Figure 5: Electrocatalytic performance of HNDCM-100,000-1,000/Co for overall water splitting in 1 M KOH.

(a,b) J–V curves after IR correction for HER and OER, respectively; (c,d) Tafel plots for the data presented in a,b, respectively; (e) Long-term stability test result of the HNDCM-100,000-1,000/Co electrode for HER and OER at a constant voltage.