The electrosorption of thiourea(TU)on single crystal electrodes:Ag(111),Ag(100)and Ag(110)was studied using electrochemical and radiochemical methods.A radiotracer method called"thin gap method"[1],with TU labeled with C-14 in 0.1 M HClO_4,was used to determine the surface concentration of the adsorbate.The real surface area of the electrodes was estimated from the underpotential deposition of lead and also from the determination of capacitance of the electrodes.The hydrogen evolution as well as surface oxidation depend on the electrode plane-the Ag(111)is the most and Ag(110)the least active,respectively.From radiometric data it follows that adsorption of TU is reversible with respect to the bulk concentration and the potential in the range of ideal polarizability of electrodes.
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