Kinetics of thiocyanate orientation conversion on Pt surface studied by in situ step-scan time-resolved microscope FTIR spectroscopy

Abstract

Fast surface dynamic processes of thiocyanate adsorbed on a nanostructured Pt microelectrode were studied by in situ step-scan time-resolved microscope FTIR spectroscopy (in situ SSTR-MFTIRS) at a time resolution of 100 μs. It was found that SCN- adsorbs preferentially on Pt surface through N atom at low potential, while through S atom at high potential. The potential-induced orientation conversion between N- and S-bounded forms is very reversible, and occurs only within 2 ms after potential alternation. However, the rate constant (4×103 s-1) of conversion from N- to S-bounded adsorption is nearly double to that of the reverse process (2×103 s-1). The difference in kinetics of two processes may be explained through the hard-soft acid-base principle. © 2012 The Author(s).