Graphene is a two-dimensional material that offers a unique combination of low density, exceptional mechanical properties, large surface area and excellent electrical conductivity. Recent progress has produced bulk 3D assemblies of graphene, such as graphene aerogels, but they possess purely stochastic porous networks, which limit their performance compared with the potential of an engineered architecture. Here we report the fabrication of periodic graphene aerogel microlattices, possessing an engineered architecture via a 3D printing technique known as direct ink writing. The 3D printed graphene aerogels are lightweight, highly conductive and exhibit supercompressibility (up to 90% compressive strain). Moreover, the Young's moduli of the 3D printed graphene aerogels show an order of magnitude improvement over bulk graphene materials with comparable geometric density and possess large surface areas. Adapting the 3D printing technique to graphene aerogels realizes the possibility of fabricating a myriad of complex aerogel architectures for a broad range of applications.

Graphene is an atomically thin, two-dimensional (2D) carbon material that offers a unique combination of low density, exceptional mechanical properties, thermal stability, large surface area, and excellent electrical conductivity. Recent progress has resulted in macro-assemblies of graphene, such as bulk graphene aerogels for a variety of applications. However, these three-dimensional (3D) graphenes exhibit physicochemical property attenuation compared to their 2D building blocks because of one-fold composition and tortuous, stochastic porous networks. These limitations can be offset by developing a graphene composite material with an engineered porous architecture. Here, we report the fabrication of 3D periodic graphene composite aerogel microlattices for supercapacitor applications, via a 3D printing technique known as direct-ink writing. The key factor in developing these novel aerogels is creating an extrudable graphene oxide-based composite ink and modifying the 3D printing method to accommodate aerogel processing. The 3D-printed graphene composite aerogel (3D-GCA) electrodes are lightweight, highly conductive, and exhibit excellent electrochemical properties. In particular, the supercapacitors using these 3D-GCA electrodes with thicknesses on the order of millimeters display exceptional capacitive retention (ca. 90% from 0.5 to 10 A·g(-1)) and power densities (>4 kW·kg(-1)) that equal or exceed those of reported devices made with electrodes 10-100 times thinner. This work provides an example of how 3D-printed materials, such as graphene aerogels, can significantly expand the design space for fabricating high-performance and fully integrable energy storage devices optimized for a broad range of applications.

We demonstrate a novel preparation method for the formation of metallic nanowires from gold, platinum, and silver using mesoporous silica SBA-15 as a template. SBA-15 controls the size and the growth direction of the nanowires and also prevents bulk aggregation of the metal. Nanowires can be isolated from the silica framework by treatment with HF.

We have investigated the phase transition between two distinct mesoporous silicas:  SBA-15, comprising a hexagonally packed arrangement of cylindrical pores (6−12 nm in diameter), and mesocellular silica foams (MCF), consisting of spherical voids (22−42 nm in diameter) interconnected by “windows” of ∼10 nm. Both SBA-15 and MCF are formed using an amphiphilic triblock copolymer (Pluronic P123) as a template. The synthesis conditions for the two materials are identical, except substantial trimethylbenzene is added to form MCF. We find that the phase transition occurs at an oil−polymer mass ratio of 0.2−0.3. Although the pore structures and pore sizes change dramatically, the mean surface curvature of the system remains essentially the same throughout the transition.