Synergistic iron-doping and structural engineering of halloysite-derived cobalt silicate hydroxide for enhanced...

The slow reaction rate of the oxygen evolution process (OER) and the high economic burden associated with precious metal catalysts significantly impede the practical adoption of OER-driven technologies. Despite recent advancements, the development of non-precious electrocatalysts with high OER activity and remarkable stability remains a significant scientific challenge. Herein, novel iron-doped cobalt silicate hydroxide (CoFeSi) electrocatalysts assembled with ultrathin nanosheets were successfully prepared using a facile hydrothermal method. Halloysite derivatives (silica nanotubes) were used as the silicon source and sacrificial template to obtain the hierarchical structure CoFeSi. The key influencing factors including hydrothermal temperature, hydrothermal time and iron precursor amounts were investigated in detail. The optimal CoFeSi sample demonstrated the minimal overpotential of 282 mV at 10 mA·cm^-2 and the lowest Tafel slope of 57 mV·dec^-1, which is obviously superior to the cobalt silicate hydroxide (CoSi) sample. In accordance with the results of 3000 consecutive cyclic voltammetry (CV) cycles and 28 h chronopotentiometry (CP), CoFeSi electrocatalyst showed outstanding long-term stability and durability. A probable enhancement mechanism of OER activity was proposed under the guidance of theoretical calculation. This work not only provides a new strategy to synthesize metal silicate-based electrocatalysts with high OER performance and low-cost, but also reveals that the doping of iron into CoSi can distinctly improve its OER activity.