Fig. 3

Cyclic voltammetry curves at different scan rates of 5 mVs^− 1 to 50 mVs^− 1 for (a) SnS@Ni/SnO₂, (b) SnS@Ni/SnO₂-100, (c) SnS@Ni/SnO₂-200, (d) SnS@Ni/SnO₂-300 and (e) comparison of all fabricated electrodes based on SnS@Ni/SnO₂ at a scan rate of 5 mV s^− 1