Engineering piezoelectricity and strain sensitivity in CdS to promote piezocatalytic hydrogen evolution

Piezocatalytic hydrogen evolution has emerged as a promising direction for the collection and utilization of mechanical energy and the efficient generation of sustainable energy throughout the day. Hexagonal CdS, as an established semiconductor photocatalyst, has been widely investigated for splitting water into H2, while its piezocatalytic performance has attracted less attention, and the relationship between the structure and piezocatalytic activity remains unclear. Herein, two types of CdS nanostructures, namely CdS nanorods and CdS nanospheres, were prepared to probe the above-mentioned issues. Under ultrasonic vibration, the CdS nanorods afforded a superior piezocatalytic H2 evolution rate of 157 μmol g−1 h−1 in the absence of any co-catalyst, which is nearly 2.8 times that of the CdS nanospheres. The higher piezocatalytic activity of the CdS nanorods is derived from their larger piezoelectric coefficient and stronger mechanical energy harvesting capability, affording a greater piezoelectric potential and more efficient separation and transfer of intrinsic charge carriers, as elucidated through piezoelectric response force microscopy, finite element method, and piezoelectrochemical tests. This study provides a new concept for the design of efficient piezocatalytic materials for converting mechanical energy into sustainable energy via microstructure regulation.