About

John Fortner is a Professor and Chair of Chemical & Environmental Engineering at Yale University. He holds a Ph.D. from Rice University and a B.S. from Texas A&M University. His research focuses on advancing water-related technologies and understanding engineering novel material interfaces as they relate to critical environmental-based health, security, and energy challenges. Fortner has received numerous awards and honors, including the Ackerman Award for Teaching and Mentoring in 2025, election as a Fellow of the Royal Society of Chemistry in 2021, and the U.S. National Science Foundation CAREER Award in 2015. He is actively involved in leadership roles such as Chair and Vice Chair of the Environmental Nanotechnology Gordon Research Conference and is an appointee to the U.S. National Academies of Sciences, Engineering, and Medicine's Board on Chemical Science and Technology. His work is characterized by a commitment to pioneering breakthroughs in environmental and energy-related fields.

Research topics

• Chemistry
• Engineering
• Computer Science
• Organic chemistry
• Chemical engineering
• Nanotechnology
• Materials science
• Geology
• Business
• Psychotherapist
• Chemical physics
• Environmental science
• Biochemical engineering
• Psychology
• Polymer chemistry
• Thermodynamics
• Environmental chemistry

Selected publications

• Elucidating an unrecognized iron leaching mechanism via sequential reduction-oxidation of passivation layer on stainless-steel cathodes for electro-Fenton process

  Water Research · 2026-02-24

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• Advancing membrane fouling control via electrically driven microbubble generation: Phosphidation-enhanced electrocatalytic activity of Ni foam and numerical optimization of operational parameters

  Water Research · 2026-03-04

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  PublisherDOI

• Solar-Driven Photocatalytic Trichloroethylene Mineralization with High CO ₂ Selectivity

  Nano Letters · 2026-02-25

  articleCorresponding

  Sunlight-driven photocatalytic oxidation, using ambient air as the oxidant, offers a sustainable route for removing chlorinated volatile organic compounds (VOCs) such as trichloroethylene (TCE). Yet, practical implementation is hindered by low reaction rates and undesirable product selectivity. Here, we present a material design strategy that overcomes both challenges. Size-controlled anatase TiO2 nanocrystals with truncated bipyramid (nanoTBP) morphology achieve exceptional photocatalytic activity for TCE degradation, comparable to rates reported for energy-intensive thermal catalysis, with unoptimized CO2/CO product ratios. Decorating as-synthesized TiO2 with Pt nanoparticles significantly enhances the CO2 selectivity but significantly diminishes the overall reaction rates. To resolve this rate–selectivity trade-off, we integrate Pt/TiO2 with pristine TiO2 into an optimized composite photocatalyst, unlocking a tandem pathway that enables both rapid degradation and complete mineralization of TCE to CO2 under solar irradiation. Taken together, this work establishes a scalable, solar-enabled, materials-based strategy for complete gas-phase mineralization of TCE, with broader implications for novel and sustainable VOC treatment processes.

  PublisherDOI

• Beyond persistence: SERS-driven strategies for PFAS detection and monitoring

  Nano Convergence · 2026-03-03

  articleOpen access

  This review explores surface-enhanced Raman spectroscopy (SERS)-driven strategies for the detection and monitoring of per- and polyfluoroalkyl substances (PFAS), a class of nearly 15,000 synthetic compounds known for their exceptional chemical stability and environmental persistence. Due to the high bond dissociation energy of carbon-fluorine bonds, PFAS accumulate globally in water and soil, posing severe risks to human health, including cancer, liver toxicity, and immune suppression. As regulatory bodies like the U.S. EPA establish stringent maximum contaminant levels as low as 4 ng/L (ppt level), there is an urgent demand for rapid, cost-effective, and portable sensing platforms to complement traditional, high-cost analytical techniques like LC-MS/MS. SERS is highlighted as a powerful analytical tool capable of providing ultra-sensitive "molecular fingerprinting" by amplifying Raman signals through localized surface plasmon resonance (LSPR) on metallic nanostructures. This paper categorizes the fundamental mechanisms of SERS-based PFAS detection into three primary interaction strategies: (1) host-guest inclusion using molecular cavities like β-cyclodextrin or MOFs, (2) covalent bonding between PFAS functional groups and substrate surfaces, and (3) physical adsorption driven by hydrophobic and electrostatic forces. Despite its potential, practical SERS deployment faces challenges such as weak PFAS-surface affinity and spectral interference from complex environmental matrices. To address these, the review discusses emerging advancements, including fluorophilic surface functionalization, deep learning-based spectral deconvolution, and the integration of microfluidic platforms for real-time monitoring. Ultimately, these SERS-driven innovations provide a critical pathway toward achieving on-site, high-throughput quantification of trace PFAS in diverse water resources.

  PublisherOA PDFDOI

• Unveiling the unrecognized role of phytic acid in promoting hydroxyl radical generation during FeS colloids oxygenation: implications for organic matter mineralization

  Water Research · 2025-10-10 · 1 citations

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• Remediation of groundwater contaminated with perfluoroalkyl acids and chlorinated ethenes using a microbial reductive dechlorination and sorptive material treatment train

  Water Research · 2025-06-10 · 4 citations

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• Tunable, Thermoresponsive Hydrogel-Based Composites for Facile, Low-Energy Water Desalination and Recovery

  ACS Applied Materials & Interfaces · 2025-11-06

  articleSenior authorCorresponding

  As clean, conventional freshwater resources decrease, treating unconventional water is a global priority. While membrane technologies such as reverse osmosis enable the use of seawater and brackish waters, their relatively high energy demands, particularly the external pressure required to overcome osmotic gradients and infrastructure requirements, limit broader adoption. Among alternative technologies, stimuli-responsive hydrogels provide a promising approach to address such limitations. In particular, thermally responsive hydrogels that can effectively reject ions while saturating (swelling) with water and then dewatering (recovery) under low-energy, controlled conditions hold considerable promise. In this work, enhanced thermoresponsive hydrogels were developed, via graphene oxide addition, and a shell–core strategy whereby the modified hydrogel core drives flow in and out (i.e., pull–push) as a function of temperature, while a thin polymer shell enhances ion (salt) rejection. This multifunctional approach allows for system tunability and thus optimization for treated water recovery. Driven by near room-temperature swings (20–40 °C), composite materials described here desalinate water at 57–78% salt rejection for varying ionic strengths (17–550 mM) and types (NaCl, CaCl2, MgCl2) with ∼5 times swelling/recovery ratios consistently for five relatively rapid treatment cycles, with a water collection rate of 7.7 kg m–2 h–1.

  PublisherDOI

• Microwave Heating of Superparamagnetic Iron-Oxide Nanoparticles Toward Environmental Hyperthermia-Based Applications

  ACS Applied Materials & Interfaces · 2025-08-25 · 2 citations

  articleCorresponding

  This article reports the effect of spherical particle size (4-30 nm) on magnetic properties and microwave (MW) reactivity of superparamagnetic iron oxide nanoparticles (SPIONs) toward environmental hyperthermia-based applications. For this, silica-coated, single domain iron oxide nanoparticles (IONPs@silica) were precisely synthesized via thermal decomposition and subsequently coated by a reverse microemulsion. Transmission electron microscopy and X-ray diffraction confirmed the formation of spherical, monodisperse, single continuous layer silica-coated magnetite nanoparticles. Magnetic measurements revealed size-dependent superparamagnetism with negligible coercivity for particles smaller than 30 nm at 300 and 350 K. Saturation magnetization increased with particle size, reaching its highest value at 30 nm due to reduced surface spin disorder. MW reactivity was evaluated by irradiating IONPs@silica in quartz sand beds (1 wt %) at 2.45 GHz for 120 s. Core sizes of 4, 17, and 30 nm IONPs@silica at 1 wt % produced statistically significant temperature increases in sand compared to the control where 17 nm particles showed the highest heating response For single-domain particles (4-21 nm), heat generationwas attributed toNéel relaxation induced by the alternating magnetic field component and electronic excitation driven by the electric field component of the MW. For larger, multidomain particles (30 nm), magnetic heating dominated, primarily through hysteresis, eddy currents, and residual losses. Among the materials evaluated, 17 nm IONPs@silica were optimal with regard to both superparamagnetism and superior MW reactivity, with their single-domain magnetic structure being retained, and relaxation mechanisms were not compromised by thermal exposure for up to five MW cycles.

  PublisherDOI

• Toward Continuous, Oriented Covalent Organic Framework Membranes for Precise Molecular Separations

  ACS Nano · 2025-08-15 · 26 citations

  reviewOpen accessCorresponding

  The goal of achieving energy-efficient, precise molecular separations has motivated interest in developing and employing porous crystalline frameworks as membrane materials. Covalent organic frameworks (COFs) are ordered crystalline matrices composed of covalently bonded organic monomers and are synthesized via reversible reticular chemistry. COFs possess high porosity, structural tunability, and chemical and thermal stability, making them ideally suited for emerging, high-value membrane separation processes, such as ion separations, organic solvent nanofiltration, and gas separations. Although a range of COF membranes have been fabricated and tested in the past decade, these membranes are primarily polycrystalline, weakly crystalline, and/or discontinuous, resulting in suboptimal performance. In this review, we identify the properties that make COFs well-suited as membrane materials, while critically outlining the shortcomings of existing disordered COF membranes. We then highlight the recent emergence of highly crystalline, continuous, oriented two-dimensional COF membranes as a promising path forward for highly selective molecular separations. These continuous, oriented COF membranes exhibit tunable one-dimensional nanochannels, allowing for ultrafast molecular transport and precise species selectivity, thereby expanding the set of separations that can be practically achieved with membrane systems. We discuss synthesis and modification techniques that result in continuous, oriented COF membranes and evaluate the performance of such membranes for a variety of molecular separations. We conclude by identifying ongoing challenges in the development of COF membranes and outlining the future of their applications in molecular separations, which will necessarily rely on advancements in the synthesis of continuous, oriented membranes.

  PublisherDOI

• Complete Reductive Defluorination of PFAS in Water Under Ambient Conditions via Plasmon-Enhanced Catalysis

  Research Square · 2025-12-17

  preprintOpen access1st authorCorresponding
  PublisherOA PDFDOI

Recent grants

• MRI: Acquisition of an X-ray/Ultraviolet Photoelectron Spectrometer (XPS/UPS)

  NSF · $521k · 2013–2015

• Platform Nanoscale Sorbents for Advanced Separation and Recovery of Metals and Metalloids in Water

  NSF · $330k · 2014–2017

• CAREER: Development and Application of Crumpled Graphene Oxide-Based Nanocomposites as a Platform Material for Advanced Water Treatment

  NSF · $500k · 2015–2020

• Atmospheric Fullerene Chemistry: Elucidating Oxidative Pathways and Characterization of Corresponding Derivatives

  NSF · $300k · 2012–2015

• UNS: Collaborative Research: Effects of Nano-Bio Interactions on Nanoparticle Fate and Transport in Porous Media

  NSF · $160k · 2017–2020

Frequent coauthors

• Wenlu Li

  48 shared

• Joseph B. Hughes

  University of Birmingham

  43 shared

• Jae‐Hong Kim

  Yale University

  27 shared

• Kurt D. Pennell

  Providence College

  26 shared

• Changwoo Kim

  25 shared

• Pedro J. J. Alvarez

  Systems Engineering Research Center

  23 shared

• Junseok Lee

  Yale University

  22 shared

• Seung Soo Lee

  Yale University

  22 shared

Awards & honors

• Ackerman Award for Teaching and Mentoring (2025)
• Elected Member (2024), Connecticut Academy of Science and En…
• Chair (2023) and Vice Chair (2019) of the Environmental Nano…
• Elected Fellow, Royal Society of Chemistry (2021)
• Appointee, U.S. National Academies of Sciences, Engineering,…