Engineering a highly dispersed co-catalyst on a few-layered catalyst for efficient photocatalytic H2 evolution: a case study of Ni(OH)2/HNb3O8 nanocomposites

Abstract

How to control the size and dispersity of co-catalysts and enhance the interaction between the catalyst and co-catalysts are open issues in catalysis. In this work, we have developed a novel approach to solve the aforementioned problems by utilizing the interlayered spatial steric inhibition effect of layered materials and the self-assembly of 2D nanosheets. A Ni(OH)₂-modified few-layered HNb₃O₈ photocatalyst is taken as a typical example. SEM and TEM results show that the co-catalyst Ni(OH)₂ with an ultrasmall size has been uniformly dispersed on the HNb₃O₈ layers through our method. However, the samples prepared by a traditional deposition method exhibit a heterogeneous Ni(OH)₂ modification with a large size. That is, our method could provide a larger number of surface active sites. Furthermore, due to the confined interlayer region of the layered HNb₃O₈, a very strong interaction between Ni(OH)₂ and HNb₃O₈ is achieved. As a result, the photogenerated charge carriers have been separated efficiently and the lifetime of the charge carrier is prolonged. Thus, the photocatalytic activities of our Ni(OH)₂/HNb₃O₈ samples are greatly enhanced. The optimal H₂ evolution rate of our sample is about 15.7 times higher than that of the sample prepared by a traditional co-catalyst modification method. This work highlights an efficient strategy for obtaining a highly dispersed co-catalyst, which might help to guide the way toward the development of highly efficient co-catalyst-modified photocatalyst systems.