Hierarchical NiMo-based 3D electrocatalysts for highly-efficient hydrogen evolution in alkaline conditions

In recent years, electro- or photoelectrochemical water splitting represents a promising route for renewable hydrogen generations but still requires the substantial development of efficient and cost-effective catalysts to further reduce the energy losses and material costs for scalable and practical applications. Here, we report the design and development of a hierarchical electrocatalyst constructed from microporous nickel foam and well-assembled bimetallic nickel-molybdenum (NiMo) nanowires, which are capable to deliver current densities as comparable to those of the state-of-the-art Pt/C catalyst at low overpotentials and even larger current densities at higher overpotentials (>124 mV). This binder-free 3D hydrogen evolution cathode catalyst also exhibits the excellent stability, without any decay of the current density observed after long-term stability tests at a low current density of 10 mA cm⁻² and a high current density of 50 mA cm⁻². By pairing this NiMo 3D cathode with a NiFe-based anode, a water electrolyzer can be achieved with a stable current density of 10 mA cm⁻² for overall water splitting at a voltage of ~1.53 V, indicating that the water splitting can be indeed realized without any performance sacrifice by using earth abundant electrocatalysts.