High-Density Three-Dimension Graphene Macroscopic Objects for High-Capacity Removal of Heavy Metal Ions

Abstract

The chemical vapor deposition (CVD) fabrication of high-density three-dimension graphene macroscopic objects (3D-GMOs) with a relatively low porosity has not yet been realized, although they are desirable for applications in which high mechanical and electrical properties are required. Here, we explore a method to rapidly prepare the high-density 3D-GMOs using nickel chloride hexahydrate (NiCl2·6H2O) as a catalyst precursor by CVD process at atmospheric pressure. Further, the free-standing 3D-GMOs are employed as electrolytic electrodes to remove various heavy metal ions. The robust 3D structure, high conductivity (~12 S/cm) and large specific surface area (~560 m2/g) enable ultra-high electrical adsorption capacities (Cd2+ ~ 434 mg/g, Pb2+ ~ 882 mg/g, Ni2+ ~ 1,683 mg/g, Cu2+ ~ 3,820 mg/g) from aqueous solutions and fast desorption. The current work has significance in the studies of both the fabrication of high-density 3D-GMOs and the removal of heavy metal ions.

Bulk scale growth of CVD graphene on Ni nanowire foams for a highly dense and elastic 3D conducting electrode

“…Furthermore, actual surface area before drying is expected to be much higher than measured value since the pore volume and thickness of 3D graphene foam inevitably shrink significantly in the process of freeze-drying [13]. The electrical conductivity of the 3D graphene foam was 17.5 S/cm, which is higher than that of previously reported 3D graphene grown via CVD and graphene oxide assemblies [2,5,9,11,13,20,22].…”

“…In order to produce high quality graphene with relatively few defects and a highly interconnected structure, the chemical vapor deposition (CVD) method has been employed, using 3D metal structures as catalyst foams, such as a commercial Ni foam [5], Ni mesh [17], Ni nanoparticles [18,19], a reduced Ni precursor [20] and so on [21,22]. 3D graphene foams have been prepared by the etching of the metal catalyst after the CVD process.…”

The New Graphene Family Materials: Synthesis and Applications in Oxygen Reduction Reaction

“…The typical process of this method is as follows: first, growing a graphene layer on the surface of a 3D metal catalyst at high temperature; then a post-treatment is used to remove the catalyst or support. Usually, nickel is used as the sacrificial template and catalyst [91][92][93][94][95]. In addition, anodic aluminum oxide (AAO) [96], ZnO [97], pyrolyzed photoresist films [98] and SiO 2 [99] can be applied as the scaffold to build the 3D macroscopic structure.…”

Three-Dimensional Porous Architectures of Carbon Nanotubes and Graphene Sheets for Energy Applications

“…The Ni foam can be subsequently removed by acid, leaving light weighted and free-standing graphene foam (Dong et al, 2012f). Recently, Li et al (2013) fabricated microporous 3D graphene foams via a rapid CVD process using nickel chloride hexahydrate as the catalyst precursor ( Figure 3B). Prolonging the growth time enhances the thickness and strength of graphene layers.…”