The correlation between lattice oxygen (O) binding energy and O oxidation activity imposes a fundamental limit in developing oxide catalysts, simultaneously meeting the stringent thermal stability and catalytic activity standards for complete oxidation reactions under harsh conditions. Typically, strong O binding indicates a stable surface structure, but low O oxidation activity, and vice versa. Using nitric oxide (NO) catalytic oxidation as a model reaction, we demonstrate that this conflicting correlation can be avoided by cooperative lattice oxygen redox on SmMn 2 O 5 mullite oxides, leading to stable and active oxide surface structures. The strongly bound neighboring lattice oxygen pair cooperates in NO oxidation to form bridging nitrate (NO 3 − ) intermediates, which can facilely transform into monodentate NO 3 − by a concerted rotation with simultaneous O 2 adsorption onto the resulting oxygen vacancy. Subsequently, monodentate NO 3 − species decompose to NO 2 to restore one of the lattice oxygen atoms that act as a reversible redox center, and the vacancy can easily activate O 2 to replenish the consumed one. This discovery not only provides insights into the cooperative reaction mechanism but also aids the design of oxidation catalysts with the strong O binding region, offering strong activation of O 2 , high O activity, and high thermal stability in harsh conditions.

Degradation in CH 3 NH 3 PbI 3 (MAPbI 3 ), when in contact with commonly used metal oxide transport layer materials in optoelectronic devices, is examined experimentally and theoretically. On the basis of the decomposition temperature, the interfacial stability decreases in the following order: MAPbI 3 + TiO 2 ∼ MAPbI 3 alone > MAPbI 3 + SnO 2 > MAPbI 3 + NiO, consistent with thermodynamic data. When MAPbI 3 contacts NiO or SnO 2 , experimental results unequivocally show interfacial decomposition occurs at a lower temperature than bulk decomposition and produces different degradation products. Density functional theory calculations reveal an altered reaction pathway on oxide surfaces and elucidate the difference between NiO and TiO 2 . These findings pinpoint the importance of understanding the interaction between halide perovskite and other materials used in a device to achieve intrinsically stable devices.

PrMn2O5 is demonstrated as a superior catalyst compared to SmMn2O5 for low temperature NO oxidation, both experimentally and theoretically.

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By combining low energy ion scattering spectroscopy and density functional theory calculation, we study the surface composition and surface formation energy of AMn2O5 (A = Sm, Bi) mullite-type oxides synthesized by different methods and their effects on NO catalytic performance. It is well-known that hydrothermal (HT) synthesis at low temperatures produces materials with higher specific surface areas (SSAs) compared with those synthesized by coprecipitation (CP) and high-temperature calcination; however, it is less clear how synthesis methods affect surface chemistry. We find that the NO oxidation performance of SmMn2O5–HT does not match the SSA increase when compared to the lower SSA SmMn2O5–CP. Combined experimental and theoretical investigation reveals that SmMn2O5–HT includes a higher fraction of inactive Sm-terminated surfaces, which explains its lower than expected activity. However, the surface chemistry change depends strongly on the A-site element. The exposed surfaces of BiMn2O5–CP are predominantly terminated by Bi and exhibit a very low activity, while BiMn2O5–HT contains active Mn-terminated surfaces. This study shows that catalytic performance is determined predominantly by surface chemistry, which depends critically on the A-site element and synthesis method and less by physical surface area.