Fig. 4. (a) Linear sweep voltammograms (LSVs) of various catalyst electrodes in their OER; 1 M KOH solution, nitrogen saturated. (b) OER LSVs at the Au–Ni electrode before (solid line) and after (dashed line) four hours of continued operation (inset). (c) and (d) TEM micrographs of Au–Ni nanoparticles before and after four hours of OER catalysis, revealing little morphological change. The scale bars are 200 nm.