Fabrication of Graphene‐Covered Micro‐Tubes for Process Intensification

Abstract

Graphene is known for its high surface-area-to-mass ratio. However, for using graphene in engineering processes such as catalytic reactors or heat exchangers, a high surface-area-to-volume ratio is essential. Currently, graphene is only prepared in sheet form, which limits its surface-area-to-volume ratio to around 200 m 2 m À3 . Herein, a technique based on chemical vapor deposition (CVD) to realize graphene on a micro-tubular substrate to not only substantially increase its surface-area-to-volume ratio to a value over 2000 m 2 m À3 but also to eliminate the maldistribution of flows commonly unavoidable in flat-sheet configurations is proposed and demonstrated. This approach uses a dual-layer micro-tubular substrate fabricated by a phase-inversion technique. In the substrate, a thin copper outer layer is used to enable the CVD growth of graphene, and an inner Cu-Fe layer is adopted to provide a strong mechanical support. This approach is feasible to produce graphene with a very high surface-area-to-volume ratio for possible applications in catalytic reactors or heat exchangers, although problems such as inter-diffusion between the two metal layers and defects in graphene need to be addressed. To the best of our knowledge, this study is the first attempt to prepare graphene with high surface-area-to-volume ratios by a CVD route.

Recent Research Progress of Ferrite Multielement Microwave Absorbing Composites

“…Graphite nanosheets with a high aspect ratio can be formed via oxidation, fast expansion at high temperatures, and ultrasonic dispersion. [ 46 ] Huang et al [ 47 ] prepared flake graphite/Co–Zn ferrite composites by coprecipitation method (Figure 2d). Due to good impedance matching, the 10% graphite mass fraction samples showed the best microwave absorption performance.…”

Facile synthesis of single‐nickel‐atomic dispersed mesoporous carbon nanosheets with controllable nitrogen doping for efficient electrochemical CO2 reduction

“…The development of highly active electrocatalysts with good selectivity and stability is very important to promote the technology of electrocatalytic reduction of CO 2 . [4][5][6] Single atom electrocatalyst (SAEC) with atomically dispersed metal sites has attracted a wide range of research hot spots because of its potential unique reaction performance and maximum atomic utilization. [7][8][9] SAEC has demonstrated ex-cellent performance in renewable energy conversion technologies such as water decomposition, CO 2 electroreduction and metal air batteries.…”

“…Using the electric energy generated by renewable energy such as solar energy, wind energy and water conservancy as the driving force to reduce CO 2 into high value‐added chemicals or fuels can solve the high atmospheric CO 2 concentration and realize resource conversion. The development of highly active electrocatalysts with good selectivity and stability is very important to promote the technology of electrocatalytic reduction of CO 2 [4–6] …”