Controlled Molybdenum Disulfide Assembly inside Carbon Nanofiber by Boudouard Reaction Inspired Selective Carbon Oxidation

Abstract

Vertical stacking and lateral growth of molybdenum disulfide (MoS ) are controlled with remarkable precision, and MoS nanotubes are directly converted from nanofibers. Predictive synthesis is enabled by identifying the specific thermodynamic region where the Boudouard reaction becomes favored. It reveals how the chemical potential of each species in the MoSCO system can predict phase behaviors.

Metal-organic Framework-driven Porous Cobalt Disulfide Nanoparticles Fabricated by Gaseous Sulfurization as Bifunctional Electrocatalysts for Overall Water Splitting

“…The ternary phase diagram, and analysis graphs of expected products depending on sulfur amount were drawn with a thermochemical database program (FACTSAGE software). The database used in this study was the FACT pure substances database (FactPS) 58 .…”

Synthetic Mechanism Discovery of Monophase Cuprous Oxide for Record High Photoelectrochemical Conversion of CO2 to Methanol in Water

“…With the bulk thermodynamic database, at the annealing temperature of 500 °C, the equilibrium p O 2 of reactions and () are 7.15 × 10 –6 and 5.37 × 10 –13 Torr, respectively (Figure S3). In fact, as we are dealing with a nanoscale material, a surface energy term should be considered as an excess energy term to the bulk thermodynamic data. − By inverse calculation of the Gibbs free energy from the database of nanoscale copper oxide, , as described in more detail in Supporting Information (Table S1), the equilibrium p O 2 for the reduction of CuO to Cu 2 O is 2.4 × 10 –3 Torr, and that for the reduction of Cu 2 O to Cu is 1.1 × 10 –5 Torr at the temperature of 500 °C. From the calculated phase boundary conditions of p O 2 for each copper oxide, we established the p O 2 values for the experiment to the Cu 2 O-stable condition: 250 and 50 μTorr, and to the Cu-stable condition: 10 and 1 μTorr, and the annealing time is controlled to 1, 3, 6, and 12 h at each p O 2 to consider the reaction kinetics.…”

Gaseous Nanocarving‐Mediated Carbon Framework with Spontaneous Metal Assembly for Structure‐Tunable Metal/Carbon Nanofibers

“…The phase diagram is based on the calculation of Δ G (Δ G = Δ G ° + RT ln a ), which includes consideration of the interactions between the components, such as the miscibility and enthalpy of mixing in a mixed system. This approach enabled us to predict the initial materials composition and processing parameters that would result in the targeted phase . The atomic mass fraction was modulated by the amount of metal precursor (10 wt%, copper acetate: Cu(COOCH 3 ) 2 , cobalt acetate: Co(COOCH 3 ) 2 , nickel acetate: Ni(COOCH 3 ) 2 , chloroplatinic acid: H 2 PtCl 6 , and iron nitrate: Fe(NO 3 ) 3 ) and polymer matrix (17.64 wt%, polyvinyl alcohol (PVA): (C 2 H 4 O) x ), the O 2 pressure in chamber, and the mass of the specimen.…”

“…Selective oxidation, which induces C oxidation and metal reduction, is a core scheme for controlling the structure of metallic species according to the degree of C decomposition. In our previous work, we have shown this thermodynamic‐grafted synthesis to be a powerful tool to precisely optimize specific structures such as copper/C core/shell, hollow, porous nanofibers and achieve metal size and distribution control, even in molybdenum disulfide (MoS 2 ) assembly …”

“…Calcination under controlled O 2 ambient conditions enables the exploitation of different oxidation tendencies between the metal ion and C ( Figure a). In Figure b, the redox aspects of the metal ion and C are categorized into three groups according to the standard formation Gibbs free energy of the compound (Δ G °) and the oxygen partial pressure (pO 2 ) . This scheme is applicable for noble and transition metals whose oxidation tendency is lower than that of C. It provides a theoretical background for distinguishing full reduction, full oxidation, and selective oxidation.…”