posted on 2019-12-18, 16:44authored byChengqi Wu, Jie Zhu, Hu Wang, Guojing Wang, Tao Chen, Yiwei Tan
The design and fabrication of efficient inexpensive electrocatalysts
are critical for electrochemical energy conversion technologies. Control
and understanding of electronic configuration at the active sites
are of fundamental importance to achieve this goal. Herein, highly
porous Ni1–xCuxO (p-Ni1–xCuxO) nanowire (NW)
arrays grown on carbon fiber paper (CFP) were synthesized, characterized,
and utilized as high-performance catalytic anode for catalyzing the
ammonia-borane (AB) electrooxidation reaction (ABOR). This electrocatalyst
shows exceptional electrocatalytic properties including an extremely
low onset potential (−0.316 V vs the reversible hydrogen electrode
(RHE)), a high Faradaic efficiency (>98%), and long-term durability
toward the ABOR, far outperforming the noble metal-based catalysts.
Reaction free energies computed as a function of electrode potential
by density-functional theory indicate that doping of Cu for Ni1–xCuxO is favorable for energetically decreasing the energy
barriers in the multistep reaction pathways. The modulation of the
electronic structure of bimetallic Ni1–xCuxO catalysts
underlies the catalytic mechanism by the electronic coupling effect
between Ni and Cu.