Multimetal doping is a promising strategy to achieve high-performance electrocatalysts for the oxygen evolution reaction (OER) due to synergistic effects; however, understanding the dynamic structure evolution and clarifying the catalytic mechanism of each individual doping metal in multimetal-based electrocatalysts remain elusive. Here, we report the synthesis of homogeneous single-metal and bimetal doping sulfides with a pyrite structure for OER catalysts via a high-pressure and high-temperature (HPHT) technique; operando Raman and X-ray absorption spectroscopy (XAS) studies are performed to capture the dynamic evolution during the OER process. Our results find that an Fe- and Ni-codoped CoS2 electrocatalyst exhibits significantly improved OER activity with an overpotential of 242 (295) mV at 10 (100) mA cm–2 and robust stability over 500 h in an alkaline medium. Operando analysis reveals that Fe and Ni incorporations not only expedite the dynamic response of self-reconstructions of the Fe,Ni-CoS2 surface but also accelerate the oxidation of Co and Fe into high-valence oxyhydroxides while suppressing nickel oxidation to form Ni­(OH)2 for optimized activity and robust stability. This finding provides a fundamental understanding of the composition design, dynamic reaction pathways, and controlling principle for highly active multimetal-based OER catalysts.

The search for new materials that can withstand the tough demands of practical hydrogen storage for use in automotive transportation is currently receiving a great deal of attention from the scientific community because of the urgency for replacements of traditional energy resources such as fossil fuels. In this work, transition metal (TM)-decorated boron-doped tetrahedral silsesquioxane frameworks (B-TSFs) for application in hydrogen storage are investigated using first-principles density functional theory calculations. We design this plausible hydrogen storage system based on the knowledge of previous works by other groups including metal atom decoration for quasi-molecular H 2 adsorption, boron substitution into benzene rings to prevent metal clustering, and assembling modified benzene rings and tetrahedral silsesquioxane cages into the framework for this study. Boron substitution substantially enhances the TM binding energy to the linker of B-TSF to suppress metal clustering as well as maintain stable hydrogen adsorption energy to TMs. The average hydrogen adsorption energy energies in Sc-, Ti-, and V-decorated B-TSF are 0.29, 0.40, and 0.69 eV, respectively, with acceptable gravimetric density of 6.9, 5.6, and 4.15 wt %. Gibbs free energy calculations are also carried out to estimate the working temperature and pressure ranges for using B-TSF as a hydrogen storage system.

We study the hydrogen adsorption in porous frameworks composed of silsesquioxane cages linked via boron substituted aromatic structures by first-principles modeling. Such polyhedral oligomeric silsesquioxane (POSS) frameworks can be further modified by decorating them with metal atoms binding to the ring structures of the linkers. We have considered Sc- and Ti-doped frameworks which bind H2 via so-called Kubas interaction between hydrogen molecules and transition metal atoms. It will be demonstrated that the maximum H2 gravimetric capacity can be improved to more than 7.5 wt % by using longer linkers with more ring structures. However, the maximum H2 volumetric capacity can be tuned to more than 70 g/L by varying the size of silsesquioxane cages. We are optimistic that by varying the building blocks, POSS frameworks can be modified to meet the targets for the gravimetric and volumetric capacities set by the U.S. Department of Energy.

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Pressure-induced homogeneous CoMoP2 irregular nanoparticles, whose surface Co atoms form Co(OH)2 shells by reconstruction, and Mo atoms maintain the structural integrity.