Silver nanoparticle/r-graphene oxide deposited mesoporous-manganese oxide nanocomposite for pollutant removal and supercapacitor applications

Abstract

Mesoporous manganese oxide was prepared by a non-ionic surfactant route using Triton X-100, followed by Ag nanoparticle (NP) and graphene oxide incorporation by an ultra-sonication-assisted process. Fine Ag NPs were incorporated into the tubular texture of mesoporous manganese oxide. The crystalline phase, particle size, and morphology of the prepared materials were characterized by X-ray diffraction (XRD), Barrett–Joyner–Halenda–Brunauer–Emmett–Teller analysis, scanning electron microscopy–energy dispersive X-ray analysis, and high-resolution transmission electron microscopy (HR-TEM). The XRD results confirmed the formation of the Mn2O3 phase for the as-prepared mesoporous manganese oxide and its nanocomposite. Very fine Ag NPs (<5–10 nm) were obtained. The mesoporous MnO2 and graphene-incorporated Ag NPs/meso-MnO2 had a tubular structure and “flaky pastry”-type morphology for the synthesized nanocomposites. HR-TEM images further confirmed the beautiful structural formation upon graphene addition and spherical/dot-shaped NP incorporation into the matrix of MnO2. Improved surface area was obtained for the Ag NPs and graphene-incorporated mesoporous MnO2 as compared to bulk MnO2. The Cr(VI) removal analysis was performed using a batch technique, and enhanced removal of Cr(VI) was achieved (>98% removal of Cr(VI) within 1–2 h of reaction time) for Ag NP-incorporated mesoporous MnO2. Efficient activity was observed because of the fine Ag NPs present in mesoporous manganese oxide, as opposed to the case of graphene oxide-doped meso-MnO2 and pristine mesoporous meso-MnO2.