Analysis of hydrogen on a platinum electrode using sub-picosecond time-resolved transient reflectivity measurements under electrochemical potential control

The capability of ultrafast photothermal investigation of a metal/solution interface during electrochemical reactions was demonstrated by using sub-pico second time-resolved transient reflectivity measurements. Reduction and oxidation of hydrogen on a polycrystalline Pt electrode in 1.0 mol/dm³ HClO₄ aqueous solution was studied. The magnitude of transient reflectivity (δR) was found to depend on the electronic potential and its sweep rates. The largest change was observed just after the pulsed illumination. At the potential sweep rate 133 mV/s, the potential-dependent part of δR linearly depended on a time-integrated current around the hydrogen adsorption potential while at 274 mV/s it did not. The experimental results were discussed in terms of interface reactions between hydrogen and hot electrons.