Abstract: A new method is developed for synthesizing Ti4O7 supported Ru@Pt core–shell catalyst (Ru@Pt/Ti4O7) through pyrolysis followed by microwave irradiation. The purpose is to improve the Ru durability of PtRu from core–shell structure and strong bonding to Ti4O7 oxide. In this method, the first step is to co-reduce the mixture of ruthenium precursor and TiO2 in a H2 reducing atmosphere under heat-treatment to obtain a Ru core on Ti4O7 support, and the second step is to create a shell of platinum via microwave irradiation. Energy dispersive X-ray spectrometry, X-ray Diffraction, High-resolution Scanning Transmission Electron Microscopy with the high-angle annular dark-field method and Electron Energy-Loss Spectroscopy are used to demonstrate that this catalyst with larger particles has a core–shell structure with a Ru core and a Pt shell. Electrochemical measurements show Ru@Pt/Ti4O7 catalyst has a higher CO-tolerance capability than that of PtRu/C alloy catalyst.

Abstract: Lignocellulosic biomass is the most abundant source of renewable biomass and is seen as a high-potential replacement for petroleum-based resources. The conversion technologies to advanced biofuels are still at a low maturity level, thus allowing for future cost reductions through technological learning. This fact is barely considered in state-of-the-art techno-economic assessments and a structured approach to account for technological learning in techno-economic assessments is needed. In this study, a framework for techno-economic assessments of advanced biofuels, integrating learning curves, is proposed. As a validation of this framework, the economic feasibility of the valorization of corn stover for the production of second-generation bioethanol in Belgium is studied. Process flowsheet simulations in Aspen Plus are developed, with an emphasis on the comparison of four different pretreatment technologies and two plant capacities at 156 dry kt biomass/y and 667 dry kt/y. The dilute acid pretreatment model of the large-scale biorefinery required the lowest minimum learning rate to reach an economically feasible biorefinery by 2030, being 3.9%, almost half as the one calculated for the smaller scale plant. This learning rate seems to be achievable based on learning rates commonly estimated in literature. We conclude that there is a potential for advanced ethanol production in Belgium under the current state of technology for large-scale biorefineries, which require additional biomass imports, when accounting for future cost reductions through learning

Abstract: A series of BiVO4/3DOM TiO2 nanocomposites have been synthesized and their photocatalytic activity was investigated under visible light irradiation using the RhB dye as model pollutant molecule in an aqueous solution. The effect of the amount of BiVO4 as visible light sensitizer on the photocatalytic activity of BiVO4/3DOM TiO2 nanocomposites was highlighted. The heterostructured composite system leads to much higher photocatalytic efficiencies than bare 3DOM TiO2 and BiVO4 nanoparticles. As the proportion of BiVO4 in BiVO4/3DOM TiO2 nanocomposites increases from 0.04 to 0.6, the photocatalytic performance of the BiVO4/3DOM TiO2 nanocomposites increases and then decreases after reaching a maximum at 0.2. This improvement in photocatalytic perfomance is related to 1) the interfacial electron transfer efficiency between the coupled materials, 2) the 3DOM TiO2 inverse opal structure with interconnected pores providing an easy mass transfer of the reactant molecules and high accessibility to the active sites and large surface area and 3) the effect of light sensitizer of BiVO4. Intensive studies on structural, textural, optical and surface properties reveal that the electronic interactions between BiVO4 and TiO2 lead to an improved charge separation of the coupled BiVO4/TiO2 system. The photogenerated charge carrier densities increase with increasing the BiVO4 content, which acts as visible light sensitizer to the TiO2 and is responsible for the enhancement in the rate of photocatalytic degradation. However, the photocatalytic activity is reduced when the BiVO4 amount is much higher than that of 3DOM TiO2. Two reasons could account for this behavior. First, with increasing BiVO4 content, the photogenerated electron/hole pairs are accumulated at the surface of the BiVO4 nanoparticles and the recombination rate increases as shown by the PL results. Second, decreasing the amount of 3DOM TiO2 in the nanocomposite decreases the surface area as shown by the BET results. Moreover, the poor adsorptive properties of the BiVO4 photocatalyst also affect the photocatalytic performance, in particular at higher BiVO4 content. The present work demonstrates that BiVO4/3DOM TiO2 is a very promising heterojunction system for visible light photocatalytic applications.

Abstract: The electrolysis of seawater, a significantly more abundant natural reservoir than freshwater, stands as a promising alternative for sustainable hydrogen production, provided that the competitive chloride electro-oxidation is minimized. Herein, we propose an original material combination to selectively trigger oxygen evolution from seawater at expenses of chlorine generation. The target systems, based on MnO2 or Mn2O3 decorated with Fe2O3 or Co3O4, are fabricated by plasma enhanced-chemical vapor deposition of manganese oxides, functionalization with Fe2O3 and Co3O4 by sputtering, and annealing in air/Ar to obtain Mn(IV)/Mn(III) oxides. Among the various options, MnO2 decorated with Co3O4 yields the best performances in alkaline seawater splitting, with an outstanding Tafel slope of approximate to 40 mV x dec(-1) and an overpotential of 450 mV, enabling to rule out chlorine evolution. These attractive performances, resulting from the synergistic contribution of catalytic and electronic effects, open the door to low-cost hydrogen generation from seawater under real-world conditions, paving the way to eventual large-scale applications.

Abstract: When ceria is used as a support for many redox catalysis involved in green catalysis, it is well-known that the overlying noble metal can gain access to a significant quantity of oxygen atoms with high mobility and fast reduction and oxidation properties under mild conditions. However, it is as yet unclear what the underlying principle and the nature of the ceria surface involved are. By using two tailored morphologies of ceria nanocrystals, namely cubes and rods, it is demonstrated from Scanning Transmission Electron Microscopy with Electron Energy Loss Spectroscopy (STEM-EELS) mapping and Pulse Isotopic Exchange (PIE) that ceria nano-cubes terminated with a polar surface (100) can give access to more than the top most layer of surface oxygen atoms. Also, they give higher oxygen mobility than ceria nanorods with a non-polar facet of (110). A new insight for the possible additional role of polar ceria surface plays in the oxygen mobility is obtained from Density Functional Theory (DFT) calculations which suggest that the (100) surface sites that has more than half-filled O on same plane can drive oxygen atoms to oxidise adsorbate(s) on Pd due to the strong electrostatic repulsion.

Abstract: This study presents new insights on the effect of (sub)micrometer particle sized materials in plasma-based CO2-
CH4 reforming by investigating the performance of SiO2 spheres (with/without supported metal) of varying
particle sizes. (Sub)micron particles synthesized through the St¨ober method were used instead of (sub)millimeter
particles employed in previous studies. Increasing particle size (from 120 nm to 2390 nm) was found to first
increase and then decrease conversion and energy yield, with optimal performance achieved using 740 nm 5 wt%
Ni loaded SiO2, which improved CO2 and CH4 conversion, and energy yield to 44%, 55%, and 0.271 mmol/kJ,
respectively, compared to 20%, 27%, and 0.116 mmol/kJ in an empty reactor at the same flow rate. This is the
first to achieve significant performance improvement in a fully packed reactor, highlighting the importance of
selecting a suitable particle size. The findings can offer guidance towards rational design of catalysts for plasmabased
reactions.

Abstract: In this work, the effects of N-doping into the Co-doped single vacancy (Co-SV-G) and di-vacancy graphene flake (Co-dV-G) are investigated and compared toward direct oxidation of methane to methanol (DOMM) employing two different oxidants (N2O and O-2) using density functional theory (DFT) calculation. We found that DOMM on CoN3-G utilizing the N2O molecule as oxygen-donor proceeds via a two-step reaction with low activation energies. In addition, we found that although CoN3-G might be a good catalyst for methane conversion, it can also catalyze the oxidation of methanol to CO2 and H2O due to the required low activation barriers. Moreover, the adsorption behaviors of CHx (x = 0-4) species and dehydrogenation of CHx (x = 1-4) species on CoN3-G are investigated. We concluded that CoN3-G can be used as an efficient catalyst for DOMM and N-2O reduction at ambient conditions which may serve as a guide for fabricating effective C/N catalysts in energy-related devices.

Abstract: Combined TiO2/SiO2 mesoporous materials were prepared by deposition of TiO2 nanoparticles synthesised via the acid-catalysed solgel method. In the first synthesis step a titania solution is prepared, by dissolving titaniumtetraisopropoxide in nitric acid. The influences of the initial titaniumtetraisopropoxide concentration and the temperature of dissolving on the final structural properties were investigated. In the second step of the synthesis, the titania nanoparticles were deposited on a silica support. Here, the influence of the temperature during deposition was studied. The depositions were carried out on two different mesoporous silica supports, SBA-15 and MCF, leading to substantial differences in the catalytic and structural properties. The samples were analysed with N2-sorption, X-ray diffraction (XRD), electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) to obtain structural information, determining the amount of titania, the crystal phase and the location of the titania particles on the mesoporous material (inside or outside the mesoporous channels). The structural differences of the support strongly determine the location of the nanoparticles and the subsequent photocatalytic activity towards the degradation of rhodamine 6G in aqueous solution under UV irradiation.

Abstract: Methane reforming by plasma catalysis is a complex process that is far from understood. It requires a multidisciplinary approach which ideally takes into account all effects from the plasma on the catalyst, and vice versa. In this contribution, we focus on the interactions of CHx (x = {1,2,3}) radicals that are created in the plasma with several nickel catalyst surfaces. To this end, we perform reactive molecular dynamics simulations, based on the ReaxFF potential, in a wide temperature range of 4001600 K. First, we focus on the H2 formation as a function of temperature and surface structure. We observe that substantial H2 formation is obtained at 1400 K and above, while the role of the surface structure seems limited. Indeed, in the initial stage, the type of nickel surface influences the CH bond breaking efficiency of adsorbed radicals; however, the continuous carbon diffusion into the surface gradually diminishes the surface crystallinity and therefore reduces the effect of surface structure on the H2 formation probability. Furthermore, we have also investigated to what extent the species adsorbed on the catalyst surface can participate in surface reactions more in general, for the various surface structures and as a function of temperature. These results are part of the ongoing research on the methane reforming by plasma catalysis, a highly interesting yet complex alternative to conventional reforming processes.

Abstract: A new, two-step nanocasting method was developed to prepare N-doped ordered mesoporous carbon (NOMC) electrocatalysts for the reduction of O2 to H2O2. Our strategy involves the sequential pyrolysis of two inexpensive and readily available N and C precursors, i.e. aniline and dihydroxynaphthalene (DHN), inside the pores of a SBA-15 hard silica template to obtain N-doped graphitic carbon materials with well-ordered pores and high surface areas (764 and 877 m2g−1). By tuning the ratio of carbon sources to silica template, it was possible to achieve an optimal filling of the pores of the SBA-15 silica and to minimise carbon species outside the pores. These NOMC materials displayed outstanding electrocatalytic activity in the oxygen reduction reaction, achieving a remarkably enhanced kinetic current density compared to state-of-the-art N-doped carbon materials (−16.7 mA cm−2 at −0.35 V vs. Ag/AgCl in a 0.1 M KOH solution as electrolyte). The NOMC electrocatalysts showed high selectivity toward the two-electron reduction of oxygen to hydrogen peroxide and excellent long-term stability.

Abstract: Adaptation of the photoresponse of anatase TiO2 to match the solar spectrum is an important scientific challenge. Modification of TiO2 with noble metal nanoparticles displaying surface plasmon resonance effects is one of the promising approaches. Surface plasmon resonance typically depends on chemical composition, size, shape and spatial organization of the metal nanoparticles in contact with TiO2. AuxAg(1 − x) alloy nanoparticles display strong composition-dependent surface plasmon resonance in the visible light region of the spectrum. In this work, a general strategy is presented to prepare plasmonic TiO2-based photocatalysts with a visible light response that can be accurately tuned over a broad range of the spectrum. The application as self-cleaning material toward the degradation of stearic acid is demonstrated for a plasmonic TiO2 photocatalyst displaying visible light photoactivity at the intensity maximum of solar light around 490 nm.

Abstract: We propose the concept of a ‘rainbow’ photocatalyst that consists of TiO2 modified with gold-silver alloy nanoparticles of various sizes and compositions, resulting in a broad plasmon absorption band that covers the entire UV–vis range of the solar spectrum. It is demonstrated that this plasmonic ‘rainbow’ photocatalyst is 16% more effective than TiO2 P25 under both simulated and real solar light for pollutant degradation at the solid-gas interface. With this we provide a promising strategy to maximize the spectral response for solar to chemical energy conversion.