Photoelectrochemical Charge Transfer Imaging at Nanoscale Catalysts

Semiconductor (SC)-based photoelectrodes, employed for the production of solar fuels, such as H 2 or small organic molecules, have garnered significant attention and extensive studies because they could play a crucial role in addressing the global energy crisis. While macroscopic photoelectrochemical (PEC) studies of these systems are routinely employed to monitor the overall activity of these systems, the spatiotemporal resolution of local PEC activity down to the nanoscale remains a challenge, which could lead to considerable improvement in photoelectrode design and engineering. Here, model Si-based photoanodes precisely coated with water-splitting Ni catalysts of various sizes are studied by photoinduced electrochemiluminescence (PECL) microscopy. Our results demonstrate that this method allows precise imaging of hole-driven photoelectrochemical reactivity down to a scale of ∼50 nm, making PECL microscopy a valuable tool for elucidating charge transfer and local interfacial activity of photoelectrodes employed in PEC solar energy conversion processes.