Highly Efficient Flexocatalysis of Two‐Dimensional Semiconductors

Abstract

Catalysis is vitally important for chemical engineering, energy, and environment. It is critical to discover new mechanisms for efficient catalysis. For piezoelectric/pyroelectric/ferroelectric materials that have a non‐centrosymmetric structure, interfacial polarization‐induced redox reactions at surfaces leads to advanced mechanocatalysis. Here, the first flexocatalysis for 2D centrosymmetric semiconductors, such as MnO2 nanosheets, is demonstrated largely expanding the polarization‐based‐mechanocatalysis to 2D centrosymmetric materials. Under ultrasonic excitation, the reactive species are created due to the strain‐gradient‐induced flexoelectric polarization in MnO2 nanosheets composed nanoflowers. The organic pollutants (Methylene Blue et al.) can be effectively degraded within 5 min; the performance of the flexocatalysis is comparable to that of state‐of‐the‐art piezocatalysis, with excellent stability and reproducibility. Moreover, the factors related to flexocatalysis such as material morphology, adsorption, mechanical vibration intensity, and temperature are explored, which give deep insights into the mechanocatalysis. This study opens the field of flexoelectric effect‐based mechanochemistry in 2D centrosymmetric semiconductors.

Efficient Electrocatalytic Reduction of CO2 to Ethanol Enhanced by Spacing Effect of CuCu in Cu2‐xSe Nanosheets

“…The thinner thickness is available to adjust the atomic spacing through defects, such as vacancies. [21] Besides, the rich 2D surfaces can also maximize the spacing enhancement effect during the catalytic reaction. [22] Moreover, the accurate thickness is measured by atomic force microscope (AFM), and the results show that the thickness are about 1.44 and 1.41 nm for Cu 2-x Se and V Se -Cu 2-x Se, respectively (Figure 1f,g).…”

Bi5Ti3FeO15 Nanofibers for Highly Efficient Piezocatalytic Degradation of Mixed Dyes and Antibiotics

“…Compared with the fresh nanofibers, there is only a very weak absorption peak at around 1250 cm –1 for the used nanofibers, indicating that the absorption effect is very weak. Recently, flexocatalysis has received much attention. , The flexocatalysis effect could happen in the piezocatalysis process, especially for two-dimensional single-crystal piezocatalyst . However, the Bi 5 Ti 3 FeO 15 nanofibers are composed of nanoparticles and when nanofibers are bent under ultrasonic vibration, these nanoparticles in nanofibers are deformed because of compression or tension.…”

“…54,55 The flexocatalysis effect could happen in the piezocatalysis process, especially for two-dimensional single-crystal piezocatalyst. 55 However, the Bi 5 Ti 3 FeO 15 nanofibers are composed of nanoparticles and when nanofibers are bent under ultrasonic vibration, these nanoparticles in nanofibers are deformed because of compression or tension. Hence, piezoelectric fields are generated within these nanoparticles due to deformation.…”

Ultra‐fast Piezocatalysts Enabled By Interfacial Interaction of Reduced Graphene Oxide/MoS2 Heterostructures

“…[5][6][7] The electric field generated by the piezoelectric effect can augment the energetics of free charges and enhance the lifetime of hot electrons to promote the piezocatalytic reaction. [4,8] The built-in electric field can also facilitate the adsorption and desorption of reactants and products on the surface of catalysts, which contributes to breaking some fundamental limitations on catalysis caused by the Sabatier principle. [4,9] Additionally, the piezotronic effect in a piezoelectric semiconductor system tunes the charge transport with the piezoelectric potential.…”

“…[3,[5][6][7]12] The 2D piezoelectric materials have attracted much attention in piezocatalysis because of their favorable piezoelectric potential, large contact area, abundant catalytic sites, and high tolerance of elastic strains. [8,13] Monolayered MoS 2 possesses…”