Understanding the Photoelectrochemical Behavior of Metal Nanoclusters: A Perspective

Since the invention of metal nanocluster (NC)-based photo-electrochemical (PEC) devices, limited progress has been made in this area due to various intricacies associated with this new class of photoactive nanomaterials. Recent research has shown that NC-TiO2 photoelectrodes possess charge separation and transfer complexities that are not seen in dye-TiO2 or quantum dot-TiO2 photoelectrodes. Even the degradation mechanism of NC-based photoelectrodes has a multitude of complexities, such that the degradation of NCs can have a silver lining of introducing plasmons to enhance charge separation in NC-TiO2 photoelectrodes. Therefore, NC-based photoelectrodes require a comprehensive overview from a photoelectrochemistry perspective to better understand these systems. In this Perspective, we provide a review of recent progress in understanding the degradation and charge transfer mechanisms of NC-TiO2 photoelectrodes. We also provide an overview of the various methodologies to control the properties of NCs for PEC applications and how these variables have been utilized to improve NC-based PEC device performance. Finally, we discuss the future of NC-based PEC devices and highlight the immense research opportunities present in this field.