Preparation And Properties Of Graphene Based Semiconductor Composite Materials

In this paper, the graphene based semiconductor composites were prepared by graphene oxide and semiconductor throught the ex intu and one pot methods. Then the properties of composites were researched. The main contents and results of the present study are as follows:1. This paper demonstrated the synthesis of ternary cooperative semiconductor-metal-graphene（Au-CdS-rGO） hetero-nanostructures. The Au-CdS core-shell nanoparticles（⁵0 nm） were sandwiched between reduced graphene nanosheets. Decorating GO with L-cysteine hydrochloride plays an important role in sustaining the highly dispersion of the Au-CdS nanoparticles（NPs）. The successful modification would introduce lots of –SH function groups on the GO-cys nanosheets,which could attract the Au-CdS NPs by formation of metal-S bonding. As-fabricated photoanode exhibited higher photocurrent density compared to single-/binary-component, which could attributed to the synergistic effect of ternary cooperative Au-CdS-rGO hetero-nanostructures. First, the hetero-nanostructure could facilite more efficient utilization of incident light, which confirmed by high incident-photon-to-current-conversion efficiency（IPCE）. The excited state electron transfer is responsible for the quenching of CdS emission. The results provide further evidence that the photogenerated electrons efficiently transfer from CdS onto Au and graphene sheet. The G Raman bands indicates the photogenerated electrons could efficiently transfer from CdS onto Au and grpahene sheets, which benefits from the LSPR-induced charge separation at the interface of Au and CdS, and the electron-accepting alibity of graphene. The obtained Au-CdS-rGO photoanode was used to quantify H2O2 concentration and the detection limit was 0.005 mmol L-1,which exhibited promising application in the photoelectrochemical sensor.2. The Cu₂O-rGO was synthesized by one pot method without any surfactant,and then experiments were performed with different Cu precursor and different weight ratio between Cu precursor and GO. Different morphologies composites were fabricated. Good crystal, narrow size distribution and good dispersion compositeswas fabricated by Cu（NO3）2 precursor and 5:1 Cu precursor : GO. XRD and TEM characterizations proved the fabricated composite was Cu₂O-rGO. And then the fabricated composite was transferred by Na2 S. TEM and XRD figures said the transferred composite was Cu₂S-rGO. Photo-thermal experiments were conducted for the fabricated composite. The value of photo-thermal conversion efficiency were26.4% 、 17.2% and 30.6% for Cu₂O-rGO 、 Cu₂ S and Cu₂S-rGO respectively. In conclusion, firstly, more light could be absorbed by GO compositing with Cu₂ S and GO was used as support for dispersing Cu₂ S. Secondly, Cu₂ S could absorb light in near-infrared which could enhance the photo-thermal conversion efficiency.