Heterogeneous Catalysis of Carbon Species Formation in Space

The formation of primary nanocarbon materials (PAHs, fullerenes, CNT, etc.) in stellar outflows from carbon-rich stars is well-known and expected to follow gas-phase soot formation mechanisms akin to those observed in low-oxygen flames in the laboratory. However, there are other well-established chemistries that can produce such materials through catalytic processes involving small saturated (e.g., [1]) and unsaturated (e.g., [2]) hydrocarbons as a found in aged, cold dense environments. The catalytic centres in such chemistry are commonly first row transition elements, in particular iron and nickel clusters. Moreover, there are even reports of aromatic molecule formation from acetylene on simple olivine mimic surfaces [3] without any catalytic metal participation. There is therefore a strong case for investigations of the surface-promoted formation of these materials in relation to a range of astrophysical environments from warming cores and corinos, through protoplanetary disks to evolved stellar systems and exo-planetary atmospheres.

In this presentation, we will outline the activities planned in a new programme entitled Astrocatalysis: In Operando Studies of Catalysis and Photocatalysis of Space-abundant Transition Metals funded by the UK EPSRC exploring the role of transition metal catalysis in astrophysical environments. As part of that programme, we will integrate experimental surface science studies of nanocarbon formation on small atom number (1-3) molecular species and on larger metallic clusters in the Astrochemistry Group at Heriot-Watt University (HWU) with computational investigations on these systems through collaboration with the Rimola Group at the Universitat Autonoma de Barcelona.

Acknowledgements
JA acknowledges EPSRC for a DTP Studentship to support his PhD studies. VC and MRSM acknowledge the support of the EPSRC through responsive mode grant no. EP/W023024/1 Astrocatalysis: In Operando Studies Of Catalysis And Photocatalysis Of Space-abundant Transition Metals. AR is indebted to the EU Horizon 2020 research and innovation programme through the European Research Council (ERC) project "Quantum Chemistry on Interstellar Grains” (QUANTUMGRAIN, Grant No. 865657) and to the MICINN for the project PID2021-126427NB-I00.

References
[1] M. Pudukudy, Z. Yaakoba, M. Z. Mazukia, M. S. Takriff, and S. S. Jahayaca, Applied Catalysis B: Environmental, 218, 298-316 (2017)
[2] W. J. Lee, S. S. A. Syed-Hassan, and C. -Z. Li, Fuel Processing Technology, 104, 319-324 (2012)
[3] V. L. Frankland, A. D. James, J. D. C. Sánchez, T. P. Mangan, K. Willacy, A. R. Poppe, and J. M. C. Plane, Icarus, 278, 88-99 (2016)