posted on 2021-05-05, 13:36authored byNan Sheng, Shiyan Chen, Minghao Zhang, Zhuotong Wu, Qianqian Liang, Peng Ji, Huaping Wang
The
large osmotic energy between river water and seawater is an
inexhaustible blue energy source; however, the complicated manufacturing
methods used for ion-exchange devices hinder the development of reverse
electrodialysis (RED). Here, we use a wet-spinning method to continuously
spin meter-scale 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized
bacterial cellulose (TOBC) nanofiber filaments, which are then used
to construct nanochannels for osmotic energy conversion. These are
then used to build a nacre-like structure by adding graphene oxide
(GO), which provides narrow nanochannels in one-dimensional and two-dimensional
nanofluid systems for rapid ion transport. With a 50-fold concentration
gradient, the nanochannels in the fibers generate electricity of 0.35
W m–2, with an ionic mobility of 0.94 and an energy
conversion efficiency of 38%. The assembly of GO and TOBC results
in a high power density of 0.53 W m–2 using artificial
seawater and river water. The RED device fabricated from TOBC/GO fibers
maintains a stable power density for 15 days. This research proposes
a simple method to reduce the size of nanochannels to improve the
ionic conductivity, ionic selectivity, and power density of cellulose-based
nanofibers to increase the possibility of their application for the
conversion of osmotic energy to electrical energy.