The β‐cyclodextrin (β‐CD) was successfully applied to synthesize Cu‐SiO2 catalysts by the sol‐gel method. The first and most important question addressed was increasing the copper loading with higher dispersion in the silica support. Another task was to elucidate the structure–performance relationship. Furthermore, catalysts with various β‐CD doping levels were systematically characterized and employed in the hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). The 0.1CD‐Cu‐SiO2 catalyst with 17.39 wt % copper showed 99.9 % DMO conversion and the highest EG selectivity of 95.0 % at 210 °C, as well a lifetime of over 240 h. The reaction results disclosed that the catalytic performance could be tuned facilely by changing the amount of β‐CD doping, which effectively influenced the Cu metallic surface area and dispersion.
The highly efficient electrochemical hydrogen evolution reaction (HER) provides a promising way to solve energy and environment problems. In this work, various transition metals (Fe, Co, Ni, Cu, Ag, and Pt) were selected to support on molybdenum carbides by a simple organic-inorganic precursor carburization process. X-ray diffraction (XRD) analysis results indicated that the β-Mo2C phase was formed in all metal-doped samples. X-ray photoelectron spectroscopy analysis indicated that the binding energy of Mo2+ species (Mo2C) shifted to a lower value after metal was doped on the molybdenum carbide surface. Comparing with pure β-Mo2C, the electrocatalytic activity for HER was improved by transition metal doping on the surface. Remarkably, the catalytic activity improvement was more obvious when Pt was doped on molybdenum carbide (2% Pt-Mo2C). The 2% Pt-Mo2C required a η10 of 79 mV, and outperformed that of pure β-Mo2C (η10 = 410 mV) and other transition metal doped molybdenum carbides, with a small Tafel slope (55 mV/dec) and a low onset overpotential (32 mV) in 0.5 M H2SO4. Also, the 2% Pt-Mo2C catalyst demonstrated a high stability for the HER in 0.5 M H2SO4. This work highlights a feasible strategy to explore efficient electrocatalysts with low cost via engineering on the composition and nanostructure.
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