The functional groups and site interactions on the surfaces of two-dimensional (2D) layered titanium carbide can be tailored to attain some extraordinary physical properties. Herein a 2D alk-MXene (Ti3C2(OH/ONa)(x)F(2-x)) material, prepared by chemical exfoliation followed by alkalization intercalation, exhibits preferential Pb(II) sorption behavior when competing cations (Ca(II)/Mg(II)) coexisted at high levels. Kinetic tests show that the sorption equilibrium is achieved in as short a time as 120 s. Attractively, the alk-MXene presents efficient Pb(II) uptake performance with the applied sorption capacities of 4500 kg water per alk-MXene, and the effluent Pb(II) contents are below the drinking water standard recommended by the World Health Organization (10 μg/L). Experimental and computational studies suggest that the sorption behavior is related to the hydroxyl groups in activated Ti sites, where Pb(II) ion exchange is facilitated by the formation of a hexagonal potential trap.

Flexible all-solid-state supercapacitors are fabricated with liquid-exfoliated black-phosphorus (BP) nanoflakes as an electrode material. These devices deliver high specific volumetric capacitance, power density, and energy density, up to 13.75 F cm(-3) , 8.83 W cm(-3) , and 2.47 mW h cm(-3) , respectively, and an outstanding long life span of over 30 000 cycles, demonstrating the excellent performance of the BP nanoflakes as a flexible electrode material in electrochemical energy-storage devices.

Epitaxial growth of A-A and A-B stacking MoS2 on WS2 via a two-step chemical vapor deposition method is reported. These epitaxial heterostructures show an atomic clean interface and a strong interlayer coupling, as evidenced by systematic characterization. Low-frequency Raman breathing and shear modes are observed in commensurate stacking bilayers for the first time; these can serve as persuasive fingerprints for interfacial quality and stacking configurations.

Element doping allows manipulation of the electronic properties of 2D materials. Enhanced transport performances and ambient stability of black-phosphorus devices by Te doping are presented. This provides a facile route for achieving airstable black-phosphorus devices.

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