Chunyang Wu

Electronic and Optoelectronic Applications Based on 2D Novel Anisotropic Transition Metal Dichalcogenides

Abstract With the continuous exploration of 2D transition metal dichalcogenides (TMDs), novel high‐performance devices based on the remarkable electronic and optoelectronic natures of 2D TMDs are increasingly emerging. As fresh blood of 2D TMD family, anisotropic MTe2 and ReX2 (M = Mo, W, and X = S, Se) have drawn increasing attention owing to their low‐symmetry structures and charming properties of mechanics, electronics, and optoelectronics, which are suitable for the applications of field‐effect transistors (FETs), photodetectors, thermoelectric and piezoelectric applications, especially catering to anisotropic devices. Herein, a comprehensive review is introduced, concentrating on their recent progresses and various applications in recent years. First, the crystalline structure and the origin of the strong anisotropy characterized by various techniques are discussed. Specifically, the preparation of these 2D materials is presented and various growth methods are summarized. Then, high‐performance applications of these anisotropic TMDs, including FETs, photodetectors, and thermoelectric and piezoelectric applications are discussed. Finally, the conclusion and outlook of these applications are proposed.

FeOx/FeP hybrid nanorods neutral hydrogen evolution electrocatalysis: insight into interface

The electrocatalytic interface plays a crucial role in driving the water splitting reaction. Herein, we report a rational constructed interface of Fe–O–P hybrid nanorods co-catalyst playing a significant role in high-performance hydrogen generation from neutral water. It is worth noting that the FeOx/FeP hybrid structure exhibits remarkably low overpotential of 96 mV at a current density of 10 mA cm−2 with a small Tafel slope of 47 mV dec−1 and maintains excellent electrolytic durability over 60 h, placing it at the forefront among the best hydrogen evolution electrocatalysts operating in neutral media. The increased Tafel value contributed by FeOx elimination demonstrates the important effect of the FeOx/FeP interface. Additionally, theoretical investigations reveal deeper insights into the FeOx/FeP interface: firstly, the FeOx facilitates the adsorption and dissociation of water molecules and accelerates the supply of hydrogen atoms in the Volmer–Heyrovsky reaction; secondly, the interface further optimizes the Gibbs free energy for hydrogen adsorption at the FeP surface.

High-Performance SERS Substrate Based on Hierarchical 3D Cu Nanocrystals with Efficient Morphology Control

Cu nanocrystals of various shapes are synthesized via a universal, eco-friendly, and facile colloidal method on Al substrates using hexadecylamine (HDA) as a capping agent and glucose as a reductant. By tuning the concentration of the capping agent, hierarchical 3D Cu nanocrystals show pronounced surface-enhanced Raman scattering (SERS) through the concentrated hot spots at the sharp tips and gaps due to the unique 3D structure and the resulting plasmonic couplings. Intriguingly, 3D sword-shaped Cu crystals have the highest enhancement factor (EF) because of their relatively uniform size distribution and alignment. This work opens new pathways for efficiently realizing morphology control for Cu nanocrystals as highly efficient SERS platforms.

Cytomembrane-Structure-Inspired Active Ni-N-O Interface for Enhanced Oxygen Evolution Reaction

Surface/interface design is one of the most significant and promising motivations to develop high-performance catalysts for electrolytic water splitting. Here, the nature of cytomembrane having the most effective and functional surface structure is mimicked to fabricate a new configuration of Ni-N-O porous interface nanoparticles (NiNO INPs) with strongly interacting nanointerface between the Ni3 N and NiO domains, for enhancing the electrocatalytic oxygen evolution reaction (OER) performance. The combination of transmission electron microscopy and electrochemical investigations, tracking the correlation between microstructure evolution and catalytic activity, demonstrate the strongly coupled nanointerface for an approximately sixfold improvement of electrolytic efficiency. Density functional theory simulates the electrocatalytic process with a maximum of 85% reduction of the energy barrier. Further investigations find that the real active site for the OER in the NiNO INPs is the strongly coupled Ni-N-O nanointerface, not the derived amorphous hydroxide, during the OER process. The determination of the correlation of constructed nanointerface with catalytic properties suggests a significant strategy toward the rational design of catalysts for efficient water electrocatalysis.