Electrochemiluminescence imaging on laser-patterned hematite electrodes decorated with MnO2 through conductivity-driven electrodeposition

In this work, we report on a laser-based strategy for spatially localizing electrochemiluminescence (ECL) in imaging applications by utilizing the contrast in electrical conductivity between laser-patterned hematite (α-Fe₂O₃) and its precursor, akaganeite (β-FeOOH). Compared to the conventional thermal annealing process of akaganeite to hematite, the laser-induced phase transformation (LIPT) process enables rapid and controllable patterning of hematite under ambient conditions, while simultaneously facilitating the phase transformation from akaganeite to hematite. Furthermore, the selective electrodeposition of MnO₂, which is electrochemically active for the ECL of luminol in the presence of H₂O₂, occurs exclusively on the patterned areas of laser-induced hematite (LIH), while the regions exhibiting poor conductivity, specifically akaganeite precursor regions, remain inactive for the electrodeposition process. This conductivity-driven selectivity facilitates localized ECL generation solely on MnO₂-decorated hematite patterns with negligible ECL from the akaganeite areas. After showcasing programmable ECL patterns (e.g., shapes and letters), we demonstrate the promising potential of the laser-based strategy that exploits LIPT with conductivity-driven material deposition for applications requiring patterned functional interfaces, exemplified by the spatially resolved ECL imaging of H₂O₂ on the MnO₂-decorated hematite patterns