A novel,
low-cost, and powerful cerium-oxide nanowire (CeO2NW) electrode
decorated with graphite felt (GF) through a
one-step hydrothermal method was proposed in this study. Subsequently,
hydrogen annealing was conducted to create defective-hydrogen-annealed
CeO2NWs decorated with GF (H–CeO2NWs–GF)
for use in vanadium redox flow batteries (VRFBs). The electrochemical
results show that the H–CeO2NWs–GF reveals
excellent electrocatalytic effects toward the VO2
+/VO2+ redox process in VRFBs at the positive electrode
to facilitate the electrochemical kinetics of the VRFBs. The VRFBs
using different electrode materials were compared with a VRFB using
H–CeO2NWs–GF. The results revealed that the
VRFB using H–CeO2NWs–GF exhibits the highest
voltage efficiency of 90.4% at a current density of 40 mA cm–2, which is significantly higher than those using pristine GF (81.1%)
and a CeO2NW electrode decorated with GF (88.4%). The significant
improvement in the electrochemical performance of H–CeO2NWs–GF might be mostly ascribed to the defect-rich
H–CeO2NWs on the GF surface, which acts as active
sites and reduces the electrochemical polarization of the redox reaction.
Moreover, the one-dimensional nature of H–CeO2NWs
is favorable for the charge-transfer process and improves the accessibility,
thus improving the electrode performance.