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Abstract Cu is the most promising metal catalyst for CO₂electroreduction (CO₂RR) to multi-carbon products, yet the structure sensitivity of the reaction and the stability versus restructuring of the catalyst surface under reaction conditions remain controversial. Here, atomic scale simulations of surface energies and reaction pathway kinetics supported by experimental evidence unveil that CO₂RR does not take place on perfect planar Cu(111) and Cu(100) surfaces but rather on steps or kinks. These planar surfaces tend to restructure in reaction conditions to the active stepped surfaces, with the strong binding of CO on defective sites acting as a thermodynamic driving force. Notably, we identify that the square motifs adjacent to defects, not the defects themselves, as the active sites for CO₂RR via synergistic effect. We evaluate these mechanisms against experiments of CO₂RR on ultra-high vacuum-prepared ultraclean Cu surfaces, uncovering the crucial role of step-edge orientation in steering selectivity. Overall, our study refines the structural sensitivity of CO₂RR on Cu at the atomic level, highlights the self-activation mechanism and elucidates the origin of in situ restructuring of Cu surfaces during the reaction. 

Compounds of polyatomic anions are investigated theoretically as hosts for thorium in nuclear clock devices. 

To date, computational methods for modeling defects (vacancies, adsorbates, etc.) have relied on periodic supercells in which the defect is far enough from its repeated image that they can be assumed non-interacting. Yet, the relative proximity and periodic repetition of the defect’s images may lead to spurious, unphysical artifacts, especially if the defect is charged and/or open-shell, causing a very slow convergence to the thermodynamic limit (TDL). In this article, we introduce a “defectless” embedding formalism such that the embedding field is computed in a pristine, primitive-unit-cell calculation. Subsequently, a single (i.e., “aperiodic”) defect, which can also be charged, is introduced inside the embedded fragment. By eliminating the need for compensating background charges and periodicity of the defect, we circumvent all associated unphysicalities and numerical issues, achieving a very fast convergence to the TDL. Furthermore, using the toolbox of post-Hartree–Fock methods, this scheme can be straightforwardly applied to study strongly correlated defects, localized excited states, and other problems for which existing periodic protocols do not provide a satisfactory description. 

Laser cooling of large, complex molecules is a long-standing goal, instrumental for enabling new quantum technology and precision measurements. A primary consideration for the feasibility of laser cooling, which determines the efficiency and technical requirements of the process, is the number of excited-state decay pathways leading to vibrational excitations. Therefore, the assessment of the laser-cooling potential of a molecule begins with estimate of the vibrational branching ratios of the first few electronic excited states theoretically to find the optimum cooling scheme. Such calculations, typically done within the Born-Oppenheimer and harmonic approximations, have suggested that one leading candidate for large, polyatomic molecule laser cooling, alkaline earth phenoxides, can most efficiently be laser cooled via the third electronically excited ( $\tilde{C}$) state. Here, we report the first detailed spectroscopic characterization of the $\tilde{C}$state in CaOPh and SrOPh. We find that nonadiabatic couplings between the $\tilde{A}, \tilde{B}$, and $\tilde{C}$states lead to substantial mixing, giving rise to vibronic states that enable additional decay pathways. Based on the intensity ratio of these extra decay channels, we estimate a nonadiabatic coupling strength of $\sim 0.1{\mathrm{cm}}^{-1}$. While this coupling strength is small, the large density of vibrational states available at photonic energy scales in a polyatomic molecule leads to significant mixing. Only the lowest excited state $\tilde{A}$is exempt from this coupling because it is highly separated from the ground state. Thus, this result is expected to be general for large molecules and implies that only the lowest electronic excited state should be considered when judging the suitability of a molecule for laser cooling. 

Thehydrogenoxidationreaction(HOR)inalkalineelectrolytesexhibitsmarkedlyslowerkineticsthanthatinacidic electrolytes.Thisposesacriticalchallengeforalkalineexchangemembranefuelcells(AEMFCs).Theslowerkineticsinalkaline electrolytesisoftenattributedtothemoresluggishVolmerstep(hydrogendesorption).IthasbeenshownthatthealkalineHOR activityonthePtsurfacecanbeconsiderablyenhancedbythepresenceofoxophilictransitionmetals(TMs)andsurface-adsorbed hydroxylgroupsonTMs(TM−OHad),althoughtheexactroleofTM−OHadremainsatopicofactivedebates.Herein,usingsingle- atomRh-tailoredPtnanowiresasamodelsystem,wedemonstratethathydroxylgroupsadsorbedontheRhsites(Rh−OHad)can profoundly reorganize the Pt surface water structure to deliver a record-setting alkaline HOR performance. In situ surface characterizations,togetherwiththeoreticalstudies,revealthatsurfaceRh−OHadcouldpromotetheoxygen-downwater(H2O↓)that favorsmorehydrogenbondwithPtsurfaceadsorbedhydrogen(H2O↓···Had-Pt)thanthehydrogen-downwater(OH2↓).TheH2O↓ furtherservesasthebridgetofacilitatetheformationofanenergeticallyfavorablesix-membered-ringtransitionstructurewith neighboringPt−Had andRh−OHad,thusreducingtheVolmerstepactivationenergyandboostingHORkinetics.