Zinc (hydr)oxide/graphite based-phase composites: effect of the carbonaceous phase on surface properties and enhancement in electrical conductivity

Abstract

Composites of zinc hydroxide with graphite-oxide and graphite derived material are prepared using in situ precipitation of Zn(OH) 2 in the presence of the dispersed graphite-based phases. The new materials are characterized by a range of methods, including SEM, infrared and Raman spectroscopy, thermal analysis, potentiometric titration, nitrogen adsorption, XPS, and electrical measurements. The results indicate that the final properties of the composites are determined by a complex interplay between the two components. When graphite-oxide is used, its oxygen containing functional groups are involved during synthesis with a zinc hydroxide precursor, leading to the formation of interface bonds between the inorganic and carbon-based phase. This new interface not only affects the chemistry of the materials but also determines texture and porosity. Another conversion of the inorganic phase to zinc oxide via thermal treatment further affects the properties of the composite, leading to the formation of additional chemical bonds between the zinc oxide and graphite-oxide phases. Even though the addition of graphite-oxide results in a highly porous material of heterogeneous nature, the thermally treated composite has a comparable electrical conductivity to the zinc hydroxide-graphite derived material composite, although having a lower density. This is attributed to the increased abundance of sp 2 hybridization, the presence of Zn 0 , and improved local electrical connectivity between the two phases of the composite through the new interface bonds.

Optical properties of porous nano-composites of zinc (hydr)oxide with graphite oxide

“…Bandosz and co-workers [2] have shown that such materials exhibit the photo-activity in the visible light [3]. The determination of the optical band gap is important because it not only controls the efficiency for solar conversion and the shape of the optical emission spectrum, but also manifests the effect of structural and thermal disorder on the electronic properties of the nano-composites [4].…”

Key role of terminal hydroxyl groups and visible light in the reactive adsorption/catalytic conversion of mustard gas surrogate on zinc (hydr)oxides

“…The peak at 300 • C can be assigned to the decomposition of the strongly adsorbed CEES and/or HEES [32,33]. Finally, the weight loss that occurred above 760 • C is linked to the removal of ZnCl 2 species [34] and/or to the reduction of zinc oxide to Zn (boiling point 907 • C) by the carbonaceous phase [8]. The traces of the latter phase might be formed during the thermal analysis (charring of organic compounds).…”

“…Whereas the adsorptive performance, as well as the photocatalytic properties of the zinc oxide are well known [8,9], the hydrated oxides have attracted less attention, even though they have been reported as superior to oxide in certain applications [10]. The latter is owing to the high reactivity of their OH groups, especially terminal ones, with specific adsorbates.…”

Effect of Reduced Graphite Oxide as Substrate for Zinc Oxide to Hydrogen Sulfide Adsorption

“…More recently, graphite oxide (GO) with metal oxide composites have been extensively studied as adsorbents [16][17][18]. Graphite oxide-based or graphene-based materials are known to be useful for water purification, toxic gas removal and ammonia adsorption applications [19][20][21].…”