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Al2O3 and Ga2O3 exhibit numerous crystal phases with distinct stabilities and material properties. However, the phase transitions among those materials are typically undesirable in industrial applications, making it imperative to elucidate the transition mechanisms between these phases. The configurational similarities between Al2O3 and Ga2O3 allow for the replication of phase transition pathways between these materials. In this study, we investigate the potential phase transition pathway of alumina from the θ-phase to the α-phase using stochastic surface walking global optimization based on global neural network potentials, while extending an existing Ga2O3 phase transition path. Through this exploration, we identify a novel single-atom migration pseudomartensitic mechanism, which combines martensitic transformation with single-atom diffusion. This discovery offers valuable insights for experimental endeavors aimed at stabilizing alumina in transitional phases. [ABSTRACT FROM AUTHOR]

Hydrogen evolution reaction (HER) by splitting water is a key technology toward a clean energy society, where Pt-based catalysts were long known to have the highest activity under acidic electrochemical conditions but suffer from high cost and poor stability. Here, we overview the current status of Pt-catalyzed HER from a theoretical perspective, focusing on the methodology development of electrochemistry simulation, catalytic mechanism, and catalyst stability. Recent developments in theoretical methods for studying electrochemistry are introduced, elaborating on how they describe solid–liquid interface reactions under electrochemical potentials. The HER mechanism, the reaction kinetics, and the reaction sites on Pt are then summarized, which provides an atomic-level picture of Pt catalyst surface dynamics under reaction conditions. Finally, state-of-the-art experimental solutions to improve catalyst stability are also introduced, which illustrates the significance of fundamental understandings in the new catalyst design. [ABSTRACT FROM AUTHOR]

Electrocatalytic carbonylation of CO and CH3OH to dimethyl carbonate (DMC) on metallic palladium (Pd) electrode offers a promising strategy for C1 valorization at the anode. However, its broader application is limited by the high working potential and the low DMC selectivity accompanied with severe methanol self‐oxidation. Herein, our theoretical analysis of the intermediate adsorption interactions on both Pd0 and Pd4+ surfaces revealed that inevitable reconstruction of Pd surface under strongly oxidative potential diminishes its CO adsorption capacity, thus damaging the DMC formation. Further theoretical modeling indicates that doping Pd with Cu not only stabilizes low‐valence Pd in oxidative environments but also lowers the overall energy barrier for DMC formation. Guided by this insight, we developed a facile two‐step thermal shock method to prepare PdCu alloy electrocatalysts for DMC. Remarkably, the predicted Pd3Cu demonstrated the highest DMC selectivity among existing Pd‐based electrocatalysts, reaching a peaked DMC selectivity of 93 % at 1.0 V versus Ag/AgCl electrode. (Quasi) in situ spectra investigations further confirmed the predicted dual role of Cu dopant in promoting Pd‐catalyzed DMC formation. [ABSTRACT FROM AUTHOR]

Effective and mild activation of O2 is essential but challenging for aerobic oxidation. In heterogeneous catalysis, high-valence manganese oxide (e.g., +4) is known to be active for the oxidation, whereas divalent MnO is ineffective due to its limited capacity to supply surface oxygen and its thermodynamically unstable structure when binding O2 in reaction conditions. Inspired by natural enzymes that rely on divalent Mn2+, we discovered that confining Mn2+ onto the Mn2O3 surface through a dedicated calcination process creates highly active catalysts for the aerobic oxidation of 5-hydroxymethylfurfural, benzyl alcohol, and CO. The Mn2O3-confined Mn2+ is undercoordinated and efficiently mediates O2 activation, resulting in 2–3 orders of magnitude higher activity than Mn2O3 alone. Through low-temperature infrared spectroscopy, we distinguished low-content Mn2+ sites at Mn2O3 surface, which are difficult to be differentiated by X-ray photoelectron spectroscopy. The combination of in-situ energy-dispersive X-ray absorption spectroscopy and X-ray diffraction further provides insights into the formation of the newly identified active Mn2+ sites. By optimizing the calcination step, we were able to increase the catalytic activity threefold further. The finding offers promising frontiers for exploring active oxidation catalysts by utilizing the confinement of Mn2+ and often-ignored calcination skills. [ABSTRACT FROM AUTHOR]

The limited surface coverage and activity of active hydrides on oxide surfaces pose challenges for efficient hydrogenation reactions. Herein, we quantitatively distinguish the long-puzzling homolytic dissociation of hydrogen from the heterolytic pathway on Ga2O3, that is useful for enhancing hydrogenation ability of oxides. By combining transient kinetic analysis with infrared and mass spectroscopies, we identify the catalytic role of coordinatively unsaturated Ga3+ in homolytic H2 dissociation, which is formed in-situ during the initial heterolytic dissociation. This site facilitates easy hydrogen dissociation at low temperatures, resulting in a high hydride coverage on Ga2O3 (H/surface Ga3+ ratio of 1.6 and H/OH ratio of 5.6). The effectiveness of homolytic dissociation is governed by the Ga-Ga distance, which is strongly influenced by the initial coordination of Ga3+. Consequently, by tuning the coordination of active Ga3+ species as well as the coverage and activity of hydrides, we achieve enhanced hydrogenation of CO2 to CO, methanol or light olefins by 4-6 times. Zhu et al. report a quantitative and time-resolved analysis of hydrogen activation on Ga2O3, specifically shedding light on the long-standing puzzle of homolytic dissociation as opposed to the heterolytic pathway on oxides. [ABSTRACT FROM AUTHOR]

The surface of a material often undergoes dramatic structure evolution under a chemical environment, which, in turn, helps determine the different properties of the material. Here, we develop a general-purpose method for the automated search of optimal surface phases (ASOPs) in the grand canonical ensemble, which is facilitated by the stochastic surface walking (SSW) global optimization based on global neural network (G-NN) potential. The ASOP simulation starts by enumerating a series of composition grids, then utilizes SSW-NN to explore the configuration and composition spaces of surface phases, and relies on the Monte Carlo scheme to focus on energetically favorable compositions. The method is applied to silver surface oxide formation under the catalytic ethene epoxidation conditions. The known phases of surface oxides on Ag(111) are reproduced, and new phases on Ag(100) are revealed, which exhibit novel structure features that could be critical for understanding ethene epoxidation. Our results demonstrate that the ASOP method provides an automated and efficient way for probing complex surface structures that are beneficial for designing new functional materials under working conditions. [ABSTRACT FROM AUTHOR]