RESUMEN
The hydrogenation of biomass-derived furan compounds provides a sustainable pathway for the production of various valuable chemicals; product selectivity among multiple reaction pathways of furan compound hydrogenation is crucially dependent on catalytic sites; however controlling reaction pathways remains challenging due to the lack of identification and understanding of active sites. In this work we reveal the role of base sites in furfural selective hydrogenation through deliberately designed and synthesized reversed catalysts, basic metal oxides and hydroxide on Cu. It is demonstrated that base species greatly enhanced the selectivity of 1, 2-pentanediol (1, 2-PeD) from furfural, presenting a nearly fourfold increase of 1, 2-PeD: methyl furan ratio over the Cu based reverse catalysts. A combination of infrared spectroscopy and DFT calculations demonstrates the strong interaction between the C-O-C bond in furan ring and the catalyst surface in preferentially parallel adsorption mode in the presence of base species on Cu, thus facilitating the activation of C-O-C bond to produce 1, 2-PeD. This work provides a strategy of designing reversed catalyst to study the effect of promoters and reveals the role of base sites in the hydrogenation of biomass-derived furan compounds to diols.
RESUMEN
Nanoparticles exhibit unique catalytic performance, depending on their nanoscale size. However, controlling the particle size of the supported catalysts is still challenging. Here, we present a method for tunable redistribution of CuOx nanoparticles on rutile TiO2 support by physically adding pristine TiO2. The redistribution is driven by the work function difference (WFD) between the TiO2 support and the TiO2 additive, both of which exhibit distinct values, as determined through Kelvin probe force microscopy and electron binding energy analysis. Addition of TiO2 with lower work function (rutile) promotes electron transfer toward the CuOx/TiO2 composite, resulting in nanoparticle aggregation, while addition of TiO2 with higher work function (anatase) results in smaller CuOx on TiO2. The increase in particle size and electron density of CuOx, driven by the addition of rutile TiO2, promoted the complete conversion of nitrobenzene (100%) within 5 h. This is 2.7 times that of dispersed and degraded CuOx driven by mixing with anatase TiO2 (36.9%).
RESUMEN
Electrocatalytic oxidation of water (i.e., oxygen evolution reaction, OER) plays crucial roles in energy, environment, and biomedicine. It is a key factor affecting the efficiencies of electrocatalytic reactions conducted in aqueous solution, e.g., electrocatalytic water splitting and glucose oxidation reaction (GOR). However, electrocatalytic OER still suffers from problems like high overpotential, sluggish kinetics, and over-reliance on expensive noble-metal-based catalysts. Herein, 15 nm thick carbon-based shell coated tungsten oxide (CTO) nanospheres are loaded on nickel foam to form CTO/NF. An enhanced electrocatalytic OER is triggered on CTO/NF, with the overpotential at 50 mA cm-2 (317 mV) and the Tafel slope (70 mV dec-1) on CTO/NF lower than those on pure tungsten oxide (360 mV, 117 mV dec-1) and noble-metal-based IrO2 catalysts (328 mV, 96 mV dec-1). A promoted electrocatalytic GOR is also achieved on CTO/NF, with efficiency as high as 189 µA mM-1 cm-2. The carbon-based shell on CTO is flexible for electron transfer between catalyst and reactants and provides catalytically active sites. This improves reactant adsorption and O-H bond dissociation on the catalyst, which are key steps in OER and GOR. The carbon-based shell on CTO retains the catalyst as nanospheres with a higher surface area, which facilitates OER and GOR. It is the multiple roles of the carbon-based shell that increases the electrocatalytic efficiency. These results are helpful for fabricating more efficient noble-metal-free electrocatalysts.