Gold Nanoparticles Incorporated in a Zinc‐Based Metal‐Organic Framework as Multifunctional Catalyst for the Oxygen Reduction and Hydrogen Evolution Reactions

Abstract

Successful synthesis of gold nanoparticles incorporated in a zinc‐based metal‐organic framework (Au@Zn‐MOF) is reported in this paper. The synthesis of Au@Zn‐MOF is confirmed by UV‐Vis, FT‐IR and X‐ray photoelectron spectroscopy (XPS) studies. The Au@Zn‐MOF catalyst demonstrates electrocatalytic activity towards the oxygen reduction reaction (ORR) and the hydrogen evolution reaction (HER). The relative catalytic performance of Au@Zn‐MOF towards ORR and HER has been studied under acidic condition. ORR proceeds via a two electron and two proton mechanism with hydrogen peroxide as the end product, while HER follows the Volmer mechanism i. e., adsorption of H+ on the catalyst's active sites. Au@Zn‐MOF exhibits an ORR onset potential of 0.45 V (vs. RHE) with two different Tafel slopes, −93 and −103.6 mV in acidic solution. Further, an excellent catalytic activity is observed for HER with an onset potential of 0.02 V (vs. RHE) and a Tafel slope of 87 mV in N2 saturated 0.1 M HClO4 solution. However, in O2 saturated 0.1 M HClO4 solution, a HER onset potential of 0.04 V (vs. RHE) is observed with two different Tafel slopes, 610 and 220 mV. The value of Tafel slopes in the presence of O2 advocates the diminution of the ORR activity because of the HER. Thus, Tafel slope values of HER and ORR suggest that protons and O2 compete to reach the electrode surface for getting reduced.

WITHDRAWN: Zn(II) Metal-organic Framework Nanoparticles: Synthesis, Characterization and Application as Optical Biosensor for Prostate-Specific Antigen

“…The Zn-MOF-NPs XRD patterns displayed sharp-peaks proved the Zn-MOF-NPs crystallinephase was progressed. Furthermore, the diffraction patterns matched with standard ZIF-8 and some prepared Zn-MOFs XRD patterns that demonstrated the e cacy synthesis of Zn MOF-NPs [48,49]. The details of the XRD data estimated using Scherrer-equation were presented in (Tables S1 and S2).…”

“…The Zn-MOF-NPs XRD spectrum in comparison with Zn-MOF published-reports [48,49] was introduced in (Fig. 2 a).…”

Mechanical Bond Approach to Introducing Self-Adaptive Active Sites in Covalent Organic Frameworks for Zinc-Catalyzed Organophosphorus Degradation

“…In addition, the Zn 2p 3/2 XPS peak is fitted with symmetrical components to verify the coordination environment of Zn atoms in Crown-COF-Zn, as shown in Figure 3 c. The curve-fitting analysis of the Zn 2p 3/2 spectrum shows BE values centered at 1021.3 eV (mass ratio, 43.0%), 1022.1 eV (mass ratio, 8.8%), and 1023.6 eV (mass ratio, 48.2%), assigned to the Zn—N, Zn—O, and Zn—Cl bonds ( Figure S14 ). 31 , 33 In addition, the mass ratios for the Zn atoms in the dumbbell-Zn ( Figure S15 ) and [2]rotaxane-Zn states are calculated to be 83.0% (1022.4 eV) and 17.0% (1021.3 eV), respectively.…”

A novel nano-lanthanum complex: synthesis, characterization and application as a macrofuran chemosensor in pharmaceutical, biological and environmental samples

“…26,27 The peak at 3210 cm À1 is assigned to the stretching of N-H. The sharp bands between 1525 and 1485 cm À1 are due to the stretching of C]C. 28,29 The bands between 1129 and 1055 cm À1 are attributed to C-H. The band at 584 cm À1 is assigned to a mixture of the covalent and ionic bonding of lanthanum ion with nitrogen n(La-N).…”