title: Photoreduction of graphene oxide with polyoxometalate clusters and its enhanced saturable absorption.
abstract: We investigated the photocatalytic abilities of three Keggin-type polyoxometalate (POM) clusters, H3PW12O40 (PW), H4SiW12O40 (SiW), and H3PMo12O40 (PMo) to reduce graphene oxide (GO) under UV-irradiation in water. UV-vis absorption and X-ray photoelectron spectroscopy were performed and show that PW and SiW can photoreduce GO effectively, in contrast to PMo. We conclude that the LUMO levels of POMs should be located energetically above the work function of GO to enable electron transfer from POM to GO. We also investigated the saturable absorption of GO and reduced GO by means of z-scan experiments at 532 nm. The POM-assisted photoreduction of GO can greatly enhance the saturable absorber properties of GO, which appears useful for modelocking in ultrafast laser systems.
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany; State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China. Electronic address: hl_li@jlu.edu.cn.
authors: Haolong
authors: H
authors: Li
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany; Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India.
authors: Jyotsana
authors: J
authors: Gupta
authors: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China.
authors: Shan
authors: S
authors: Wang
authors: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China.
authors: Na
authors: N
authors: Zhang
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany. Electronic address: bubeck@mpip-mainz.mpg.de.
authors: Christoph
authors: C
authors: Bubeck
keywords: Graphene; Photoreduction; Photosensitization; Polyoxometalate; Saturable absorption