Efficient Charge Separation via MoSe₂ Nanosheets with Tunable 1T Phase Contents: Piezoreduction of Cr(VI) to Cr(III) and Piezodegradation of RhB

Abstract

Piezocatalysis is a promising technology to address environmental pollution by converting mechanical energy into chemical energy. Herein, MoSe 2 nanosheets with different 1T phase percentages (ranging from 30 to 80%) were constructed by adjusting hydrothermal temperature. Moreover, the roles of phase engineering in the piezocatalysis were thoroughly investigated by degrading rhodamine B and reducing Cr(VI) in ultrasonic vibration conditions. In particular, MoSe 2 prepared at 220 °C (MoSe 2 -220) exhibits ultrahigh observed constant k obs and degradation rate k, which is superior to most reported catalysts to date. The experimental results indicate that the introduction of the 1T phase increases the active sites of the material, improves the conductivity, and inhibits the recombination of electrons and holes. Moreover, an internal electric field in the 2H phase induced by piezoelectric polarization is facilitated to separate electron−hole pairs, enabling the degradation and reduction to proceed. The capture experiments and EPR tests further confirm that • O 2 − and • OH are main reactive species, and a rational mechanism is finally put forward. This study offers a clear understanding of phase engineering in piezocatalysis and provides an efficiency strategy to construct highly efficient piezocatalysts.

Recent advances in molybdenum diselenide-based electrocatalysts: preparation and application in the hydrogen evolution reaction

“…109 But note that the morphological effect of MoSe 2 -based electrocatalysts for enhanced HER performance is only focused on in the few abovementioned explorations. 26,91,92,108,109,194,196…”

“…MoSe 2 -based materials with different morphology indicate various physicochemical property and electrocatalytic HER performance, which influence their applications and sufficient exertion of property. MoSe 2 nanosheets or nanoflowers often showed the piezoflexoelectric effect for the degradation of dyes, 53,92,195 piezoreduction of Cr(VI) to Cr(III), 196 and the improved HER activity. 91,92,196 Moreover, morphology reconstruction and elec-tronic optimization of Mo-doped nickel-iron selenide nanospheres can remarkably affect the HER activity.…”

Mechanistic Study of Rhodamine B Piezocatalytic Decomposition Using Poly(vinylidene difluoride) and Related Polymers

“…Perhaps, the best studied piezoelectric polymer is poly­(vinylidene difluoride) ([CH 2 CF 2 ] n , PVDF) and related co-polymers. In this paper, we show that PVDF can be an effective piezocatalyst, as demonstrated for the decomposition of a common organic dye pollutant, rhodamine B (RhB). ,, …”

“…There has been increasing interest in using the piezoelectric effect in a variety of applications, such as energy harvesting, − tactile sensors, − biology, − and chemical catalysis. − Typically, mechanical motion is used to invoke an electric field on the surface of the piezoelectric material, and this electric field influences the reactivity of the surrounding medium. In general, the piezoelectric material used is a metal oxide since it can have large electrical–mechanical coupling coefficients.…”

“…In this paper, we show that PVDF can be an effective piezocatalyst, as demonstrated for the decomposition of a common organic dye pollutant, rhodamine B (RhB). 15,21,23 PVDF can be found in multiple crystalline forms, primarily alpha, beta, and gamma phases, as shown in Scheme 1. 24−26 The phases differ by their relative conformations along the polymer chain.…”