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Electricity is the basic and essential need for every single person and guarantees the development of society, industry, and the economy. The limited conventional fossil fuel meets the challenge of the sharply increasing demand, while may lead to severe pollution. Emerging green energy harvesting systems can convert ambient kinetic, thermal, and solar energy to electricity effectivity. In this review paper, the authors provide an overview of the new and emerging methods, droplet‐based electricity generators, that convert energy from the ubiquitously existing water droplets. The authors begin with a brief introduction of the working principle for droplet‐based power generators. Existing configurations of the droplet‐based power generator are also summarized, including 1) single electrode, 2) transistor‐based, and 3) direct current generator. Then, a detailed discussion of the design and operation factors that may impact the energy harvesting efficiency of droplet‐based power generators is provided. Hybrid energy harvester that integrates droplet‐based power generators with other triboelectric, pyroelectric, and photovoltaic‐based devices are summarized. Finally, challenges and perspectives regarding the future development of droplet‐based power generators are described. The reviews demonstrate a highly efficient method for energy harvesting from water droplets to meet the vital needs of the energy crisis. [ABSTRACT FROM AUTHOR]

Water‐borne diseases resulting from pathogen infection are especially challenges in areas with inadequate sanitation and power supply. Here a novel disinfection system is developed for bacterial and viral inactivation in water using a self‐powered supercoiling‐mediated rotational triboelectric nanogenerator (S‐TENG) as a power source to drive a new oxidation‐assisted electroporation mechanism. Owing to its rational design, the S‐TENG achieves an ultrafast rotation (≈7500 rpm), therefore it enables a simultaneous nanowire‐enhanced localized electric field and generation of oxidative species resulting in high disinfection performance: >99.9999% microbial inactivation at a high flux of 15 000 L h‐1 m‐2. An integrated S‐TENG‐powered disinfection prototype using an enlarged electrode (area of 50 cm2) achieves complete disinfection when the gravity‐driven natural water flows through the whole system at a high rate (1 L min‐1). This rapid, self‐powered water disinfection method is a potential solution for urgent water disinfection needs during disasters and pandemics, and water disinfection in areas with inadequate power supply. [ABSTRACT FROM AUTHOR]

Contaminated drinking water is one of the main pathogen transmission pathways making waterborne illnesses such as diarrheal diseases and gastroenteritis a huge threat to public health, especially in the areas where sanitation facilities and gird power are inadequate such as rural and disaster hit areas. Self‐powered water disinfection systems are a promising solution in these cases. In this review paper, the authors provide an overview of the new and emerging methods of applying energy harvesting materials and devices as a source of power for water disinfection systems microbial disinfection in water by harnessing ambient forms of energy such as mechanical motion, light, and heat into electricity. The authors begin with a brief introduction of the different energy harvesting technologies commonly applied in water disinfection; triboelectric, piezoelectric, pyroelectric, and photovoltaic effects. Various microbial disinfection mechanisms and types of device construction are summarized. Then, a detailed discussion of the energy harvester‐driven water disinfection process is provided. Finally, challenges and perspectives regarding the future development of self‐powered water disinfection are described. [ABSTRACT FROM AUTHOR]

Disinfection is an essential process to protect people from waterborne pathogen infections. Conventional water disinfection methods (e.g., chlorination and ultraviolet radiation) have made considerable contributions to water safety, but are accompanied by obvious drawbacks such as carcinogenic byproduct formation, energy intensiveness, and/or regrowth of pathogens. Here, we develop an electroporation-disinfection cell (EDC) that enables fast water disinfection using a polydopamine-protected copper-phosphide-nanowire-modified copper foam (PDA-Cu3PNW-Cu) electrode powered by a high-frequency alternating current (AC; 106 Hz). Electroporation relies on a strong electric field to damage microorganism membranes without byproduct formation. The PDA film ensures a robust nanowire structure against the hydraulic detachment and reduces mechanical erosion. High-frequency AC as the power source can effectively eliminate electrochemical corrosion and extend the electrode lifetime. EDCs with PDA-Cu3PNW-Cu electrodes achieved complete disinfection (no live microorganism in the effluent) with a low voltage (peak voltage of 1 V) and a high flux (2 m3 h−1 m−2). Under such operating conditions, the PDA-Cu3PNW-Cu electrodes enable complete E. coli disinfection (＞6.0 log removal efficiency) for 15 days. To our knowledge, this is the highest value obtained to date for nanostructure-modified electrodes for low-voltage electroporation: 30 times the previously reported maximum lifetime. [ABSTRACT FROM AUTHOR]

Pathogen infection has become the major reason for human morbidity and mortality in the world. However, common bacterial inactivation methods (e.g., chlorination, ultraviolet radiation, and ozonization) have significant drawbacks such as carcinogenic byproduct formation, energy intensiveness, and/or regrowth of pathogens. Nanowire-assisted low-voltage electroporation enables effective and energy-efficient bacterial inactivation. Here, we develop a new Cu3P nanowire-assisted copper mesh (Cu3PNW–Cu) electrode via an in situ growth followed by a phosphidation method and, for the first time, introduce the Cu3PNWs in the water purification process. An electroporation-disinfection cell (EDC) equipped with two such electrodes achieves superior bacterial inactivation performance (＞6.0 log removal; no live bacteria in the effluent) with a low voltage of 1 V and a high flux of 2.0 m3 h−1 m−2. Under such operating conditions, the Cu3PNW–Cu electrode continuously treats water for 12 h while maintaining complete bacterial inactivation. The disinfection mechanism of electroporation guarantees an exceedingly low level of energy consumption: only 1.2 J for treating 1 L of water. To our knowledge, this is the lowest value obtained to date: ＞5 orders of magnitude lower than the typical energy consumption for bacterial inactivation using electroporation (150 kJ L−1). [ABSTRACT FROM AUTHOR]

Correction for ‘Low-voltage alternating current powered polydopamine-protected copper phosphide nanowire for electroporation-disinfection in water’ by Zheng-Yang Huo et al., J. Mater. Chem. A, 2019, 7, 7347–7354. [ABSTRACT FROM AUTHOR]

Airborne pathogens retain prolonged infectious activity once attached to the indoor environment, posing a pervasive threat to public health. Conventional air filters suffer from ineffective inactivation of the physics-separated microorganisms, and the chemical-based antimicrobial materials face challenges of poor stability/efficiency and inefficient viral inactivation. We, therefore, developed a rapid, reliable antimicrobial method against the attached indoor bacteria/viruses using a large-scale tunneling charge-motivated disinfection device fabricated by directly dispersing monolayer graphene on insulators. Free charges can be stably immobilized under the monolayer graphene through the tunneling effect. The stored charges can motivate continuous electron loss of attached microorganisms for accelerated disinfection, overcoming the diffusion limitation of chemical disinfectants. Complete (>99.99%) and broad-spectrum disinfection was achieved <1 min of attachment to the scaled-up device (25 square centimeters), reliably for 72 hours at high temperature (60°C) and humidity (90%). This method can be readily applied to high-touch surfaces in indoor environments for pathogen control.

More than 10% of the people in the world still suffer from inadequate access to clean water. Traditional water disinfection methods (e.g., chlorination and ultraviolet radiation) include concerns about the formation of carcinogenic disinfection byproducts (DBPs), pathogen reactivation, and/or excessive energy consumption. Recently, a nanowire-assisted electroporation-disinfection method was introduced as an alternative. Here, we develop a new copper oxide nanowire (CuONW)-modified three-dimensional copper foam electrode using a facile thermal oxidation approach. An electroporation-disinfection cell (EDC) equipped with two such electrodes has achieved superior disinfection performance (>7 log removal and no detectable bacteria in the effluent). The disinfection mechanism of electroporation guarantees an exceedingly low operation voltage (1 V) and level of energy consumption (25 J L(-1)) with a short contact time (7 s). The low operation voltage avoids chlorine generation and thus reduces the potential of DBP formation. Because of irreversible electroporation damage on cell membranes, no regrowth and/or reactivation of bacteria occurs during storage after EDC treatment. Water disinfection using EDCs has great potential for practical applications.