Fast Capture, Collection, and Targeted Transfer of Underwater Gas Bubbles Using Janus-Faced Carbon Cloth Prepared by a Novel and Simple Strategy

Abstract

Transportation of bubbles in liquids in a controlled fashion is a challenging task and an important subject in numerous industrial processes, including elimination of corrosive gas bubbles in fluid transportation pipes, water electrolysis, reactions between gases, heat transfer, etc. Using superaerophilic surfaces represents a promising solution for bubble movement in a programmed way. Here, a novel and low-cost method is introduced for the preparation of Janus-faced carbon cloth (Janus-CC) using poly­(dimethylsiloxane) (PDMS) coating and then burning one side of the carbon cloth/PDMS on an alcoholic burner. The results show that the superhydrophobic face behaves as a superaerophilic surface, while the superhydrophilic side is aerophobic underwater. Subsequently, the Janus-CC is applied for pumpless transport of underwater gas bubbles even under harsh conditions. The movement of gas bubbles on the surface of the Janus-CC is interpreted based on the formed gaseous film on the aerophilic side of the Janus-CC. Various applications of the prepared Janus-CC for underwater bubble transportation, such as underwater gas distributor, gas collector membrane, gas transport for chemical reactions, unidirectional gas membrane, and elimination of gas bubbles in transport pipe, are presented.

Enhanced Oxygen Accumulation for a Hydrophobic Cathode in Lean-Oxygen Seawater Batteries

“…Due to its operating conditions in an immersed lean-oxygen environment of the gas-consuming cathode, the discharge voltage and output power of SWBs are low caused by the limited oxygen reduction reaction (ORR) electron transfer and oxygen mass transfer kinetics. − Concerning the sluggish ORR kinetics, much effort has been devoted to improving the catalysts’ intrinsic activity by introducing more active sites or manipulating their electronic structure. − Our group has employed strategies of charge separation and electronic axial stretching to design oxygenophilic electrocatalysts for lean-oxygen environments. − Although the study of the catalyst on the atomic or electronic scale has improved the battery performance significantly, more efficient oxygen accumulation on the catalyst is urgently required in such a lean-oxygen seawater environment. Therefore, understanding the ORR process at the seawater/cathode interface from an electrochemical reactor perspective is crucial for gaining deeper insights into its oxygen transfer kinetics. − Empirical evidence from related fields has underscored the significant promise of surface engineering techniques in augmenting the efficiency of underwater gas-involving reactions. − This is particularly important for facilitating oxygen mass transfer by regulating the interfacial structure and properties. Wettability control strategy provides a unique pathway for underwater systems that require gas-involved reactions and has broad applications across various fields, including gas sensors, CO 2 reduction reactions (CO 2 RR), , nitrogen reduction reactions (NRR), metal–air batteries, , and fuel cells .…”

Multifunctional polyimide-based femtosecond laser micro/nanostructured films with triple Janus properties

“…Also, more diverse and complex applications require multifunctional surfaces [13][14][15][16] with two or more distinct physical properties. These "Janus films" [17][18][19][20][21][22] can possess unique structures, which allow their two sides to exhibit different properties and charac-teristics, resulting in a wide range of functionalities making them useful in many applications. For example, Janus film properties can combine multiple aspects of traditional functional materials, such as waterproofing, [23][24][25] breathability, 26,27 and heat insulation, 28,29 but through material selection and design, they can also possess special functions including optical, [30][31][32][33] electrical, [34][35][36] magnetic 37,38 or acoustic 39,40 properties.…”

Passive Automatic Switch Relying on Laplace Pressure for Efficient Underwater Low-Gas-Flux Bubble Energy Harvesting

“…For example, a bubble on the surface of a hydrophobic conical thorn can spontaneously move from the tip to the root of the thorn driven by Laplace pressure. , Similarly, a bubble attached to the surface of a wedge-shaped hydrophobic structure can automatically move from the narrow end to the wide end. − In neither of these cases can the bubble move in the opposite direction. In addition to geometric gradients, wettability gradients can also generate a Laplace pressure on the surface of a bubble, enabling it to spontaneously move from the hydrophilic (aerophobic) side to the hydrophobic (aerophilic) side without reverse transport. , A Janus membrane with one hydrophilic surface and one hydrophobic surface is able to achieve unidirectional penetration of bubbles. − In the interface mechanical behaviors of these bubble-manipulation structures, Laplace pressure drives the bubbles to automatically move along the direction of geometric or wettability gradient, and it prevents reverse movement. Although these bubble-manipulation structures can achieve passive self-transport, all of them cannot realize a switching operation for bubble accumulation and concentrated release.…”