A potential method to tune reactivity: In organic chemistry, reaction rates are often sensitive to substituents that either donate or withdraw electron density from a reactive carbon center. Heo et al. now report that when reactants are tethered to an electrode, the polarization effect of an applied potential can exert an analogous influence, essentially acting as a tunable functional group. The authors demonstrate rate modulations in ester hydrolysis and arene cross-coupling, as well as a two-step acid-to-amide conversion that benefits from inversion of the polarization midway through the reaction. Science , this issue p. 214

Shape-retentive core-removal increases Pt accessibility while maintaining Pt{110}-rich surface activity, resulting in an enhancement in ORR mass activity.

Structural and electronic descriptors are widely used to rationalize electrocatalytic activity, but their predictive relevance can depend on the reaction pathway and adsorbed intermediates involved. Systematic comparisons of this reaction dependence using the same well-defined Pd nanostructures remain relatively limited. Here, two structurally related penta-twinned Pd nanocrystals, penta-twinned Pd nanosheets and decahedral nanocrystals, were comparatively evaluated for the oxygen reduction reaction, ethanol oxidation reaction, and formic acid oxidation reaction. For ORR, the more downshifted d-band center of penta-twinned Pd nanosheets accompanied higher intrinsic activity. In contrast, penta-twinned Pd nanosheets and decahedral nanocrystals exhibited nearly identical EOR-specific activities, together with closely comparable CO-stripping peak potentials. For FAOR, the activity order was reversed, with decahedral nanocrystals showing higher specific activity than penta-twinned Pd nanosheets. These contrasting trends demonstrate that the catalytic consequences of surface geometry and electronic structure depend on the adsorbates and elementary reaction pathways involved, highlighting the need to interpret catalyst descriptors in a reaction-specific context.

Alloying metals with unfavorable bulk mixing thermodynamics remains challenging because conventional synthesis often favors elemental segregation rather than compositionally mixed nanoparticles. This study aimed to determine whether direct tip sonication can promote compositional intermixing in metal pairs with limited bulk miscibility and to distinguish sonication-specific effects from conventional thermal and chemical effects. Using Au–Mo as a model system, tip sonication of gold acetate and molybdenum hexacarbonyl in oleic acid successfully produced Au–Mo intermixed nanoparticles with an average diameter of 4.46 ± 0.89 nm and a bulk composition of 96.97 at% Au and 3.03 at% Mo. We also revealed that tip sonication alone was insufficient to induce alloy formation; rather, successful Au–Mo mixing required an appropriate precursor combination and solvent environment, highlighting the cooperative roles of physical energy input and reaction chemistry. The applicability of this strategy was further examined using other compositionally challenging metal pairs, including Ag–Rh and Au–Pt, for which tip sonication likewise produced bimetallic nanoparticles with spatially intermixed elemental distributions. Overall, these findings identify tip sonication as a simple nonequilibrium solution-phase route for accessing compositionally challenging dilute alloy nanoparticles.