14:20 〜 14:35
[BBG01-03] Alkaline hydrothermal vents as chemiosmotic energy convertors
Deep-sea alkaline hydrothermal vents (HVs) are of fundamental interest as the origins of life reactors. Here we conducted a detailed structural and compositional analysis of alkaline HVs collected from Shinkai Seep Field in the southern Mariana forearc, and discovered a hidden property of HVs that originate from the structure.
We find that HVs have a hierarchical nanostructure with periodic layers of aligned nanoparticles. A preferred orientation of {001} crystallographic plane of brucite and alignment of crystals were observed in the inorganic wall of HV, and these alignments were continued for millimeter scale. The driving force behind this remarkable alignment is expected to come from diffusio-phoretic forces originating from the chemical gradient during the formation process. This inorganic wall with directional nanopores separates two solutions, sea water and vent fluid, making the HV exposed to the gradient condition. The walls of HVs are mainly composed of brucite where diverse ions can be easily adsorbed, and this provides the HV to have diverse surface charges depending on the spatial locations and its intercalated species. By using the ordered nanopores and leveraging the surface charges inside the HV, we demonstrate chemical osmotic energy conversion in the HV for the first time. We observe a large osmotically induced current of HV produced from ion gradients. The HV accomplishes osmotic power harvesting by selectively transporting various ions, Na+, K+, Cl-, and proton through the surface of nanopores inside the walls.
Our observations show that aligned complex structures can be formed by simple chemical gradients in natural geological settings, and the structure are further equipped with energy harvesting capability. The research results not only provide a new strategy for the nanostructure fabrication but also give hints to the study of the origin of life by answering how simple inorganic systems can evolve into complex systems and achieve functions.
We find that HVs have a hierarchical nanostructure with periodic layers of aligned nanoparticles. A preferred orientation of {001} crystallographic plane of brucite and alignment of crystals were observed in the inorganic wall of HV, and these alignments were continued for millimeter scale. The driving force behind this remarkable alignment is expected to come from diffusio-phoretic forces originating from the chemical gradient during the formation process. This inorganic wall with directional nanopores separates two solutions, sea water and vent fluid, making the HV exposed to the gradient condition. The walls of HVs are mainly composed of brucite where diverse ions can be easily adsorbed, and this provides the HV to have diverse surface charges depending on the spatial locations and its intercalated species. By using the ordered nanopores and leveraging the surface charges inside the HV, we demonstrate chemical osmotic energy conversion in the HV for the first time. We observe a large osmotically induced current of HV produced from ion gradients. The HV accomplishes osmotic power harvesting by selectively transporting various ions, Na+, K+, Cl-, and proton through the surface of nanopores inside the walls.
Our observations show that aligned complex structures can be formed by simple chemical gradients in natural geological settings, and the structure are further equipped with energy harvesting capability. The research results not only provide a new strategy for the nanostructure fabrication but also give hints to the study of the origin of life by answering how simple inorganic systems can evolve into complex systems and achieve functions.