RESUMEN
In the pursuit of eco-friendly alternatives for refrigeration technology, electrocaloric materials have emerged as promising candidates for efficient solid-state refrigeration due to their high efficiency and integrability. However, current advancements in electrocaloric effects (ECEs) are often constrained by high temperatures and elevated electric fields (E-field), limiting practical applicability. Informed by phase-field simulation, this study introduces a (1-x)Pb(Yb1/2Nb1/2)O3-xPb(Mg1/3Nb2/3)O3 system, strategically engineered to incorporate highly ordered YN and disordered MN mixtures. The synergistic interplay between E-field/temperature-induced polarization reorientation and cation shift initiates multiple ferroelectric-antiferroelectric-paraelectric phase transitions. Our results demonstrate that under a moderate E-field of 50 kV cm-1, the x = 0.22 composition achieves remarkable performance with a giant temperature change (ΔT) of 3.48 K, a robust ECE strength (ΔT/ΔE) of 0.095 K cm kV-1, and a wide temperature span (Tspan) of 38 °C. Notably, the disrupted lattice structure contributes to ultralow electrostrains below 0.008%, with an average electrostrictive coefficient Q33 of 0.007 m4 C-2. The significantly weakened electrostrictive activity favors enhancing the performance stability of subsequent devices. This work introduces an innovative strategy for developing robust electrocaloric materials, offering substantial ΔT and low electrostrains, presenting promising advancements in ECE applications with an extended lifetime.
RESUMEN
Transition metal dichalcogenides (TMDs) possess several advantages, such as high conductivity, stable structure, and low cost, making them promising catalysts for carbon dioxide electroreduction. However, the high overpotential and the desorption characteristics of the reaction products during the reduction of carbon dioxide present significant challenges in the field of catalysis. In this study, we have further enhanced the catalytic activity of the original WS2 structure by constructing a heterojunction. We systematically investigate the catalytic activity of MoS2/WS2 heterojunctions supported by transition metals using density functional theory (DFT) calculations. The findings of this study are as follows: (1) the unique multiphase structure enhances the catalytic performance for CO2 reduction. (2) After constructing the MoS2/WS2 heterojunction, the electronic properties and conductivity of the heterojunction can be significantly enhanced, thereby facilitating the catalytic reduction of carbon dioxide. The Cu loading on the Cu@MoS2/WS2 heterojunction significantly reduces the overpotential, with a very low limit potential of -0.58 V. The adsorption behavior of CO on the Cu@MoS2/WS2 heterojunction was evaluated using adsorption energy, desorption energy, and density of states (DOS). The appropriate interaction between CO and Cu@ MoS2/WS2 promotes the reduction of CO2 to CO and facilitates smooth desorption of CO, demonstrating a strong catalytic effect on the CO2 reduction reaction (CO2RR). Therefore, it can be seen that Cu@MoS2/WS2 may be considered as potential single-atom catalysts (SACs) for CO2 reduction electrocatalysts. Finally, it is hoped that our results will provide theoretical support for the development of efficient CO2 reduction catalysts.
RESUMEN
The effects of charging on the magnetic anisotropy energy (MAE) of rhenium atom in nitrogenized-divacancy graphene (Re@NDV) are investigated using density functional theory (DFT) calculations. High-stability and large MAE of 71.2 meV are found in Re@NDV. The more exciting finding is that the magnitude of MAE of a system can be tuned by charge injection. Moreover, the easy magnetization direction of a system may also be controlled by charge injection. The controllable MAE of a system is attributed to the critical variation in dz2 and dyz of Re under charge injection. Our results show that Re@NDV is very promising in high-performance magnetic storage and spintronics devices.
RESUMEN
The electrochemical CO2 reduction reaction (CO2RR) has become a promising technology to resolve globally accelerating CO2 emissions and produce chemical fuels. In this work, the electrocatalytic performance of transition metal (TM = Cu, Cr, Mn, Co, Ni, Mo, Pt, Rh, Ru and V) triatomic clusters embedded in a graphdiyne (GDY) monolayer (TM3@GDY) for CO2RR is investigated by density functional theory (DFT) calculations. The results indicate that Cr3@GDY possesses the best catalytic performance with a remarkably low rate-limiting step of 0.39 eV toward the CO2 product, and it can also effectively suppress the hydrogen evolution reaction (HER) during the entire CO2RR process. Studies on the rate-limiting steps (CHO* + H+ + e- â CHOH) of Crn@GDY (n = 1-4) structures demonstrate that the high catalytic performance is attributed to the strong synergistic reaction of three Cr atoms interacting with the C atom for the Cr3@GDY structure. The strong synergistic reaction gives rise to the weakest interaction between O-Cr atoms, which leads to the strongest interaction between O-H atoms and makes the hydrogenation process easier for the Cr3@GDY structure. Furthermore, ab initio molecular dynamics simulations (AIMD) at 500 K reveal the high thermodynamic stability of the Cr3@GDY structure. These studies may provide a new approach for designing highly efficient electrocatalysts for the CO2RR under ambient conditions.
