Synthesis of size-selected Pt/GONR nanocomposites for visible-light-enhanced methanol oxidation reaction in an alkaline solution

Abstract In this study, we prepared size-selected Pt/graphene oxide nanoribbon (GONR) composites as fuel-cell anode photoelectrocatalysts for methanol oxidation reaction (MOR) in an alkaline solution. Additionally, we used a light-emitting diode (LED) and a Xeon (Xe) lamp to increase the current densities of methanol oxidation reaction while photoelectrochemical phenomenon occurred upon our catalysts. The major parameter of our research is microwave powers for unzipping GONRs for electrochemical and photoeletrochemical measurements. Firstly, we utilized microwave heating to fabricate GONRs and load Pt nanoparticles made by chemical reduction methods. Secondly, we carried out the electrochemical and photoeletrochemical measurements using electrocatalyst-modified screen-printed carbon electrodes. The size distribution of Pt colloidal nanoparticles was characterized by transmission electron microscopy. The compositions of composite catalysts were determined by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The MOR photocurrent density of Pt/GONR (200 W) in cyclic voltammograms is 458 mA/mg_Pt under LED illumination. The photocurrent increase of this condition is 38.0% which is better than its dark one. Furthermore, we can obtain the MOR photocurrent density of 608, 696, and 794 mA/mg_Pt using Xe lamp with a power of 500, 750, and 1000 mW/cm^2. Graphical abstract Highlights The Pt/graphene oxide nanoribbon composites was used as electrocatalysts for the methanol oxidation reaction in an alkaline solution. The visible light sources help to improve the peak oxidation currents of the reaction using our electrocatalysts. Discussion The requirements for a best carbon support for a specific photoelectrochemical reaction remain an issue. The quantitative analyses of the current increase induced by photon energy in a specific electrochemical reaction are not well resolved yet.