Hybrid Ni₂P/CoP Nanosheets as Efficient and Robust Electrocatalysts for Domestic Wastewater Splitting

The development of low-cost, robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction (HER). Herein, a self-standing electrocatalyst, Ni₂P/CoP nanosheet, was fabricated directly on three-dimensional Ni foams by two facile steps, which illustrated both high activity and stability for HER in different electrolytes. Benefiting from the porous structures of nanosheets with large specific surface area and the hybrid Ni₂P/CoP, the as-prepared electrocatalyst presented remarkable HER with overpotentials of 65.2 and 87.8 mV to reach a current density of −10 mA cm⁻² in neutral and alkaline media, respectively. Density function theory calculations revealed a lower activation energy of water dissociation and efficient HER steps of hybrid Ni₂P/CoP nanosheets compared with mono CoP. The self-standing electrocatalyst maintained excellent chemical stability. Additionally, the HER process in domestic wastewater was realized with more impressive performance by using Ni₂P/CoP nanosheets compared with commercial Pt/C. Hydrogen was continuously generated for 20 h in mildly alkaline dishwashing wastewater. This work provides a feasible way to fabricate non-noble metal and self-standing hybrid bimetallic phosphides for HER in neutral and alkaline media, showing great potential for efficient hydrogen production by re-utilizing wastewater resources.