The Journal of Physical Chemistry Letters最新文献

CuInP₂S₆ (CIPS) is a two-dimensional van der Waals material that is ferrielectric at room temperature (T_C of 315 K). This T_C can be raised up to 335 K by synthesizing CIPS with Cu deficiencies (Cu_1–xIn_1+x/3P₂S₆, CIPS-IPS), which causes the material to self-segregate into separate CIPS and In_4/3P₂S₆ (IPS) domains. Using Brillouin light scattering microscopy, we examine the phonon spectra of CIPS, IPS, and CIPS-IPS (x = 0.2, 0.3, 0.5, 0.6, 0.8) at room temperature and across T_C. We observe unique longitudinal acoustic (LA) phonon signatures for pure CIPS and IPS; however, the CIPS-IPS samples host LA phonons corresponding to both CIPS and IPS, due to the formation of the in-plane heterostructures. These phonons soften in CIPS and CIPS-IPS near their respective values of T_C, and there are sharp discontinuities in the phonon frequencies at T_C, indicative of the ferrielectric-to-paraelectric phase transition. The temperature and width of this transition is dependent on composition, with pure CIPS showing the sharpest transition at 40.0 °C, while reduction in Cu leads to broadening and an increased T_C, caused by the strain exerted on the CIPS domains by the IPS domains. This strain also manifests in IPS domains, as the phonons soften to accommodate the structural change in the CIPS domains.

Perylene-based organic anodes, as an alternative to metallic Zn for aqueous Zn-ion batteries, store Zn²⁺ through a Zn enolate coordination mechanism, which potentially bypasses challenges such as dendrite and hydroxide formation associated with a Zn anode. However, organic anodes exhibit low electrical conductivity and show a low rate performance. Molecular aggregation of conjugated aromatics plays a key role in the electrical conductivity of this class of material, and it is important to understand their impact on the battery rate performance. In this work, we combined electrochemistry and in situ attenuated total reflection infrared characterization to demonstrate the dominating role of aggregates in perylene-based electrodes in the enhancement of the electrode kinetics. We demonstrated the use of noncovalent interaction to form a supermolecular network that exhibits more than 4 orders of magnitude increase in the electron transfer rate, and provides nearly doubled charge storage capacity. The aggregation of perylene units was driven by π–π stacking and hydrogen bonding between the active material and a mediator, ethylene diamine. We showed that, in practice, this additive-mediated aggregation can occur during solution process at a moderate temperature.

Solvents can profoundly influence reaction outcomes and mechanisms through the solvation of the reaction components. Here, we determined the Ni–O bond heterolytic energy [ΔG_het(Ni–O)] of nickel phenolates using dimethyl sulfoxide (DMSO) and acetonitrile (MeCN) as solvents. The results showed that ΔG_het(Ni–O) in DMSO is larger than that in MeCN. This counterintuitive thermodynamics suggests that low-polarity MeCN can stabilize ionic species, generated from Ni–O bond heterolysis, more effectively than high-polarity DMSO, challenging the conventional notion of solvent polarity effects. Further experimental and theoretical studies elucidated the origin of this unique solvent effect, which cannot be observed in Pd–O systems. This work underscores the crucial role of solvents in modulating the stability of transition metal species, which can even reverse reaction thermodynamics.

In alloy systems, the strain and ligand effects are prevalent, but it is challenging to study the impact of either on the material structure independently. We conducted high-energy-resolution fluorescence detection (HERFD) X-ray absorption spectroscopy (XAS) and resonant X-ray emission spectroscopy (XES)/resonant inelastic X-ray scattering (RIXS) spectroscopy on a Pt₃Mg alloy-based carbon material (Pt₃Mg–N–C). By introducing a size-comparable atom, the strain effect is minimized, allowing the Pt d-density of states (d-DOS) to be primarily affected by the ligand effect. The experimental results reveal that Pt gains electrons in Pt₃Mg–N–C, exhibiting a more symmetric d-band shape and a downshift of the d-band center compared to Pt metal, which is further confirmed by density functional theory (DFT) calculations. The correlation between the Pt d-DOS and oxygen reduction reaction (ORR) activity is also discussed.

Accelerating quantum dynamical simulations with quantum computing has received considerable attention but remains a significant challenge. In variational quantum algorithms for quantum dynamics, designing an expressive and shallow-depth parametrized quantum circuit (PQC) is a key difficulty. Here, we propose a multiset variational quantum dynamics algorithm (MS-VQD) tailored for nonadiabatic dynamics involving multiple electronic states. The MS-VQD employs multiple PQCs to represent the electronic–nuclear coupled wave function, with each circuit adapting to the motion of the nuclear wavepacket on a specific potential energy surface. By simulating excitation energy transfer dynamics in molecular aggregates described by the Frenkel–Holstein model, we demonstrate that the MS-VQD achieves the same accuracy as the traditional VQD while requiring significantly shallower PQCs. Notably, its advantage increases with the number of electronic states, making it suitable for simulating nonadiabatic quantum dynamics in complex molecular systems.