Controlled construction of uniform pompon-like Pb-ICP microarchitectures as a precursor for PbO semiconductor nanoflakes

Abstract

Three-dimensional hierarchical Pb-infinite coordination polymer (Pb-ICP) pompon-like microstructures with high degree of uniformity were prepared from Pb2+ ions and bi-carboxylic acid organic linker by precipitation and hydrothermal methods. Our bottom-up process revealed the direct assembly of nanosheets with 70 nm thickness to give pompon-like structure without the addition of any surfactants. Reaction parameters are critical to size and shape control and structural uniformity of the Pb-ICP nanostructures. The morphology could be tuned by adjusting the time and the reaction procedures. Based on the result of a series of comparative experiments, it was concluded that the possible formation mechanism of the pompon-like microspheres is through the intertwined nanosheets self-assembly. Photoluminescence spectroscopy shows the quenching of emission peaks of the bi-carboxylic acid linker after coordination to Pb2+ ion. Ligand-free PbO nanoflakes with a mean diameter of 40 nm were simply obtained by calcination of pompon-like Pb-ICP at 500 °C for 2 h under static air. The well crystallized PbO nanoflakes exhibit large band gap due to quantum confinement effect.