The Rationale Design of Electrochemical Redox Couple for Efficient Conversion of Light into Mechanical Energy

Abstract

Over the last decades, scientists have endeavored to develop nanoscopic machines and envisioned that these tiny machines could be exploited in biomedical applications and novel material fabrication. Recently, visible-/near-infrared light-driven nanomotors based on a single silicon nanowire by employing the photoelectrochemical redox reaction has been successfully demonstrated.1 However, the conversion efficiency from light into mechanical energy is still unsatisfactory due to the inefficient photoelectrochemical reaction of redox couples, such as hydroquinone/benzoquinone, at the electrodes. To improve the energy conversion efficiency, we systematically examined a series redox couples by experimental study and numerical simulation. Their performance can be assessed by the proposed figure of merit, which involves parameters such as the overpotential and the kinetic constants of corresponding electrode reactions. This result provides the roadmap for the selection of high efficient redox couple system, which moves a step forward to efficiently harness the light energy for nanoscale mechanical motion and opens up new opportunities for the realization of many novel functions such as biocompatible nanorobots and controllable self-assembly.