The composition-dependent change in the work-function (WF) of binary silver–potassium nanoparticles has been studied experimentally by synchrotron-based x-ray photoelectron spectroscopy (PES) and theoretically using a microscopic jellium model of metals. The Ag–K particles with different K fractions were produced by letting a beam of preformed Ag particles pass through a volume with K vapor. The PES on a beam of individual non-supported Ag–K nanoparticles created in this way allowed a direct absolute measurement of their WF, avoiding several usual shortcomings of the method. Experimentally, the WF has been found to be very sensitive to K concentration: Already at low exposure, it decreased down to ≈2 eV—below the value of pure K. In the jellium modeling, considered for Ag–K nanoparticles, two principally different adsorption patterns were tested: without and with K diffusion. The experimental and calculation results together suggest that only efficient surface alloying of two metals, whose immiscibility was long-term textbook knowledge, could lead to the observed WF values.
Free silver nanoparticles doped by potassium: Work-function change in experiment and theory
Mikko-Heikki Mikkelä, Kari Jänkälä, Marko Huttula, Olle Björneholm, Maxim Tchaplyguine; Free silver nanoparticles doped by potassium: Work-function change in experiment and theory. J. Chem. Phys. 21 June 2021; 154 (23): 234708. https://doi.org/10.1063/5.0052101
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