Iridium Nanoparticles Anchored on Reduced Graphene Oxide for Efficient Photoelectrochemical Photodetection

Abstract Despite the extensive and mature research on iridium (Ir) complexes for electro-to-light conversion, there is a striking imbalance in Ir-based optoelectronic materials for light-to-electricity conversion, particularly high-performance photodetectors, which have rarely been investigated. In this study, Ir nanoparticles (NPs) were loaded onto reduced graphene oxide (rGO), abbreviated as Ir NP/rGO, using commercial tris(2-(4,6-difluorophenyl)pyridine) iridium(III) and graphene oxide (GO) via hydrogen bonding interaction, followed by vacuum calcination, for the first time, for the construction of a photoelectrochemical (PEC)-type photodetector. The PEC result demonstrates that the as-obtained Ir NP/rGO-based PEC electrode shows the best PEC signal (e.g., current density and responsivity) at the smallest diameter of studied It NPs that were calcinated at the lowest temperature (600 °C). The current density and responsivity for the Ir NP/rGO-based PEC electrode in 0.5 M KOH can reach 34.7 μA cm−2 and 294 μA W−1, respectively, both of which are remarkably higher than those of emerging nanostructure-based PEC electrodes. Moreover, the Ir NP/rGO-based PEC electrode achieves competitive detectivity, comparable response/recovery time, as well as robust PEC stability. It is anticipated that Ir-based nanostructures can offer promising avenues for the rational design of high-efficiency, stable optoelectronic devices, including photodetectors, PEC sensors, and optoelectronic switches.