Hydrovoltaic Electricity Generator with Hygroscopic Materials: A Review and New Perspective

Abstract

The global energy crisis caused by the overconsumption of non‐renewable fuels has prompted researchers to develop alternative strategies for producing electrical energy. In this review, we introduce a fascinating strategy that simply utilizes water, an abundant natural substance throughout the globe and even in air as moisture, as a power source. The concept of the hydrovoltaic electricity generator (HEG) proposed herein involves generating an electrical potential gradient by exposing the two ends of the HEG device to dissimilar physicochemical environments, which leads to the production of an electrical current through the active material. HEGs, with a large variety of viable active materials, have much potential for expansion toward diverse applications including permanent and/or emergency power sources. In this review, we discuss representative HEGs that generate electricity by the mechanisms of diffusion, streaming, and capacitance as case studies for building a fundamental understanding of the electricity generation process. In particular, by comparing the use and absence of hygroscopic materials, we meticulously elucidate HEG mechanism studies to establish active material design principles. We conclude the review with future perspectives on electrode design using conducting nanomaterials, considerations for high performance device construction, and potential impacts of the HEG technology in improving our livelihoods.This article is protected by copyright. All rights reserved

Synergistic Effects of TiO2 and Carbon Black for Water Evaporation-Induced Electricity Generation

“…Additionally, the contact angles between the film surface and water before and after annealing were measured as 41° (Figure h) and 4.7° (Figure i), indicating the excellent hydrophilicity of the annealed TC film. The above results indicate that TC film is a porous hydrophilic material primarily composed of elements such as Ti, O, and C, giving TC film the potential to be used in hydrovoltaic electricity generation …”

“…The above results indicate that TC film is a porous hydrophilic material primarily composed of elements such as Ti, O, and C, giving TC film the potential to be used in hydrovoltaic electricity generation. 37 Electrical output performance of TC-WEGs. To investigate the power generation performance of TC-WEGs, a device was placed in an acrylic container and the deionized water was added until the bottom electrode was fully submerged (Figure 2a).…”

Advances in Smart Photovoltaic Textiles

“…A Hydrovoltaic Energy Generator (HEG) is another emerging device, effectively utilizing the physiochemical properties of water to generate electricity, (Figure g). With the capacity to charge wearable devices continuously with DC power from an endless natural source, such as ambient humidity, HEGs are becoming increasingly popular in research and academia . A group of researchers recently developed a HEG using the ionic polymer nafion and a poly­( N -isopropyl­acrylamide) hydrogel.…”

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“…Humankind will soon need new materials and specialized techniques for energy harvesting to enable smart systems. Thus, developing energy harvesting materials and technologies that can harvest energy from the environment, such as mechanical vibration (triboelectric), − heat (hhermoelectric), , piezoelectric (stress-induced), , pyroelectric, , tides/waves (hydroelectric), magnetic field (magnetoelectric), environmental humidity (hydrovoltaic), , etc., to generate electrical power for self-power devices is very necessary. In 2006, Wang et al developed the first piezoelectric nanogenerator using ZnO nanowire, which created a new avenue in the nanogenerator field.…”