Boosting the performance of alkaline direct ethanol fuel cell with low-Pd-loading nickel foam electrode via mixed acid-etching

Nickel foam has been widely used as an electrode supporting material for alkaline direct ethanol fuel cells (ADEFC). However, the smooth skeleton surface of pristine nickel foam results in low specific surface area, such that a high-load catalyst is required to deal with ethanol oxidation, which limits its application as a catalyst support. Therefore, efforts to enhance the roughness of skeleton surface and reduce the catalyst loading have been intensively made. One of the conventional approaches is hydrochloric acid (HCl) etching method, which can remove the inert layer but does not change the surface roughness. In this paper, a mixed acids treated nickel foam anode with low Pd loading (0.35 mg cm−2) is prepared by simply soaking for three times for ADEFC performance testing. The peak power density reaches 30 mW cm−2, which is double the performance of the HCl treated anode. The performance improvement is attributed to the micro-holes produced by mixed acids etching, which enhance the roughness of skeleton and improve electrochemical active surface area (ECSA) of the catalyst. This work opens a new platform for in-depth exploration on metal foam electrodes in fuel cells.