Abstract
Despite the enormous success and popularity of density-functional theory, systematic verification and validation studies are still limited in number and scope. Here, we propose a protocol to ...test publicly available pseudopotential libraries, based on several independent criteria including verification against all-electron equations of state and plane-wave convergence tests for phonon frequencies, band structure, cohesive energy and pressure. Adopting these criteria we obtain curated pseudopotential libraries (named SSSP or standard solid-state pseudopotential libraries), that we target for high-throughput materials screening (“SSSP efficiency”) and high-precision materials modelling (“SSSP precision”). This latter scores highest among open-source pseudopotential libraries available in the Δ-factor test of equations of states of elemental solids.
Perovskite oxides have been at the forefront among catalysts for the oxygen evolution reaction (OER) in alkaline media offering a higher degree of freedom in cation arrangement. Several highly OER ...active Co-based perovskites have been known to show extraordinary activities and stabilities when the B-site is partially occupied by Fe. At the current stage, the role of Fe in enhancing the OER activity and stability is still unclear. In order to elucidate the roles of Co and Fe in the OER mechanism of cubic perovskites, two prospective perovskite oxides, La0.2Sr0.8Co1–x Fe x O3−δ and Ba0.5Sr0.5Co1–x Fe x O3−δ with x = 0 and 0.2, were prepared by flame spray synthesis as nanoparticles. This study highlights the importance of Fe in order to achieve high OER activity and stability by drawing relations between their physicochemical and electrochemical properties. Ex situ and operando X-ray absorption spectroscopy (XAS) was used to study the local electronic and geometric structure under oxygen evolving conditions. In parallel, density function theory computational studies were conducted to provide theoretical insights into our findings. Our findings show that the incorporation of Fe into Co-based perovskite oxides alters intrinsic properties rendering efficient OER activity and prolonged stability.
The development of new batteries has historically been achieved through discovery and development cycles based on the intuition of the researcher, followed by experimental trial and error—often ...helped along by serendipitous breakthroughs. Meanwhile, it is evident that new strategies are needed to master the ever‐growing complexity in the development of battery systems, and to fast‐track the transfer of findings from the laboratory into commercially viable products. This review gives an overview over the future needs and the current state‐of‐the art of five research pillars of the European Large‐Scale Research Initiative BATTERY 2030+, namely 1) Battery Interface Genome in combination with a Materials Acceleration Platform (BIG‐MAP), progress toward the development of 2) self‐healing battery materials, and methods for operando, 3) sensing to monitor battery health. These subjects are complemented by an overview over current and up‐coming strategies to optimize 4) manufacturability of batteries and efforts toward development of a circular battery economy through implementation of 5) recyclability aspects in the design of the battery.
This review gives an overview over the current state‐of‐the‐art and the future needs and in battery research with special emphasis on the five research pillars of the European Large‐Scale Research Initiative BATTERY 2030+, namely 1) BIG‐MAP, 2) self‐healing battery materials, 3) sensing to monitor battery health, and 4) manufacturability and 5) recyclability of batteries.
Oxynitride perovskites such as BaTaO2N are among the most promising materials to achieve efficient direct solar-to-chemical conversion. Albeit photoelectrochemical water splitting has been ...demonstrated, the required overpotentials remain prohibitively large compared with the theoretically accessible values, particularly for the oxygen evolution reaction (OER). Here, we apply density functional theory (DFT) calculations to investigate the use of strain and cationic doping with Ca and Sr to optimize the OER theoretical overpotential. For the TaON-terminated BaTaO2N (001) surface, 4% compressive uniaxial strain can lower the theoretical overpotential to η = 0.59 V, under operational conditions. For the most stable TaO2N-(100) termination, 1% tensile uniaxial strain, which is perfectly accessible by experiments, is enough to reduce the theoretical overpotential from η = 0.43 V to η = 0.37 V under (photo)electrochemical conditions. This value is close to the minimum predicted theoretical overpotential and points out how strain engineering could be efficiently used to improve the electrocatalytic reactions.
The widespread popularity of density functional theory has given rise to an extensive range of dedicated codes for predicting molecular and crystalline properties. However, each code implements the ...formalism in a different way, raising questions about the reproducibility of such predictions. We report the results of a community-wide effort that compared 15 solid-state codes, using 40 different potentials or basis set types, to assess the quality of the Perdew-Burke-Ernzerhof equations of state for 71 elemental crystals. We conclude that predictions from recent codes and pseudopotentials agree very well, with pairwise differences that are comparable to those between different high-precision experiments. Older methods, however, have less precise agreement. Our benchmark provides a framework for users and developers to document the precision of new applications and methodological improvements.
Proton exchange membrane water electrolysis (PEMWE) is a promising technology for electricity-to-fuel conversion which allows for direct production of hydrogen from water. One of the key problems ...limiting widespread implementation of PEMWE into energy systems is the sluggish kinetics of the anodic process: the oxygen evolution reaction (OER). Additionally, state-of-the-art OER materials contain large amounts of low abundant noble metals (Ru, Ir), and therefore, development of low-cost, highly active and stable OER catalysts remains an important challenge. We developed a synthetic approach to the iridium pyrochlores–complex oxides of iridium with reduced content of the noble metal as compared to IrO2. The materials were synthesized from molten sodium nitrate (Adams fusion method) at moderate temperatures (500–575 °C) and consist of highly crystalline iridium pyrochlore nanoparticles with surface areas of up to 40 m2 g–1, which is a significant improvement compared to the traditional high temperature solid-state synthesis. Electrochemical measurements in acidic media showed that yttrium and bismuth pyrochlore catalysts possess high OER activity approaching the activity of state-of-the-art IrO2 nanoparticles. High intrinsic activities and stability behavior of yttrium iridium catalysts were correlated with the formation of the highly active IrO x surface layer due to leaching of the Y3+ cations into the electrolyte solution, revealed both experimentally and computationally using density functional theory calculations.
The increasing demand pressures the vegetable oil industry to develop novel refining methods. Degumming with type C phospholipases (PLCs) is a green technology and provides extra oil. However, ...natural PLCs are not active under the harsh conditions used in oil refining plants, requiring additional unit operations. These upfront capital expenditures and the associated operational costs hinder the adoption of this method. Here, we present a process based on ChPLC, a synthetic PLC obtained by consensus sequence design, possessing superior thermal stability and catalytic properties. Using ChPLC, crude soybean oil degumming was completed at 80 °C in 30 min, the temperature and residence time imposed by the design of existing oil refining plants. Remarkably, an extra yield of oil of 2% was obtained using 60% of the dose recommended for PLCs marketed today, saving upfront investments and reducing the operational cost of degumming. A techno-economic analysis indicates that, for medium size plants, ChPLC reduces the overall cost of soybean oil enzymatic degumming by 58%. The process presented here facilitates the implementation of enzymatic technologies to oil producers, regardless of their processing capacity, bringing potential annual benefits in the billion-dollar range for the global economy.
PDF
