The Wadsley-Roth phase (W 0.2 V 0.8) 3 O 7 , crystallizing in a structure obtained through crystallographic shear of 3×3×∞ ReO 3 blocks, is a somewhat rare exemplar for this class of compounds in that it contains a relatively small amount of 4d and/or 5d transition elements. Here we demonstrate that it functions as a high-rate, high-capacity material for lithium ion batteries. Electrochemical insertion and de-insertion in micron sized particles made by conventional solid-state preparation and in sub-100 nm particles made by combining sol-gel precursors with freeze-drying methods, indicate good rate capabilities. The materials display high capacity-close to 300 mAh g −1 at low rates-corresponding to insertion of up to 1.3 Li per transition metal at voltages above 1 V. Li insertion is associated with multielectron redox for both V and W observed from ex-situ X-ray photoelectron spectroscopy. The replacement of 4d and 5d elements with vanadium results in a higher voltage than seen in other, usually niobium-containing shear-structured electrode materials, and points to new opportunities for tuning voltage, electrical conductivity, and capacity in compounds in this structural class.

Development of catalytic materials that can effectively facilitate currently challenging chemical transformations requires enhanced understanding of reaction mechanisms and insight into the structure and composition of optimal active site geometries. New methods for translating fundamental insights obtained in highly controlled environments to industrially viable catalysts that function under dramatically different operating conditions can accelerate the catalyst design process. This Perspective highlights the application of noble metal nanoparticles with well-defined surfaces as nanoscale experimental models that open up opportunities to correlate fundamental reactivity and catalytic performance across reaction environments of increasing complexity. Recent advances in synthetic control over both nanoparticle shape and composition allow for the generation of specific active site geometries of interest in materials that can be stable in both ultrahigh vacuum and elevated pressure gas-phase environments and potentially in solution-phase and electrocatalytic systems as well. Coupled with significant recent developments in surface science techniques, including operando spectroscopy methods, the use of nanoscale model surfaces represents a promising approach to establishing principles of reactivity and catalytic behavior in these diverse environments.

Widespread implementation of polymer electrolyte fuel cells is limited by the performance of Pt catalysts because of the high cost of Pt and the propensity for catalyst surfaces to lose activity as a result of surface poisoning. AuPt core–shell particles show potential to address these issues, but offer new challenges because of the immiscibility of Au and Pt during particle growth. In this work, AuPt core–shell particles with distinct shapes are made using a one‐pot synthesis under mild reaction conditions by exploiting the difference in reduction rate between Au and Pt ions. Employing this approach results in smooth, well‐defined surfaces, rather than the more commonly observed dendritic or island‐like Pt shells that generally form when presynthesized Au cores are used to template Au‐core/Pt‐shell particle growth. By using the established mechanisms of Au nanoparticle growth, facile modification of particle shape and size is achieved with no significant change to the Pt surface. Consequently, this approach also offers a synthetic route to the preparation of more complex AuPt nanostructures, such as those with exotic shapes and high‐energy surface facets.

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MoO2 is an exciting candidate for next-generation energy storage. It can be used for fast-charging applications in nanoscale form, but its kinetic performance is often limited by insulating MoO3 surface oxide layers. Here, we developed methods to produce polymer-templated porous MoO2 powders where electrical conductivity was well-maintained throughout the structure, even in the presence of some surface oxidation. Porosity, pore size, and crystallite size were controlled by varying the amount and size of the colloidal templates and through calcination temperature. The electrochemical performance was correlated with nanoscale structure: samples with high porosity, medium pore sizes, and good crystallinity display optimal rate capabilities, with over 100 mAh/g delivered in 3 min and 93% capacity retention after 1000 cycles. Kinetic studies were performed on samples with the largest and smallest crystallite sizes to understand the charge storage mechanism. In the sample with the smallest crystallite size, 85% of the total stored charge was capacitive, compared to 60% for the largest crystallite size. Sloping voltage profiles in materials with smaller domain sizes further suggest suppression of intercalation-induced phase transitions. This work thus provides insights into the mechanisms of charge storage in nanoscale MoO2 and design parameters for the production of fast charging materials.