A composite nanomaterial of ZnO impregnated by, e.g., a green copper phthalocyanine compound (CuPc) can be an efficient solar light photocatalyst for water remediation. The composite may include hollow shell microspheres and hollow nanospheres of CuPc-ZnO. CuPc may function as a templating and/or structure modifying agent, e.g., for forming hollow microspheres and/or nanospheres of ZnO particles. The composite can photocatalyze the degradation of organic pollutants such as crystal violet (CV) and 2,4-dichlorophenoxyacetic acid as well as microbes in water under solar light irradiation. The ZnO—CuPc composite can be stable and recyclable under solar irradiation.