Vertically Aligned Porous Nickel(II) Hydroxide Nanosheets Supported on Carbon Paper with Long‐Term Oxygen Evolution Performance

Abstract Vertically aligned Ni(OH) 2 nanosheets were grown on carbon paper (CP) current collectors through a simple and cost‐effective hydrothermal approach. The as‐grown nanosheets are porous and highly crystallized. If used as a monolithic electrode for electrochemical water oxidation in alkaline solution, the carbon paper supported Ni(OH) 2 nanosheets CP@Ni(OH) 2 exhibit high electrocatalytic activity and excellent long‐term stability. The electrode can attain an anodic current density of 20 mA cm −2 at a low overpotential of 338 mV, comparable to that of state‐of‐the‐art RuO 2 nanocatalysts supported on CP (CP/RuO 2 ) with the same catalyst loading. Significantly, CP@Ni(OH) 2 shows much better long‐term stability than CP/RuO 2 upon continuous galvanostatic electrolysis, particularly at a high industry‐relevant current density such as 100 mA cm −2 . CP@Ni(OH) 2 can sustain water oxidation at 100 mA cm −2 for 50 h without any degradation, whereas the performance of CP/RuO 2 is much poorer and deteriorates gradually over time. CP@Ni(OH) 2 electrodes hold substantial promise for use as low‐costing water oxidation anodes in electrolyzers.