Efficient Alkaline Water/Seawater Hydrogen Evolution by a Nanorod‐Nanoparticle‐Structured Ni‐MoN Catalyst with Fast Water‐Dissociation Kinetics

Abstract

Achieving efficient and durable nonprecious hydrogen evolution reaction (HER) catalysts for scaling up alkaline water/seawater electrolysis is desirable but remains a significant challenge. Here, a heterogeneous Ni‐MoN catalyst consisting of Ni and MoN nanoparticles on amorphous MoN nanorods that can sustain large‐current‐density HER with outstanding performance is demonstrated. The hierarchical nanorod–nanoparticle structure, along with a large surface area and multidimensional boundaries/defects endows the catalyst with abundant active sites. The hydrophilic surface helps to achieve accelerated gas‐release capabilities and is effective in preventing catalyst degradation during water electrolysis. Theoretical calculations further prove that the combination of Ni and MoN effectively modulates the electron redistribution at their interface and promotes the sluggish water‐dissociation kinetics at the Mo sites. Consequently, this Ni‐MoN catalyst requires low overpotentials of 61 and 136 mV to drive current densities of 100 and 1000 mA cm−2, respectively, in 1 m KOH and remains stable during operation for 200 h at a constant current density of 100 or 500 mA cm−2. This good HER catalyst also works well in alkaline seawater electrolyte and shows outstanding performance toward overall seawater electrolysis with ultralow cell voltages.

Strategies of Anode Design for Seawater Electrolysis: Recent Development and Future Perspective

“…Despite the outstanding achievements, many Earth‐abundant TM electrocatalysts suffered from limited activity and selectivity in seawater electrolytes. [ 125 ] Scalable and innovative strategies using advanced technologies such as machine learning and material genome to engineer the surface, electronic, and crystalline structure to increase the selective active sites for OER, enhance the ECSA, charge and mass diffusion, and gas detachment would be desirable to meet the needs for practical catalysts. We speculate the following anticipation and strategies.…”

Recent advances in transition metal‐based electrocatalysts for seawater electrolysis

“…In recent years, the introduction of water dissociation sites has developed as a potential candidate for seawater electrolysis due to its enhancement of HER kinetics. For example, to optimize the water dissociation of Mo sites, Wu et al synthesized a high‐activity Ni‐MoN electrocatalyst by introducing Ni 89 . Research showed that Ni could enhance the highly conductive metallic state of MoN, and then optimize the water adsorption and dissociation.…”

“…For example, to optimize the water dissociation of Mo sites, Wu et al synthesized a high-activity Ni-MoN electrocatalyst by introducing Ni. 89 Research showed that Ni could enhance the highly conductive metallic state of MoN, and then optimize the water adsorption and dissociation. In all, Ni-MoN showed excellent HER performance (29 mV @ 10 mA cm À2 ) and stability (100 h @ 500 mA cm À2 ) in 1 M KOH seawater electrolytes.…”

Synergistic effect of nanosheet-array-like NiFe-LDH and reduced graphene oxide modified Ni foam for greatly enhanced oxygen evolution reaction and hydrogen evolution reaction

“…5 The earliest considerable research efforts into OER catalysts with superior performance were dedicated to noble metal materials such as Ru, Ir, RuO 2 and IrO 2 , 6 and the best HER catalysts are Pt and its oxide, but these noble metal materials have huge disadvantages of high cost, scarcity and low dual-functionality for the OER and HER, limiting their largescale commercial applications. In recent years, people have become committed to the design and synthesis of efficient, durable, low-cost and highly abundant transition metal substitutes, especially nickel, [7][8][9][10] iron, 11,12 cobalt 13 and the corresponding oxides, 14 hydroxides, 15 phosphides, 16 sulfides, 17,18 selenides 19 and nitrides. 20 As high-performance electrocatalysts, NiFe-based hydroxides/oxides have been extensively studied and are considered to be excellent electrocatalysts with low overpotential.…”