Efficient photocatalytic generation of hydrogen by twin Zn0.5Cd0.5S nanorods decorated with noble metal-free co-catalyst and reduction of 4-nitrophenol in water

Abstract

The development of heterostructure photocatalysts composed of homo- or hetero-junction is a favorable approach for efficient visible-light-assisted photocatalytic conversion of solar energy into clean fuel, H2. Further, for large-scale production of hydrogen, the use of cost-effective earth-abundant photocatalysts is highly desirable. Consequently, herein we report the synthesis of heterostructure photocatalysts composed of twin Zn0.5Cd0.5S nanorods (NRs) decorated with noble-metal-free co-catalyst, Ni(OH)2 nanoparticles (NPs) for efficient visible-light-assisted H2 generation from water. Remarkably, the optimized heterostructure, Zn0.5Cd0.5S/7wt%Ni(OH)2 (CN-7) showed excellent catalytic activity with an H2 generation rate of 139 mmol g-1 h−1 which was found to be about 1.5 and 9.4 times higher than those of pristine Zn0.5Cd0.5S NRs (C-1) and CdS/7wt%Ni(OH)2, respectively. Moreover, the photocatalyst is recyclable for several cycles and can work in both acidic and basic conditions. A probable mechanism of the H2 generation by Zn0.5Cd0.5S/Ni(OH)2 heterojunction has also been discussed. Interestingly, the photocatalytic activity was extended for efficient reduction of 4-nitrophenol from water using the in situ generated hydrogen as a reducing agent. Overall, this is a unique demonstration wherein water a green solvent is utilized as a source of reducing agent for visible-light-driven reduction of the environmental pollutants from water.