Employing Ag2Cu2O3, a mixed metal oxide, as a template catalyst material for electrochemical reduction of CO enables generation of multi-carbon products with a faradaic efficiency of close to 92%, at a current density of 600 mA cm−2.

High-precision thermodynamic data were derived for single-layer graphene growth on Cu by measuring an increase or decrease in graphene flake size during chemical vapor deposition (CVD) in a reactive CH4/H2 atmosphere. An immediate flake shape change was observed when crossing the thermodynamic equilibrium of graphene formation, which was used as a sensitive criterion when systematically varying the CVD parameters during growth at 975–1080 °C. Extraction of the reaction enthalpy (ΔR H° = 91.8 ± 2.4 kJ·mol–1) and entropy (ΔR S° = 108.0 ± 1.8 J·mol–1·K–1) provides the anchoring point highly needed for calibration of experimental reactor studies or theoretical work. Comparing the Gibbs free energy with the thermodynamic data of graphite formation verifies that self-limiting single-layer graphene growth on copper occurs purely kinetically. Thermodynamics always favors the formation of multilayer graphene. Identifying the CVD parameter space where multilayer graphene is formed while single-layer graphene decays will foster the development of future synthesis strategies. The gained knowledge is transferable to other CVD-based graphene growth systems.

The kinetics of the chemical vapor deposition (CVD) of graphene on Cu in CH4 + H2 were investigated by monitoring the graphene flake size as a function of CVD growth time. A growth model was set up which relates the CVD parameters to the mass action constant Q exp of the methane decomposition reaction toward graphene at a given temperature T. Graphene growth was shown to proceed from pre-equilibrated adsorbed carbon (Cad) within a wide CVD parameter range. The model not only leads to the correct scaling relation of the growth kinetics but quantitatively determines how far the CVD parameters deviate from thermal equilibrium and correctly predicts the absolute flake size increase per time. Fitting experimental data delivers the energy barrier for carbon detachment from the graphene island edge (E det = 4.7 ± 0.3 eV) and the methane decomposition entropy toward Cad on Cu (Δdec S° = 260 ± 20 J mol–1 K–1). The latter value is used to estimate the vanishingly small Cad equilibrium concentration of 3 × 10–10 monolayers at 1045 °C. The universal validity of the model is proven by comparison with literature data providing the correct order of magnitude growth velocities up to 1000 μm/h. The performed reactor experiments deliver data that match the predicted flake growth velocity with a precision of about 50%. The obtained results can be used to calibrate any hot wall CVD reactor setup for the methane decomposition reaction toward graphene on Cu. The description can be directly applied for any hydrocarbon in the gas feed, and the technique can be easily applied for other catalytic support surfaces.