Differentiating electrochemically active regions of indium tin oxide electrodes for hydrogen evolution and reductive decomposition reactions. An in situ optical microscopy approach

Indium tin oxide (ITO) is an important electrode material in electrochemical studies. However, it presents some chemical and limitations, which are often underestimated. In this work the behavior of ITO investigated under opto-electrochemical monitoring a scanning cell microscopy, SECCM, configuration during hydrogen evolution reaction (HER) 5 mM H2SO4, concentration for remains stable. The situ optical through interference reflection microscopy (IRM) allows discriminating formation H2 nanobubbles, NBs, In(0) nanoparticles, NPs, issued from HER reduction respectively. A segregation potential space between NBs NPs on observed, attributed to intrinsic variation conductivity. This further evidenced by changing droplet position substrate SECM investigation. Besides onset shifted toward less negative potentials when conductivity increases whereas mostly unchanged.