In Situ Visualization of Electrocatalytic Reaction Activity at Quantum Dots for Water Oxidation

Exploring electrocatalytic reactions on the nanomaterial surface can give crucial information for the development of robust catalysts. Here, electrocatalytic reaction activity at single quantum dots (QDs) loaded silica microparticle involved in water oxidation is visualized using electrochemiluminescence (ECL) microscopy. Under positive potential, the active redox centers at QDs induce the generation of hydroperoxide surface intermediates as coreactants to remarkably enhance ECL emission from luminol derivative molecules for imaging. For the first time, in situ visualization of the catalytic activity of water oxidation with QDs catalyst was achieved, supported by a linear relation between ECL intensity and turn over frequency. A very slight diffusion trend attributed to only the luminol species proved in situ capture of hydroperoxide surface intermediates at catalytic active sites of QDs. This work provides tremendous potential in online imaging of electrocatalytic reactions and visual evaluation of catalyst performance.