To overcome the thermal instability of a p-doped organic hole transporting layer using the state-of-the-art p-type dopant, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, a potent electron accepter, 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, has been found to possess superior thermal stability and proved to be an excellent p-type dopant.

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Two-dimensional (2D) multiferroic materials combining intrinsic ferroelectricity, ferromagnetism, and ferroelasticity, which promise piezo-magnetoelectric effects, are highly desired for their potential applications in high-density and multi-functional spintronic devices. However, a room-temperature 2D triferroic semiconductor has never been reported. Here, on the basis of first-principle calculations, we predict that the CrNCl monolayer is a potential 2D triferroic semiconductor with ferroelectricity, ferromagnetism, and ferroelasticity coexisting and strongly coupling at room temperature. The strong d-p hybridizations between Cr and N ions give rise to Cr–N dimerizations, leading to spontaneous symmetry-breaking and an in-plane electric polarization, as well as a remarkable enhancement of ferromagnetic super-exchange interactions. Moreover, the ferroelastic transition is accompanied by a 90° rotation of the in-plane electric polarization and the magnetic easy axis, suggesting a strong piezo-magnetoelectric effect. These findings provide insights into multiferroic behaviors in 2D systems and can help facilitate further advancements in spintronics.

In phosphate adsorption, the interaction between MgO and the carbon network in Mg-biochar is an overlooked factor that contributes to active MgO facet generation for enhancing phosphate adsorption. However, the complex water matrix adsorption mechanism underlying the adaptability of MgO-biochar and enhanced phosphate adsorption are not fully studied. Herein, Mg-stirred leaf biochar (Mg-SLBC) was prepared by the Mg-stirring modification method. Mg-SLBC possessed the highest adsorption capacity (79.28 mg g–1) to phosphate among the adsorbents. In addition, Mg-SLBC had a good performance for phosphate adsorption in a complex water matrix. Phosphate adsorption by Mg-SLBC was not affected by Cl–, NO3 –, SO4 2–, humic acid, metal ions, and Ca2+ but was inhibited by Mg2+ and HCO3 –. For long-term adsorption, Mg-SLBC could constantly adsorb phosphate to avoid phosphate accumulation (<2 mg L–1). Meanwhile, phosphate adsorption by Mg-SLBC was a spontaneous process (ΔG, −6.884 kJ mol–1), which was dominated by inner-sphere complexation. Owing to high combination between MgO and the carbon network, there were more active MgO facets (e.g., (1 1 0) and (2 0 0)) to induce stronger unbalanced electron distribution in Mg-SLBC. Thereby, Mg-SLBC, with high adsorption capacity and adaptability, could effectively adsorb phosphate in a complex water matrix.

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