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Resumo(s)
Proton exchange membrane water electrolysis (PEMWE) showes substantial advantages over the conventional
alkaline water electrolysis (AWE) for power-to-hydrogen (PtH) conversion, given the faster response and wider
dynamic current range of the PEMWE technology. However, PEMWE is currently still expensive due partly to the
high voltage needed to operate at high current densities and inevitable usage of precious iridium/rutheniumbased
catalysts to expedite the slow kinetics of the oxygen evolution reaction (OER) and to ensure sufficient
durability under strongly acidic conditions. Herein, we report that ruthenium doped α-manganese oxide (Ru/
α-MnO2) nanorods show outstanding electrocatalytic performance toward the hydrazine (N2H4) oxidation reaction
(HzOR) in near-neutral media (weak alkaline and weak acid), which can be used to replace the energydemanding
OER for PEMWE. The as-prepared Ru/α-MnO2 is found to comprise abundant defects. When used
to catalyze HzOR in the acid-hydrazine electrolyte (0.05 M H2SO4 + 0.5 M N2H4), it can deliver an anodic current
density of 10 mA cm 2 at a potential as low as 0.166 V vs. reversible hydrogen electrode (RHE). Moreover, Ru/
α-MnO2 exhibits remarkable corrosion/oxidation resistance and remains electrochemically stable during HzOR
for at least 1000 h. Theoretical calculations and experimental studies prove that Ru doping elongates the Mn–O
bond and produces abundant cationic defects, which induces charge delocalization and significantly lowers
material’s electrical resistance and overpotential, resulting in excellent HzOR catalytic activity and stability. The
introduction of N2H4 significantly reduces the energy demand for hydrogen production, so that PEMWE can be
accomplished under remarkably low voltages of 0.254 V at 10 mA cm 2 and 0.935 V at 100 mA cm 2 for a long
term without notable degradation. This work opens a new avenue toward energy-saving PEMWE with earthabundant
OER catalysts.
Descrição
Palavras-chave
Cationic defect Ru doping PEM water electrolysis Hydrazine oxidation reaction Electrocatalysis
Contexto Educativo
Citação
Editora
Elsevier