2D/2D Heterojunction of Ni−Co−P/Graphdiyne for Optimized Electrocatalytic Overall Water Splitting

The development of efficient catalysts for water splitting in alkaline condition is central to produce hydrogen for renewable energy storage. Herein, we fabricated a new 2D/2D heterojunction via directly electrodepositing of ternary Ni−Co−P nanosheets on graphdiyne (GDY) nanowalls. Benefiting from the synergistic interaction between Ni−Co−P and GDY, Ni−Co−P/GDY shows obviously improved activity for electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), realizing a large current density of 300 mA/cm2 for HER at low overpotential of 313 mV, much lower than that of commercial 20 wt% Pt/C (430 mV), and a much better OER performance than the commercial RuO2. A small cell voltage of 1.60 V is sufficient to achieve the standard 10 mA/cm2 current density by Ni−Co−P/GDY as a bifunctional electrode for water splitting in 1.0 M KOH solution. Raman, XPS and Surface valence band photoemission spectroscopic measurements confirm that the GDY‐incorporation strategy optimizes the electronic structure of the Ni−Co−P and thus promotes its electrocatalytic activity. Rational design: A new 2D/2D heterojunction of Ni−Co−P/GDY has been fabricated through the strong interaction from metal ions and the unique acetylenic bonds in GDY for overall water splitting. A small cell voltage of 1.60 V is sufficient to achieve the standard 10 mA/cm2 current density for water splitting in 1.0 M KOH solution.