Simultaneous Detection and Photocatalysis Performed on 3D Graphene/ZnO Hybrid Platform

MERCEDES, MESSINA; MARCOS COUSTET; JUAQUIN UBOGUI; REMIGIO, RUIZ; FABIO, SACCONE; FRANCISCO J. IBAÑEZ; CECILIA, DOS SANTOS CLARO

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2019 vol. 36 p. 2231 - 2239

0743-7463

The synergy between graphene foam (Gf) and ZnO nanoparticles (NPs) allows the detection of analytes at low conentrations, which can be subsequently photocatalyzed on the hybrid surface as well as in the liquid phaseupon illumination with low-power UV−vis light-emitting diode (LED) lamps. Detection of methylene blue (MB) and bisphenol A (BPA) is monitored either by graphene-enhanced Raman scattering (GERS) or molecular doping/sensing upon analyte adsorption. Using GERS, we were able to detect concentrations as low as 0.3 ppm of MB, which remained adsorbed on the graphene surface after a photocatalytic conversion of 88% (total conversion). The photocatalysisperformances of BPA and MB performed in the liquid phase were lower and corresponded to 73 and 33% as indicated by gas chromatography−mass spectrometry (GC/MS) and UV−vis, respectively. The kinetics of photocatalysis was fitted with a quasi-first-order reaction, and the apparent rate constant (kapp) was calculated according to the Langmuir−Hinshelwood model. The fastest kinetics was achieved with the hybrid platform named Gf-ZnO400, which was thermally treated at high temperatures and with most of the Ni etched away. This is consistent with the excellent electronic interaction between ZnO and graphene foam as indicated by photoelectrochemistry analysis. We mainly employed Raman scattering and UV−vis spectroscopy analyses for detection and photocatalysis applications; however, we also used other complementary techniques such as focused ion-beam scanning electron microscopy (FIB-SEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance, GC/MS, and photoelectrochemistry to explore the synergetic behavior of these two nanomaterials. This work brings about new insights into the detection of analyte molecules followed by photocatalysis performed in the solid and liquid states.