Accelerated dehydrogenation kinetics through Ru, Fe dual-doped Ni2P as bifunctional electrocatalyst for hydrazine-assisted self-powered hydrogen generation

Seawater electrolysis is a potential way to realize the large-scale hydrogen production without relying on freshwater resources, but limited by the chlorine evolution reaction (ClER) on the anode and high potential for seawater electrolysis. In this work, MOF-derived Ru, Fe dual-doped Ni2P nanosheets (RuFe-Ni2P@NF) is constructed to serve as bifunctional catalyst for chlorine-free hydrogen production by hybrid hydrogen evolution reaction (HER) coupled with hydrazine oxidation reaction (HzOR) in seawater. As an ideal bifunctional electrocatalyst for overall hydrazine splitting (OHzS) in seawater, RuFe-Ni2P@NF catalyst only needs 0.69 V to achieve 1000 mA cm(-2). Moreover, the energy-saving H-2 production is realized by utilizing OHzS unit, which can save 4.70 W . h of electricity compared with the N2H4-free unit for producing 1.0 L of H-2. Moreover, the direct hydrazine fuel cell (DHzFC) is assembled to drive OHzS to realize the self-powered H-2 production. The industrial hydrazine sewage can serve as feed for the above eletrolysis system, which has been degraded to similar to 8 ppb rapidly. DFT calculations demonstrate that the Ru and Fe dual-doping can not only realize the thermoneutral Delta G(H)* for HER but also decrease the free energy of dehydrogenation of *N2H3 to *N2H2 for HzOR, realizing the intrinsically enhanced dehydrogenation kinetics.

Automated summary

In this study, a MOF-derived Ru, Fe dual-doped Ni2P nanosheets (RuFe-Ni2P@NF) were constructed as a bifunctional catalyst for chlorine-free hydrogen production in seawater. The catalyst only required 0.69 V to achieve 1000 mA cm(-2) of overall hydrazine splitting in seawater. An energy-saving H-2 production was realized by utilizing this catalyst, saving 4.70 W . h of electricity compared to the N2H4-free unit for producing 1.0 L of H-2. Furthermore, a direct hydrazine fuel cell was assembled to drive the self-powered H-2 production.