The Combination of 2D Layered Graphene Oxide and 3D Porous Cellulose Heterogeneous Membranes for Nanofluidic Osmotic Power Generation

Abstract

Salinity gradient energy, as a type of blue energy, is a promising sustainable energy source. Its energy conversion efficiency is significantly determined by the selective membranes. Recently, nanofluidic membrane made by two-dimensional (2D) nanomaterials (e.g., graphene) with densely packed nanochannels has been considered as a high-efficient membrane in the osmotic power generation research field. Herein, the graphene oxide-cellulose acetate (GO–CA) heterogeneous membrane was assembled by combining a porous CA membrane and a layered GO membrane; the combination of 2D nanochannels and 3D porous structures make it show high surface-charge-governed property and excellent ion transport stability, resulting in an efficient osmotic power harvesting. A power density of about 0.13 W/m2 is achieved for the sea–river mimicking system and up to 0.55 W/m2 at a 500-fold salinity gradient. With different functions, the CA and GO membranes served as ion storage layer and ion selection layer, respectively. The GO–CA heterogeneous membrane open a promising avenue for fabrication of porous and layered platform for wide potential applications, such as sustainable power generation, water purification, and seawater desalination.

A Novel Thin Film Composite Membrane for Osmotic Energy Generation

“…This interesting phenomenon arising from overlapping EDL in the ion transport regions results in ion enrichment in the confined spaces, where the ion transport behavior is determined by the surface and space charges of the TFC membranes rather than by the bulk concentration. 4,40 It is found that the current densities of the TFC membranes gradually decrease when increasing load resistance (Figure 4D), and the output power density reached its peak value when the load resistance was approximately 20 kΩ (Figure 4E). Compared with PVA or SPEEK-PVA membranes, the SPEEK/G-PVA TFC membrane showed the highest output power density of 5.89 W m −2 (Figure 4E,F).…”

“…Above this point, the ionic conductance follows the bulk rule of linearly increasing with concentration due to the thin electrical double layer (EDL). , While when the concentration is below the critical point, a strong nonlinear relationship is observed, and the ionic conductivity deviates sharply from the bulk value, reaching a plateau. This interesting phenomenon arising from overlapping EDL in the ion transport regions results in ion enrichment in the confined spaces, where the ion transport behavior is determined by the surface and space charges of the TFC membranes rather than by the bulk concentration. , It is found that the current densities of the TFC membranes gradually decrease when increasing load resistance (Figure D), and the output power density reached its peak value when the load resistance was approximately 20 kΩ (Figure E). Compared with PVA or SPEEK-PVA membranes, the SPEEK/G-PVA TFC membrane showed the highest output power density of 5.89 W m –2 (Figure E,F).…”

Membranes for Osmotic Power Generation by Reverse Electrodialysis

“…A graphene oxide nanosheet is decorated with epoxy, phenyl hydroxyl and carboxylic groups, which renders a negative surface charge in a hydrated state. The vacuum filtration of a dispersion with exfoliated graphene oxide nanosheets is a common way to prepare the graphene oxide stack [ 85 ]. Owing to the high aspect ratio, the graphene oxide nanosheets stack horizontally, which forms a paper-like layered structure.…”

Efficient photo-driven ion pump through slightly reduced vertical graphene oxide membranes

“…10 GOMs, being one of the most typical 2D nanofluidic membranes, possess densely packed 2D nanochannels functionalized with oxygen-containing groups, making them highly promising for applications in energy conversion and storage. [30][31][32][33][34] Additionally, the bandgap of GO can be adjusted by changing the content of oxygen-containing groups, rendering it suitable for photoelectric applications. [35][36][37] To further enhance the performance of GOMs, we explored slightly reduced vertical GOMs, featuring short channel lengths and efficient light absorption for better photo-driven ion pump properties.…”