Simultaneous Piezoelectrocatalytic Hydrogen-Evolution and Degradation of Water Pollutants by Quartz Microrods@Few-Layered MoS₂ Hierarchical Heterostructures.

Abstract

Intense light attenuation in water/wastewater results in photocatalysts exhibiting a low quantum efficiency. This study develops a novel piezoelectrocatalysis system, which involves quartz microrods (MRs) abundantly decorated with active-edge-site MoS₂ nanosheets to form a quartz microrods@few-layered MoS₂ hierarchical heterostructure (QMSH). Through theoretical calculations, it is found that the quartz MRs serve as a parallel-plate capacitor, which is self-powered to provide an internal electric field to the few-layered MoS₂ nanosheets surrounding the quartz MR surfaces, and the piezoelectric potential (piezopotential) effectively facilitates redox reactions with the free carriers in MoS₂ . The self-powered quartz MRs in the QMSH present an internal bias to the MoS₂ nanosheets, thus yielding a piezoelectrocatalysis system. An efficient piezoelectrocatalytic hydrogen evolution reaction and decomposition of wastewater without light irradiation can be achieved simultaneously. The second-order rate constant of the QMSH is ≈0.631 L mg^-1 min^-1 , which is 650-fold that of quartz MRs, indicating that the piezoelectric heterostructural catalysts display exceptionally high efficiency on piezoelectrocatalytic redox reactions rather than in the piezocatalytic process. The H₂ -production rate of QMSH catalysts approaches ≈6456 µmo1 g^-1 h^-1 and peaks at ≈16.8 mmol g^-1 in 8 h. The piezoelectrocatalytic process may be a promising method for treating industrial wastewater and producing clean energy.