Binder-free graphene oxide doughs

Abstract

Graphene oxide (GO) sheets have been used to construct various bulk forms of GO and graphene-based materials through solution-based processing techniques. Here, we report a highly cohesive dough state of GO with tens of weight percent loading in water without binder-like additives. The dough state can be diluted to obtain gels or dispersions, and dried to yield hard solids. It can be kneaded without leaving stains, readily reshaped, connected, and further processed to make bulk GO and graphene materials of arbitrary form factors and tunable microstructures. The doughs can be transformed to dense glassy solids of GO or graphene without long-range stacking order of the sheets, which exhibit isotropic and much enhanced mechanical properties due to hindered sliding between the sheets. GO dough is also found to be a good support material for electrocatalysts as it helps to form compliant interface to access the active particles.

Ultratough graphene–black phosphorus films

“…Like bulk materials, 2D films can achieve high toughness via the mechanism of crack arrest or plastic deformation (5). Recently, inspired by the hierarchical microscale/nanoscale structure and abundant interface interactions of natural nacre (6), various interfacial interactions, such as hydrogen bonding, ionic bonding, π-π stacking interactions, and covalent bonding, have been demonstrated to enhance the toughness of graphene-based films (7)(8)(9)(10). These interfacial effects can not only inhibit the crack propagation of graphene films but also effectively improve their plastic deformation.…”

Graphene Oxide “Surfactant”‐Directed Tunable Concentration of Graphene Dispersion

“…Previous studies have shown that GO and carbon nanotubes' dispersions of different concentrations can be divided into four states. [29,52] In our experiment, increasing GO/G concentrations results in a continuous transition between four states, from a dilute dispersion (<10 mg mL −1 ) to a thick paste (10-50 mg mL −1 ), a free-standing gel (50-100 mg mL −1 ), and eventually, a kneadable, playdough-like material (>100 mg mL −1 ). These four states were further transformed into 1D graphene fibers, 2D graphene films, or 3D graphene doughs using various material-processing techniques ( Figure S25, Supporting Information).…”

“…Preparation of a Continuous Transition between Four States: The preparation method was modified from a published article. [29] The preparation method of the diluted dispersion is mentioned above. The thick paste was prepared using high-pressure homogenizers.…”

“…For example, low‐concentration graphene dispersions can be used to make the conductive film and heat dissipation film; [ 24–26 ] high‐concentration graphene dispersions can be spun into high‐performance graphene fibers [ 27,28 ] and ultrahigh concentration graphene dispersions can be used for energy storage. [ 29 ] So far, low‐concentration graphene dispersions are easily obtained using traditional graphene dispersants. However, it is difficult to prepare high‐concentration or ultrahigh concentration graphene dispersions due to the requirement of a high concentration of dispersant, which inevitably can cause the instability of graphene dispersions.…”

“…For example, GO in aqueous solution can exhibit from low‐concentration dispersions to high‐concentration dense solids with the increase of GO concentration. [ 29 ] What is more, GO can be captured by the rising bubble of aqueous solution and then transported to the water surface to activate the interface. [ 36,37 ] Therefore, GO could be expected to act as a special “surfactant” to disperse graphene through π–π interactions between the π‐conjugated basal plane in aqueous solution with high concentration.…”