Size-controlled synthesis of Pd nanosheets for tunable plasmonic properties

Abstract

Hexagonal Pd nanosheets with extremely thin thickness are synthesized in high yields by reducing the Pd salt precursor in N,N-dimethylformamide (DMF) containing tungsten hexacarbonyl (W(CO)₆), citric acid (CA), and cetyltrimethylammonium bromide (CTAB). During the reaction, W(CO)₆ spontaneously decomposes to W particles and CO, serving as reducing and capping agents in the synthesis of Pd nanosheets, respectively. We found that the use of CA and CTAB is both beneficial to promote the formation of hexagonal Pd nanosheets with stacking faults. In addition, the edge length of the Pd nanosheets can be simply tuned by varying the amount of CA fed in the synthesis. Such nanosheets can be further grown by subsequent seeded growth with as-preformed Pd nanosheets as the seeds. The Pd nanosheets with different edge lengths exhibit tunable localized surface plasmon resonance (LSPR) in the range of 820–1067 nm, and thus hold great potential in the field of plasmon-enhanced catalysis.