Synthesis of Au-NiOx/ultrathin graphitic C3N4 nanocomposite for electrochemical non-platinum oxidation of methanol

The Au-NiO x /g-C 3 N 4 (graphitic C 3 N 4 ) nanocomposite is synthesized and utilized as catalyst for the electrochemical oxidation of methanol in the alkaline electrolyte . Au and Ni nanoparticles are uniformly dispersed on ultrathin g-C 3 N 4 nanosheets by in-situ synthesis with nickel nitrate and chloroauric acid as Ni and Au resource respectively. The structure, morphology and component of the prepared nanocomposites are characterized by different techniques like transmission electron microscopy , X-ray diffraction, elemental mapping image and X-ray photoelectron spectroscopy. The results prove that the nanoparticles are well-distributed and embedded in g-C 3 N 4 nanosheets. The electrochemical performance of different nanocomposite for methanol oxidation reaction (MOR) is tested under alkaline conditions via electrochemical technologies. Compared to the pure g-C 3 N 4 and Au/g-C 3 N 4 , the NiO x /g-C 3 N 4 exhibits electrochemical catalytic effect toward methanol electro-oxidation with the existence of Ni. This electrochemical catalytic performance is enhanced significantly for the Au-NiO x /g-C 3 N 4 , whose oxidation peak current density is 2.32 times higher than NiO x /g-C 3 N 4 . The slope value drew from the Tafel plots shows that the Au-NiO x /g-C 3 N 4 owns the lowest Tafel slope (67.00 mV/dec). After the 7200 s stability test, the Au-NiO x /g-C 3 N 4 catalyst can still maintain a high current density . Long-term stability and good anti-poisoning ability promise Au-NiO x /g-C 3 N 4 a competitive non-Pt catalyst for the methanol oxidation.