ORALS

SESSION: EnergyTueAM-R11	8th Intl. Symp. on Sustainable Energy Production: Fossil; Renewables; Nuclear; Waste handling , processing, & storage for all energy production technologies; Energy conservation
Tue. 28 Nov. 2023 / Room: DiscoRoom
Session Chairs: Manfred Mauntz; Harold Dodds; Session Monitor: TBA

12:25: [EnergyTueAM03] OS Keynote
ATOMIC HYDROGEN CAN BE GENERATED ELECTROCHEMICALLY AND EFFICIENTLY STORED ON SINGLE LAYER GRAPHENE
Dongping Zhan¹ ; Alexander Oleinick² ; Irina Svir³ ; Zhongqun Tian⁴ ; Christian Andre Amatore⁵ ; ¹Department of Chemistry, Xiamen University, Xiamen, China; ²CNRS, Paris, France; ³CNRS & PSL, Paris, France; ⁴Department of Chemistry, Xiamen Uinversity, Xiamen, China; ⁵CNRS & PSL, French Academy of Sciences, Paris, France;
Paper Id: 175 [Abstract]

Provided that hydrogen can be safely stored and transported at high densities, hydrogen fuel cells would offer highly efficient and completely environmentally friendly solutions for vehicle propulsion. However, neither compressed gas nor liquid hydrogen seems safe enough for everyday use in mobile applications given the risk of accidents and their possible consequences in urban environments related to the high flammability of hydrogen. Therefore, approaches consisting in adsorbing hydrogen atoms (i.e., H rather than H2) appear to offer an excellent solution for its storage in order to propel light and heavy vehicles in urban environments and evidently in between cities. Moreover, compared to solutions based on electric batteries, the ecological and environmental advantage would be obvious.Among the possible materials for storing hydrogen, graphene (Gr) has been suggested to be one of the most promising materials provided that a significant H/Gr weight ratio (ww%) is achieved. Specifically, the US Department of Energy (DOE) has set a target of 5.5 ww% to be achieved by 2025 as a condition for becoming operational. This goal is however extremely far from what can be achieved presently by direct storage of hydrogen molecules (H2) even using single graphene monolayers (SLGr) by physical adsorption because this requires extreme temperatures and pressures given the too weak attractive van der Waals forces and the stability of H2 with respect to its two dissociated atoms (H) and the intrinsic stability of the graphene sp2-carbon resonant network.In this respect, if possible, a stable chemical adsorption of atomic hydrogen on SLGr appears as the Holy Grail with a theoretical maximum storage capacity of 7.7 ww% for Gr-H atomic adducts and optimal safety conditions and performance. However, generating compact Gr-H adducts from H2 again requires extreme temperatures and pressures.On the contrary, hydrogen atoms can easily be produced under mild conditions by electrochemical reduction of common aqueous acidic solutions at the surface of a platinum nanoelectrode placed in straight contact with a SLGr (see adjacent figure) and spread spontaneously on the graphene sheet by reversible adsorption and site to site hopping diffusion at room temperature and atmospheric pressure and without significantly distorting the graphene geometry suggesting a physisorption rather than a covalent bonding [1]. The amount of platinum needed is minimal because it only serves as a catalyst as we were able to demonstrate using dynamic electrochemistry and SERS isotopic Raman spectroscopy. In addition, the process significantly rapid kinetics and its storage capacity (6.6 ww%, viz., more than 85% of the theoretical maximum, being already higher than the target set by DOE [2]) are associated with a substantial stability of the Gr-H layers at room temperature and atmospheric pressure. Furthermore, one would not need to proceed through the intermediacy of hydrogen gas for Gr-H reservoir loading, nor for its unloading to feed fuel cells anodes, removing then two important steps. The authors would like to acknowledge support from joint sino-french CNRS IRP NanoBioCatEchem. CA thanks Xiamen University for his Distinguished Visiting Professor position.

References:
[1] Q. He, L. Zeng, L. Han, M.M. Sartin, J. Peng, J.F. Li, A. Oleinick, I. Svir, C. Amatore, Z.Q. Tian, D. Zhan. Electrochemical Storage of Atomic Hydrogen on Single Layer Graphene J. Am. Chem. Soc., 143, 2021, 18419–18425.
[2] Hydrogen and Fuel Cell Technologies Office. Target Explanation Document: Onboard Hydrogen Storage for Light-Duty Fuel Cell Vehicles. https://www.energy.gov/eere/fuelcells/downloads/target-explanation-document-onboard-hydrogen-storagelight-duty-fuel-cell.

SESSION: OxidativeWedPM3-R1	Ozawa International Symposium (3rd Intl. Symp. on Oxidative Stress for Sustainable Development of Human Beings)
Wed. 29 Nov. 2023 / Room: Dreams 1
Session Chairs: TBA Session Monitor: TBA

17:55: [OxidativeWedPM313] OL
MICRO-ELECTROCHEMISTRY AND RAMAN SPECTROSCOPY FOR SINGLE CELL ANALYSIS
Keke Hu¹ ; Xiang Wang¹ ; Chuan Liu¹ ; Bin Ren¹ ; Andrew Ewing² ; Zhongqun Tian³ ; ¹Xiamen University, Xiamen, China; ²Gothenburg University, gothenburg, Sweden; ³Department of Chemistry, Xiamen Uinversity, Xiamen, China;
Paper Id: 447 [Abstract]

 In multicellular organisms, cells typically communicate by sending and receiving chemical signals. Chemical messengers involved in the exocytosis of neuroendocrine cells or neurons are generally assumed to only originate from the fusing of intracellular large dense core vesicles (LDCVs) or synaptic vesicles with the cellular membrane following stimulation. Accumulated evidence suggests that exosomes - one of the main extracellular vesicles (EVs) - carrying cell-dependent DNA, mRNA and proteins etc. play an essential role in cellular communication. Due to experimental limitations, it has been difficult to monitor the real-time release of individual exosomes, which impedes a comprehensive understanding of the basic molecular mechanisms and the functions of exosomes. We introduce amperometry with microelectrodes to capture the dynamic release of single exosomes from a single living cell, distinguish them from other EVs and identify between the molecules inside exosomes and those secreted from LDCVs. We show that similar to many LDCVs and synaptic vesicles, exosomes released by neuroendocrine cells also contain catecholamine transmitters. This finding reveals long-range chemical communication via exosome-encapsulated chemical messengers and a potential interconnection between the two release pathways, changing the canonical view of exocytosis of neuroendocrine cells and possibly neurons. This defines a new mechanism for chemical communication at the fundamental level and opens new avenues in the research of the molecular biology of exosomes in the neuroendocrine and central nervous systems. In addition, electrochemically renewable surface-enhanced Raman spectroscopy (SERS) microprobes enable real-time dynamic measurement of ROS released from single cells, which lays the foundation for the development of the integrated technology of electrochemistry and Raman.                                                                                                                                                                                                                                                              

References:
[1]K. Hu, K. L. V. Long, F. Wang, X. Zhang, C. Gu, N. Fang, N. T. N. Phan and A. G. Ewing, J. Am. Chem. Soc. 2023, 21, 11499.