Sulfhydryl-functionalized carbon dots modified ball cactus-like Au composites facilitating the electrocatalytic ethanol oxidation through adsorption effect

Direct ethanol fuel cells (DEFCs) are considered as the ideal green power suppliers because of high energy density and non-toxicity of ethanol. Here the ball cactus-like gold (Au) particles reduced by hydrogen peroxide solution are coated with sulfhydryl-functionalized carbon dots (SCDs-Au). When the SCDs-Au composite is employed as the anodic electrocatalyst for ethanol oxidation reaction, an anode peak current density of 23.23 mA cm−2 (mass activity of 102.65 mA mg−1) is obtained at 0.19 V (vs. SCE) in 1.0 M KOH and 1.0 M ethanol at a scan rate of 20 mV s−1, which is about 4.4 times than that of Au without modification of SCDs. The higher catalytic activity is attributed to the higher ethanol adsorption capability caused by the shell-like SCDs. According to the adsorption experiment, ethanol adsorption capability of SCDs-Au is calculated as 2.8 times than that of Au without modification. At the same time, the addition of SCDs improves the electrocatalytic stability of Au. Such a surface modification method can be applied in other catalyst design processes. The ball cactus-like gold (Au) particles reduced by hydrogen peroxide solution are coated with sulfhydryl-functionalized carbon dots (SCDs-Au). SCDs-Au shows enhanced anode current density for ethanol oxidation attributed to the higher ethanol adsorption capability caused by CDs shell.