Herein, we report an allyl-imidazolium ionic liquid decorated COF and its covalent composite COF@chitosan aerogel, which were shown to be excellent selective CO₂ adsorbents and chemical conversion catalysts.

Stable ferroelectricity with an in-plane spontaneous polarization of 2.00 × 10⁻¹⁰ C/m is found in two-dimensional (2D) β-GeS monolayers from theoretical calculations, which can be effectively tuned by the applied tensile strains. The Curie temperature of the monolayer is evaluated to be 358 K by ab initio molecular dynamics simulations. Remarkably, the 2D ferroelectricity is found to exist in 2D few-layer β-GeS nanosheets which could be synthesized in experiments. The strong spontaneous polarization and giant pyroelectric coefficient accompanied by the appearance of phase transition near room temperature facilitate the development of β-GeS monolayers or nanosheets for applications in ferroelectric, pyroelectric, and piezoelectric devices with superior performance.

Two-dimensional (2D) ferroelectricity and ferromagnetism have attracted a lot of attention due to their promising applications, but 2D materials with both properties are quite rare. Here, by performing first-principles calculations, we propose that monolayer γ-GeSe is a 2D ferroelectric material with an out-of-plane polarization of about 6.48 × 10⁻¹² C/m. It has a Mexican-hat-like band structure, leading to itinerant ferromagnetism upon hole doping. This ferromagnetic phase transition occurs when the doping concentration is about 7.4 × 10¹²/cm², and the ferromagnetism can be maintained near 880 K when increasing the doping concentration. Both the ferroelectricity and the induced ferromagnetism can be well modulated by strain. These features make γ-GeSe a promising material for making microelectronics and spintronics devices. Our work also paves the way for searching long-sought high temperature 2D multiferroics.

An Ni(NCS) ₂ monolayer is a robust bipolar magnetic semiconductor, in which completely spin-polarized currents with reversible spin polarization can be created and controlled simply by applying a gate voltage.

Looking for the high-performance alternatives to conventional lead-containing piezoelectric materials such as lead zirconate titanate (PZT) is absolutely vital for the development of low-dimensional innovative piezoelectric devices. Herein, we present our first-principles calculations on several new monolayers consisting of ternary In-containing sesquichalcogenides, which exhibit high stability and extraordinary piezoelectric properties. Our calculations predict that the in-plane (d₁₁) and out-of-plane (d₃₁) piezoelectric coefficients of BiInSe₃, SbInSe₃, BiInTe₃, and SbInTe₃ monolayers are much larger than those of most previously reported two-dimensional (2D) materials and widely studied wurtzite-type bulk piezoelectrics. Very strikingly, BiInTe₃ monolayer possesses a d₁₁ as high as 362 pm V⁻¹ due to its mechanical flexibility, which is the highest among those reported in 2D materials and for the first time reaches those (∼360 pm V⁻¹) in bulk lead-containing piezoelectric materials such as PZT. The theoretical predictions of the giant piezoelectricity in these 2D materials suggest that they have great potentials for the applications in atomically thin lead-free piezoelectric devices such as sensors and energy harvesters.