Suppressing the Agglomeration of ZnO Nanoparticles in Air by Doping with Lower Electronegativity Metallic Ions: Implications for Ag/ZnO Electrical Contact Composites

Abstract

Due to the strong surface energy and polarity, ZnO nanoparticles are prone to adsorbing the OH groups dissociated from water in the air, leading to easy agglomeration and hence deteriorating the dispersion of ZnO in composites. In this work, it has been theoretically and experimentally demonstrated that doping with lower electronegativity metallic ions is an effective strategy to suppress the agglomeration of ZnO nanoparticles. By calculating the adsorption energies and electronic structures of OH/M-doped ZnO configurations (M = Li+, Cu2+, Al3+), it was found that metallic ion doping with a lower electronegativity (in comparison to that of the host Zn2+) can efficiently reduce the adsorption of OH groups on the ZnO surface due to the lower effective bond order of M–O bonds. Guided by the theoretical results, various M-doped ZnO nanoparticles (M = Li+, Cu2+, Al3+) were prepared and characterized by X-ray photoelectron spectroscopy and a laser particle sizer, which confirmed that the lower the electronegativity of dopants, the lower the OH groups’ adsorbed amounts and aggregate sizes of M-doped ZnO nanoparticles. This work provides a general avenue to design the composition of M-doped ZnO nanoparticles for suppressing agglomeration and enhance the dispersion of ZnO in composites.

Polyacrylamide gel synthesis of CuO/CuFe2O4 nanoparticles for H2S gas sensing

“…The high surface area of nanoparticles results in high surface energy. In order to lower their surfaces and create an energetically more stable state, nanoparticles cling together and form agglomerated states [75][76][77].…”

Surface Engineering on Ag-Decorated Co3O4 Electrocatalysts for Boosting Nitrate Reduction to Ammonia

“…If the doping element had a higher electronegativity (stronger capability to attract the shared electrons) than that of the base element, the electron density around the based element decreases and the BE increases with positive shift in XPS and vice versa. 49,50 ), and other chemisorbed water species (O H O 2 ). From the spectra, a redshift of O L indicated the partial removal of Co−O bonds with reduced states of Co species created under Ag doping.…”

“…As the prepared Co 3 O 4 is a p-type semiconductor with a lower Fermi level and higher work function (Φ) than that of metallic Ag, a charge flow would occur from metal to semiconductor with downward bending when there is an ohmic contact. , In the case of modifying a catalyst by metal doping, the BE peak position depends on the oxidation state and local chemical environment of the base element. If the doping element had a higher electronegativity (stronger capability to attract the shared electrons) than that of the base element, the electron density around the based element decreases and the BE increases with positive shift in XPS and vice versa. , It is well-known that the Ag (1.93) possesses a higher electronegativity than Co (1.88), thus theoretically leading to a decrease in the electron density of the base Co element if it was a partial Ag substitution of Co. However, the BE peak shift in Co 2p 3/2 in XPS showing Co as an electron acceptor rather than donator proves that Ag atoms do not substitute for Co atoms.…”

Photocatalytic Degradation of Orange II by Active Layers of Ag-Doped CuO Deposited by Spin-Coating Method

“…The solution -gelation consists of a solution based on precursors in the liquid phase which is transformed into a solid by a sum of chemical reactions of the polymerization type at room temperature. Thin layers can be manufactured and prepared by several deposition techniques such as spray pyrolysis [15], dipcoating [16] and spin-coating [17], DC reactive sputtering [18] and thermal evaporation [19]. The last one is an inexpensive technique that allows a variety of materials to be obtained.…”