Intensifying electrified flow-through water treatment technologies via local environment modification

Abstract

● Modifying local environment can intensify the performance of flow-through electrodes.

● Reaction rate and selectivity can be improved by local environment modification.

● Modifications include spatial confinement, enhanced local field, and periodic vortex.

● Near-complete removal of low-concentration emerging contaminants can be realized.

● Electrified flow-through systems are promising for fit-for-purpose water treatment.

Removing high-risk and persistent contaminants from water is challenging, because they typically exist at low concentrations in complex water matrices. Electrified flow-through technologies are viable to overcome the limitations induced by mass transport for efficient contaminant removal. Modifying the local environment of the flow-through electrodes offers opportunities to further improve the reaction kinetics and selectivity for achieving near-complete removal of these contaminants from water. Here, we present state-of-the-art local environment modification approaches that can be incorporated into electrified flow-through technologies to intensify water treatment. We first show methods of nanospace incorporation, local geometry adjustment, and microporous structure optimization that can induce spatial confinement, enhanced local electric field, and microperiodic vortex, respectively, for local environment modification. We then discuss why local environment modification can complement the flow-through electrodes for improving the reaction rate and selectivity. Finally, we outline appropriate scenarios of intensifying electrified flow-through technologies through local environment modification for fit-for-purpose water treatment applications.

Graphical abstract

Keywords

Point-of-use water treatment / Electrified membrane / Advection-enhanced mass transport / Water decontamination and disinfection / Emerging contaminants

1 Introduction

Addressing the lack of clean and safe water is among the most serious challenges of our time for humanity’s sustainability. The rapid expansion of urbanization and industrialization inevitably leads to the generation of a large number of high-risk and persistent contaminants, such as pharmaceuticals and personal care products (PPCPs), persistent organic pollutants (POPs), antibiotic-resistant pathogens, nutrients, and heavy metals. The release of these high-risk contaminants threatens water resources and aquatic ecosystems (Chaplin et al., 2019; Zuo et al., 2023). However, conventional water treatment technologies generally suffer from limited treatment efficiency and selectivity as well as high energy consumption for realizing near-complete removal of these trace contaminants from water (Hodges et al., 2018).

Electrified flow-through technologies offer an efficient and energy-saving alternative for fit-for-purpose water treatment with high throughput (Sun et al., 2021). Flow-through electrodes with porous structures enable highly exposed electrocatalysts inside the pores and intensify reactants approaching the internal surfaces to enhance contaminant removal (Chen et al., 2024). Notably, a flow-through electrode can also serve as an electrified membrane with both electroactivity and separation properties when its pore size is on the micro/nanoscale (Chaplin et al., 2019; Sun et al., 2021). The compact and modular construction enables electrified flow-through technologies to be readily incorporated into existing water treatment systems for pre- and/or post-treatment, such as portable drinking water treatment and wastewater reclamation (Hodges et al., 2018; Zuo et al., 2023), or to serve as point-of-use devices for fit-for-purpose applications (Sun et al., 2021). Additionally, electrified flow-through systems can be powered by renewable energy (e.g., solar and wind energy) and even off-grid energy (e.g., triboelectricity), considering their energy-efficient, chemical-free, and modular features (Huo et al., 2020).

Emerging contaminants are often present at relatively low concentrations (ng/L to μg/L for chemicals; < 100 CFU or PFU/mL for pathogens) in complex water conditions. This requires the flow-through electrodes to realize a high reaction rate and selectivity for removing the trace target contaminants from water (Hodges et al., 2018). To further intensify emerging contaminant removal, a viable option is to modify the local environment of the electrodes through methods such as nanospace incorporation, local geometry adjustment, and microporous structure optimization, to induce specific functions that can be triggered during flow-through operation (Grommet et al., 2020; Chen et al., 2024).

Here, we propose potential approaches, focusing on modifying the local environment of the electrodes, to address the challenges of electrified flow-through technologies for removing contaminants with low concentrations from water (Fig.1). We first present methods and mechanisms that fit the local environment modification, including inducing spatial confinement, enhancing local electric field, and introducing microperiodic vortex. We then discuss why modifying the local environment can complement electrified flow-through water treatment and how flow-through operation excites the confinement effect to improve the reaction rate and selectivity. Finally, we exemplify scenarios of intensifying electrified flow-through technologies through local environment modification for fit-for-purpose water treatment applications.

2 Methods and mechanisms of local environment modification

Electrified flow-through technologies offer a viable alternative for efficient emerging contaminant removal from water (Fig.1(a)). Modifying the local environment of the flow-through electrode could further enhance the removal efficiency under low concentrations. The local environment, particularly the reaction conditions at or near the water-electrode interface, significantly influences the reaction pathways by modulating electron transfer (Chen et al., 2024). Thus, modifying the local environment can regulate the thermodynamic and kinetic properties of the reactions to improve reaction rate and selectivity (Liu et al., 2020). In this section, we present strategies for local environment modification by incorporating micro/nanostructures on the flow-through electrode inner surface to promote electrochemical reactions (Fig.1(b)).

2.1 Confinement effect

The confinement effect can result in a higher local concentration compared with the bulk solution by accumulating the reactants within a range of nanospaces, such as cavities, pores, and channels (Grommet et al., 2020). For example, modifying carbon nanotubes (CNTs) by Co₃O₄ nanoparticles can accumulate nonpolar organic pollutants, such as bisphenol A, on the hydrophobic CNT surface (Liu et al., 2023). The accumulated bisphenol A can easily react with the Co₃O₄ nanoparticles loaded at the local region to reduce the mass transport distance to enhance the utilization of the short-lived reactive species, such as singlet oxygen (¹O₂). By increasing the local catalyst loading in the nanospaces, the interactions between catalysts and reagents can also be intensified by the confinement effect to increase reaction rates (Grommet et al., 2020; Qiao et al., 2020). Therefore, a viable way to achieve this goal is to incorporate atomic-scaled nanoclusters and single atoms into the pores or hollows of nanomaterials, such as metal-organic frameworks (MOFs), zeolites, and CNTs.

Conducting reactions in a confined space can also increase the selectivity of a specific reaction over others. By modifying the local environment in nanospaces via exposing the active crystal facet, adjusting hydrophobicity, and forcing reactant orientation, the target contaminants can be selectively adsorbed and degraded through a controlled pathway (Chen et al., 2024). For example, Mn-doped Fe₂O₃ nanoparticles exhibit facet-dependent adsorption: [001]- and [116]-faceted nanoparticles show selective adsorption of Pb²⁺ and Hg²⁺, respectively (Yuan et al., 2017). Metal ions can be selectively adsorbed with high capacity by controlling the Mn doping level to adjust the crystal facet, followed by depositing these controlled nanoparticles in the porous materials with nanospaces. These absorbed metal ions can be selectively reduced to metal particles by subsequent electrified reduction and removed from water. Additionally, reaction pathways can also be regulated by controlling the adsorption of the intermediate products in confined spaces to modify the selectivity. Pt single atoms anchored in CNT nanochannels have different neighboring dopants, including C, N, and S. The doping affects the adsorption of the intermediates during 2e⁻ electrochemical oxygen reduction (Zhao et al., 2022). The N- and S-doped Pt single-atom catalysts allow stronger adsorption of the intermediates (*OOH) within the nanoconfined spaces, resulting in much higher selectivity for hydrogen peroxide (H₂O₂) production (81.4%) compared with the Pt single-atom catalysts without doping (23.3%).

The confinement effect can also be applied for pathogen disinfection in water. Nanospaces created by molecular imprinting can provide specific binding sites of complementary size and shape to the biomolecular templates to adsorb target molecules (Yuan et al., 2020). High-risk pathogens or harmful genes can be adsorbed selectively when applying molecular imprinting with negative copies of the oligopeptides of microbial outer structures or DNA fragments to the electrodes for subsequent inactivation. Considering that harmful pathogens typically account for a small percentage of the total microorganisms in the environment, selectively inactivating the target pathogens can avoid the overuse of disinfectants to eliminate the formation of disinfection by-products. In addition, the selective removal of harmful genes, such as antibiotic resistance genes, holds promise to reduce the spread of antibiotic resistance in the environment.

2.2 Nanogeometry-enhanced local electric field

Free charges tend to accumulate in regions with the smallest radius of curvature in the electrode. One-dimensional (1D) nanomaterials with high aspect ratios, including nanowires, nanorods, and nanotubes, can effectively accumulate charges at the tips and form intensified local electric fields (Huo et al., 2020). When modifying the electrodes with the 1D nanomaterials, the electroporation effect can be readily induced at the tips to damage bacterial membranes and viral capsids (Huo et al., 2016). This 1D nanomaterial-assisted electroporation enables reaction-free, physics-based disinfection that requires insignificant energy consumption (10⁻⁴ to 10⁻² kWh/(m³ × order)) and short contact time (< 10 s) (Huo et al., 2022).

Local electric fields can also promote the adsorption of charged ions, allowing increased local interfacial reactant concentrations to accelerate reactions (Chen et al., 2024). For example, by incorporating gold nanorods into electrodes, the local electric field can effectively absorb K⁺ at the cathode surface (Liu et al., 2016). These concentrated K⁺ can stabilize carbon dioxide at the tip region of the gold nanorods by non-covalent adsorption, enabling an enhanced local concentration for accelerating further reduction. Additionally, the high voltage under the local electric fields can promote reactions that require high potentials, such as generating hydroxyl radicals (^•OH) through water oxidization.

2.3 Microporous flow pattern control

should diffuse to the electrode surface for degradation through concentration gradient. Optimizing local flow patterns by incorporating micro/nanoscale structures, such as cavities and channels, to generate vortices could overcome the limitation induced by diffusive transport. For example, the introduction of gyroid microstructures to a porous electrode can effectively promote the formation of strong periodic vortices in the diffuse layer to enhance mass transport (Yu et al., 2023). This gyroid porous electrode enables an enhanced nitrate reduction, 83% higher than that of the random porous electrode. Additionally, adjusting the pore size of the electrode porous structure can also optimize the mass transport of the target containments (Zhou et al., 2018). When functionalized with lamellar-structured graphene hydrogels, the densely packed porous electrode with nanoscale interlayer spacing allows water to flow along the narrow nanochannels and avoid the formation of dead volume zones, resulting in enhanced Pb²⁺ deposition.

3 Intensifying electrified flow-through treatment by local environment modification

Local environment modification typically involves confinement, nanogeometry optimization, and local flow-pattern regulation within the diffusion boundary layers of the water-electrode interface. Reactions under flow-by operation are limited by mass transport because reaction kinetics are dominated by reagent diffusion through the boundary layer. Flow-through operation allows water to flow through the porous electrodes to induce advection, which significantly reduces the thickness of the diffusion boundary layer to accelerate mass transport (Sun et al., 2021). Therefore, the performance of local environment modification can be maximized with sufficient mass transport during flow-through operation. In this section, we discuss the strategies of flow-through operation to excite the local environment modification for enhancing the removal of low-concentration contaminants (Fig.1(c)).

3.1 Advection-enhanced mass transport

Applying electrified flow-through operation can effectively compress the diffusion layer at the water-electrode interface to a scale comparable to the pore radius. The induced advection-enhanced mass transport can accelerate the target contaminants approaching the inner electrode surface. The functions of local environment modification near the surface can effectively play a role in improving the reaction rate and/or selectivity, realizing near-complete contaminant removal at low concentrations in complex water matrices. For example, 1D nanomaterial-assisted electroporation for disinfection is only effective when the microorganisms approach the tips with sufficient proximity, because the local electric field exists only near the tip regions (Huo et al., 2016). By applying a flow-through electrode whose surface is vertically decorated with 1D nanomaterial, the microorganisms can effectively approach the electrode surface through advective transport, realizing complete disinfection within 10 s. In contrast, the disinfection performance decreased by more than five orders of magnitude under the same operating conditions without mass transport acceleration (Huo et al., 2021).

Enhancing mass transport also contributes to the regulation of local flow pattern that affects adsorption between the reagents and electrocatalysts to modify selectivity. In electrochemical nitrate reduction, a CNT electrified membrane incorporating Cu single atoms enhances the adsorption of the reduction intermediates during flow-through operation, enabling a near-complete conversion of low-concentration nitrate (10 mg-N/L) with high selectivity of 86% for nitrogen generation in 10 s (Wang et al., 2023). This is a significant enhancement over the flow-by operation, which achieves only 30% nitrate removal with a limited nitrogen selectivity of 7% under the same operating conditions.

3.2 Pressure-promoted confinement

Pressure is applied to drive water flow through the porous electrode. This external force enables reactants in water to be advected into nanospaces such as the interlayer of 2D nanosheets (e.g., graphene, MXene, and MoS₂ nanosheets) to induce the confinement effects. For example, a laminate flow electrode consisting of monolayer Co-doped TiO₂ nanosheets has sub-nanometer (several angstroms) interlayer channels (Meng et al., 2022). The contaminants in water advected into the layered confined channels can react in situ with the decorated atomic catalysts inside the channels. Fast degradation of ranitidine is achieved with a reaction rate of 1.06 m/s, five orders of magnitude higher than that under the flow-by mode.

Selectivity can also be adjusted when water flows through confined nanochannels (Yang et al., 2019). By flowing H₂O₂ into a nanochannel CNT (diameter of 7 nm), the decorated Fe₂O₃ nanoparticles (particle size of 2 nm) inside the CNT convert H₂O₂ to ¹O₂. This pathway is different from the typical Fenton reactions in bulk solutions that generate ^•OH. The Fe₂O₃ nanoparticles exhibit stronger electronic interaction in the confined nanochannel to selectively convert the H₂O₂ to HO₂^•/O₂^{• −} for further ¹O₂ generation. In contrast to the short-lived and non-selective ^•OH, the meta-stable ¹O₂ in the CNT nanochannels shows higher selectivity toward electron-rich compounds for a 22.5-fold faster degradation of methylene blue. Additionally, the flow direction between the fluid and electrode interface can also be regulated during flow-through operation, which can include periodic vertexing to further enhance mass transport (Yu et al., 2023).

3.3 Sufficient exposure on active sites

Flow-through electrodes with micro/nanochannels offer more surface area for catalyst decoration and exposure compared with flat electrodes (Yang et al., 2023). The high surface area provides sufficient active sites for efficient contaminant degradation during flow-through operation. The active surface area of a flow-through RuO₂-doped porous electrode (pore size of 25 μm) is 400 times higher than that of a flow-by plate electrode (Chen et al., 2022). Reducing the pore size of porous electrodes can increase the utilization of active sites under the same electrode porosity. A 25-μm pore size electrode enabled higher efficiency to reduce the energy consumption to 60.4 kWh/kg-N, 39.9% less than that of the 90-μm pore size electrode, when achieving complete ammonia removal (Chen et al., 2022).

4 Perspectives, applications, and outlook

Electrified flow-through operation can effectively decrease the thickness of the diffusion boundary layer to a length scale comparable to the pore radius. Advection in the porous electrodes significantly accelerates the transport of the target contaminants to the confined region. This enables local environment modification that primarily dominates within the diffusion boundary layer of the water-electrode interface to effectively play a role in increasing local concentrations, modifying adsorption, and/or optimizing flow patterns to further improve the reaction rates and selectivity. Therefore, electrified flow-through water treatment can be significantly enhanced via local environment modification to achieve near-complete removal of high-risk, persistent contaminants with low concentrations. Some related examples of removing low-concentration PPCPs, POPs, harmful pathogens, nutrients (N and P), and heavy metals from water are shown in Tab.1.

By improving the reaction kinetics and selectivity through local environment modification, the electrified flow-through technologies can realize fit-for-purpose removal of target contaminants with high water treatment throughput. For example, a metal-deposited ceramic membrane can selectively produce ¹O₂ to remove electron-rich contaminants of PPCPs and POPs in confined micropores (Zhao et al., 2020). CNT electrified membranes can enhance the adsorption of the reactants in nanopores for achieving near-complete removal of nutrients (N and P) with high selectivity (Jin et al., 2023; Wang et al., 2023). Additionally, 1D nanomaterial-assisted electroporation can effectively induce sub-lethal damage on bacteria under a high water flux of 10⁴ L/(m²·h) during flow-through operation. The low-concentration chlorine that typically exists in tap water (~0.5 mg-Cl₂/L) is sufficient to aggravate such damages for complete bacterial inactivation (Huo et al., 2022). Notably, the energy consumption of the electrified flow-through water treatment is low: 10⁻³ to 10¹ kWh/(m³ × order) for contaminant degradation and 10⁻⁴ to 10¹ kWh/(m³ × order) for disinfection (Tab.1; Miklos et al., 2018; Huo et al., 2020; Sun et al., 2021). Rational module configuration, such as a tubular concentric structure, also facilitates the scale-up of the electrified flow-through systems (Pei et al., 2022).

Electrified flow-through technologies can also be integrated into existing water treatment processes for pre- and/or post-treatment, ideally suitable for high-standard portable drinking water treatment and wastewater reclamation (Fig.1). For example, 1D nanomaterial-modified flow-through electrodes can achieve efficient and energy-saving disinfection under high water flux. Such electrodes can be applied for treating drinking water after storage and piped distribution to eliminate the impacts of microbial regrowth (Huo et al., 2016). Additionally, carbonaceous electrified membranes enable near-complete and selective removal of low-concentration nutrients from water (Jin et al., 2023; Wang et al., 2023). The application of such membranes may address the critical need for nutrient control for wastewater reclamation, because eutrophication can be triggered by the low-concentration nutrients if the reclaimed water is reused as a supplemental source for surface water.

The modular and compact construction facilitates electrified flow-through systems to be applied for decentralized, point-of-use applications, such as household and rural water treatment. For example, carbonaceous electroactive filters can effectively remove multiple organic pollutants, toxic metals, and pathogens simultaneously under a long operation time (several months) with low manufacturing cost (< 20 USD) (Liu et al., 2020). Further, low and/or intermittent energy inputs are sufficient to power the electrified flow-through systems for point-of-use water treatment in many cases (Huo et al., 2023). For this reason, renewable and even off-grid energy sources, such as wind, solar, and thermal energy, are available to power the flow-through systems instead of grid electricity, offering a promising alternative where centralized water treatment is not feasible (Rahimi et al., 2018).

Modifying the local environment of the flow-through electrodes to intensify water treatment should overcome the limitations related to the cost and stability of the functionalized nanomaterials, especially during long-term operation. Scalable system configurations with large surface area and stable structure of the electrodes can further lower the treatment costs when scaled up. Further, foulants contained in the complex water matrices may block the confined range during flow-through operation, requiring the electrodes to possess antifouling and/or self-cleaning properties for fouling control (Wang et al., 2020). These fouling control properties can improve the operational stability of the systems when treating water with complex matrices, therefore extending the lifespan of the flow-through electrodes and reducing the maintenance costs. Specifically, self-cleaning is more energy efficient than antifouling in real applications because of its intermittent operation (Sun et al., 2021). Additionally, techno-economic analysis and life cycle assessment are necessary to quantify economic and environmental impacts, including manufacturing costs, greenhouse gas emissions, and potential toxicity to humans and the ecosystems, before expanding the electrified flow-through systems for water treatment in large scales (Xia et al., 2021; Sun et al., 2023). A cradle-to-gate assessment helps to further improve the design of the confined nanospaces in the electrodes and the electrified flow-through systems to meet the needs of fit-for-purpose water treatment, especially when considering the potential scenarios of powering the systems with renewable energy.

References

[1] Chaplin B P. (2019). The prospect of electrochemical technologies advancing worldwide water treatment. Accounts of Chemical Research, 52(3): 596–604

[2] ChenCJin HWangPSunXJaroniecM ZhengYQiao S Z (2024). Local reaction environment in electrocatalysis. Chemical Society Reviews, Advance Article.

[3] Chen Y, Zhang G, Ji Q, Lan H, Liu H, Qu J. (2022). Visualization of electrochemically accessible sites in flow-through mode for maximizing available active area toward superior electrocatalytic ammonia oxidation. Environmental Science & Technology, 56(13): 9722–9731

[4] Gao Y, Liang S, Liu B, Jiang C, Xu C, Zhang X, Liang P, Elimelech M, Huang X. (2023). Subtle tuning of nanodefects actuates highly efficient electrocatalytic oxidation. Nature Communications, 14(1): 2059

[5] Grommet A B, Feller M, Klajn R. (2020). Chemical reactivity under nanoconfinement. Nature Nanotechnology, 15(4): 256–271

[6] Guo D, Liu Y, Ji H, Wang C C, Chen B, Shen C, Li F, Wang Y, Lu P, Liu W. (2021). Silicate-enhanced heterogeneous flow-through electro-Fenton system using iron oxides under nanoconfinement. Environmental Science & Technology, 55(6): 4045–4053

[7] Hodges B C, Cates E L, Kim J H. (2018). Challenges and prospects of advanced oxidation water treatment processes using catalytic nanomaterials. Nature Nanotechnology, 13(8): 642–650

[8] Huo Z, Kim Y J, Chen Y, Song T, Yang Y, Yuan Q, Kim S W. (2023). Hybrid energy harvesting systems for self-powered sustainable water purification by harnessing ambient energy. Frontiers of Environmental Science & Engineering, 17(10): 118

[9] Huo Z Y, Du Y, Chen Z, Wu Y H, Hu H Y. (2020). Evaluation and prospects of nanomaterial-enabled innovative processes and devices for water disinfection: a state-of-the-art review. Water Research, 173: 115581

[10] Huo Z Y, Kim Y J, Suh I Y, Lee D M, Lee J H, Du Y, Wang S, Yoon H J, Kim S W. (2021). Triboelectrification induced self-powered microbial disinfection using nanowire-enhanced localized electric field. Nature Communications, 12(1): 3693

[11] Huo Z Y, Winter L R, Wang X, Du Y, Wu Y H, Hübner U, Hu H Y, Elimelech M. (2022). Synergistic nanowire-enhanced electroporation and electrochlorination for highly efficient water disinfection. Environmental Science & Technology, 56(15): 10925–10934

[12] Huo Z Y, Xie X, Yu T, Lu Y, Feng C, Hu H Y. (2016). Nanowire-modified three-dimensional electrode enabling low-voltage electroporation for water disinfection. Environmental Science & Technology, 50(14): 7641–7649

[13] Jin L, Ren Y, Zheng W, Pan F, You S, Liu Y. (2023). Surface engineering of electrified MXene filter for enhanced phosphate removal. ACS ES&T Engineering, 3(12): 2243–2251

[14] Kang Y, Gu Z, Ma B, Zhang W, Sun J, Huang X, Hu C, Choi W, Qu J. (2023). Unveiling the spatially confined oxidation processes in reactive electrochemical membranes. Nature Communications, 14(1): 6590

[15] Liu M, Pang Y, Zhang B, De Luna P, Voznyy O, Xu J, Zheng X, Dinh C T, Fan F, Cao C. . (2016). Enhanced electrocatalytic CO₂ reduction via field-induced reagent concentration. Nature, 537(7620): 382–386

[16] Liu T, Xiao S, Li N, Chen J, Zhou X, Qian Y, Huang C H, Zhang Y. (2023). Water decontamination via nonradical process by nanoconfined Fenton-like catalysts. Nature Communications, 14(1): 2881

[17] Liu Y, Gao G, Vecitis C D. (2020). Prospects of an electroactive carbon nanotube membrane toward environmental applications. Accounts of Chemical Research, 53(12): 2892–2902

[18] Meng C, Ding B, Zhang S, Cui L, Ostrikov K K, Huang Z, Yang B, Kim J H, Zhang Z. (2022). Angstrom-confined catalytic water purification within Co-TiO_x laminar membrane nanochannels. Nature Communications, 13(1): 4010

[19] Miklos D B, Remy C, Jekel M, Linden K G, Drewes J E, Hübner U. (2018). Evaluation of advanced oxidation processes for water and wastewater treatment: a critical review. Water Research, 139: 118–131

[20] Pei S, Wang Y, You S, Li Z, Ren N. (2022). Electrochemical removal of chlorophenol pollutants by reactive electrode membranes: scale-up strategy for engineered applications. Engineering (Beijing), 9: 77–84

[21] Qian J, Gao X, Pan B. (2020). Nanoconfinement-mediated water treatment: From fundamental to application. Environmental Science & Technology, 54(14): 8509–8526

[22] Rahimi M, Straub A P, Zhang F, Zhu X, Elimelech M, Gorski C A, Logan B E. (2018). Emerging electrochemical and membrane-based systems to convert low-grade heat to electricity. Energy & Environmental Science, 11(2): 276–285

[23] Sun M, Wang X, Winter L R, Zhao Y, Ma W, Hedtke T, Kim J H, Elimelech M. (2021). Electrified membranes for water treatment applications. ACS ES&T Engineering, 1(4): 725–752

[24] Sun Y, Bai S, Wang X, Ren N, You S. (2023). Prospective life cycle assessment for the electrochemical oxidation wastewater treatment process: from laboratory to industrial scale. Environmental Science & Technology, 57(3): 1456–1466

[25] Wang X, Sun M, Zhao Y, Wang C, Ma W, Wong M S, Elimelech M. (2020). In situ electrochemical generation of reactive chlorine species for efficient ultrafiltration membrane self-cleaning. Environmental Science & Technology, 54(11): 6997–7007

[26] Wang X, Wu X, Ma W, Zhou X, Zhang S, Huang D, Winter L R, Kim J H, Elimelech M. (2023). Free-standing membrane incorporating single-atom catalysts for ultrafast electroreduction of low-concentration nitrate. Proceedings of the National Academy of Sciences of the United States of America, 120(11): e2217703120

[27] Xia Q, Chen C, Yao Y, Li J, He S, Zhou Y, Li T, Pan X, Yao Y, Hu L. (2021). A strong, biodegradable and recyclable lignocellulosic bioplastic. Nature Sustainability, 4(7): 627–635

[28] Yang K, Zhang X, Zu D, Zhou H, Ma J, Yang Z. (2023). Shifting emphasis from electro- to catalytically active sites: Effects of pore size of flow-through anodes on water purification. Environmental Science & Technology, 57(48): 20421–20430

[29] Yang Z, Qian J, Yu A, Pan B. (2019). Singlet oxygen mediated iron-based Fenton-like catalysis under nanoconfinement. Proceedings of the National Academy of Sciences of the United States of America, 116(14): 6659–6664

[30] Yu Y, Pei S, Zhang J, Ren N, You S. (2023). Bio-inspired porous composite electrode for enhanced mass transfer and electrochemical water purification by modifying local flow pattern. Advanced Functional Materials, 33(26): 2214725

[31] Yuan Q, Li P, Liu J, Lin Y, Cai Y, Ye Y, Liang C. (2017). Facet-dependent selective adsorption of Mn-doped α-Fe₂O₃ nanocrystals toward heavy-metal ions. Chemistry of Materials, 29(23): 10198–10205

[32] Yuan Q, Zhang D, Yu P, Sun R, Javed H, Wu G, Alvarez P J J. (2020). Selective adsorption and photocatalytic degradation of extracellular antibiotic resistance genes by molecularly-imprinted graphitic carbon nitride. Environmental Science & Technology, 54(7): 4621–4630

[33] Zhao J, Fu C, Ye K, Liang Z, Jiang F, Shen S, Zhao X, Ma L, Shadike Z, Wang X. . (2022). Manipulating the oxygen reduction reaction pathway on Pt-coordinated motifs. Nature Communications, 13(1): 685

[34] Zhao Y, Sun M, Wang X, Wang C, Lu D, Ma W, Kube S A, Ma J, Elimelech M. (2020). Janus electrocatalytic flow-through membrane enables highly selective singlet oxygen production. Nature Communications, 11(1): 6228

[35] Zhou Y, Ji Q, Liu H, Qu J. (2018). Pore structure-dependent mass transport in flow-through electrodes for water remediation. Environmental Science & Technology, 52(13): 7477–7485

[36] Zuo K, Garcia-Segura S, Cerrón-Calle G A, Chen F Y, Tian X, Wang X, Huang X, Wang H, Alvarez P J J, Lou J. . (2023). Electrified water treatment: fundamentals and roles of electrode materials. Nature Reviews. Materials, 8(7): 472–490

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