The Journal of Physical Chemistry Letters最新文献

Synergistic therapy combining photothermal therapy and photodynamic therapy is considered to be a promising approach to treat cancer, but the precise temperature control of deep tissue remains a great challenge in achieving effective treatment. Herein, a two-dimensional Bi₂WO₆:Nd³⁺/Yb³⁺/Er³⁺@MoS₂ nanoplatform with photothermal and photodynamic functions was constructed, where semiconductor MoS₂ serves as both a photothermal agent and a photosensitizer. The photothermal conversion performance and the reactive oxygen species generation capacity of the nanoplatform were validated under the irradiation of 808 nm laser; meanwhile, the two sets of luminescence intensity ratios (I_Yb3+/I_Nd3+ and I_Er3+/I_Nd3+) in the biological window region were selected as near-infrared temperature probes to monitor the heat generated during the photosynergistic process in real time. The feasibility of nanoplatform as an intratissue temperature probe and antibacterial agent was further assessed by vitro experiments, which provides an idea for designing multifunctional photosynergistic therapy nanoplatform.

PbS quantum dots (QDs) are attractive near-infrared (NIR) materials, but traditional synthetic methods require inert atmosphere and/or high temperature. Herein we develop a facile, room-temperature synthetic route for in situ halide passivated PbS QDs through controllable reactions between lead halide, N,N′-diphenyl thiourea, and oleyamine (OLA) in toluene. Contrast experiments and theoretical calculations reveal that the OLA plays a bifunctional role as a mild base to initiate the formation of PbS monomers and as a dynamic ligand to control the crystallization of PbS QDs and further ligand exchange. The oleic acid-capped PbS QDs exhibit high photoluminescence quantum yields up to 45%. The scaled-up synthesis on multigram scales shows great batch-to-batch consistency. We further demonstrate high-power NIR light-emitting diodes using the PbS QDs as color converters, delivering NIR optical power of 9.2 mW at 160 mA. This work provides a simple and versatile synthetic route for high-quality PbS QDs and boosts the applications of NIR materials.

Pt catalyst has been considered as the state-of-the-art catalyst for hydrogen evolution reaction (HER) under acid condition. However, its catalytic kinetics under alkaline conditions is not well-understood. Herein, we report a Ni–Pt(SAs) (SAs = single atoms) catalyst with Pt atomically dispersed in a Ni matrix, and it possesses an impressive HER performance with an overpotential as low as 210 mV at 500 mA cm^–2 in strong alkaline electrolyte (7 M KOH), which is much higher than Pt nanoparticle-modified Ni catalyst (Ni–Pt(NPs)). Kinetics analysis reveals that Pt doping in the Ni matrix can accelerate the Volmer step on the Ni–Pt surface. Moreover, Ni–Pt(SAs) displays a more favorable kinetics for H₂ formation reaction at high current density than Ni–Pt(NPs). Theoretical calculations reveal that atomically dispersed Pt weakens the adsorption of both H and OH on the surface of Ni–Pt electrode and promotes H₂ formation from surface H on Ni–Pt(SAs).

The cryopreservation of cells, tissue, and organs is essential in both fundamental research and practical applications, such as modern regenerative medicine and technological applications. However, the formation of ice crystals during ice recrystallization can have harmful or even fatal effects on biological systems. To address this challenge, we explore the ice recrystallization inhibition (IRI) activity of two natural silk proteins of Bombyx mori, fibroin and sericin. We found that silk fibroin (SF) had higher ice recrystallization inhibition activity than silk sericin (SS). Moreover, SF aqueous solutions perform better in inhibiting ice recrystallization than SF phosphate-buffered saline solutions. Sum-frequency generation spectroscopy shows that stronger electrostatic interactions are responsible for the higher IRI ability of SF. This work is significant for broadening the applications of silk proteins in biomedical fields.

Multiphase chemical systems are greatly different than bulk solutions, as they provide a unique environment for reactions to proceed and have unique physicochemical properties. Thus, new tools need to be developed to gain a more detailed understanding of these systems. Here, we use electrogenerated chemiluminescence (ECL) to elucidate phase boundaries precisely and comprehensively between aqueous droplets and an organic continuous phase owing to ECL’s unprecedented spatial resolution (a few micrometers) confined at the electrode surface. Phase-resolved mapping was accomplished by selecting a luminophore that is soluble in both phases while selecting two coreactants that are exclusively soluble in one phase or the other. This type of system allows us to map the complex liquid|electrode and the liquid|liquid interfaces in a multiphase system. We show that electrical connectivity is not conserved throughout solvent inclusions, which result from neighboring droplet coalescence, indicating an unexpected initial lack of electronic communication. These results have great importance to energy storage and conversion devices and wearable/implantable sensors, which are dominated by complex, multiphase environments.

Self-assembling of nanoparticles into complex superstructures is very challenging, which usually depends on postorganizing techniques or pre-existing templates such as polypeptide chains or DNA or external stimulus. Such self-assembled processes typically lead to close-packed structures. Here, it has been demonstrated that under carefully template-free reaction conditions CdS quantum dots (QDs) could be synthesized and simultaneously self-assembled into complex superstructures without compromising individual QD properties. The superstructures of CdS QDs attained by the chemical-based method demonstrate Stokes-shifted photoluminescence (PL) from trap states. Remarkably, the PL decay of superstructures exhibits a single-exponential feature. This behavior is unusual for the synthesized superstructures, indicating that the trap states are restricted to a narrow range. The growth mechanism of these superstructures is explained through the formation of liquid crystal phases (LCPs) with the help of a small-angle X-ray scattering (SAXS) analysis.

Using ab initio lattice dynamics and a unified heat transport theory, we compute the lattice thermal conductivity (κ_L) of Li₅Sn, a newly synthesized crystalline material for Li-ion batteries. The weak bonding in the Li-rich environment leads to significant softening of the optical phonon modes, temperature-induced hardening, and strong anharmonicity. This complexity is captured in the particle-like and glass-like components of κ_L by accounting for the temperature-dependent interatomic force constants acting on the renormalized phonon frequencies and three- and four-phonon scatterings contributing to the phonon lifetime. We predict very low room-temperature κ_L values of 0.857, 0.599, and 0.961 W/mK for the experimental Cmcm phase and 0.996, 0.908, and 1.385 W/mK for the theoretically predicted Immm phase along the main crystallographic directions. Both phases display complex crystal behavior with glass-like transport exceeding 20% above room-temperature and an unusual κ_L temperature dependence. Our results can be used to inform system-level thermal models of Li-ion batteries.

We employed infrared scattering-type scanning near-field optical microscopy (IR-sSNOM) to study surface plasmon polaritons (SPPs) in trilayer graphene (TLG). Our study reveals systematic differences in near-field IR spectra and SPP wavelengths between Bernal (ABA) and rhombohedral (ABC) TLG domains on SiO₂, which can be explained by stacking-dependent intraband conductivities. We also observed that the SPP reflection profiles at ABA-ABC boundaries could be mostly accounted for by an idealized domain boundary defined by the conductivity discontinuity. However, we identified distinct shapes in the SPP profiles at the edges of the ABA and ABC TLG, which cannot be solely attributed to idealized edges with stacking-dependent conductivities. Instead, this can be explained by the presence of various edge structures with local conductivities differing from those of bulk TLGs. Our findings unveil a new structural element that can control SPP, and provide insights into the structures and electronic states of the edges of few-layer graphene.

The oxygen evolution reaction (OER) from water is a sequential oxidation reaction process, involved in transformation of multiple reaction intermediates. For photo(electro)catalytic OER, revealing the intermediates transformation kinetics is quite challenging due to its coupling with photogenerated charge dynamics. Herein, we specifically study the transformation kinetics of the OER intermediates in rationally thin hematite photoanodes through increasing the ratio between surface intermediates and photogenerated charges in bulk. We directly identify the formation and consumption kinetics of one-hole OER intermediate (Fe^IV═O) in photoelectrochemical water oxidation using operando transient absorption (TA) spectroscopy. The microsecond formation kinetics of the Fe^IV═O species are sensitively changed by the excitation mode of Fe₂O₃. The subsecond consumption kinetics are closely dependent on surface Fe^IV═O species density, demonstrating that the cooperation of Fe^IV═O intermediates is the key to accelerating water oxidation kinetics on the Fe₂O₃ surface. This work provides insight into understanding and controlling water oxidation reaction kinetics on Fe₂O₃ surface.