The major challenge facing lithium–oxygen batteries is the insulating and bulk lithium peroxide discharge product, which causes sluggish decomposition and increasing overpotential during recharge. Here, we demonstrate an improved round-trip efficiency of ~80% by means of a mesoporous carbon electrode, which directs the growth of one-dimensional and amorphous lithium peroxide. Morphologically, the one-dimensional nanostructures with small volume and high surface show improved charge transport and promote delithiation (lithium ion dissolution) during recharge and thus plays a critical role in the facile decomposition of lithium peroxide. Thermodynamically, density functional calculations reveal that disordered geometric arrangements of the surface atoms in the amorphous structure lead to weaker binding of the key reaction intermediate lithium superoxide, yielding smaller oxygen reduction and evolution overpotentials compared to the crystalline surface. This study suggests a strategy to enhance the decomposition rate of lithium peroxide by exploiting the size and shape of one-dimensional nanostructured lithium peroxide.

Achieving high electrochemical conversion of carbon dioxide (CO 2 ) into valuable fuels and chemicals is one of the most promising directions to address environmental and energy challenges. Although several single-crystal based studies and simulation results have reported that rich in steps on Cu (100) surfaces are favorable to convert toward C 2 alcohol products, most studies are still stuck in low-index (100) facets or surface defectderived low density of step-sites. In the present work, we report the high production of ethanol by synthesizing a wrinkled Cu catalyst with high facets via a chemical vapor deposition (CVD) graphene growth process. Under our approach, we used graphene as a guiding material to produce wrinkled Cu film for use as an electrocatalyst. The graphene-grown Cu films are not only mass-producible but composed of a high density of step-sites with highfacet atomic arrangements, including the ( 200) and (310) facets, which are difficult to synthesize using existing methods. The wrinkled Cu film with a unique atomic arrangement showed high ethanol selectivity, achieving 40% faradaic efficiency (FE) at −0.9 V vs reversible hydrogen electrode (RHE), one of the largest selectivity values reported thus far for a Cu-based CO 2 conversion catalyst. The C 2 selectivity and productivity was 57% FE and −2.2 mA/cm 2 at −1.1 V vs RHE, respectively. Density functional theory (DFT) calculation results demonstrated that such a high ethanol productivity is mainly attributable to the (310) facet of the wrinkles, which feature a low C−C coupling barrier (0.5 eV) and a preferred reaction path toward ethanol among other products.

Electrochemical CO2 transformation to high‐value ethylene (C2H4) at high currents and efficiencies is desired and yet remains a grand challenge. We show for the first time that coupling single Sb atoms and oxygen vacancies of CuO enable synergistic electrocatalytic reduction of CO2 to C2H4 at low overpotentials. Highly dispersed Sb atoms occupying metal substitutional sites of CuO are synthesized under mild conditions. The overall CO2 reduction faradaic efficiency (FE) reaches 89.3 ± 1.1% with an FE toward C2H4 exceeding 58.4% at a high‐current density of 500 mA/cm2. Addition of the p‐block metal is found to induce transformation of CuO from flakes to nanoribbons rich in nanoholes and oxygen vacancies, greatly enhancing CO2 adsorption and activation while suppressing hydrogen evolution. Further density functional theory calculations with in situ X‐ray diffraction reveal that combining Sb sites and oxygen vacancies prominently lessen the dimerization energy of adsorbed CO intermediate, thus boosting the conversion of CO2 to produce C2H4. This study provides a new perspective for promoting selective C–C coupling for electrochemical CO2 reduction.

Interaction between metal and oxides is an important molecular-level factor that influences the selectivity of a desirable reaction. Therefore, designing a heterogeneous catalyst where metal-oxide interfaces are well-formed is important for understanding selectivity and surface electronic excitation at the interface. Here, we utilized a nanoscale catalytic Schottky diode from Pt nanowire arrays on TiO2 that forms a nanoscale Pt-TiO2 interface to determine the influence of the metal-oxide interface on catalytic selectivity, thereby affecting hot electron excitation; this demonstrated the real-time detection of hot electron flow generated under an exothermic methanol oxidation reaction. The selectivity to methyl formate and hot electron generation was obtained on nanoscale Pt nanowires/TiO2, which exhibited ~2 times higher partial oxidation selectivity and ~3 times higher chemicurrent yield compared to a diode based on Pt film. By utilizing various Pt/TiO2 nanostructures, we found that the ratio of interface to metal sites significantly affects the selectivity, thereby enhancing chemicurrent yield in methanol oxidation. Density function theory (DFT) calculations show that formation of the Pt-TiO2 interface showed that selectivity to methyl formate formation was much larger in Pt nanowire arrays than in Pt films because of the different reaction mechanism.

Catalytic selectivity, or the production of only one desired molecule that may be used as a fuel or chemical out of several thermodynamically possible molecules, is the foundation of surface chemistry. During catalytic reactions, electronic excitation taking place on the surface creates energetic electrons called “hot electrons” that have a significant impact on catalytic reactions. Despite its importance in fundamentally understanding electronic excitation on the surface, no reports show the relation between hot electron flow and catalytic selectivity. Here, using a Pt/n-type TiO2 Schottky nanodiode, we show the intrinsic relation between hot electron flow and catalytic selectivity. On the Pt thin film, hot electron flow was generated by methanol oxidation exhibiting a two-path reaction of either full oxidation to CO2 or partial oxidation to methyl formate; a steady-state chemicurrent was detected. We show that the activation energy of the chemicurrent is quite close to that of the turnover frequency, indicating that the chemicurrent originated from the catalytic reaction on the Pt thin film. The dependence of the chemicurrent on methanol partial pressure was investigated by varying the partial pressure of methanol (1–4 Torr). We show that hot electron generation is more effective in the reaction pathway that produces methyl formate. On the basis of these results, we conclude that the selectivity for methyl formate production correlates well with hot electron generation because of the higher exothermicity of generating the intermediate, as was confirmed using theoretical calculations based on the density functional theory.