Synergetic Piezo-Photocatalytic Hydrogen Evolution on Cdx Zn1-x S Solid-Solution 1D Nanorods.

Abstract

Conversion of solar and mechanical vibration energies for catalytic water splitting into H2 has gained substantial attention recently. However, the sluggish charge separation and inefficient energy utilization in photocatalytic and piezocatalytic processes severely restrict the catalytic activity. In this paper, efficient piezo-photocatalytic H2 evolution from water splitting is realized via simultaneously converting solar and vibration energy over one-dimensional (1D) nanorod-structured Cdx Zn1-x S (x=0, 0.2, 0.4, 0.6, 0.8, 1) solid solutions. Under combined visible light and ultrasound irradiation, Cd0.4 Zn0.6 S 1D nanorods deliver a prominently synergetic piezo-photocatalytic H2 yield rate of 4.45mmolg-1 h-1 , far exceeding that under sole ultrasound or illumination. The consumedly promoted catalytic activity of Cd0.4 Zn0.6 S is attributed to strengthened charge separation by piezo-potential as disclosed by light-assisted scanning Kelvin probe force microscopy (SKPFM), increased strain sensitivity, and desirable optimization between piezoelectricity and visible-light response due to the formation of 1D configuration and solid solution. Metal and metal oxide depositions disclose that reduction and oxidation reactions separately occur at the tips and lateral edges of the Cd0.4 Zn0.6 S nanorods, in which the spatially separated reactive sites also contribute to super catalytic activity. This work is expected to inspire a new design strategy of coupled catalysis reactions for efficient renewable fuel production.