Low-frequency vibration induced piezoelectric boost to photocatalytic hydrogen evolution through 2D-2D-stacked MoS2-carbon nitride

Abstract

MoS2-carbon nitride heterostructures which are highly sensitive to low-frequency vibration are demonstrated to be the catalysts for piezo-photocatalytic hydrogen evolution reaction (HER). The configuration of MoS2 nanostructure on carbon nitride plays a crucial role in the piezo-photocatalytic HER activity of MoS2-carbon nitride heterostructure. With the cocatalyst of Pt NPs on the carbon nitride portion, 2D-2D stacked MoS2-carbon nitride catalyst exhibits considerably higher HER rate compared to the pristine carbon nitride and MoS2 nanoflower (NF)-carbon nitride catalysts under illumination coupling with the mechanical energy of vortex-induced shearing force. Experimental and calculation results indicate that the MoS2 nanosheets mainly perform as the piezopotential generator to induce an electric field in the carbon nitride counterpart. With the configuration of 2D-2D stacking, the light harvesting of carbon nitride in the heterostructure remains the same as the pristine one. Nevertheless, the recombination of photogenerated electron-hole pairs in the carbon nitride portion of the MoS2-carbon nitride heterostructure is inhibited due to the electric field induced by MoS2 nanosheet under low-frequency vortex vibration, resulting in the significantly boosted HER rate obtained from the 2D-2D stacked MoS2-carbon nitride heterostructure.