posted on 2019-05-22, 00:00authored byZijian Yuan, Seong-Min Bak, Pengsong Li, Yin Jia, Lirong Zheng, Yu Zhou, Lu Bai, Enyuan Hu, Xiao-Qing Yang, Zhao Cai, Yongming Sun, Xiaoming Sun
Sustainable
water-splitting hydrogen production has long been considered
one of the most promising energy conversion technologies, but enormous
challenges remain: for instance, water electrolysis suffers from high
overpotential and over energy consumption under neutral pH conditions.
Here, taking advantage of the memory effect of layered double hydroxide
(LDH), we report an energy-efficient neutral water electrolyzer material
based on LDH with multiple vacancy defects. Benefiting from the improved
electrical conductivity, larger electrochemical surface area (ECSA),
and faster charge transfer, the NiFe LDH with O, Ni, and Fe vacancies
exhibits a low overpotential of 87 mV at 10 mA/cm2 for
hydrogen evolution reaction (HER) in a pH 7 buffer electrolyte. Impressively,
the as-fabricated vacancy-containing NiFe LDH (v-NiFe LDH) splits
water with a current density of 10 mA/cm2 at ∼1.60
V in a two-electrode device, outperforming most other water-splitting
catalysts in neutral media. Such an electrolyzer setup could be powered
by a commercial 2.0 V solar cell, producing hydrogen at a current
density as high as 100 mA/cm2.