Ru Clusters Embedded in Nitrogen- and Boron-Codoped Graphene Nanoplatelets as a Bifunctional Electrocatalyst for Effective Overall Water Splitting

Heteroatom-doped carbon materials and their composites have attracted great interest as efficient electrocatalysts for high-performance electrochemical water splitting. Herein, a series of nitrogen- and boron-codoped graphene nanoplatelets ((B, N)x-GnPs1–x (x = 0, 0.2, 0.5, and 0.8)) and their ruthenium composites (Ruy@((B, N)0.5-GnPs0.5)1–y (y = 0, 0.05, 0.1, 0.2, and 0.4)) were synthesized as highly efficient bifunctional electrocatalysts for overall water splitting. (B, N)x-GnPs1–x were prepared by a ball-milling approach followed by the activation of H2O, while Ruy@((B, N)0.5-GnPs0.5)1–y were synthesized by a simple self-assembly approach. The optimal composite, Ru0.1@((B, N)0.5-GnPs0.5)0.9, demonstrates excellent activity in 1 M KOH, requiring low overpotentials of 55 (HER) and 297 mV (OER) at 10 mA cm–2, along with low Tafel slopes and good stability. When employed as both the anode and cathode in a full water electrolyzer, it achieves a low cell voltage of 1.753 V at 10 mA cm–2 and maintains stable operation for over 65 h.