Highly efficient visible-light-driven oxygen-vacancy-based Cu2+1O micromotors with biocompatible fuels

Abstract

Photocatalytic light-driven micro/nanomotors have exhibited great potential in various applications ranging from environmental to biomedical fields. However, in order to expand the practicality of synthetic micromotors, overcoming the challenges of efficiently converting visible light energy to mechanical propulsion energy in fully-biocompatible environments has become critically important. Here, we firstly introduce oxygen vacancies into micromotors by a one-pot method without any additional modification and report a highly efficient Cu₂₊₁O light-driven micromotor with simple fabrication, low cost, and excellent motion performance under low intensity, multi-wavelength visible light (from blue to red) and with biocompatible fuels. Under visible light (1/3 light intensity of sunlight), such oxygen vacancy-based micromotors can reach a maximum speed of 18 body length s⁻¹ in pure water which is comparable to that of conventional Pt-based catalytic micromotors fueled by toxic H₂O₂. In addition, the motors show over 100 body length s⁻¹ at very low concentrations of additional biocompatible fuels (0.2 mM tannic acid) which is comparable to the speed of bubble-driven microrockets. Even under blue light with only 1/44 of the intensity of sunlight, the motors can be propelled at speeds of 10 body length s⁻¹ in water, indicating that they are the most efficient visible-light driven micromotors fueled by pure water to date. These exceptionally high speeds set new records for photocatalytic micromotors operated in fully green environments, and the proposed novel fabrication approach may pave a new way for designing and mass-producing highly efficient, smart micromachines for on-demand operations, motion-based sensing, and enhanced cargo transportation.