碱性直接醇燃料电池非铂阳极催化剂

Non-Pt Anode Catalysts for Alkaline Direct Alcohol Fuel Cells

以纳米Pd,Pd-Ru,Au和Au-Ru为碱性直接醇燃料电池非Pt阳极催化剂,考察了其对甲醇、乙醇和乙二醇的电氧化性能.结果表明,Pd在酸中对醇电氧化的催化活性很低,但在碱中表现出较高的催化活性,起波电势约为0.4V(vsRHE);引入Ru助催化剂后,起波电势负移约0.15V;Pd-Ru对乙醇的电氧化表现出很高的活性,在0.3～0.4V电势范围内其活性为Pt-Ru的4倍.Au在酸中几乎不催化醇类分子的电氧化,但在碱中表现出一定的催化活性,在高于0.6V(vsRHE)的电势范围内可观察到醇氧化阳极电流.Au-Ru的催化活性高于Au,但起波电势没有明显负移,这可能表明当电势不足够正时醇分子在Au表面的吸附脱氢步骤是速率控制步骤.

Pd- and Au-based binary catalysts have been tested as non-Pt anode catalysts for alkaline direct alcohol fuel cells toward the electrooxidation of methanol, ethanol, and ethylene glycol. The activity of Pd for alcohol oxidation is very low in acid but relatively high in alkaline, in which an onset potential can be observed around 0.4 V （vs RHE）. After incorporation of Ru, the onset potential shifts negatively ca 0.15 V. It is notable that Pd-Ru is extremely active for ethanol oxidation, and the current density is four times that on Pt-Ru within 0.3 -0.4 V. Whereas Au is inert in acid for the electrooxidation of alcohol, but it is somewhat active in alkaline. An anodic current of alcohol oxidation can be observed in alkaline at potentials positive than 0.6 V （vs RHE）. Au-Ru exhibits higher activity than Au at relatively positive potentials, but it does not cause a negative shift in the onset potential, which may imply that the dissociative adsorption of alcohol molecules on the Au surface is the rate-determining step at relatively negative potentials.