In2S3/g-C3N4/CoZnAl-LDH composites with the lamellar dual S-scheme heterostructure and its enhanced photocatalytic performance

The construction of heterostructures is considered as an excellent strategy to achieve efficient charge separation and enhance photocatalytic activity. In this paper, CoZnAl-LDH was first prepared by a temperature-programmed hydrothermal method. Then g-C3N4/CoZnAl-LDH composite was synthesized by loading g-C3N4 in situ, followed by supporting In2S3 on the surface of composite g-C3N4/CoZnAl-LDH. Finally, a novel dual S-scheme lamellar photocatalyst In2S3/g-C3N4/CoZnAl-LDH with ternary heterojunction was prepared. The crystal structure, morphology, composition and surface physicochemical properties of as-prepared photocatalysts were characterized by various testing methods. The results show that the lamellar In2S3/g-C3N4/CoZnAl-LDH composite mainly presents the characteristic structure of CoZnAl-LDH hydrotalcite compounds, and In2S3 and g-C3N4 are attached to the surface of CoZnAl-LDH. Compared with CoZnAl-LDH, the light absorption range of In2S3/g-C3N4/CoZnAl-LDH composite material is obviously broadened, and the specific surface area is increased. The results of multi-mode photocatalytic degradation of pollutants show that the photocatalytic degradation activity of In2S3/g-C3N4/CoZnAl-LDH composite with In2S3 loading weight ratio of 40% is significantly higher than that of a single CoZnAl-LDH or g-C3N4/CoZnAl-LDH composite material. In addition, the composite exhibits enhanced photocatalytic hydrogen production capacity (404.78 μmol/g hydrogen production in 8 h, which is more than 6 times that of the monomer CoZnAl-LDH). Moreover, the photocatalytic activity remains stable after 3 cycles of experiments. The introduction of g-C3N4 and In2S3 on the CoZnAl-LDH matrix to form a dual S-scheme heterostructure is one of the main reasons for the enhanced photocatalytic activity.