thank Jan D’Haen from Hasselt University for SEM-EDX measurement.

The thermodynamics and kinetics of the structural phase transition from monoclinic VO2 (M) to rutile VO2 (R) and vice versa were studied for particulate materials obtained by bead milling of VO2 (M) powder. Using wet bead milling, we decreased the particle size of VO2 (M) powder from similar to 1 mu m to 129 nm. With progressive milling, the switching enthalpy decreased from 47 J g(-1) to 29 J g(-1) due to a loss of crystallinity. The switching kinetics were studied using Friedman's differential isoconversional method. The activation energy vertical bar E-alpha vertical bar decreases with increasing difference between the actual temperature of the material and its switching temperature (T-0). Furthermore, vertical bar E-alpha vertical bar decreases with progressive milling, and kinetic asymmetry is induced. For milled particulate materials, vertical bar E-alpha vertical bar is lower for the switch from VO2 (R) to VO2 (M) than for the opposite switch. For hydrothermally synthesized nanoparticles, vertical bar E-alpha vertical bar is in the same order of magnitude, albeit with inverse switching asymmetry. Latter may result from different defects that are introduced during both preparation techniques. Applying layers of milled particulate material to glass sheets yielded thermochromic coatings with luminous transmission of 40.7% and solar modulation of 8.3%. This demonstrates that milled VO2 particles have potential for use in energy efficient thermochromic windows. The authors thank NWO-SIA (RAAK-PRO project Window of the Future) for their financial support. The authors acknowledge financial support from the European Fund for Regional Development through the cross-border collaborative Interreg V program Flanders-The Netherlands (project SUNOVATE), co-financed by the Belgian province of Limburg and the Dutch provinces of Limburg and Noord-Brabant. Furthermore, the authors gratefully acknowledge Dr. Marcel Verheijen (Eindhoven University of Technology and Eurofins Materials Science) for the TEM analyses, Dr. Martijn Brouwer and Dr. Man Xu (both TNO) for the optical profilometry measurements and Dr. Marta Jezierska-Switala (TNO) for the XRD analyses.

Electrochemical energy storage plays a vital role in combating global climate change. Nowadays lithium-ion battery technology remains the most prominent technology for rechargeable batteries. A key performance-limiting factor of lithium-ion batteries is the active material of the positive electrode (cathode). Lithium- and manganese-rich nickel manganese cobalt oxide (LMR-NMC) cathode materials for Li-ion batteries are extensively investigated due to their high specific discharge capacities (>280 mAh/g). However, these materials are prone to severe capacity and voltage fade, which deteriorates the electrochemical performance. Capacity and voltage fade are strongly correlated with the particle morphology and nano- and microstructure of LMR-NMCs. By selecting an adequate synthesis strategy, the particle morphology and structure can be controlled, as such steering the electrochemical properties. In this manuscript we comparatively assessed the morphology and nanostructure of LMR-NMC (Li1.2Ni0.13Mn0.54Co0.13O2) prepared via an environmentally friendly aqueous solution-gel and co-precipitation route, respectively. The solution-gel (SG) synthesized material shows a Ni-enriched spinel-type surface layer at the {200} facets, which, based on our post-mortem high-angle annual dark-field scanning transmission electron microscopy and selected-area electron diffraction analysis, could partly explain the retarded voltage fade compared to the co-precipitation (CP) synthesized material. In addition, deviations in voltage fade and capacity fade (the latter being larger for the SG material) could also be correlated with the different particle morphology obtained for both materials.

Ni-rich layered lithium transition metal oxides (LiNi x Mn y Co z O 2) have gained significant attention as high-capacity positive electrode materials for lithium-ion batteries. However, their poor cyclability, capacity retention, and rate capability at higher working potentials limit their applications in commercial batteries. Here, we demonstrate a cost-effective chemical solution deposition route of a thin TiO x shell on LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC-622) particles and the effect of surface modification on the electrochemical properties. The crystallinity and morphology of the NMC-622 particles are unaffected by the deposition step and verified by powder X-ray diffraction and electron microscopy. High-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) analysis showed that the TiO x surface layer is amorphous and prone to enhance the electronic conductivity of the cathode material. The TiO x-coated material has an improved rate performance and experiences a lower charge-transfer resistance compared to the pristine material. The effect of the surface modification on the electrochemical performance of NMC-622 was investigated further by the assembly of NMC-622/Li 4 Ti 5 O 12 (LTO) full cells. The beneficial impact of the TiO x coating on the electrochemical performance of NMC-622 positive electrodes in lithium-ion battery applications was showcased by the higher initial Coulombic efficiency and lower aging rates during 150 cycles at 1C in NMC-622/LTO cells.

Sodium-ion batteries are alternatives for lithium-ion batteries in applications where cost-effectiveness is of primary concern, such as stationary energy storage. The stability of sodium-ion batteries is limited by the current generation of electrolytes, particularly at higher temperatures. Therefore, the search for an electrolyte which is stable at these temperatures is of utmost importance. Here, such electrolytes are introduced in the form of nonflammable deep eutectic solvents (DESs), consisting of sodium bis(trifluoromethane)sulfonimide (NaTFSI) dissolved in N-methyl acetamide (NMA). Increasing the NaTFSI concentration replaces NMA-NMA hydrogen bonds with strong ionic interactions between NMA, Na+, and TFSI-. These interactions lower NMA's highest occupied molecular orbital (HOMO) energy level compared with that of TFSI-, leading to an increased anodic stability (up to approximate to 4.65V versus Na+/Na). (Na3V2(PO4)(2)F-3/carbon nanotube [CNT])/(Na2+xTi4O9/C) full cells show 97.0% capacity retention after 250 cycles at 0.2C and 55 degrees C. This is considerably higher than for (Na3V2(PO4)(2)F-3/CNT)/(Na2+xTi4O9/C) full cells containing a conventional electrolyte. According to the electrochemical impedance analysis, the improved electrochemical stability is linked to the formation of more robust surface films at the electrode/electrolyte interface. The improved durability and safety highlight that DESs can be viable electrolyte alternatives for sodium-ion batteries. The authors acknowledge the Research Foundation Flanders (FWO Vlaanderen) for financial support under the project number G053519N. This work was further supported by Hasselt University and FWO Vlaanderen via the Hercules project AUHL/15/2-GOH3816N. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by FWO Vlaanderen and the Flemish Government, Department EWI. The graphical abstract is adapted from the solar panel by Nawicon from the Noun Project.

Glass windows allow natural light to enter buildings, but the main disadvantage is that heat from the sun penetrates, increasing the inner temperature. Therefore, the aim of a smart window is to diminish the solar heat gain dynamically throughout the day without an external control system. Vanadium dioxide (VO2) is a thermochromic material with a transition temperature (Tc) which allows perspective for implementation into coatings. • When T of the coating < Tc → near IR light allowed through, therefore heating up the building on the inside. • When T of the coating > Tc → blocking of IR light. VO2-based coatings display a low transmission in the visible (~40 %), which is too low for application on architectural glazing. Furthermore, dopants are required to lower the transition temperature from 68 °C to 20-30 °C. However, dopants reduce the switching temperature and solar modulation behaviour. The objective is to a develop nano-porous thermochromic VO2-coating, with a switching temperature between 20-30 °C, and increased transmission in the visible. A liquid citrato-oxalato-VO2+ solution is dried using a freeze dryer, this solid complex is annealed under nitrogen in a tube furnace. Many parameters need to be monitored, the main ones are; heating rate, final temperature and isothermal period at final temperature. Annealing allows the formation of the VO2 and removal of organic material. The quality of the produced monoclinic VO2 depends on the parameters, therefore the dependence on each is investigated. High temperatures remove more organic material and improve the quality. Further optimisation is required to form the desired phase of VO2, without oxidising the vanadium to other phases. Additionally, comparison with doped precursor with different metals will be carried out.

Silver nanowire networks have demonstrated significant potential as semi-transparent electrodes for various applications. However, for their widespread utilisation in devices, upscaled coating technologies such as screen-printing need to be explored and related to this, the formulation of suitable inks is indispensable. This work contributes to this effort by the synthesis of Ag-NW based formulations. The rheological characteristics that are essential for screen-printing are obtained by the addition of hydrophobically modified cellulose. The electrical and optical characteristics of screen-printed features on PET are compared by a Van der Pauw method and UV–vis spectroscopy. Despite the presence of the cellulose additive, the screen-printed electrodes exhibit a transmittance from 92.8% to 57.3% and a sheet resistance down to 27 Ohm sq−1. Based on the percolation theory in composites, a mathematical expression is presented, which allows the in-depth analysis of the resulting opto-electrical properties. The application potential of the nanowire-containing formulations is finally demonstrated by screen-printing functional, flexible electroluminescent devices. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 641864.

Hexagonal boron nitride (hBN) nanowalls were deposited by unbalanced radio frequency sputtering on (100)-oriented silicon, nanocrystalline diamond films, and amorphous silicon nitride (Si3N4) membranes. The hBN nanowall structures were found to grow vertically with respect to the surface of all of the substrates. To provide further insight into the nucleation phase and possible lattice distortion of the deposited films, the structural properties of the different interfaces were characterized by transmission electron microscopy. For Si and Si3N4 substrates, turbostratic and amorphous BN phases form a clear transition zone between the substrate and the actual hBN phase of the bulk nanowalls. However, surprisingly, the presence of these phases was suppressed at the interface with a nanocrystalline diamond film, leading to a direct coupling of hBN with the diamond surface, independent of the vertical orientation of the diamond grain. To explain these observations, a growth mechanism is proposed in which the hydrogen terminated surface of the nanocrystalline diamond film leads to a rapid formation of the hBN phase during the initial stages of growth, contrary to the case of Si and Si3N4 substrates. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. The Hercules Foundation Flanders is acknowledged for financial support of the Raman equipment.

The crucial requirement for diamond growth at low temperatures, enabling a wide range of new applications, is a high plasma density at a low gas pressure, which leads to a low thermal load onto sensitive substrate materials. While these conditions are not within reach for resonance cavity plasma systems, linear antenna microwave delivery systems allow the deposition of high quality diamond films at temperatures around 400 degrees C and at pressures below 1 mbar. In this work the codeposition of high quality plates and octahedral diamond grains in nanocrystalline films is reported. In contrast to previous reports claiming the need for high temperatures (T >= 850 degrees C), low temperatures (320 degrees C

Field electron emission (FEE) properties of vertically aligned hexagonal boron nitride nanowalls (hBNNWs) grown on Si have been markedly enhanced through the use of nitrogen doped nanocrystalline diamond (nNCD) films as an interlayer. The FEE properties of hBNNWs-nNCD heterostructures show a low turn-on field of 15.2 V/mu m, a high FEE current density of 1.48 mA/cm(2) and life-time up to a period of 248 min. These values are far superior to those for hBNNWs grown on Si substrates without the nNCD interlayer, which have a turn-on field of 46.6 V/mu m with 0.21 mA/cm(2) FEE current density and life-time of 27 min. Cross-sectional TEM investigation reveals that the utilization of the diamond interlayer circumvented the formation of amorphous boron nitride prior to the growth of hexagonal boron nitride. Moreover, incorporation of carbon in hBNNWs improves the conductivity of hBNNWs. Such a unique combination of materials results in efficient electron transport crossing nNCD-to-hBNNWs interface and inside the hBNNWs that results in enhanced field emission of electrons. The prospective application of these materials is manifested by plasma illumination measurements with lower threshold voltage (370 V) and longer life-time, authorizing the role of hBNNWs-nNCD heterostructures in the enhancement of electron emission. The authors like to thank the financial support of the Research Foundation Flanders (FWO) via Research Project G.0456.12, G0044.13N and the Methusalem "NANO" network. Kamatchi Jothiramalingam Sankaran, Stuart Turner, and Paulius Pobedinskas are Postdoctoral Fellows of the Research Foundations Flanders (FWO).

Due to a dominant one-dimensional growth rate, nanoparticles of zinc oxide often show a rodlike morphology. As a result, the synthesis of small spherical nanoparticles of undoped ZnO remains challenging. This paper presents two procedures that successfully produce a powder consisting of equiaxed zinc oxide nanoparticles: one using a polyethylene glycol- (PEG-) assisted solvothermal method and the other by calcination of zinc oxalate obtained from a microemulsion-mediated method. In the latter, zinc-substituted aerosol OT (AOT) is used as a surfactant. The samples are characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transforminfrared spectroscopy (FTIR), transmission electron microscopy (TEM), photon correlation spectroscopy (PCS), and photoluminescence (PL) spectroscopy. Both synthesis techniques produce nanoparticles with similar sizes in the range of 10 to 20 nm. Dense aggregates observed in the calcined powder are infrequent in the case of the solvothermal method. M. K. Van Bael and A. Hardy are postdoctoral fellows of the Fund for Scientific Research of Flanders (FWO Vlaanderen).