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Abstract In this work, a new type of multifunctional materials (MFMs) called self‐regenerative Ni‐doped CaTiO₃/CaO is introduced for the integrated CO₂capture and dry reforming of methane (ICCDRM). These materials consist of a catalytically active Ni‐doped CaTiO₃and a CO₂sorbent, CaO. The article proposes a concept where the Ni catalyst can be regenerated in situ, which is crucial for ICCDRM. Exsolved Ni nanoparticles are evenly distributed on the surface of CaTiO₃under H₂or CH₄, and are re‐dispersed back into the CaTiO₃lattice under CO₂. The Ni‐doped CaTiO₃/CaO MFMs show stable CO₂capture capacity and syngas productivity for 30 cycles of ICCDRM. The presence of CaTiO₃between CaO grains prevents CaO/CaCO₃thermal sintering during carbonation and decarbonation. Moreover, the strong interaction of CaTiO₃with exsolved Ni mitigates severe accumulation of coke deposition. This concept can be useful for developing MFMs with improved properties that can advance integrated carbon capture and conversion. 

Compositionally complex oxides (CCOs) are an emerging class of materials encompassing high entropy and entropy stabilized oxides. These promising advanced materials leverage tunable chemical bond structure, lattice distortion, and chemical disorder for unprecedented properties. Grain boundary (GB) and point defect segregation to GBs are relatively understudied in CCOs even though they can govern macroscopic material properties. For example, GB segregation can govern local chemical (dis)order and point defect distribution, playing a critical role in electrochemical reaction kinetics, and charge and mass transport in solid electrolytes. However, compared with conventional oxides, GBs in multi-cation CCO systems are expected to exhibit more complex segregation phenomena and, thus, prove more difficult to tune through GB design strategies. Here, GB segregation was studied in a model perovskite CCO LaFe0.7Ni0.1Co0.1Cu0.05Pd0.05O3−x textured thin film by (sub-)atomic-resolution scanning transmission electron microscopy imaging and spectroscopy. It is found that GB segregation is correlated with cation reducibility—predicted by an Ellingham diagram—as Pd and Cu segregate to GBs rich in oxygen vacancies (VO··). Furthermore, Pd and Cu segregation is highly sensitive to the concentration and spatial distribution of VO·· along the GB plane, as well as fluctuations in atomic structure and elastic strain induced by GB local disorder, such as dislocations. This work offers a perspective of controlling segregation concentration of CCO cations to GBs by tuning reducibility of CCO cations and oxygen deficiency, which is expected to guide GB design in CCOs. 

Semiconductor surfaces provide efficient pathways for injecting native point defects into the underlying bulk. In the case of interstitial atoms in rutile, the TiO 2 (110) surface exemplifies this behavior, although extended defects in the bulk such as platelets and crystallographic shear planes act as net sources or sinks depending upon specific conditions. The present work constructs a quantitative microkinetic model to describe diffusion and based upon isotopic gas–solid exchange experiments. Key activation barriers for are 0.55 eV for surface injection, 0.50 eV for site-to-site hopping diffusion, and 3.3 eV for dissociation of titanium interstitials from extended defects.