Reverse micelle synthesis of AuNi alloy as electrocatalyst of borohydride oxidation

The carbon supported AuNi electrocatalyst (AuNi/C) for electrochemical oxidation of borohydride is prepared in water-in-oil microemulsion of water/AOT/n-heptane. The effects of the molar ratios of water to AOT (Rω) on the particle size and catalytic performance are systemically investigated. It has been found that when the Rω is less than 10, the particle size increases with the increase of Rω value, and the particle size is decreased after Rω > 10 due to two-phase separation of the microemulsion. The morphology and structure of as-prepared AuNi/C electrocatalysts are examined by transmission electron microscopy (TEM) and X-ray diffractometer (XRD). It is confirmed that all AuNi nanoparticles are spherical with average diameters in the range of 3–9 nm and uniformly distributed on the surfaces of carbon. The electrooxidation behaviors of BH 4 − on the AuNi/C anodic electrocatalyst have been investigated. The results show that the catalytic activity of BH 4 − oxidation on AuNi/C electrocatalyst is apparently improved and the smaller particle size can get a higher catalytic activity.