RESUMEN
Single atom catalysts (SACs) possess unique catalytic properties due to low-coordination and unsaturated active sites. However, the demonstrated performance of SACs is limited by low SAC loading, poor metal-support interactions, and nonstable performance. Herein, we report a macromolecule-assisted SAC synthesis approach that enabled us to demonstrate high-density Co single atoms (10.6 wt % Co SAC) in a pyridinic N-rich graphenic network. The highly porous carbon network (surface area of â¼186 m2 g-1) with increased conjugation and vicinal Co site decoration in Co SACs significantly enhanced the electrocatalytic oxygen evolution reaction (OER) in 1 M KOH (η10 at 351 mV; mass activity of 2209 mA mgCo-1 at 1.65 V) with more than 300 h stability. Operando X-ray absorption near-edge structure demonstrates the formation of electron-deficient Co-O coordination intermediates, accelerating OER kinetics. Density functional theory (DFT) calculations reveal the facile electron transfer from cobalt to oxygen species-accelerated OER.
RESUMEN
Herein, a Pd nanoparticle-embedded SBVCN-37 heterostructure photocatalyst was synthesized and employed in the water-splitting reaction and for the synthesis of imines via a one-pot tandem reaction involving the photocatalytic reduction of nitrobenzene and oxidation of benzyl alcohol, followed by their condensation reaction. The embedded Pd nanoparticles (mean diameter â¼ 5-7 nm) act as an electron mediator and enhance the catalytic activity of SBVCN-37 during the oxidation and reduction reactions. The experimental results confirm that the light-induced holes owing to the favourable redox potential of the catalyst oxidize N2H4 to N2 and liberate H+ ions, which subsequently react with photogenerated electrons to facilitate the reduction of nitrobenzene. The obtained quantum yields for benzyl alcohol oxidation and nitrobenzene reduction were calculated to be 2.08% and 6.53% at λ = 420 nm light illumination, respectively. Furthermore, the obtained apparent quantum yields for the OER and HER were calculated to be 10.22% and 12.72% at 420 nm, respectively, indicating the excellent potential of the investigated photocatalyst for solar fuel production. Photoelectrochemical (PEC) and time-resolved and steady-state photoluminescence measurements reveal that the optimum amount of Pd nanoparticles over SBVCN-37 is the crucial factor for achieving the highest photocurrent response, lowest charge transfer resistance, and efficient carrier mobility, leading to prominent catalytic activity. Furthermore, the Mott-Schottky (M-S) analysis confirmed that the deposition of Pd nanoparticles effectively reduced the over-potential and fine-tuned the band edge potential required for the HER and OER reactions, respectively.
RESUMEN
In this study, CuCo2O4 and CuCo2O4 decorated nanocrystalline ZSM-5 materials were prepared. For comparative study, a series of MCo2O4 spinels were also prepared. Materials were characterized by the complementary combination of X-ray diffraction, N2-adsorption, UV-visible, and electron microscopic techniques. A simple and rapid method for the simultaneous determination of paracetamol and epinephrine at MCo2O4 spinels modified electrodes is presented in this manuscript. Among the materials investigated in this study, CuCo2O4 decorated nanocrystalline ZSM-5 exhibited the highest electrocatalytic activity with excellent stability, sensitivity, and selectivity. Analytical performance of the sensor was demonstrated in the determination of epinephrine and paracetamol in the commercial pharmaceutical samples.