Upconversion photoinduced electrochemiluminescence of luminol-H2O2 at Si/SiOx/Ni photoanodes

n-Si/SiOx/Ni photoanodes are investigated for upconversion photoinduced electrochemiluminescence (PECL) employing the 3-aminophthalhydrazide (luminol)-hydrogen peroxide (H2O2) model electrochemiluminescent (ECL) system at pH 13. We show that IR excitation of the photoanode at 850 nm produces PECL emission at 440 nm resulting in an anti-Stokes shift of -410 nm at biases higher than 0 V vs Ag/AgCl. Due to the alkaline pH value of the electrolyte that prevents Ni dissolution, this upconverting system is active for a longer period (several hours) than reported durations for similar photoanodes operating at neutral pH. The PECL intensity can be controlled by the applied potential and the power density of the incident IR light. This new PECL system opens up promising perspectives for light-addressable electrodes, microscopy, and imaging.