Alloying is an important strategy for the design of catalytic materials beyond pure metals. The conventional alloy catalysts however lack precise control over the local atomic structures of active sites. Here we report on an investigation of the active-site ensemble effect in bimetallic Pd–Au electrocatalysts for CO2 reduction. A series of Pd@Au electrocatalysts are synthesized by decorating Au nanoparticles with Pd of controlled doses, giving rise to bimetallic surfaces containing Pd ensembles of various sizes. Their catalytic activity for electroreduction of CO2 to CO exhibits a nonlinear behavior in dependence of the Pd content, which is attributed to the variation of Pd ensemble size and the corresponding tuning of adsorption properties. Density functional theory calculations reveal that the Pd@Au electrocatalysts with atomically dispersed Pd sites possess lower energy barriers for activation of CO2 than pure Au and are also less poisoned by strongly binding *CO intermediates than pure Pd, with an intermediate ensemble size of active sites, such as Pd dimers, giving rise to the balance between these two rate-limiting factors and achieving the highest activity for CO2 reduction.

Electroreduction of CO 2 represents a promising solution for addressing the global challenges in energy and sustainability. This reaction is highly sensitive to the surface structure of electrocatalysts and the local electrochemical environment. We have investigated the effect of Cu nanoparticle shape on the electrocatalysis of CO 2 reduction by using gasdiffusion electrodes (GDEs) and flowing alkaline catholytes. Cu nanocubes of ∼70 nm in edge length are synthesized with {100} facets preferentially exposed on the surface. They are demonstrated to possess substantially enhanced catalytic activity and selectivity for CO 2 reduction, compared to Cu nanospheres of similar particle sizes. The electrocatalytic performance was further found to be dependent on the concentration of electrolyte (KOH). The Cu nanocubes reach a Faradaic efficiency of 60% and a partial current density of 144 mA/cm 2 toward ethylene (C 2 H 4 ) production, with the catalytic enhancement being attributable to a combination of surface structure and electrolyte alkalinity effects.

To complement a previous study relating to ear disease in temporal bones from South Dakota Indian burials, radiographs were made looking for altered mastoid development suggesting the presence of infections during the period of their growth. Infection has been implicated as a causative, accentuating, or precipitating factor in the disease otosclerosis. Theories relating to the development of the mastoids are discussed and a pertinent bibliography is presented. In total 417 temporal bones were examined. Of these 251 representing 130 individuals were from Arikara burials, and 166 representing 91 individuals, were from Middle Plains Woodland people, Sioux Historic, and other miscellaneous burials. One hundred eleven Arikara temporal bones (44%) showed evidence of altered pneumatization (diploic‐10, sclerotic‐13, mixed‐88), while 86 other culture temporal bones (51.8%) demonstrated similar changes (diploic‐4, sclerotic‐13, mixed‐69). Unilateral and bilateral variable air cell patterns were found. There was no age, sex, or ear lateralization of air cell patterns. No evidence of the effect of cholesteatoma, cancer, surgery, or other bone disease was found. These findings suggest that the people represented by these skulls must have had a significant amount of infectious middle ear disease during the period of the development of their mastoids.

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