Nature chemistry最新文献

Understanding the electric double layer (EDL) of stepped Pt electrodes is crucial for comprehending the reaction environment for electrocatalytically relevant Pt electrodes, which typically comprise a complex mixture of facet orientations, steps and defects. Here we systematically investigate the EDL structure of these surfaces by periodically perturbing (111) terraces by either (110)- or (100)-type steps. We find that the minimum in the differential capacitance C_d,min in 0.1 mM HClO₄ is highly structure sensitive. We attribute this observation to inherent differences in affinity for H₂O dissociation between (110) and (100) facets. Using a continuum model, we confirm that the potential of C_d,min (E_d,min) closely approximates the potential of zero free charge E_pzfc for the (110)-stepped series. Together with ab initio molecular dynamics simulations, we reveal that OH_ads at step sites leads to a different step-density-dependent trend between E_pzfc and the work function. Our approach yields a unified picture of the EDL structure on stepped Pt surfaces, bridging the gap between model single-crystal surfaces and practically relevant heterogeneous Pt electrodes.

Electrochemical CO reduction has the potential to enable low-carbon-intensity chemicals and fuels, but the reaction yields a mixture of multi-carbon products, and the underlying selectivity-driving mechanisms are unclear. Here we explore trends in alkali cations and find, in contradistinction to carbon dioxide electroreduction, that lithium promotes ethylene production. We study the electrolyte-catalyst interface using operando Raman spectroscopy and simulations and find that hydrated Li⁺ on the electrode surface has the greatest hydrogen bonding and the least cation-dipole interaction with the oxygen site on intermediates. These interactions suppress hydrogenation on carbon and promote the competing hydrodeoxygenation reaction that leads to hydrocarbons. We leverage this understanding and reduce the oxygen affinity of copper via antimony doping, suppressing the formation of the O-tethered CHCHO* intermediate on the surface that would otherwise lead to oxygenates. Combining these strategies, we achieve an ethylene faradaic efficiency of 79% at 150 mA cm^-2 and an energy efficiency of 39% in a membrane electrode assembly electrolyser.

The Strychnos alkaloids have long been regarded as landmark targets for chemical synthesis due to their captivating architectures and notorious biological properties. However, the design of approaches that access multiple family members in an asymmetric, concise and atom-economical fashion remains an important challenge. Here we show that thiophene S,S-dioxides (TDOs) offer a modular, rapid entry to Strychnos natural products via inverse electron demand Diels-Alder cascades. We demonstrate that exceptional levels of stereocontrol can be achieved in asymmetric TDO cycloadditions, affording tricyclic indolines of utility in medicinal chemistry research and enabling the stereoselective synthesis of eight Strychnos alkaloids by the shortest routes described so far, including a synthesis of the iconic family member brucine. Using a machine-learning approach, computational studies provide insight into the source of stereoinduction and reveal an intriguing and unexpected spontaneous cheletropic extrusion of SO₂.