Industrially benign super-compressible piezoresistive carbon foams with predefined wetting properties: from environmental to electrical applications

Abstract

In the present work electrically conductive, flexible, lightweight carbon sponge materials derived from open-pore structure melamine foams are studied and explored. Hydrophobic and hydrophilic surface properties - depending on the chosen treatment conditions - allow the separation and storage of liquid chemical compounds. Activation of the carbonaceous structures substantially increases the specific surface area from ~4 m2g−1 to ~345 m2g−1, while retaining the original three-dimensional, open-pore structure suitable for hosting, for example, Ni catalyst nanoparticles. In turn the structure is rendered suitable for hydrogenating acetone to 2-propanol and methyl isobutyl ketone as well for growing hierarchical carbon nanotube structures used as electric double-layer capacitor electrodes with specific capacitance of ~40 F/g. Mechanical stress-strain analysis indicates the materials are super-compressible (>70% volume reduction) and viscoelastic with excellent damping behavior (loss of 0.69 ± 0.07), while piezoresistive measurements show very high gauge factors (from ~20 to 50) over a large range of deformations. The cost-effective, robust and scalable synthesis - in conjunction with their fascinating multifunctional utility - makes the demonstrated carbon foams remarkable competitors with other three-dimensional carbon materials typically based on pyrolyzed biopolymers or on covalently bonded graphene and carbon nanotube frameworks.

Catalytic Hydrogenation of d-Xylose Over Ru Decorated Carbon Foam Catalyst in a SpinChem® Rotating Bed Reactor

“…The aforementioned characteristics allow the carbon foam to be adapted to various purposes, ranging from electrical to chemical applications. In our previous study we have shown the possibility to use these carbon foams as catalyst support in a gas phase reaction among other applications [13]. In this study, the carbon foam again demonstrates its applicability as a support for ruthenium clusters in three-phase hydrogenation of D-xylose.…”

“…[13]. Briefly, melamine-based polymer foam (BASF, Basotect Ò G, used as received) was pyrolyzed at 800°C (1 h with the ramping rate of 1°C/min) in a quartz reactor under N 2 flow (50 ml/min), followed by an activation process at 800°C with CO 2 (1 ml/min, 2 % by volume in N 2 ) for 2 h. After completed pyrolysis/activation process, the system was allowed to cool to ambient temperature.…”

“…Unfortunately, screens with very small holes will result in the blocking of the screen rendering the SRBR concept unpractical. Consequently, our monolith-type, flexible Ru/CF catalyst with high mechanical strength [13] can be seen as a solution. First, because of its flexibility, higher Ru/CF catalyst loading (very low density of around 8 mg cm -3 ) can be obtained by pressing the foam into the SRBR.…”

“…1a) during the hydrogenation D-xylose experiments. Originating from melamine foam, the 3D-structured carbon foam possesses a lot of interesting properties such as good electrical conductivity, low density, high compressibility and surface area as well as high concentration of functional groups such as carboxylic and hydroxyl groups on its surface thus rendering the immobilization of metal nano-particles straightforward [13]. The aforementioned characteristics allow the carbon foam to be adapted to various purposes, ranging from electrical to chemical applications.…”

Robust hierarchical 3D carbon foam electrode for efficient water electrolysis

“…S1a) 19 . Additionally, due to the simple and cost effective synthesis methods (pyrolysis and activation), the melamine based carbon foam has great potential for large-scale applications.…”