Liqian Wu

MoS2-Based Mixed-Dimensional van der Waals Heterostructures: A New Platform for Excellent and Controllable Microwave-Absorption Performance

It is widely recognized that constructing multiple interface structures for enhanced interface polarization is beneficial to microwave absorption. Here, we report our work of achieving excellent microwave-absorption performance and controlling better-defined interfaces in vertically stacked two-dimensional (2D) MoS2 with other dimensional building blocks. The optimal reflection loss and effective absorbing bandwidth (reflection loss <-10 dB) of several mixed-dimensional van der Waals heterostructures are as follows: (i) for 2-0 type (2D MoS2/zero-dimensional Ni nanoparticles), -19.7 dB and 2.92 GHz; (ii) for 2-1 type (2D MoS2/one-dimensional carbon nanotubes), -47.9 dB and 5.60 GHz; and (iii) for 2-3 type (2D MoS2/three-dimensional carbon layers), -69.2 dB and 4.88 GHz. As a result, by selected synthesis of different types of microstructures, we can regulate and control microwave-absorption properties in MoS2 mixed-dimensional van der Waals heterostructures. In addition, attributing to the better-defined interfaces generated in mixed-dimensional van der Waals heterostructures, we found an alternative strategy to improve microwave attenuation properties of 2-0, 2-1, and 2-3 samples by controlling interfacial contacts. The results indicate that mixed-dimensional van der Waals heterostructures provide a new stage for the next generation of microwave-absorbing materials.

An efficient Co 3 S 4 /CoP hybrid catalyst for electrocatalytic hydrogen evolution

The development of efficient, universal and inexpensive electrocatalysts for hydrogen evolution reaction (HER) is central to the area of sustainable energy conversion. Considering the Co-based sulfides/phosphides have the same catalytic mechanism with the hydrogenases occurring in nature. Here, a new catalyst based on Co3S4/CoP hybrid that is comprised entirely cheap and earthabundant elements, was first synthesized via a two-step method, the Co(CO3)0.5(OH)·0.11H2O precursor was prepared by a hydrothermal method, followed by phosphidation and sulphidation under Ar atmosphere simultaneously. The resulting Co3S4/CoP hybrid material possessed porous core-shell structure with a homogeneous element distribution and large electroactive surface area (~21.04 mF cm−2). More importantly, the nanostructured Co3S4/CoP electrode exhibits excellent HER properties in acid medium with a low onset overpotential of 34 mV, a small Tafel slope of 45 mV dec−1, as well as a large exchange current density of 150 μA cm−2. These results obtained in this study indicate that the Co3S4/CoP hybrid nanorod is promising replacement to the Pt-based catalysts for H2 production. Moreover, the synthetic method presented in this work can provide an efficient way to synthesis other nanocomposites.