High-performance bifunctional water splitting under harsh alkaline conditions by hydrothermally prepared MnNiBP circular microclusters

While electrochemical water splitting offers a clean pathway to renewable hydrogen energy, its practical implementation requires cost-effective bifunctional electrocatalysts that are robust enough to sustain long-term operation under harsh alkaline conditions at elevated temperatures, thereby lowering the energy barriers for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, we report MnNiBP circular microclusters (CMCs) as a bifunctional electrocatalyst for overall water splitting, synthesized by a single-step hydrothermal method. The MnNiBP CMCs exhibit low HER and OER overpotentials of 88 mV and 290 mV at 100 mA cm -2 , and maintain efficient overall water splitting with bifunctional cell voltages of 2.92 V in 1 M KOH and 2.72 V in 6 M KOH at 2000 mA cm -2 . Bifunctional MnNiBP exhibits excellent long-term durability under industrial conditions, operating continuously at 1000 mA cm -2 for 150 h with minimal degradation. When integrated into a hybrid system with Pt/C as the cathode (Pt/C||MnNiBP), this hybrid configuration delivers a record-low cell voltage of 2.56 V in 6 M KOH at 2000 mA cm -2 , outperforming the benchmark configuration. The superior performance of MnNiBP can be attributed to the synergistic interactions among Mn, Ni, B, and P, which enable efficient overall water splitting. Collectively, the favorable reaction kinetics, efficient electron transport, and the intrinsic catalytic properties of MnNiBP support its high activity for water splitting.