Enhanced Activity and Selectivity for Nitrogen Reduction Reaction in Electrides-Based Heterostructures: A DFT Computational Study.

Developing sustainable and efficient catalysts for ammonia synthesis from atmospheric molecular N2 under ambient conditions presents a significant 21st-century challenge. Two-dimensional heterostructures, particularly single-atom catalysts (SACs) supported on two-dimensional materials, have emerged as a promising avenue due to their remarkable catalytic activity and selectivity. Electrides, characterized by an abundance of free electrons and high surface activity, have attracted substantial attention in this context. Through density functional theory (DFT) calculations, this study proposes electride-graphene heterostructures (EGHS) as catalysts to effectively regulate charge distribution at the catalytic center, facilitating the optimization of catalytic performance. The EGHS model addresses challenges related to excessive adsorbate binding, mitigating electron transfer compared to electride monolayer adsorption. This novel approach utilizes heterogeneous heterostructures to finely tune the catalytic site, optimizing electron input for enhanced catalysis. Based on the optimized charge transfer for N2 activation, the Cr-doped EGHS (Cr@EGHS) exhibits a promising performance in the nitrogen reduction reaction, leading to, a relatively low limiting potential of -0.85 V and high selectivity. The hypothesis charge transfer depend on N2 activation is further supported by modulating the distance between component layers of heterostructure. These findings contribute to design principles for 2D heterostructure catalysts and offer a reference for experimental synthesis.

Magnetic skyrmions and their manipulations in a 2D multiferroic CuCrP2Te6 monolayer.

Magnetic skyrmions and their effective manipulations are promising for the design of next-generation information storage and processing devices, due to their topologically protected chiral spin textures and low energy cost. They, therefore, have attracted significant interest from the communities of condensed matter physics and materials science. Herein, based on density functional theory (DFT) calculations and micromagnetic simulations, we report the spontaneous 2 nm-diameter magnetic skyrmions in the monolayer CuCrP2Te6 originating from the synergistic effect of broken inversion symmetry and strong Dzyaloshinskii-Moriya interactions (DMIs). The creation and annihilation of magnetic skyrmions can be achieved via the ferroelectric to anti-ferroelectric (FE-to-AFE) transition, due to the variation of the magnetic parameter D2/|KJ|. Moreover, we also found that the DMIs and Heisenberg isotropic exchange can be manipulated by bi-axial strain, to effectively enhance skyrmion stability. Our findings provide feasible approaches to manipulate the skyrmions, which can be used for the design of next-generation information storage devices.

Bimetallic conjugated metal-organic frameworks as bifunctional electrocatalysts for overall water splitting.

Stable, high-efficiency, and highly active electrocatalysts are critical for the conversion of renewable energy through overall water splitting. Our first-principles calculations identify two-dimensional conjugated metal-organic frameworks (2D c-MOFs) with dual metal sites as promising candidates for this process. Among them, PcCo-O8-Rh stands out as the best catalyst, with Rh serving as the active site for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), resulting in a low ηHER/ηOER of -0.19/0.25 V. Our findings suggest that the HER/OER activity of PcTM-O8-TM' can be optimized through tensile strain, as it is related to the absorption strength of intermediates and the d-band center (εd) of the TM atom. This study presents a new family of 2D c-MOFs as high-performance bifunctional electrocatalysts for overall water splitting, paving the way towards sustainable energy conversion.

Catalysis based on ferroelectrics: controllable chemical reaction with boosted efficiency.

Catalysts, which can accelerate chemical reactions, show promising potential to alleviate environmental pollution and the energy crisis. However, their wide application is severely limited by their low efficiency and poor selectivity due to the recombination of photogenerated electron-hole pairs, the back-reaction of interactants. Accordingly, ferroelectrics have emerged as promising catalysts to address these issues with the advantages of promoted light adsorption, boosted catalytic efficiency as a result of their intrinsic polarization, suppressed electron-hole pair recombination, and superior selectivity via the ferroelectric switch. This review summarizes the recent research progress of catalytic studies based on ferroelectric materials and highlights the controllability of catalytic activity by the ferroelectric switch. More importantly, we also comprehensively highlight the underlying working mechanism of ferroelectric-controlled catalysis to facilitate a deep understanding of this novel chemical reaction and guide future experiments. Finally, the perspectives of catalysis based on ferroelectrics and possible research opportunities are discussed. This review is expected to inspire wide research interests and push ferroelectric catalysis to practical applications.