Accelerating hydrazine-assisted hydrogen production kinetics with Mn dopant modulated CoS2 nanowire arrays

Electrochemical H-2 production from water splitting is an environmentally sustainable technique but remains a great challenge due to the sluggish anodic oxygen evolution reaction (OER). Replacing the OER with the thermodynamically more favorable electrocatalytic oxidation process is an effective strategy for highly efficient H-2 generation. Herein, Mn-doped CoS2 has predicted an excellent bifunctional electrocatalyst for the hydrogen evolution reaction (HER) and the hydrazine oxidation reaction (HzOR). With the introduction of Mn, the Gibbs free energy of the adsorbed H* and the potential rate-limiting step (the dehydrogenation of *NH2NH2 to *NHNH2) for the HzOR process of the catalyst can be significantly reduced. As expected, the Mn-CoS2 catalyst exhibited excellent catalytic activity and robust long-term stability for the HER and HzOR. In detail, the Mn-CoS2 catalyst only acquired potentials of 46 and 77 mV versus the reversible hydrogen electrode for achieving a current density of 10 mA cm(-2) for the cathodic HER and anodic HzOR, respectively. In addition, the Mn-CoS2 electrode only needs a cell voltage of 447 mV to output 200 mA cm(-2) in the overall hydrazine splitting system as well as exhibits a robust long-term H-2 production. This work provides theoretical guidance for the design of advanced bifunctional electrocatalysts and promotes high efficiency and energy-saving H-2 production technology.

Automated summary

This study reports a Mn-doped CoS2 catalyst with excellent bifunctional electrocatalytic activity and long-term stability for the hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR). The introduction of Mn significantly reduces the Gibbs free energy of the adsorbed H* and the potential rate-limiting step for the HzOR process. This work provides theoretical guidance for the design of advanced bifunctional electrocatalysts and promotes high efficiency and energy-saving H-2 production technology.