Efficient hydrogen recovery from wastewater treatment by piezo-photocatalytic heterostructure

Abstract

Hydrogen (H2) recovery during wastewater treatment has been considered as a promising direction to accomplish environmental sustainability. However, the effective H2 evolution in contaminants degradation process was still a major challenge. In this research, an advanced piezo-photocatalytic induced hydro-energy system is proposed, in consideration of improving the separation and transfer efficiency of photogenerated electrons and holes. As expected, the catalytic performance was significantly enhanced under the stress of ultrasound-induced piezoelectric field (major nitenpyram degradation within 60 min, H2 evolution was 746.56 μmol g−1 h−1). Experiments and density functional theory calculations illustrated that the introduced piezoelectric field directionally tuned the energy band structure of heterostructure, triggering a change in the electron transfer path within the heterostructure, which facilitated the major electrons transferred to zinc oxide (H2 evolution) and holes accumulated in molybdenum sulfide (hydroxyl radical generation), further accelerating contaminants degradation and H2 evolution. Furthermore, the in-depth mechanism of contaminants degradation and H2 evolution under the influence of piezoelectric field was further explored. The piezo-photocatalytic system of this work first accomplished H2 recovery in wastewater treatment on heterostructure, providing a constructive strategy for the design of environmentally sustainable catalytic systems.