PDF Publication Title:
Text from PDF Page: 081
4.4. XPSMODELEDUSINGDFT 69 It is reasonable to assume that an improved description of the Ru and Ti cations is required to describe the energetics correctly. Both Ti and Ru are d elements, and the effect of the spatial distribution of the d orbitals is key to describe both structure and energetics of their oxides. We therefore attempted to add the AOM to the force field. The first attempt was based on standard deterministic fitting. However, the best FF that could be found in this way only managed to minimize the energy differences between the three systems. Therefore, several attempts to optimize the parameters for the AOM using a GA were performed. In the GA, an array of the FF parameters was used as the chromosome, and the fitness of each chromosome was evaluated by relaxing the structures of the three mixed ox- ide systems, and comparing volumes with the volumes obtained using DFT, and the relative energies between the three systems with the corresponding relative DFT energies. Initial testing of the GA indicated that it was able to find Bucking- ham potentials of comparable quality to those obtained using deterministic fitting. However, when using the GA to fit also the AOM parameters, to attempt to find a FF that could describe both structural parameters and energetics, we found no set of parameters that recovered the correct energetic orderings. Again, the best solution found was a set of parameters that minimized the energy differences be- tween the three systems. Although we failed to find a FF that could describe the energies and structures of RuO2-TiO2 mixed oxides, the new FF (that is the com- bination of the new Ti-O parameters and the Battle et al. [233] Ru-O parameters) is at least able to describe the structure of such oxides more accurately than previ- ous Buckingham-based force fields. The results also indicate that something more than the AOM model is needed to describe the energetics correctly. It is possible that it is necessary to depart from a constant charge description of the cations to achieve this goal, as impressive results for the description of pure rutile TiO2 have been obtained with charge-equilibration models[238]. 4.4 Understanding X-ray photoelectron spectroscopy using density functional theory The HER has been studied on two materials, MoS2 and RuO2, based on com- parisons between experimental and calculated XPS chemical shifts. In the first study[20], we used this method to further the understanding of the mechanism of HER on MoS2, a material that has been devoted study as it is active for HER even though Mo is not a noble metal[48, 49]. In the second study, we calculated XPS binding energies for RuO2 and for a variety of hydrogenated RuO2 structures and Ru oxides and hydroxides to reconsider conclusions drawn in previous work[51] regarding structural changes in RuO2 during HER.PDF Image | Studies of Electrode Processes in Industrial Electrosynthesis
PDF Search Title:
Studies of Electrode Processes in Industrial ElectrosynthesisOriginal File Name Searched:
electrosynthesis.pdfDIY PDF Search: Google It | Yahoo | Bing
Salgenx Redox Flow Battery Technology: Power up your energy storage game with Salgenx Salt Water Battery. With its advanced technology, the flow battery provides reliable, scalable, and sustainable energy storage for utility-scale projects. Upgrade to a Salgenx flow battery today and take control of your energy future.
| CONTACT TEL: 608-238-6001 Email: greg@salgenx.com | RSS | AMP |