In this work, a series of VO x -loaded In2O3 catalysts were prepared, and their catalytic performance was evaluated for CO2-assisted oxidative dehydrogenation of propane (CO2-ODHP) and compared with In2O3 alone. The optimal composition is obtained on 3.4V/In2O3 (surface V density of 3.4V nm–2), which exhibited not only a higher C3H6 selectivity than other V/In catalysts and In2O3 under isoconversion conditions but also an improved reaction stability. To elucidate the catalyst structure–activity relationship, the VO x /In2O3 catalysts were characterized by chemisorption [NH3-temperature-programmed desorption (TPD), NH3-diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), CO2-TPD, and CO2-DRIFTS], H2-temperature-programmed reduction (TPR), in situ Raman spectroscopy, UV–vis diffuse reflectance spectroscopy, near-ambient pressure X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and further examined using density functional theory. The In–O–V structure and the extent of oligomerization, which play a crucial role in improving selectivity and stability, were identified in the VO x /In2O3 catalysts. In particular, the presence of surface VO x (i) inhibits the deep reduction of In2O3, thereby preserving the activity, (ii) neutralizes the excess basicity on In2O3, thus suppressing propane dry reforming and achieving a higher propylene selectivity, and (iii) introduces additional redox sites that participate in the dehydrogenation reaction by utilizing CO2 as a soft oxidant. The present work provides insights into developing selective, stable, and robust metal-oxide catalysts for CO2-ODHP by controlling the conversion of reagents via desired pathways through the interplay between acid–base interactions and redox properties.

The configurational complexity and distinct local atomic environments of high entropy oxides remain largely unexplored, leaving structure‐property relationships and the hypothesis that the family offers rich tunability for applications ambiguous. This work investigates the influence of cation size and materials synthesis in determining the resulting structure and magnetic properties of a family of high entropy rare‐earth zirconates (HEREZs, nominal composition RE2Zr2O7 with RE = rare‐earth element combinations including Eu, Gd, Tb, Dy, Ho, La, or Sc). The structural characterization of the series is examined through synchrotron X‐ray diffraction and pair distribution function analysis, and electron microscopy, demonstrating average defect‐fluorite structures with considerable local disorder, in all samples. The surface morphology and particle sizes are found to vary significantly with preparation method, with irregular micron‐sized particles formed by high temperature sintering routes, spherical nanoparticles resulting from chemical co‐precipitation methods, and porous nanoparticle agglomerates resulting from polymer steric entrapment synthesis. In agreement with the disordered cation distribution found across all samples, magnetic measurements indicate that all synthesized HEREZs show frustrated magnetic behavior, as seen in a number of single‐component RE2Zr2O7 pyrochlore oxides. These findings advance the understanding of the local structure of high entropy oxides and demonstrate strategies for designing nanostructured morphologies in the class.

The oxygen vacancy structure of ceria plays a key role in its performance as a favored material for catalysis applications. Here, we develop an understanding of the effects of Pt loading on the structural evolution of ceria nanorods under redox gas environments that mimic real automotive catalytic converters. In situ neutron scattering studies under redox flow reveal that both CeO2 and Pt–CeO2 nanorods share a bulk fluorite structure with the presence of surface Frenkel-type oxygen defects. However, Pt–CeO2 nanorods are more easily reducible than CeO2 rods as evidenced by an increased concentration of Ce3+, determined by NAP-XPS. Importantly, this work finds no evidence of oxygen vacancy ordered surface reconstruction which has been reported in earlier ex situ investigations. Thus, this work highlights the discrepancy between ex situ and in situ structural observations and emphasizes the need for robust in situ investigations of catalysts to develop industrially relevant materials.

Integration of renewable feedstocks into the current energy infrastructure will require the development of catalysts and sorbents that can maintain high surface area and catalytic activity under challenging thermal/hydrothermal environments and acid gas (SOx, NOx and H2S) exposure. The design of new stable and acid-gas-resistant catalysts requires a deep understanding of sintering and acid gas interaction with active sites. Addressing these challenges will require advanced operando characterization of materials to effectively guide materials discovery. Studying the time-resolved structural evolution of materials under gas flow conditions is key to understanding catalytic performance under real-world operating conditions with the end goal of extracting design strategies for industrially relevant catalysts. Total scattering, including both Bragg and diffuse scattering signals, enables the study of structural evolution in catalysts and can provide key insights into how long-range, nanoscale, and local atomic structure motifs differ and deliver unique properties. Synchrotron X-ray scattering provides active metal site sensitivity and unprecedented temporal resolution, while neutron scattering offers light atom sensitivity and superior penetration of sample environments. We present in-situ studies following multiple length scales of interest in two very different catalytic material systems with these probes: (1) the oxidation and reduction behaviors of ceria nanorods at elevated temperatures, specifically following the nature of oxygen vacancies; and (2) sinter resistance, degradation, and regeneration behavior of novel high-entropy fluorite catalyst supports under acid gas exposure. Further, we will discuss the design and development of the hazardous gas handling system (HGHS) system under construction at the Nanoscale Ordered Materials Diffractometer (NOMAD) at the Spallation Neutron Source at Oak Ridge National Lab. The HGHS will deliver in-situ exposure to industrially-relevant acid gas at NOMAD, enabling investigations of acid gas interactions with sorbents and catalysts, which will be a unique capability among neutron sources in the world and will aid in the design of new materials and processes with higher energy efficiency and a smaller emissions footprint.