Toward Small-Diameter Carbon Nanotubes Synthesized from Captured Carbon Dioxide: Critical Role of Catalyst Coarsening

Small-diameter carbon nanotubes (CNTs) often require increased sophistication and control in synthesis processes, but exhibit improved physical properties and greater economic value over their larger-diameter counterparts. Here, we study mechanisms controlling the electrochemical synthesis of CNTs from the capture and conversion of ambient CO₂ in molten salts and leverage this understanding to achieve the smallest-diameter CNTs ever reported in the literature from sustainable electrochemical synthesis routes, including some few-walled CNTs. Here, Fe catalyst layers are deposited at different thicknesses onto stainless steel to produce cathodes, and atomic layer deposition of Al₂O₃ is performed on Ni to produce a corrosion-resistant anode. Our findings indicate a correlation between the CNT diameter and Fe metal layer thickness following electrochemical catalyst reduction at the cathode-molten salt interface. Further, catalyst coarsening during long duration synthesis experiments leads to a 2× increase in average diameters from 3 to 60 min durations, with CNTs produced after 3 min exhibiting a tight diameter distribution centered near ∼10 nm. Energy consumption analysis for the conversion of CO₂ into CNTs demonstrates energy input costs much lower than the value of CNTsa concept that strictly requires and motivates small-diameter CNTsand is more favorable compared to other costly CO₂ conversion techniques that produce lower-value materials and products

The potential effect of a 100-year pluvial flood event on metro accessibility and ridership: A case study of central Shanghai, China

The Shanghai Metro constitutes a sizeable share of the municipal public transit. This paper presents a gravity-based approach for evaluating the potential effect of a 100-year pluvial flood (PF) event on metro accessibility and ridership. Since physical geographers have examined PF hazards and human geographers have analyzed metro accessibility separately, we seek to fill the research gap through examining metro accessibility and ridership together under adverse circumstances. To this end, road inundations are initially modeled by FloodMap-HydroInundation2D. Accessibility to metro stations by three access modes (walking, cycling, and driving) is measured through three impedance functions (inverse power, negative exponential, and modified Gaussian). Ridership measure mainly concerns the distance-decay effect on stations' attraction for passengers. The results indicate that inundation depth on more than 95% of the road links would reach 10–20 cm in the PF scenario, and road links with inundation deeper than 20 cm and 30 cm account for 47% and 15% of the road network respectively, which imposes notable restrictions on access journeys especially by cycling and driving. Metro accessibility in central Shanghai is quite equitable, even in the PF scenario. 87% of the communities can access the metro stations at the medium and medium-high accessibility levels in the normal scenario, but 80% can access only at the low and medium levels in the PF scenario. Due to the inaccessibility of neighboring station(s) in the PF scenario, 15 more stations may face the challenge of serving more than 50,000 passengers, which is much larger than their normal ridership. These findings have important implications for the formulation of safer usage of public transport in the face of heavy rainfall and associated flood events

Determination and Correlation of Dipyridamole p‑Toluene Sulfonate Solubility in Seven Alcohol Solvents and Three Binary Solvents

The solubility of dipyridamole p-toluene sulfonate in seven monosolvents (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol, 2-butanol) and three different binary solvents (methanol + ethanol, methanol + 1-propanol, methanol + 1-butanol) was measured by a gravimetric method at temperatures ranging from 288.15 to 328.15 K. The experimental results indicate that the solubility of dipyridamole p-toluene sulfonate increases with increasing temperature while showing negative correlation with the mole fraction of organic solvents (ethanol, 1-propanol, 1-butanol) at a given temperature in binary solvents. The Apelblat model, the CNIBS/R-K model, and the modified version of Jouyban-Acree models (the Apel-JA equation) were used to correlate the experimental data, and the calculated results of above models were found to agree well with the experimental data

Determination and Correlation of Dipyridamole p‑Toluene Sulfonate Solubility in Seven Alcohol Solvents and Three Binary Solvents

The solubility of dipyridamole p-toluene sulfonate in seven monosolvents (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol, 2-butanol) and three different binary solvents (methanol + ethanol, methanol + 1-propanol, methanol + 1-butanol) was measured by a gravimetric method at temperatures ranging from 288.15 to 328.15 K. The experimental results indicate that the solubility of dipyridamole p-toluene sulfonate increases with increasing temperature while showing negative correlation with the mole fraction of organic solvents (ethanol, 1-propanol, 1-butanol) at a given temperature in binary solvents. The Apelblat model, the CNIBS/R-K model, and the modified version of Jouyban-Acree models (the Apel-JA equation) were used to correlate the experimental data, and the calculated results of above models were found to agree well with the experimental data

Ultralow Frequency Electrochemical–Mechanical Strain Energy Harvester Using 2D Black Phosphorus Nanosheets

Advances in piezoelectric or triboelectric materials have enabled high-frequency platforms for mechanical energy harvesting (>10 Hz); however, virtually all human motions occur below 5 Hz and therefore limits application of these harvesting platforms to human motions. Here we demonstrate a device configuration based on sodiated black phosphorus nanosheets, or phosphorene, where mechanoelectrochemical stress–voltage coupling in this material is capable of efficient energy harvesting at frequencies as low as 0.01 Hz. The harvester is tested using both bending and pressing mechanical impulses with peak power delivery of ∼42 nW/cm² and total harvested energy of 0.203 μJ/cm² in the bending mode and ∼9 nW/cm² and 0.792 μJ/cm² in the pressing mode. Our work broadly demonstrates how 2D materials can be effectively leveraged as building blocks in strategies for efficient electrochemical strain energy harvesting

Sulfur Nanocrystals Confined in Carbon Nanotube Network As a Binder-Free Electrode for High-Performance Lithium Sulfur Batteries

A binder-free nano sulfur–carbon nanotube composite material featured by clusters of sulfur nanocrystals anchored across the superaligned carbon nanotube (SACNT) matrix is fabricated via a facile solution-based method. The conductive SACNT matrix not only avoids self-aggregation and ensures dispersive distribution of the sulfur nanocrystals but also offers three-dimensional continuous electron pathway, provides sufficient porosity in the matrix to benefit electrolyte infiltration, confines the sulfur/polysulfides, and accommodates the volume variations of sulfur during cycling. The nanosized sulfur particles shorten lithium ion diffusion path, and the confinement of sulfur particles in the SACNT network guarantees the stability of structure and electrochemical performance of the composite. The nano S-SACNT composite cathode delivers an initial discharge capacity of 1071 mAh g^–1, a peak capacity of 1088 mAh g^–1, and capacity retention of 85% after 100 cycles with high Coulombic efficiency (∼100%) at 1 C. Moreover, at high current rates the nano S-SACNT composite displays impressive capacities of 1006 mAh g^–1 at 2 C, 960 mAh g^–1 at 5 C, and 879 mAh g^–1 at 10 C

Melting Behavior of Zipper-Structured Lipopeptides in Lipid Bilayer

A zipper-structured lipopeptide is expected to play a role of “intelligent valve” in the lipid bilayer. In this paper, a series of zipper-structured lipopeptides have been designed for preparing thermocontrollable hybrid liposomes. Their conformational transition as a function of temperature in lipid bilayer has been investigated for understanding the influences of molecular structure and bilayer property on biofunction. The melting temperatures <i>T</i>_m of the lipopeptides have been found to depend on their molecular structures. When the lipopeptides have been doped in bilayer, an increase of size of alkyl chain increases the stability of the α-helix resulting in a decrease in fluidity of lipid bilayer. However, an increase of amino groups at N-terminal is found to decrease the stability of the spatial structure. The thermocontrollability of the “valve” in lipid bilayer is confirmed by drug release experiments under different temperatures. Meanwhile, effects of bilayer properties on the thermosensitivity of lipopeptides have also been investigated. Results show the <i>T</i>_m of lipopeptide doped in bilayer decreases with the increase of membrane fluidity. Furthermore, the reversibility of the thermocontrolled “valve” is also proven by release drug under intermittent temperatures. It could be concluded that the molecular structure of the lipopeptide, as well as the property of bilayer, give great influence on the biofunction of the hybrid liposomes