Three-Dimensional Hierarchical Nickel Cobalt Phosphide Nanoflowers as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction under Both Acidic and Alkaline Conditions

The sustainable hydrogen fuel from water electrolysis demands the development of efficient and robust non-noble electrocatalysts for the hydrogen evolution reaction (HER). Tuning the morphology and chemical composition is paramount to constructing electrocatalysts with superior activity and stability. In this work, novel ternary nickel-doped cobalt phosphide (Ni–Co–P) nanoflowers assembled by porous and unltrathin nanosheets were first prepared by a facile solvothermal reaction following a phosphidation procedure. The Ni–Co–P nanoflowers exhibited remarkable electrocatalytic HER performance, exhibiting overpotentials of as low as 83 and 92 mV at 10 mA cm –2 and small Tafel slopes of 46.6 and 49.6 mV dec –1 under1 M KOH and 0.5 M H 2 SO 4 conditions, respectively, which was one of the most active earth-abundant electrocatalysts. Additionally, the electrocatalysts exhibited high durability for HER under both alkaline and acidic conditions. Various techniques further demonstrated that the superior activity of Ni–Co–P nanoflowers was attributed to the unique 3D hierarchical morphology and the modified electron structure due to Ni incorporation. The superior activity and stability of novel Ni–Co–P nanoflowers hold promising potential for applications in the production of hydrogen fuel from water splitting.