In this work, cobalt and lithium from the cathodes of spent lithium-ion batteries were recycled to synthesize a mixture of Co3O4 and LiCoO2. The positive electrode was leached with citric acid in the green recycling. After being heated to 85 degrees C, the leaching solution formed a pink sol, and after being dried at 120 degrees C for 24 h, it formed a gel, which is a precursor material for Co(3)O4 and LiCoO2 synthesis. A mixture of Co3O4 and LT-LiCoO2 was obtained after the calcination of the precursor material at 450 degrees C for 3 h. The photocatalytic properties of the Co3O4 and LiCoO2 were tested in the discoloration of methylene blue dye. The discoloration efficiency of methylene blue dye in the presence of Co3O4 and LiCoO2 was 90% after 10 h and 100% after 24 h of heterogeneous catalysis. The contribution of this work is that it presents a means to produce valuable materials with photocatalytic properties from recycled batteries through a spent Li-ion battery recycling process without polluting the environment. (C) 2017 Elsevier B.V. All rights reserved.