Recent Advances in Fibrous Materials for Hydroelectricity Generation

Abstract

Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable development. Hydroelectricity generation from ubiquitous and spontaneous phase transitions between liquid and gaseous water has been considered a promising strategy for mitigating the energy crisis. Fibrous materials with unique flexibility, processability, multifunctionality, and practicability have been widely applied for fibrous materials-based hydroelectricity generation (FHG). In this review, the power generation mechanisms, design principles, and electricity enhancement factors of FHG are first introduced. Then, the fabrication strategies and characteristics of varied constructions including 1D fiber, 1D yarn, 2D fabric, 2D membrane, 3D fibrous framework, and 3D fibrous gel are demonstrated. Afterward, the advanced functions of FHG during water harvesting, proton dissociation, ion separation, and charge accumulation processes are analyzed in detail. Moreover, the potential applications including power supply, energy storage, electrical sensor, and information expression are also discussed. Finally, some existing challenges are considered and prospects for future development are sincerely proposed.

Keywords: Fibrous material; Hydroelectricity; Ion diffusion; Streaming potential.

Fig. 1

a Year-on-year change in electricity demand by region (2019–2025). b Changes in global electricity generation by source (2022–2025). The data is obtained from the International Energy Agency

Fig. 2

Schematic of streaming potential and ion diffusion-induced FHG. Schematics of a EDL at the solid-water interface and b the streaming potential within a nanochannel. Schematics of c the water gradient mode and d the oxygen functional group gradient mode

Fig. 3

The constructions and characteristics of FHG devices. Reproduced with permission from Ref. [89], Copyright 2017, Elsevier; Ref. [90], Copyright 2018, Elsevier; Ref. [91], Copyright 2020, American Chemical Society; Ref. [92], Copyright 2024, American Chemical Society; Ref. [93], Copyright 2023, Elsevier; Ref. [94], Copyright 2024, American Association for the Advancement of Science

Fig. 4

Manufacturing of fibrous materials with different constructions. The manufacturing process of a 1D fiber. Reproduced with permission from Ref. [101]. Copyright 2022, Wiley–VCH. b 1D yarn. Reproduced with permission from Ref. [102]. Copyright 2023, Elsevier. c 2D fabric. Reproduced with permission from Ref. [49]. Copyright 2023, Wiley–VCH. d 2D membrane. Reproduced with permission from Ref. [103]. Copyright 2023, American Chemical Society. e 3D fibrous framework. Reproduced with permission from Ref. [104]. Copyright 2024, Wiley–VCH. f 3D fibrous gel. Reproduced with permission from Ref. [92]. Copyright 2024, American Chemical Society

Fig. 5

Fibrous materials for water harvesting during FHG. a1 Schematic of the design concept and fabrication process. a2 Schematic of FHG enabled by directional migration of free ions with opposite charges within hydrated nanochannels. a3 Graphical illustration of FHG process. Reproduced with permission from Ref. [75]. Copyright 2022, American Chemical Society. b1 Schematic of the tree-like fibrous membranes. b2 Water contact angle of the fibrous membranes with different TBAB content. b3 Specific surface area and average pore size of the fibrous membranes with different TBAB content. Reproduced with permission from Ref. [119]. Copyright 2022, Elsevier

Fig. 6

Fibrous materials for proton dissociation during FHG. a1 Schematic diagram of a self-supporting bilayer generator. a2 Schematic mechanism of the bilayer generator. a3 Variations of oxygen content and conductivity of carbon foams with carbonization time at 800 °C (inset, digital photograph of carbon foams). a4 Real-time open-circuit voltages. a5 Peak voltages induced by carbon foams in water. Reproduced with permission from Ref. [74]. Copyright 2024, American Chemical Society. b1 Resistance, b2 zeta potential, and b3 FHG output of the wood-based generator under different concentrations of FeCl₃ solution. Reproduced with permission from Ref. [135]. Copyright 2022, Royal Society of Chemistry

Fig. 7

Fibrous materials for ion separation during FHG. a1 Schematic diagram of an asymmetric hierarchical textile for FHG. a2 Voltage in response to dropping water onto the asymmetric textile with the resistance of 200 kΩ (left) and 50 kΩ (right). a3 Schematic illustration of the establishment of a potential difference between the asymmetric areas when half-wetted and fully-wetted. Reproduced with permission from Ref. [157]. Copyright 2022, Elsevier. b1 Schematic diagram of four functions of hierarchical porous nanofibers. b2 Incremental hole area versus hole width curve. b3 Proportion of mesopores and micropores in hierarchical porous nanofibers with different PAN-PMMA ratios. b4 FHG output of devices with different PAN-PMMA ratios. Reproduced with permission from Ref. [43]. Copyright 2022, Wiley–VCH GmbH

Fig. 8

Fibrous materials for charge accumulation during FHG. a Schematic diagram of the manufacturing of flexible FHG device. b Schematic diagram of the FHG device with varied geometric morphology of flexible FHG device. c Effect of aerogel geometric morphology on electricity output. Reproduced with permission from Ref. [44]. Copyright 2021, Elsevier

Fig. 9

Applications of FHG. a1 Measured electricity output of three paper-based generators connected in parallel or series. Photograph of a2 an electronic calculator, a3 an LED bulb, and a4 a wearable watch driven by arrayed connected generators. Reproduced with permission from Ref. [88]. Copyright 2020, Elsevier. b Voltage–time curves of commercial capacitors charged by fluidic nanogenerators connected in series. Reproduced with permission from Ref. [65]. Copyright 2021, American Chemical Society. c1 The device containing CNT fibers is woven into the fabric. c2 A series of potential applications for FHG devices. Reproduced with permission from Ref. [101]. Copyright 2022, Wiley–VCH GmbH. d1 Schematic diagram of a wearable self-powered sensing system. Real-time V_oc variation of the FHG ion sensor during d2 running at different speeds and d3 running with and without water intake. d4 Real-time V_oc curves of wearable single and two FHG devices in series generated during running. Reproduced with permission from Ref. [174]. Copyright 2023, Wiley–VCH GmbH. e1 Schematic diagram of the FHG structure and attachment position for wearable sweat sensing. e2 Real-time V_oc variation of different positions during constant riding. Reproduced with permission from Ref. [116]. Copyright 2024, Wiley–VCH GmbH. f1 Schematic illustration of unit coordinates. f2 The device containing 136 units is attached to a mask. f3 Peak voltage outputs of the units located in different coordinates. Expression of the electronic label: voltage outputs of all the units after a deep breath (ΔRH = 35%). Reproduced with permission from Ref. [89]. Copyright 2017, Elsevier