Pulsed Nanoelectrospray Ionization Boosts Ion Signal in Whole Protein Mass Spectrometry

Electrospray ionisation (ESI) is renowned for its ability to ionise intact proteins for sensitive detection by mass spectrometry (MS). However, the use of a conventional direct current ESI voltage can result in the formation of relatively large initial droplet sizes, which can limit efficient ion desolvation and sensitivity. Here, pulsed nanoESI (nESI) MS using nanoscale emitters with inner diameters of ~250 nm is reported. In this approach, the nESI voltage is rapidly pulsed from 0 to ~1.5 kV with sub-nanosecond rise times, duty cycles from 10 to 90%, and repetition rates of 10 to 350 kHz. Using pulsed nESI, the performance of MS for the detection of intact proteins can be improved in terms of increased ion abundances and decreased noise. The absolute ion abundances and signal-to-noise levels of protonated ubiquitin, cytochrome C, myoglobin, and carbonic anhydrase II formed from standard denaturing solutions can be increased by up to 82% and 154% using an optimal repetition rate of ~200 kHz compared to conventional nESI-MS. Applying pulsed nESI-MS to a mixture of four proteins resulted in the signal for each protein increasing by up to 184% compared to the more conventional nESI-MS. For smaller ions (≤1032 m/z), the signal can also be increased by the use of high repetition rates (200–250 kHz), which is consistent with the enhanced performance depending more on general factors associated with the ESI process (e.g., smaller initial droplet sizes and reduced Coulombic repulsion in the spray plume) rather than analyte-specific effects (e.g., electrophoretic mobility). The enhanced sensitivity of pulsed nESI is anticipated to be beneficial for many different types of tandem mass spectrometry measurements.

Exohedral Functionalization of Fullerene by Substituents Controlling of Molecular Organization for Spontaneous C60 Dimerization in Liquid Crystal Solutions and in a Bulk Controlled by a Potential

A study was carried out on the possibility of orderly and spontaneous dimerization at room temperature of C60 cages in fullerene liquid crystal fullerene dyads (R-C60). For this purpose, dyads with a structural elements feature supporting π-stacking and Van der Waals interactions were tested, due to the presence of terthiophene donors linked through an α-position or dodecyloxy chains. In addition, this possibility was also tested and compared to dyads with shorter substituents and the pristine C60. Research has shown that only in dyads with the features of liquid crystals, π-dimerization of C60 units occurs, which was verified by electrochemical and spectroelectrochemical (ESR) measurements. Cyclic voltammetry and differential voltammetry studies reveal π-dimerization in liquid crystal dyad solution even without the possibility of previous polymerization (cathodic or anodic) under conditions in the absence of irradiation and without the availability of reaction initiators, and even with the use of preliminary homogenization. These dyads undergo six sequential, one-electron reductions of π-dimer (R-C60···C60-R), where two electrons are added successively to each of the two fullerene cages and first form two radical anion system (R-C60)•−(R-C60)•− without pairing with the characteristics of two doublets. Similarly, the second reductions of π-dimer occur at potentials that are close to the reduction potential for the conversion to a system of two triplet dianions (R-C60)2−(R-C60)2−. Electron paramagnetic resonance spectra indicate a significant interaction between C60 cages. Interestingly, the strength of intermolecular bonds is so significant that it can overcome Coulombic repulsion, even with such highly charged particles as dianions and trianions. Such behavior has been revealed and studied so far only in covalently bonded C60 dimers.

Mechanistic Origin of Superionic Lithium Diffusion in Anion-Disordered Li6PS5X Argyrodites

The rational development of fast–ion-conducting solid electrolytes for all-solid-state lithium-ion batteries requires understanding the key structural and chemical principles that give some materials their exceptional ionic conductivities. For the lithium argyrodites Li₆PS₅<i>X</i> (<i>X</i> = Cl,Br,I), the choice of the halide, <i>X</i>, strongly affects the ionic conductivity, with room-temperature ionic conductivities for <i>X</i> = {Cl, Br} ×10³ higher than for <i>X</i> = I. This variation has been attributed to differing degrees of S/<i>X</i> anion disorder. For <i>X</i> = {Cl, Br} the S/<i>X</i> anions are substitutionally disordered, while for <i>X</i> = I the anion sublattice is fully ordered. To better understand the role of substitutional anion disorder in enabling fast lithium-ion transport, we have performed a first-principles molecular dynamics study of Li₆PS₅I and Li₆PS₅Cl, with varying amounts of S/<i>X</i> anion-site disorder. Considering the S/<i>X</i> substructure as a tetrahedrally close-packed lattice, we identify three partially occupied lithium sites that form a contiguous three-dimensional network of face-sharing tetrahedra. The active lithium-ion diffusion pathways within this network, however, depend on the S/<i>X</i> anion configuration. For anion-disordered systems, the active site–site pathways give a percolating three-dimensional diffusion network; whereas for anion-ordered systems, critical site–site pathways are inactive, giving a disconnected diffusion network with lithium motion restricted to local orbits around S positions. Analysis of the lithium substructure and dynamics in terms of the lithium coordination around each sulfur site shows a mechanistic link between substitutional anion disorder and lithium disorder, which enables fast lithium diffusion. In anion-ordered systems the Li-ions are pseudo-ordered, with preferential 6-fold coordination of sulfur sites. Long-ranged lithium diffusion disrupts this SLi₆ pseudo-ordering, and is therefore disfavoured. In anion-disordered systems, a uniform 6-fold S–Li coordination is frustrated due to Li–Li Coulombic repulsion. Lithium positions become disordered, giving a range of S–Li coordination environments. Long-ranged Li diffusion is now possible with no net change in S–Li coordination numbers. This gives rise to superionic lithium transport in the anion-disordered systems, which is effected by a concerted string-like diffusion mechanism.

Mechanistic Origin of Superionic Lithium Diffusion in Anion-Disordered Li6PS5X Argyrodites

The rational development of fast–ion-conducting solid electrolytes for all-solid-state lithium-ion batteries requires understanding the key structural and chemical principles that give some materials their exceptional ionic conductivities. For the lithium argyrodites Li₆PS₅<i>X</i> (<i>X</i> = Cl,Br,I), the choice of the halide, <i>X</i>, strongly affects the ionic conductivity, with room-temperature ionic conductivities for <i>X</i> = {Cl, Br} ×10³ higher than for <i>X</i> = I. This variation has been attributed to differing degrees of S/<i>X</i> anion disorder. For <i>X</i> = {Cl, Br} the S/<i>X</i> anions are substitutionally disordered, while for <i>X</i> = I the anion sublattice is fully ordered. To better understand the role of substitutional anion disorder in enabling fast lithium-ion transport, we have performed a first-principles molecular dynamics study of Li₆PS₅I and Li₆PS₅Cl, with varying amounts of S/<i>X</i> anion-site disorder. Considering the S/<i>X</i> substructure as a tetrahedrally close-packed lattice, we identify three partially occupied lithium sites that form a contiguous three-dimensional network of face-sharing tetrahedra. The active lithium-ion diffusion pathways within this network, however, depend on the S/<i>X</i> anion configuration. For anion-disordered systems, the active site–site pathways give a percolating three-dimensional diffusion network; whereas for anion-ordered systems, critical site–site pathways are inactive, giving a disconnected diffusion network with lithium motion restricted to local orbits around S positions. Analysis of the lithium substructure and dynamics in terms of the lithium coordination around each sulfur site shows a mechanistic link between substitutional anion disorder and lithium disorder, which enables fast lithium diffusion. In anion-ordered systems the Li-ions are pseudo-ordered, with preferential 6-fold coordination of sulfur sites. Long-ranged lithium diffusion disrupts this SLi₆ pseudo-ordering, and is therefore disfavoured. In anion-disordered systems, a uniform 6-fold S–Li coordination is frustrated due to Li–Li Coulombic repulsion. Lithium positions become disordered, giving a range of S–Li coordination environments. Long-ranged Li diffusion is now possible with no net change in S–Li coordination numbers. This gives rise to superionic lithium transport in the anion-disordered systems, which is effected by a concerted string-like diffusion mechanism.

Mechanistic Origin of Superionic Lithium Diffusion in Anion-Disordered Li6PS5X Argyrodites

The rational development of fast–ion-conducting solid electrolytes for all-solid-state lithium-ion batteries requires understanding the key structural and chemical principles that give some materials their exceptional ionic conductivities. For the lithium argyrodites Li₆PS₅<i>X</i> (<i>X</i> = Cl,Br,I), the choice of the halide, <i>X</i>, strongly affects the ionic conductivity, with room-temperature ionic conductivities for <i>X</i> = {Cl, Br} ×10³ higher than for <i>X</i> = I. This variation has been attributed to differing degrees of S/<i>X</i> anion disorder. For <i>X</i> = {Cl, Br} the S/<i>X</i> anions are substitutionally disordered, while for <i>X</i> = I the anion sublattice is fully ordered. To better understand the role of substitutional anion disorder in enabling fast lithium-ion transport, we have performed a first-principles molecular dynamics study of Li₆PS₅I and Li₆PS₅Cl, with varying amounts of S/<i>X</i> anion-site disorder. Considering the S/<i>X</i> substructure as a tetrahedrally close-packed lattice, we identify three partially occupied lithium sites that form a contiguous three-dimensional network of face-sharing tetrahedra. The active lithium-ion diffusion pathways within this network, however, depend on the S/<i>X</i> anion configuration. For anion-disordered systems, the active site–site pathways give a percolating three-dimensional diffusion network; whereas for anion-ordered systems, critical site–site pathways are inactive, giving a disconnected diffusion network with lithium motion restricted to local orbits around S positions. Analysis of the lithium substructure and dynamics in terms of the lithium coordination around each sulfur site shows a mechanistic link between substitutional anion disorder and lithium disorder, which enables fast lithium diffusion. In anion-ordered systems the Li-ions are pseudo-ordered, with preferential 6-fold coordination of sulfur sites. Long-ranged lithium diffusion disrupts this SLi₆ pseudo-ordering, and is therefore disfavoured. In anion-disordered systems, a uniform 6-fold S–Li coordination is frustrated due to Li–Li Coulombic repulsion. Lithium positions become disordered, giving a range of S–Li coordination environments. Long-ranged Li diffusion is now possible with no net change in S–Li coordination numbers. This gives rise to superionic lithium transport in the anion-disordered systems, which is effected by a concerted string-like diffusion mechanism.

Statistical Description of Non-Equilibrium Many-Particle Systems

In most cases, the systems of interacting particles are non-equilibrium. In this review, a new approach based on the application of a non-equilibrium statistical operator is presented, which allows the inhomogeneous distributions of the particles and the temperature to be taken into account. The method uses the saddle-point procedure to find dominant contributions to the partition function of the system and enables all of its thermodynamic parameters to be determined. Probable peculiarities in the behavior of the systems with interaction – such as gravitational systems, systems with Coulombic repulsion, and so forth – under various thermodynamic conditions are predicted. A new approach is proposed to describe non-equilibrium systems in the energy space, which is an extension of the Gibbs approach to macroscopic systems under non-equilibrium conditions. It allows the stationary states and the dynamics of non-equilibrium systems to be described.

Mechanistic Origin of Superionic Lithium Diffusion in Anion-Disordered Li6PS5X Argyrodites

The rational development of fast–ion-conducting solid electrolytes for all-solid-state lithium-ion batteries requires understanding the key structural and chemical principles that give some materials their exceptional ionic conductivities. For the lithium argyrodites Li₆PS₅<i>X</i> (<i>X</i> = Cl,Br,I), the choice of the halide, <i>X</i>, strongly affects the ionic conductivity, with room-temperature ionic conductivities for <i>X</i> = {Cl, Br} ×10³ higher than for <i>X</i> = I. This variation has been attributed to differing degrees of S/<i>X</i> anion disorder. For <i>X</i> = {Cl, Br} the S/<i>X</i> anions are substitutionally disordered, while for <i>X</i> = I the anion sublattice is fully ordered. To better understand the role of substitutional anion disorder in enabling fast lithium-ion transport, we have performed a first-principles molecular dynamics study of Li₆PS₅I and Li₆PS₅Cl, with varying amounts of S/<i>X</i> anion-site disorder. Considering the S/<i>X</i> substructure as a tetrahedrally close-packed lattice, we identify three partially occupied lithium sites that form a contiguous three-dimensional network of face-sharing tetrahedra. The active lithium-ion diffusion pathways within this network, however, depend on the S/<i>X</i> anion configuration. For anion-disordered systems, the active site–site pathways give a percolating three-dimensional diffusion network; whereas for anion-ordered systems, critical site–site pathways are inactive, giving a disconnected diffusion network with lithium motion restricted to local orbits around S positions. Analysis of the lithium substructure and dynamics in terms of the lithium coordination around each sulfur site shows a mechanistic link between substitutional anion disorder and lithium disorder, which enables fast lithium diffusion. In anion-ordered systems the Li-ions are pseudo-ordered, with preferential 6-fold coordination of sulfur sites. Long-ranged lithium diffusion disrupts this SLi₆ pseudo-ordering, and is therefore disfavoured. In anion-disordered systems, a uniform 6-fold S–Li coordination is frustrated due to Li–Li Coulombic repulsion. Lithium positions become disordered, giving a range of S–Li coordination environments. Long-ranged Li diffusion is now possible with no net change in S–Li coordination numbers. This gives rise to superionic lithium transport in the anion-disordered systems, which is effected by a concerted string-like diffusion mechanism.

Black phosphorus quantum dots in inorganic perovskite thin films for efficient photovoltaic application

Black phosphorus quantum dots (BPQDs) are proposed as effective seed-like sites to modulate the nucleation and growth of CsPbI2Br perovskite crystalline thin layers, allowing an enhanced crystallization and remarkable morphological improvement. We reveal that the lone-pair electrons of BPQDs can induce strong binding between molecules of the CsPbI2Br precursor solution and phosphorus atoms stemming from the concomitant reduction in coulombic repulsion. The four-phase transition during the annealing process yields an α-phase CsPbI2Br stabilized by BPQDs. The BPQDS/CsPbI2Br core-shell structure concomitantly reinforces a stable CsPbI2Br crystallite and suppresses the oxidation of BPQDs. Consequently, a power conversion efficiency of 15.47% can be achieved for 0.7 wt % BPQDs embedded in CsPbI2Br film-based devices, with an enhanced cell stability, under ambient conditions. Our finding is a decisive step in the exploration of crystallization and phase stability that can lead to the realization of efficient and stable inorganic perovskite solar cells.

Dispersing nano- and micro-sized portlandite particulates via electrosteric exclusion at short screening lengths

Coulombic repulsion alone is insufficient to mitigate aggregation of suspensions with strong charge screening, while superior interparticle separations are created via steric hindrance when dispersant layer thickness exceeds the Debye length.