Harvesting Electrical Power during Carbon Capture using Various Amine Solvents.

There exists an urgent demand for the advancement of technologies that reduce and capture carbon dioxide (CO2) emissions to mitigate anthropogenic contributions to climate change. This paper compares the maximum power densities achieved from the combination of reverse electrodialysis (RED) with carbon capture (CC) using various CC solvents. Carbon capture reverse electrodialysis (CCRED) harvests energy from the salinity gradients generated from the reaction of CO2 with specific solvents, generally amines. To eliminate the requirement of freshwater as an external resource, we took advantage of a semiclosed system that would allow the inputs to be industrial emissions and heat and the outputs to be electrical power, clean emissions, and captured CO2. We assessed the power density that can be attained using CCRED with five commonly studied CC solvents: monoethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), 2-amino-2-methyl-2-propanol (AMP), and ammonia. We achieved the highest power density, 0.94 W m-2 cell-1, using ammonia. This work provides a foundation for future iterations of CCRED that may help to incentivize adoption of CC technology.

One-Step Ring Opening Metathesis Block-Like Copolymers and their Compositional Analysis by a Novel Retardation Technique.

Using a one-step synthetic route for block copolymers avoids the repeated addition of monomers to the polymerization mixture, which can easily lead to contamination and, therefore, to the unwanted termination of chain growth. For this purpose, monomers (M1-M5) with different steric hindrances and different propagation rates are explored. Copolymerization of M1 (propagating rapidly) with M2 (propagating slowly), M1 with M3 (propagating extremely slowly) and M4 (propagating rapidly) with M5 (propagating slowly) yielded diblock-like copolymers using Grubbs' first (G1) or third generation catalyst (G3). The monomer consumption was followed by 1 H NMR spectroscopy, which revealed vastly different reactivity ratios for M1 and M2. In the case of M1 and M3, we observed the highest difference in reactivity ratios (r1 =324 and r2 =0.003) ever reported for a copolymerization method. A triblock-like copolymer was also synthesized using G3 by first allowing the consumption of the mixture of M1 and M2 and then adding M1 again. In addition, in order to measure the fast reaction rates of the G3 catalyst with M1, we report a novel retardation technique based on an unusual reversible G3 Fischer-carbene to G3 benzylidene/alkylidene transformation.

Unidirectional supramolecular self-assembly inside nanocorrals via in situ STM nanoshaving.

Self-assembly of an alkylated diacetylene derivative is spatially confined via in situ scanning tunneling microscopy (STM) nanoshaving inside covalently modified highly ordered pyrolytic graphite (CM-HOPG). In contrast to unconstrained self-assembly that occurs randomly along three thermodynamically equivalent surface lattice directions, spatially confined assemblies are shown to form along chosen substrate orientations. Experimental statistics suggest two mechanisms for breaking the rotational degeneracy of the surface. First, the assembly orientation is biased via lateral confinement inside nanocorrals that do not match the substrate symmetry. Second, an interaction between the assembling molecules and the STM tip during nanoshaving guides 2D crystal nucleation and growth. The results presented here open new possibilities to regulate and orient self-assembled architectures via in situ nanomechanical manipulation techniques and provide mechanistic insights into the process.