Structural and compositional control in copper selenide nanocrystals for light-induced self-repairable electrodes

In nature, self-healing can be induced by sunlight for damage and wound repair, and this phenomenon is very important to living species for prolonging their lives. This self-repairing feature is obviously highly desirable for non-biological materials and manmade systems. In this paper, we demonstrate, for the first time, that battery electrodes can be self-repaired when exposed to sunlight. Here, we show that the optical, and photoelectrochemical (PEC) properties can be controlled by varying structural and compositional parameters of copper selenide nanocrystals (NCs). Cation to anion ratio in copper selenide (Cu_2±xSe) NCs can be controlled over a wide range of 1.3-2.7 by simply changing the reaction temperature and impurity. Light-induced self-repairable behavior is demonstrated with electrochemical (EC) and PEC performances of electrodes made with stoichiometric copper selenide NCs. This nature-inspired, self-repairing behavior can be applied to batteries, supercapacitors, and photo-electrochemical fuel generators.