Fig. 3

XRD pattern of a CuO matched with the reported JCPDS data [JCPDS No. 80-0076], and b Co3O4 matched with the reported JCPDS data [JCPDS No. 42-1467]
XRD pattern of a CuO matched with the reported JCPDS data [JCPDS No. 80-0076], and b Co3O4 matched with the reported JCPDS data [JCPDS No. 42-1467]