Coupling Effect of Piezo–Flexocatalytic Hydrogen Evolution with Hybrid 1T‐ and 2H‐Phase Few‐Layered MoSe2 Nanosheets

• Published in: Advanced energy materials 2020-11, Vol.10 (42), p.n/a
• Main Authors: Chung, Yun‐Jung, Yang, Cheng‐Shiun, Lee, Jyun‐Ting, Wu, Guan Hua, Wu, Jyh Ming
• Format: Article
• Language: English
• Subjects: Bending moments; Cantilever beams; catalysis; Coupling; Coupling (molecular); Electric contacts; Electric fields; flexoelectric; hydrogen evolution reaction; Hydrogen evolution reactions; Molybdenum compounds; molybdenum diselenide; Nanosheets; piezoelectric; Piezoelectricity; Traction force
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202002082

Hybrid 1T‐ and 2H‐phase MoSe2 nanosheets with active reaction sites, which display strong piezoelectric responses and extraordinary flexoelectric potential (flexopotential), are demonstrated. The strain‐induced piezoelectric potential (piezopotential) establishes at interfacial areas between 1T and 2H‐phase that modulates the local‐contact characteristics to enhance charge separation. The piezo‐ and flexopotential coupling effect is observed not only on edge‐site MoSe2 nanosheets but also on polarized surfaces of the MoSe2 nanosheets across the top and bottom surfaces, thus establishing an internal electric field to separate electron–hole pairs and proceeding with electrochemical reaction with polar molecules, generating hydrogen gas at ≈5000 µmol g−1 h−1. The nanosheets assemble nanoflowers with abundant edge‐sites, which serve as cantilever beams for traction force at the free ends of nanosheets. On increasing the bending moment, an extraordinary flexopotential results along the z‐axis. The strain gradients induce piezo–flexoelectric coupling effects on numerous edge‐site nanosheets, structural boundaries, and the polarized surface along the z‐axis, which potentially facilitate a state‐of‐the‐art catalytic hydrogen evolution reaction. Hybrid 1T‐ and 2H‐phase MoSe2 nanosheets with active reaction sites, which display strong piezoelectric responses, extraordinary flexoelectric potential (flexopotential) and exhibit a highly efficient hydrogen evolution reaction through mechanical forces without light irradiation, are demonstrated. These results potentially provide novel insights into the development of clean energy and for other environmental applications.