Rh/RhOx nanosheets as pH-universal bifunctional catalysts for hydrazine oxidation and hydrogen evolution reactions

Hydrazine oxidation reaction (HzOR)-assisted hydrogen evolution is a promising effluent treatment and energy conversion method for resolving the global energy shortage and environmental crisis. However, highly efficient and pH-universal electrocatalysts are still lacking to boost the sluggish kinetics of both the cathodic hydrogen evolution reaction (HER) and anodic HzOR. Here, Rh/RhOx nanosheets with Rh-O-Rh interfaces are fabricated by alkali-assisted synthesis and the H-2 reduction route. When they are employed as efficient bifunctional electrocatalysts, the Rh/RhOx nanosheets exhibit outstanding performance and stability for the HER and HzOR in pH-universal electrolytes. The two-electrode electrolyzer delivers a current density of 10 mA cm(-2) with an ultra-low voltage of 0.068, 0.268, and 0.348 V in 1.0 M KOH/0.5 M N2H4, 1.0 M PBS/0.3 M N2H4 and 0.5 M H2SO4/0.5 M N2H4, respectively. The performance can be maintained over 65 h for the HER and HzOR under neutral conditions. Density functional theory calculations indicate that the high activity is derived from the Rh-O-Rh interfaces. The regulation of the interface greatly improves the activity of the catalyst and reduces energy consumption, which is more conducive to the production of hydrogen.

Automated summary

The Rh/RhOx nanosheets with Rh-O-Rh interfaces synthesized in this study exhibit outstanding performance and stability as efficient bifunctional electrocatalysts for hydrogen evolution and hydrazine oxidation reaction in pH-universal electrolytes. The high activity is derived from the regulated interface, which greatly improves the catalyst's activity and reduces energy consumption, showing promise for hydrogen production in resolving energy and environmental crises.