Catalysis
We are interested in exploring the applications of graphene oxide and graphene oxide hybrid materials in different catalytic systems such as photocalaysis, electrocatalysis, and carbocatalysis.
Graphene-based photo- and electrocatalsysts
Harnessing the potential of light and current to carry on energy for chemical reactions can be done by developing robust and active catalysts. As we have dealt with synthesizing composites involving graphene, we aim to harness the enhancing activity of synthesized graphene oxide nanocomposites and extend their applications towards photocatalytic and electrocatalytic activities.
The study of photocatalytic activity of certain materials like semiconductor metal oxides or plasmonic metal nanoparticles have been well-studied for over decades now. However, the possible role of graphene towards such properties has not been explored despite its unique activities. Earlier on, we managed to produce graphene–semiconductor hybrid panels (GHP) with controlled graphene thickness, coverage, and size at the semiconductor interface. We observed that photocatalytic enhancement at the interface is dependent on the number of graphene thickness with the GHP composed 3 graphene layers as having the maximum performance observed in photodegradation of methylene blue [1].
We extended the active role of graphene oxide towards electrocatalysis by adding graphene onto metal oxides to study synergystic enhancement. We have synthesized nanostructured cobalt manganese oxide with 3D nanovoids, a known H2O2 degradation electrocatalyst, with graphene oxide (G-CMO) which filled the nanovoids through electrostatic interaction. This creates a heterojunction interface between the two components causing a synergistic sensitivity towards H2O2. The interfacial combination of pure 2D graphene sheets with 3D nanovoids results in the synergistically electrocatalytsis active for hydrogen peroxide sensor applications.[2] Other systems of nanostructured cobalt oxides, gold/Si selective heterojunction also show highly sensitivity and selectivity toward H2O2 sensing. [3] Further four electron oxygen reduction reaction has been successfully demonstrated in a silver-to-iron oxide heterojunction supported on graphene. [4]
Carbocatalysis
Carbocatalysis, the use of metal free carbon based material as a heterogeneous catalyst, is an emerging field. Graphene oxide bears different oxygen groups (ketones, carboxylic acids, epoxides, and alcohols) which may serve as active sites for facilitating organic transformations. We actively investigate the application of highly oxidized graphene oxide as catalyst for organic compound synthesis with potential medicinal applications.
References/Related Works:
[1] Kuo, C.-C.; Chen, C.-H.* Graphene thickness-controlled photocatalysis and surface enhanced Raman scattering. Nanoscale 6, 12805 (2014)
[2] Lan, W.-J.; Chen, C.-H.* Hybridization of Graphene in 3D Complex Nanovoids: Synergistic Nanocomposites for Electrocatalytic Reduction of Hydrogen Peroxide. Electrochim. Acta 180, 1014 (2015)
[3] Huang, C.-W.; Valinton, J. A. A.; Hung, Y.-J.; Chen, C.-H.* Facet-specific Heterojunction in Gold-decorated Pyramidal Silicon for Electrochemical Hydrogen Peroxide Sensing. Sens. Actuators B: Chem. 226, 463 (2018)
[4] Chen, W.-Q.; Chung, M.-C.; Valinton, J. A. A.; Penaloza Jr, D.P.; Chuang, S.-H.; Chen, C.-H.* Heterojunctions of Silver–iron Oxide on Graphene for Laser-coupled Oxygen Reduction Reactions. Chem. Commun. 54, 7900 (2018)
[5 ]Chu, Y.-L.; Chen, Y.-H.; Li, W.-C.; Chu, J.-H.; Chen, C.-H.*; Chiang, M.-C.* Mechanistic Insights into Light-Driven Graphene-Induced Peroxide Decomposition: Radical Generation and Disproportionation. Chem. Commun. 52, 9291 (2016)