Liquid exfoliating CdS and MoS2 to construct 2D/2D MoS2/CdS heterojunctions with significantly boosted photocatalytic H2 evolution activity

Abstract

Fabrication of 2D/2D heterojunction photocatalysts have attracted more attentions due to their inherent merits involving the large contact interface, short charge migration distance and plentiful active sites, which are beneficial for the enhancement of photocatalytic activity. Herein, a series of 2D/2D MoS2/CdS type-I heterojunctions were prepared by incorporation the exfoliating of bulk CdS and MoS2 with post-sintering procedure. Multiple characteristic techniques were employed to corroborate the formation of heterojunctions. By optimizing the 2D MoS2 amounts in the heterojunction, the 7 wt.% 2D/2D MoS2/CdS heterojunction displayed the maximal photocatalytic H2 evolution rate of 18.43 mmol h−1 g−1 under visible light irradiation in the presence of lactic acid as the sacrificial reagent, which was 6 times higher than that of pristine 2D CdS. Based on the photoelectrochemical and photoluminescence spectra tests, it could be deduced that the charge separation and transfer of 2D/2D MoS2/CdS heterojunction was tremendously improved, and the recombination of photoinduced electron-hole pairs was effectively impeded. Moreover, the 2D MoS2 was used as a cocatalyst to provide the abundant active sites and lower the overpotential for H2 generation reaction. The current work would offer an insight to fabricate the 2D/2D heterojunction photocatalysts for splitting H2O into H2.