characterizationofcomncatalystbyinsituxrayabsorptionspectroscopyandwaveletanalysisforfischertropschtoolefinsreaction

Cobalt carbide has recently been reported to catalyse the FTO con version of syngas with high selectivity for the production of lower olefins (C2-C4). Clarifying the formation process and atomic structure of cobalt carbide will help understand the catalytic mechanism of FTO. Herein, hydrogenati on of carb on monoxide was investigated for cobalt carbide synthesized from CoMn catalyst, followed by X-ray diffraction, transmission electron microscopy, temperature programmed reaction and in situ X-ray absorption spectroscopy. By monitoring the evolution of cobalt carbide during syngas conversion, the wavelet transform results give evidenee for the formation of the cobalt carbide and clearly demonstrate that the active site of catalysis was cobalt carbide

characterizationofcomncatalystbyinsituxrayabsorptionspectroscopyandwaveletanalysisforfischertropschtoolefinsreaction

Cobalt carbide has recently been reported to catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins(C_2 –C_4). Clarifying the formation process and atomic structure of cobalt carbide will help understand the catalytic mechanism of FTO. Herein, hydrogenation of carbon monoxide was investigated for cobalt carbide synthesized from CoMn catalyst, followed by X-ray diffraction, transmission electron microscopy, temperature programmed reaction and in situ X-ray absorption spectroscopy. By monitoring the evolution of cobalt carbide during syngas conversion, the wavelet transform results give evidence for the formation of the cobalt carbide and clearly demonstrate that the active site of catalysis was cobalt carbide

characterizationofcomncatalystbyinsituxrayabsorptionspectroscopyandwaveletanalysisforfischertropschtoolefinsreaction

Cobalt carbide has recently been reported to catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins(C_2 –C_4). Clarifying the formation process and atomic structure of cobalt carbide will help understand the catalytic mechanism of FTO. Herein, hydrogenation of carbon monoxide was investigated for cobalt carbide synthesized from CoMn catalyst, followed by X-ray diffraction, transmission electron microscopy, temperature programmed reaction and in situ X-ray absorption spectroscopy. By monitoring the evolution of cobalt carbide during syngas conversion, the wavelet transform results give evidence for the formation of the cobalt carbide and clearly demonstrate that the active site of catalysis was cobalt carbide

Highly Active Surface Structure in Nanosized Spinel Cobalt-Based Oxides for Electrocatalytic Water Splitting

Spinel cobalt-based oxides are a promising family of materials for water splitting to replace currently used noble-metal catalysts. Identifying the highly active facet and the corresponding coordinated structure of surface redox centers is pivotal for the rational design of low-cost and efficient nanosized catalysts. Using high-resolution transmission electron microscopy and advanced X-ray techniques, as well as ab initio modeling, we found that the activity of Co³⁺ ions exhibits the surface dependence owing to the variability of its electronic configurations. Our calculation shows that the Co³⁺ site in {100} facet of nanosized Li₂Co₂O₄ exhibits an impressive intrinsic activity with low overpotential, far lower than that of the {110} and {111} facets. The unique, well-defined CoO₅ square-pyramidal structure in this nonpolar surface stabilizes the unusual intermediate-spin states of the Co³⁺ ion. Specially, we unraveled that oxygen ion anticipates the redox process via the strong hybridization Co 3d–O 2p state, which produces a 3d_<i>z</i>^₂1.1 filling orbit. Finally, a spin-correlated energy diagram as a function of Co–O distance was devised, showing that the covalency of Co–O significantly affects the spin state of Co³⁺ ions. We suggest that the nonpolar surface that contains CoO₅ units in the edge-sharing systems with the short Co–O bond distance is a potential candidate for alkaline water electrolysis

Manipulating local coordination of copper single atom catalyst enables efficient CO2-to-CH4 conversion

Abstract Electrochemical CO2 conversion to methane, powered by intermittent renewable electricity, provides an entrancing opportunity to both store renewable electric energy and utilize emitted CO2. Copper-based single atom catalysts are promising candidates to restrain C-C coupling, suggesting feasibility in further protonation of CO* to CHO* for methane production. In theoretical studies herein, we find that introducing boron atoms into the first coordination layer of Cu-N4 motif facilitates the binding of CO* and CHO* intermediates, which favors the generation of methane. Accordingly, we employ a co-doping strategy to fabricate B-doped Cu-N x atomic configuration (Cu-N x B y ), where Cu-N2B2 is resolved to be the dominant site. Compared with Cu-N4 motifs, as-synthesized B-doped Cu-N x structure exhibits a superior performance towards methane production, showing a peak methane Faradaic efficiency of 73% at −1.46 V vs. RHE and a maximum methane partial current density of −462 mA cm−2 at −1.94 V vs. RHE. Extensional calculations utilizing two-dimensional reaction phase diagram analysis together with barrier calculation help to gain more insights into the reaction mechanism of Cu-N2B2 coordination structure

Defect-free-induced Na\u3csup\u3e+\u3c/sup\u3edisordering in electrode materials

For reaching high-performance of electrode materials, it is generally believed that understanding the structure evolution and heterogeneous alignment effect is the key. Presently, a very simple and universally applicable self-healing method is investigated to prepare defect-free Prussian blue analogs (PBAs) that reach their theoretical capacity as cathode materials for sodium-ion batteries (SIBs). For direct imaging of the local structure and the dynamic process at the atomic scale, we deliver a fast ion-conductive nickel-based PBA that enables rapid Na+ extraction/insertion within 3 minutes and a capacity retention of nearly 100% over 4000 cycles. This guest-ion disordered and quasi-zero-strain nonequilibrium solid-solution reaction mechanism provides an effective guarantee for realizing long-cycle life and high-rate capability electrode materials that operate via reversible two-phase transition reaction. Unconventional materials and mechanisms that enable reversible insertion/extraction of ions in low-cost metal-organic frameworks (MOFs) within minutes have implications for fast-charging devices, grid-scale energy storage applications, material discovery, and tailored modification