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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.