Electrochemical CO2 reduction provides a promising strategy to synthesize C2+ compounds with reduced carbon intensity; however, high overall energy consumption restricts practical implementation. Using acidic media enables high CO2 utilization and low liquid product crossover, but to date has suffered low C2+ product selectivity. Here we hypothesize that adjacent pairs of atomic-copper active sites may favour C–C coupling, thus facilitating C2+ product formation. We construct tandem electrocatalysts with two distinct classes of active sites, the first for CO2 to CO, and the second, a dual-atomic-site catalyst, for CO to C2+. This leads to an ethanol Faradaic efficiency of 46% and a C2+ product Faradaic efficiency of 91% at 150 mA cm−2 in an acidic CO2 reduction reaction. We document a CO2 single-pass utilization of 78% and an energy efficiency of 30% towards C2+ products; an ethanol crossover rate of 5%; and an ethanol product concentration of 4.5%, resulting in an exceptionally low projected energy cost of 249 GJ t−1 for the electrosynthesis of ethanol via the CO2 reduction reaction. (Figure presented.)

Zinc oxide (ZnO) is a semiconductor with a wide range of applications, and often the properties are modified by metal-ion doping. The distribution of dopant atoms within the ZnO crystal strongly affects the optical and magnetic properties, making it crucial to comprehend the structure down to the atomic level. Our study reveals the dopant structure and its contents in Eu-doped ZnO nanosponges with up to 20% Eu-O clusters. Eu was distributed over the ZnO:Eu crystals, with an additional amorphous intercrystalline phase observed, especially in the 20% Eu sample. The electron pair distribution function revealed the presence of nonperiodic Eu3+-oxide clusters and proved highly effective for analyzing the coordination environment of Eu-O, ranging from 2.0 to 2.8 A. It uncovered three-, four-, and five-coordinate Eu-O configurations in the 20% Eu sample, and there were significant changes in Eu coordination between the samples, which is ascribed due to the intercrystalline phase. The proposed method offers a potential characterization routine for a detailed investigation of complex doped materials.

The development of robust nickel catalysts on porous substrates offers great potential for converting carbon dioxide (CO₂) into methane, thereby helping to address the global warming and sustainability challenges. This study investigates the dispersion and stability of Ni nanolayers by grafting bifunctional groups over the hierarchical zeolite 13X (h13X) support using (3-aminopropyl)triethoxysilane (APTES). The Ni nanolayers, with a thickness of 1.5–7 nm, were deposited around the edges of h13X and analyzed using STEM imaging. A clear shift in the binding energies was observed by XPS analysis, substantiating the enhanced metal-support interaction (MSI) between NiO and h13X. The influence of reaction temperature on APTES incorporation into h13X was revealed by H₂-TPR and CO₂-TPD, with notable variations in the reducibility and surface basicity profiles of the catalysts. The optimized catalyst exhibited CO₂ conversion of 61 % with CH₄ selectivity of 97 % under GHSV of 60,000 mlg_Cat^-1h^-1 at 400 °C and 1 bar and demonstrated robust stability over a period of 150 h without discernible degradation. The enhanced performance could be attributed to the strengthened MSI and reduced size of Ni nanolayers over h13X. These findings highlight the development of robust heterogeneous catalysts by changing the surface chemistry of support material for various catalytic applications.

Conversion of carbon dioxide (CO₂) into value-added products is aimed to develop scalable technologies to promote a circular economy. While the electrochemical reduction of CO₂ to carbon monoxide (CO) and formic acid has advanced significantly, a major challenge remains achieving further reduced and more energy-dense products, such as methanol (MeOH), through sustainable pathways. Herein, we report a molecular electrode capable of direct six-electron reduction of CO₂ to MeOH using water as a proton source with a global Faradaic efficiency (FE_G) of 22% and product selectivity of 61% for MeOH. The design consists of an active copper-hydride center surrounded by two closely spaced benzimidazole–hydride units, facilitating the catalytic transfer of three hydrides to produce MeOH. The concurrent formation of formic acid and the absence of formaldehyde suggest that MeOH is generated via a formato pathway. DFT investigations revealed the complete mechanistic pathway, which supports the experimental observations. The morphology and stability of the electrode were evaluated before and after prolonged electrolysis (12 h) experiments using electron microscopic techniques.

We provide experimental evidence that is inconsistent with often proposed Langmuir−Hinshelwood (LH) mechanistic hypotheses for water-promoted CO oxidation over Au–Fe₂O₃. Passing CO and H₂O, but no O₂, over Au-γ-Fe₂O₃ at 25 °C, we observe significant CO₂ production, inconsistent with LH mechanistic hypotheses. Experiments with H₂¹⁸O further show that previous LH mechanistic proposals cannot account for water-promoted CO oxidation over Au-γ-Fe₂O₃. Guided by density functional theory, we instead postulate a water-promoted Mars–van Krevelen (w-MvK) reaction. Our proposed w-MvK mechanism is consistent both with observed CO₂ production in the absence of O₂ and with CO oxidation in the presence of H₂¹⁸O and ¹⁶O₂. In contrast, for Au-TiO₂, our data is consistent with previous LH mechanistic hypotheses. 

When electrocatalysts are prepared, modification of the morphology is a common strategy to enhance their electrocatalytic performance. In this work, we have examined and characterized nanorods (3D) and nanosheets (2D) of nickel molybdate hydrates, which previously have been treated as the same material with just a variation in morphology. We thoroughly investigated the materials and report that they contain fundamentally different compounds with different crystal structures, chemical compositions, and chemical stabilities. The 3D nanorod structure exhibits the chemical formula NiMoO4<middle dot>0.6H(2)O and crystallizes in a triclinic system, whereas the 2D nanosheet structures can be rationalized with Ni3MoO5-0.5x(OH)(x)<middle dot>(2.3 - 0.5x)H2O, with a mixed valence of both Ni and Mo, which enables a layered crystal structure. The difference in structure and composition is supported by X-ray photoelectron spectroscopy, ion beam analysis, thermogravimetric analysis, X-ray diffraction, electron diffraction, infrared spectroscopy, Raman spectroscopy, and magnetic measurements. The previously proposed crystal structure for the nickel molybdate hydrate nanorods from the literature needs to be reconsidered and is here refined by ab initio molecular dynamics on a quantum mechanical level using density functional theory calculations to reproduce the experimental findings. Because the material is frequently studied as an electrocatalyst or catalyst precursor and both structures can appear in the same synthesis, a clear distinction between the two compounds is necessary to assess the underlying structure-to-function relationship and targeted electrocatalytic properties.

Electron magnetic circular dichroism (EMCD) is a powerful technique for estimating element-specific magnetic moments of materials on nanoscale with the potential to reach atomic resolution in transmission electron microscopes. However, the fundamentally weak EMCD signal strength complicates quantification of magnetic moments, as this requires very high precision, especially in the denominator of the sum rules. Here, we employ a statistical resampling technique known as bootstrapping to an experimental EMCD dataset to produce an empirical estimate of the noise-dependent error distribution resulting from application of EMCD sum rules to bcc iron in a 3-beam orientation. We observe clear experimental evidence that noisy EMCD signals preferentially bias the estimation of magnetic moments, further supporting this with error distributions produced by Monte-Carlo simulations. Finally, we propose guidelines for the recognition and minimization of this bias in the estimation of magnetic moments.

Na₄Fe₃(PO₄)₂(P₂O₇) (NFPP) as a promising cathode material for sodium-ion batteries possesses excellent structural stability, minimal volume change, low cost, and non-toxicity. However, its practical application is hindered by the formation of impurity phases and its intrinsically low electronic conductivity. Herein, crystalline high purity carbon-coated NFPP (NFPP/CC) is synthesized by performing a green and scalable combustion method to enhance its overall electrochemical performance. The effects of pre-treatment and the calcination atmosphere on the structure and purity of NFPP are systematically investigated for a variety of synthesis parameters. The electrochemical performance of NFPP cathodes is evaluated in both half-cells with the sodium metal anode and full-cells with the hard-carbon anode via galvanostatic charge–discharge cycling measurements. The “combustion” synthesized NFPP/CC cathode delivers a reversible discharge capacity of ∼102 mA h g⁻¹ at 0.1C in an operating voltage window of 1.8–3.8 V (vs. Na/Na⁺) retaining 99.7% of its initial capacity over 100 cycles. Furthermore, it demonstrates enhanced rate capability in comparison to the NFPP/CC cathode synthesized via the conventional calcination route. This study sheds light on using the combustion method as a facile and effective strategy to simultaneously mitigate the formation of impurity phases, reduce the carbon content, enhance the quality of carbon coating, improve the homogeneity of nanoparticles and pores within the structure, and enhance the electronic conductivity and physical stability of NFPP cathodes, paving the way for their practical application in high-performance sodium-ion batteries.

The rising demand for high-performance lithium-ion batteries, pivotal to electric transportation, hinges on key materials like the Ni-rich layered oxide LiNi_xCo_yAl_zO₂ (NCA) used in cathodes. The present study investigates the redox mechanisms, with particular focus on the role of oxygen in commercial NCA electrodes, both fresh and aged under various conditions (aged cells have performed >900 cycles until a cathode capacity retention of ∼80%). Our findings reveal that oxygen participates in charge compensation during NCA delithiation, both through changes in transition metal (TM)–O bond hybridization and formation of partially reversible O₂, the latter occurs already below 3.8 V vs. Li/Li⁺. Aged NCA material undergoes more significant changes in TM–O bond hybridization when cycling above 50% SoC, while reversible O₂ formation is maintained. Nickel is found to be redox active throughout the entire delithiation and shows a more classical oxidation state change during cycling with smaller changes in the Ni–O hybridization. By contrast, Co redox activity relies on a stronger change in Co–O hybridization, with only smaller Co oxidation state changes. The Ni–O bond displays an almost twice as large change in its bond length on cycling as the Co–O bond. The Ni–O₆ octahedra are similar in size to the Co–O₆ octahedra in the delithiated state, but are larger in the lithiated state, a size difference that increases with battery ageing. These contrasting redox activities are reflected directly in structural changes. The NCA material exhibits the formation of nanopores upon ageing, and a possible connection to oxygen redox activity is discussed. The difference in interaction of Ni and Co with oxygen provides a key understanding of the mechanism and the electrochemical instability of Ni-rich layered transition metal oxide electrodes. Our research specifically highlights the significance of the role of oxygen in the electrochemical performance of electric-vehicle-grade NCA electrodes, offering important insights for the creation of next-generation long-lived lithium-ion batteries.

Celulose nanofibers are lightweight, recycable, biodegradable, and renewable. Hence, there is a great interest of using them instead of fossil-based components in new materials and biocomposites. In this study, we disclose an environmentally benign (green) one-step reaction approach to fabricate lactic acid ester functionalized cellulose nanofibrils from wood-derived pulp fibers in high yields. This was accomplished by converting wood-derived pulp fibers to nanofibrillated “cellulose lactate” under mild conditions using lactic acid as both the reaction media and catalyst. Thus, in parallel to the cellulose nanofibril production, concurrent lactic acid-catalyzed esterification of lactic acid to the cellulose nanofibers surface occured. The direct lactic acid esterification, which is a surface selective functionalization and reversible (de-attaching the ester groups by cleavage of the ester bonds), of the cellulose nanofibrils was confirmed by low numbers of degree of substitution, and FT-IR analyses. Thus, autocatalytic esterification and cellulose hydrolysis occurred without the need of metal based or a harsh mineral acid catalysts, which has disadvantages such as acid corrosiveness and high recovery cost of acid. Moreover, adding a mineral acid as a co-catalyst significantly decreased the yield of the nanocellulose. The lactic acid media is successfully recycled in multiple reaction cycles producing the corresponding nanocellulose fibers in high yields. The disclosed green cellulose nanofibril production route is industrial relevant and gives direct access to nanocellulose for use in variety of applications such as sustainable filaments, composites, packaging and strengthening of recycled fibers.