Catalysts are often immobilized on support materials to aid recovery and reuse, increase dispersion, inhibit sintering, and in some cases to synergistically increase reaction rates or selectivities through interactions between the active catalytic and the support. Graphene, an ideal support candidate, has been engineered into 3D architectures through pillaring, exploding and crumpling to prevent sheets restacking and keep high surface area. Among the recently developed 3D architectures is our crumpled graphene nanoparticles or “nanosacks”, which can be used as support loaded with reactive or catalytic particles for a specific chemical function. We explored the behavior of crumpled graphene nanoreactors containing nanoscale ZnO, Ag, Ni, Cu, Fe, or TiO2 particles, either alone or in combination. We show that the complex 3D crumpled structure and electrical conductivity of the graphene shell gives rise to novel behavior that includes (i) inhibition of particle sintering (Ag, Fe), (ii) enhancement of particle oxidation (Cu, Ag) through improved electron transfer, (iii) cathodic protection against oxidation (Ag) using a co-imbedded sacrificial particle (Ni), (iv) TiO2-mediated photochemical control of silver ion release, (v) and enhanced performance in the Fe-based reduction of environmental Cr(VI). These novel behaviors coupled with the continuous fabrication method and the flexible ability to fill the graphene shells with one or multiple types of chemically reactive or catalytic particles, make crumpled graphene nanoreactors attractive for a variety of applications in catalysis, as well as other fields.
Zhongying Wang is a fifth-year graduate student in Professor Hurt’s group, and he’s working on the development of graphene-based materials as catalyst supports loading catalytic-reactive nanoparticles. The electrochemical behavior of these novel hybrid materials is studied in collaboration with the Palmore group.