NiSe/Ni2P Nanoparticles Encapsulated in Carbon Nanotubes to Construct Self-Supported Electrodes for Efficient Water Splitting

The design of bifunctional catalytic electrodes with high performance and low cost is the key to improving hydrogen production efficiency by water splitting. However, achieving the coexistence of high activity and stability of catalytic materials still faces challenges. Herein, we designed and prepared a self-supported electrode material (Ni₂P/NiSe@CNTs/CC) through the combined action of metal-catalyzed carbon nanotube (CNTs) growth, selenization, and phosphating. In this process, CNTs are grown in situ on the carbon cloth (CC) surface, and the inner cavity is filled with heterogeneous Ni₂P/NiSe nanoparticles. The optimized Ni₂P/NiSe@CNTs/CC electrode demonstrates an overpotential of 116.2 mV at -10 mA cm-² for hydrogen evolution reaction (HER) and 332.4 mV at 50 mA cm-² for oxygen evolution reaction (OER) in 1.0 M KOH electrolyte, respectively. Accordingly, the Ni₂P/NiSe@CNTs/CC||Ni₂P/NiSe@CNTs/CC couple achieves efficient water splitting with a cell voltage of 1.67 V at 10 mA cm-² and 2.01 V at 50 mA cm-², respectively. Moreover, Ni₂P/NiSe@CNTs/CC||Ni₂P/NiSe@CNTs/CC couple only decays by 0.5% after 100 hours of continuous operation at 10 mA cm-², indicating that it has considerable stability. Dynamic bubble monitoring results display that the Ni₂P/NiSe@CNTs/CC electrode/ electrolyte interface has a strong bubble escape capability, which promotes the cyclic service of the catalytic active sites.