Hydrazine-Assisted Acidic Water Splitting Driven by Iridium Single Atoms.

Abstract

Water splitting, an efficient technology to produce purified hydrogen, normally requires high cell voltage (>1.5V), which restricts the application of single atoms electrocatalyst in water oxidation due to the inferior stability, especially in acidic environment. Substitution of anodic oxygen evolution reaction (OER) with hydrazine oxidation reaction (HzOR) effectually reduces the overall voltage. In this work, the utilization of iridium single atom (Ir-SA/NC) as robust hydrogen evolution reaction (HER) and HzOR electrocatalyst in 0.5m H2 SO4 electrolyte is reported. Mass activity of Ir-SA/NC is as high as 37.02 A mgIr -1 at overpotential of 50mV in HER catalysis, boosted by 127-time than Pt/C. Besides, Ir-SA/NC requires only 0.39V versus RHE to attain 10mA cm-2 in HzOR catalysis, dramatically lower than OER (1.5V versus RHE); importantly, a superior stability is achieved in HzOR. Moreover, the mass activity at 0.5V versus RHE is enhanced by 83-fold than Pt/C. The in situ Raman spectroscopy investigation suggests the HzOR pathway follows *N2 H4 →*2NH2 →*2NH→2N→*N2 →N2 for Ir-SA/NC. The hydrazine assisted water splitting demands only 0.39V to drive, 1.25V lower than acidic water splitting.