Jiayin Yuan, studied Chemistry at Shanghai Jiao Tong University in 1998-2002. He then moved to Germany and completed his master’s degree in 2004 and PhD degree in 2009. Next he joined the Max Planck Institute of Colloids and Interfaces, Germany and stayed there as a research group leader for 6 years. In 2017 he was appointed as Associate Professor at Clarkson University, USA. In 2018 he came to Stockholm University as a Wallenberg Academy Fellow and since 2019 he has been a full professor in Materials Chemistry with research expertise in functional polymers and carbon materials, including both basic research and applications in sustainable development. Since 2021 he has served as the Director of the Stockholm Material Hub (www.stockholmmaterial.com).
See our group website: www.yuan-group.com
2011-2016 at Uni Potsdam, Germany
Bachelor students in Chemistry "General Chemistry", "Polymer Chemistry I" and "II".
Master and PhD students in Chemistry "Modern Aspects of Colloid Science"
Master students in Chemistry "Biopolymer"
2014-2016 at Max Planck Institute of Colloids and Interfaces, Germany
2015 for PhD students in IMPRS (International Max Planck Research School) on Multiscale Bio- Systems) "Synthetic biomimetic actuator"
2015 for PhD students in IMPRS (International Max Planck Research School) on Multiscale Bio- Systems) "Membrane structures and applications"
2017-2018 at Clarkson University, USA
Undergradudate and graduate students 2017 Spring semester CM484/584 "Functional polymer systems"
2017 Spring semester for undergradudate students "Freshman seminar" on March. 1st.
2017 Summer CM990 for graduate students "Thesis research."
2017 Fall semester CM435/535 for undergradudate and graduate students"Better materials through chemistry"
2017 Fall semester CM890 for graduate students"Directed Study"
2017 Fall semester CM990 for graduate students "Thesis research."
2018 Spring for undergraduate and graduate students "Colloids and Interfaces"(with Dr. Weiyi Zhang together)
from 2019 at Stockholm University
master students 2019 Spring semester "Soft Matter"
PhD students 2020 Spring & Autumn semester "Materials chemistry" (oral exam)
His group is currently interested in the synthesis and exploration of new syntheses, properties and functions of ionic polymers and heteroatom-doped porous carbon materials that are prepared via simple chemistry.
A selection from Stockholm University publication database
Atomically Dispersed Semi-Metallic Selenium on Porous Carbon Membrane as an Electrode for Hydrazine Fuel Cells
2019. Tongzhou Wang (et al.). Angewandte Chemie International Edition 58 (38), 13466-13471Article
Electrochemically functional porous membranes of low cost are appealing in various electrochemical devices used in modern environmental and energy technologies. Herein we describe a scalable strategy to construct electrochemically active, hierarchically porous carbon membranes containing atomically dispersed semi-metallic Se, denoted SeNCM. The isolated Se atoms were stabilized by carbon atoms in the form of a hexatomic ring structure, in which the Se atoms were located at the edges of graphitic domains in SeNCM. This configuration is different from that of previously reported transition/noble metal single atom catalysts. The positively charged Se, enlarged graphitic layers, robust electrochemical nature of SeNCM endow them with excellent catalytic activity that is superior to state-of-the-art commercial Pt/C catalyst. It also has long-term operational stability for hydrazine oxidation reaction in practical hydrazine fuel cell.
Ionic organic cage-encapsulating phase-transferable metal clusters
2019. Su-Yun Zhang (et al.). Chemical Science 10 (5), 1450-1456Article
Exploration of metal clusters (MCs) adaptive to both aqueous and oil phases without disturbing their size is promising for a broad scope of applications. The state-of-the-art approach via ligandbinding may perturb MCs' size due to varied metal-ligand binding strength when shuttling between solvents of different polarity. Herein, we applied physical confinement of a series of small noble MCs (<1 nm) inside ionic organic cages (I-Cages), which by means of anion exchange enables reversible transfer of MCs between aqueous and hydrophobic solutions without varying their ultrasmall size. Moreover, the MCs@I-Cage hybrid serves as a recyclable, reaction-switchable catalyst featuring high activity in liquid-phase NH3BH3 (AB) hydrolysis reaction with a turnover frequency (TOF) of 115 min(-1).
Fine tuning the hydrophobicity of counter-anions to tailor pore size in porous all-poly(ionic liquid) membranes
2019. Zhiping Jiang (et al.). Polymer international 68 (9), 1566-1569Article
Charged porous polymer membranes (CPMs) emerging as a multifunctional platform for diverse applications in chemistry, materials science and biomedicine have been attracting widespread attention. Fabrication of CPMs in a controllable manner is of particular significance for optimizing their function and maximizing practical values. Herein, we report the fabrication of CPMs exclusively from poly(ionic liquid)s (PILs), and their pore size and wettability were precisely tailored by rational choice of counter-anions. Specifically, a stepwise subtle increase in hydrophobicity of the counter-anions by extending the length of fluorinated alkyl substituents, i.e. from bis(trifluoromethane sulfonyl)imide to bis(pentafluoroethane sulfonyl)imide and bis(heptafluoropropane sulfonyl)imide, decreased the average pore size gradually from 1546 to 157 and 77 nm, respectively. Meanwhile, the corresponding water contact angles increased from 90 degrees to 102 degrees and 120 degrees. The sensitive control over the porous architectures and surface wettability of CPMs by systematic variation of anion hydrophobicity provides solid proof of the impact of PIL anions on CPM structure.
Linear Main-Chain 1,2,4-Triazolium Poly(ionic liquid)s
2019. Mohamed Yahia (et al.). ACS Macro Letters 8 (10), 1372-1377Article
Linear main-chain 1,2,4-triazolium-based poly(ionic liquid)s (PILs) were synthesized in this contribution. The polymerization process is experimentally very simple and involves only a single-step polycondensation of a commercially available monomer in DMSO as solvent at 120 degrees C. Their thermal stability and solubility were analyzed in terms of different counteranions. Due to the ease of this synthetic route, it was readily applied to graft onto sulfonated cellulose nanocrystals (CNCs) via a one-step in situ polymerization. The as synthesized PIL@CNC hybrid colloids exhibit adaptive dispensability in water and organic solvents.
Long-term stable poly(ionic liquid)/MWCNTs inks enable enhanced surface modification for electrooxidative detection and quantification of dsDNA
2019. Larisa Sigolaeva (et al.). Polymer 168, 95-103Article
This work demonstrates the use of imidazolium-based poly(ionic liquid)s (PILs) as efficient dispersants of multiwalled carbon nanotubes (MWCNTs). With these polymeric dispersants, highly stable fine dispersions of MWCNTs (inks) can be easily prepared in aqueous media and applied for rather simple but efficient surface modification of screen-printed electrodes (SPEs). Such a modification of SPEs remarkably increases the electroactive surface area and accelerates the electron transfer rate due to synergistic combination of specific features of MWCNTs such as strong adsorptive property and high specific surface with the advantages of PILs like ion conductivity and dispersability. We further show that the PIL/MWCNT-modified SPEs can be beneficially utilized for direct electrochemical analysis of double stranded DNA (dsDNA). Specifically, it is exemplified by the direct electrooxidation of guanine and adenine bases in salmon testes dsDNA chosen as a model system. The linear ranges for the determination of dsDNA correspond to 5-500 mu g/mL for the oxidative peak of guanine and 0.5-50 mu g/mL for the oxidative peak of adenine. This makes direct electrochemical dsDNA detection with the use of the easy-preparable PIL/MWCNT-modified SPEs strongly competing to currently applied spectral and fluorescent techniques. Furthermore, we show that the developed constructs are capable of sensing a single point mutation in the 12-bases single-stranded DNA fragments. Such detection is of high clinical significance in choosing an adequate anticancer treatment, where the electrochemical identification of the point mutation could offer time and cost benefits.
Organic Molecule-Driven Polymeric Actuators
2019. Huijuan Lin (et al.). Macromolecular rapid communications 40 (7)Article
Inspired by the motions of plant tissues in response to external stimuli, significant attention has been devoted to the development of actuating polymeric materials. In particular, polymeric actuators driven by organic molecules have been designed due to their combined superiorities of tunable functional monomers, designable chemical structures, and variable structural anisotropy. Here, the recent progress is summarized in terms of material synthesis, structure design, polymer-solvent interaction, and actuating performance. In addition, various possibilities for practical applications, including the ability to sense chemical vapors and solvent isomers, and future directions to satisfy the requirement of sensing and smart systems are also highlighted.
Poly(Ionic Liquid)-Derived Graphitic Nanoporous Carbon Membrane Enables Superior Supercapacitive Energy Storage
2019. Weiyi Zhang (et al.). ACS Nano 13 (9), 10261-10271Article
High energy/power density, capacitance, and long-life cycles are urgently demanded for energy storage electrodes. Porous carbons as benchmark commercial electrode materials are underscored by their (electro)chemical stability and wide accessibility, yet are often constrained by moderate performances associated with their powdery status. Here via controlled vacuum pyrolysis of a poly(ionic liquid) membrane template, advantageous features including good conductivity (132 S cm(-1) at 298 K), interconnected hierarchical pores, large specific surface area (1501 m(2) g(-1)), and heteroatom doping are realized in a single carbon membrane electrode. The structure synergy at multiple length scales enables large areal capacitances both for a basic aqueous electrolyte (3.1 F cm(-2)) and for a symmetric all-solid-state supercapacitor (1.0 F cm(-2)), together with superior energy densities (1.72 and 0.14 mW h cm(-2), respectively) without employing a current collector. In addition, theoretical calculations verify a synergistic heteroatom co-doping effect beneficial to the supercapacitive performance. This membrane electrode is scalable and compatible for device fabrication, highlighting the great promise of a poly(ionic liquid) for designing graphitic nanoporous carbon membranes in advanced energy storage.
Poly(ionic liquid)-Derived N-Doped Carbons with Hierarchical Porosity for Lithium- and Sodium-Ion Batteries
2019. Walid Alkarmo (et al.). Macromolecular rapid communications 40 (1)Article
The performance of lithium- and sodium-ion batteries relies notably on the accessibility to carbon electrodes of controllable porous structure and chemical composition. This work reports a facile synthesis of well-defined N-doped porous carbons (NPCs) using a poly(ionic liquid) (PIL) as precursor, and graphene oxide (GO)-stabilized poly(methyl methacrylate) (PMMA) nanoparticles as sacrificial template. The GO-stabilized PMMA nanoparticles are first prepared and then decorated by a thin PIL coating before carbonization. The resulting NPCs reach a satisfactory specific surface area of up to 561 m(2) g(-1) and a hierarchically meso- and macroporous structure while keeping a nitrogen content of 2.6wt%. Such NPCs deliver a high reversible charge/discharge capacity of 1013 mA h g(-1) over 200 cycles at 0.4A g(-1) for lithium-ion batteries, and show a good capacity of 204 mAh g(-1) over 100 cycles at 0.1A g(-1) for sodium-ion batteries.
2019. Xianjing Zhou, Jens Weber, Jiayin Yuan.Article
Capture and conversion of CO2 are of great importance for environment-friendly and sustainable development of human society. Poly(ionic liquid)s (PILs) combine some unique properties of ILs with those of polymers and are versatile materials for CO2 utilization. In this contribution, we briefly outline innovative PILs emerged over the past few years, such as polytriazoliums, deep eutectic monomer-based PILs, and polyurethane PILs. Additionally, we discuss their advantages and challenges as materials for carbon capture and storage and the fixation of CO2 into useful materials.
Porous Poly(ionic liquid) Membranes Functionalized with Metal Nanoparticles
2019. Atefeh Khorsand Kheirabad, Jiayin Yuan.Conference
Functional nanoporous polymer membranes with expanded surface area can be applied in broad fields, including separation, filtration, catalysis and energy applications. There are a number of established methods for the preparation of nanoporous membranes using neutral or weakly charged polymers. Although, fabrication of nanoporous polymer membranes from strong polyelectrolytes is far more difficult, we present our approach to nanoporous polyelectrolyte membranes by using poly(ionic liquid)s. 
Poly(ionic liquid)s (PILs) are the polymerization products of ionic liquids (ILs), which combine certain properties and functions of polymeric materials (e,g. durability and good processability) and ILs (e.g. ion conductivity and thermal stability). We have exploited these favorable properties in the fabrication of nanoporous membranes from imidazolium based PILs through electrostatic complexation of PILs with polyacids. [2-4] The porous structure forms as a result of microphase separation of the hydrophobic PIL chains from the aqueous environment and is simultaneously stabilized by ionically crosslinked networks between the cationic PIL and the negatively charged neutralized polyacids. The as-obtained nanoporous membrane features a gradient profile in the cross-linking density along the membrane cross-section, triggered by the diffusive penetration of a base molecule from the top to the bottom into the PIL-polyacid blend film. The membrane pore sizes can be tuned from nano- to micrometer scale by varying the degree of electrostatic complexation.
Furthermore, the membrane features high actuation speed in response to acetone vapor phase (also some other organic vapors) on account of its gradient in cross-linking density and the intrinsic porous nature of the membrane that enhances the internal mass transport. Such membranes may serve as environmental sensors to detect solvent quality.  In this meeting, we will update you with our latest progress in making nanoparticle-decorated nanoporous PIL membranes in a single step.
Porous Poly(ionic liquid) Membranes and Ionic Organic Cages
2019. Atefeh Khorsand Kheirabad, Jian-ke Sun, Jiayin Yuan.Conference
This poster will present two topics that are active in our research group, the porous poly(ionic liquid) membranes and the ionic organic cages.
Functional nanoporous polymer membranes with expanded surface area can be applied in broad fields, including separation, filtration, catalysis and energy applications. There are a number of established methods for the preparation of nanoporous membranes using neutral or weakly charged polymers. Although, fabrication of nanoporous polymer membranes from strong polyelectrolytes is far more difficult, we present our approach to nanoporous polyelectrolyte membranes by using poly(ionic liquid)s.  Poly(ionic liquid)s (PILs) are the polymerization products of ionic liquids, which combine certain properties and functions of polymeric materials (e,g. durability and good processability) and ILs (e.g. ion conductivity and thermal stability). We have exploited these favorable properties in the fabrication of nanoporous membranes from imidazolium based PILs through electrostatic complexation of PILs with polyacids. [2,3] The porous structure forms as a result of microphase separation of the hydrophobic PIL chains from the aqueous environment and is simultaneously stabilized by ionically crosslinked networks between the cationic PIL and the negatively charged neutralized polyacids. The membrane pore sizes can be tuned from nano- to micrometer scale by varying the degree of electrostatic complexation. In this meeting, we will update you with our latest progress in making nanoparticle-decorated nanoporous PIL membranes in a single step.
In the ionic organic cage part, we present our work about operating ionic organic cages (I-cages) to enclose small noble metal clusters (MCs) with adaptivity to water-oil phase. Organic molecular cages are a kind of multifunctional materials with molecular solubility, intrinsic open channels and unique ability to accommodate guest objects such as (MCs).  Herein, we report physical confinement of small noble MCs inside I-cages.  Metal clusters (MCs) are small sized particles < 2nm with significant properties such as discrete electronic structures, intense photoluminescence, high catalytic activity (hydrogeneration, oxidation, and coupling reactions). Dominated synthesis methods of MCs includes the surface-binding ligand approach (amphiphilic capping agents, and water-oil phase transfer agents). 
Templated synthesis of cyclic poly(ionic liquid)s
2019. Qingquan Tang (et al.). Reactive & functional polymers 138, 1-8Article
Charged cyclic polymers, e.g. cyclic DNAs and polypeptides, play enabling roles in organisms, but their synthesis was challenging due to the well-known polyelectrolyte effect. To tackle the challenge, we developed a templated method to synthesize a library of imidazolium and pyridinium based cyclic poly(ionic liquid)s. Cyclic templates, cyclic polyimidazole and poly(2-pyridine), were synthesized first through ring-closure method by light-induced Diels - Alder click reaction. Through quaternization of cyclic templates followed by anion metathesis, the cyclic poly(ionic liquid)s were synthesized, which paired with varied counter anions.
Thermo-sensitive Microgels Supported Gold Nanoparticles as Temperature-mediated Catalyst
2019. Xian-Jing Zhou (et al.). Chinese Journal of Polymer Science 37 (3), 235-242Article
Microgels with a thermo-sensitive poly(N-isopropylacrylamide) (polyNIPAm) backbone and bis-imidazolium (VIM) ionic cross-links, denoted as poly(NIPAm-co-VIM), were successfully prepared. The as-synthesized ionic microgels were converted to nanoreactors, denoted as Au@PNI MGs, upon generation and immobilization of gold nanoparticles (Au NPs) of 5-8 nm in size into poly(NIPAm-co-VIM). The content of Au NPs in microgels could be regulated by controlling the 1,6-dibromohexane/vinylimidazole molar ratio in the quaternization reaction. The microgel-based nanoreactors were morphologically spherical and uniform in size, and presented reversible thermo-sensitive behavior with volume phase transition temperatures (VPTTs) at 39-40 degrees C. The Au@PNI MGs were used for the reduction of 4-nitrophenol, of which the catalytic activity could be modulated by temperature.
All-Poly(ionic liquid) Membrane-Derived Porous Carbon Membranes
2018. Yue Shao (et al.). ACS Nano 12 (11), 11704-11710Article
Herein, we introduce a straightforward, scalable, and technologically relevant strategy to manufacture charged porous polymer membranes (CPMs) in a controllable manner. The pore sizes and porous architectures of CPMs are well-controlled by rational choice of anions in poly(ionic liquid)s (PILs). Continuously, heteroatom-doped hierarchically porous carbon membrane (HCMs) can be readily fabricated via morphology-maintaining carbonization of as-prepared CPMs. These HCMs, as photothermal membranes, exhibited excellent performance for solar seawater desalination, representing a promising strategy to construct advanced functional nanomaterials for portable water production technologies.
Ambient Electrosynthesis of Ammonia
2018. Hong Wang (et al.). Angewandte Chemie International Edition 57 (38), 12360-12364Article
Ammonia, a key precursor for fertilizer production, convenient hydrogen carrier, and emerging clean fuel, plays a pivotal role in sustaining life on Earth. Currently, the main route for NH3 synthesis is by the heterogeneous catalytic Haber-Bosch process (N-2+ 3H(2) -> 2NH(3)), which proceeds under extreme conditions of temperature and pressure with a very large carbon footprint. Herein we report that a pristine nitrogen-doped nanoporous graphitic carbon membrane (NCM) can electrochemically convert N-2 into NH3 in an acidic aqueous solution under ambient conditions. The Faradaic efficiency and rate of production of NH3 on the NCM electrode reach 5.2% and 0.08 gm(-2) h(-1), respectively. Functionalization of the NCM with Au nanoparticles dramatically enhances these performance metrics to 22% and 0.36 gm(-2) h(-1), respectively. As this system offers the potential to be scaled to industrial levels it is highly likely that it might displace the century-old Haber-Bosch process.
Cooking carbon in a solid salt
2018. Jiang Gong (et al.).Article
Porous heteroatom-doped carbons are desirable for catalytic reactions due to their tunable physicochemical properties, low cost and metal-free nature. Herein, we introduce a facile, general bottom-up strategy, so-called cooking carbon in a solid salt, to prepare hierarchically porous heteroatom-doped carbon foams by using poly(ionic liquid) as precursor and a common inorganic salt as structural template. The obtained carbon foams bear hierarchical micro-/meso-/macropores, large specific surface area and rich nitrogen dopant. The combination of these favorable features facilitates the catalytic degradation of aqueous organic pollutants by persulfate under visible light irradiation, in which they prevail over the state-of-the-art metal-/carbon-based catalysts.
2018. Weiyi Zhang, Qiang Zhao, Jiayin Yuan. Angewandte Chemie International Edition 57 (23), 6754-6773Article
The past decade has witnessed rapid advances in porous polyelectrolytes and there is tremendous interest in their synthesis as well as their applications in environmental, energy, biomedicine, and catalysis technologies. Research on porous polyelectrolytes is motivated by the flexible choice of functional organic groups and processing technologies as well as the synergy of the charge and pores spanning length scales from individual polyelectrolyte backbones to their nano-/micro-superstructures. This Review surveys recent progress in porous polyelectrolytes including membranes, particles, scaffolds, and high surface area powders/resins as well as their derivatives. The focus is the interplay between surface chemistry, Columbic interaction, and pore confinement that defines new chemistry and physics in such materials for applications in energy conversion, molecular separation, water purification, sensing/actuation, catalysis, tissue engineering, and nanomedicine.
Porous polycarbene-bearing membrane actuator for ultrasensitive weak-acid detection and real-time chemical reaction monitoring
2018. Jian-Ke Sun (et al.). Nature Communications 9Article
Soft actuators with integration of ultrasensitivity and capability of simultaneous interaction with multiple stimuli through an entire event ask for a high level of structure complexity, adaptability, and/or multi-responsiveness, which is a great challenge. Here, we develop a porous polycarbene-bearing membrane actuator built up from ionic complexation between a poly(ionic liquid) and trimesic acid (TA). The actuator features two concurrent structure gradients, i.e., an electrostatic complexation (EC) degree and a density distribution of a carbene-NH3 adduct (CNA) along the membrane cross-section. The membrane actuator performs the highest sensitivity among the state-of-the-art soft proton actuators toward acetic acid at 10(-6) mol L-1 (M) level in aqueous media. Through competing actuation of the two gradients, it is capable of monitoring an entire process of proton-involved chemical reactions that comprise multiple stimuli and operational steps. The present achievement constitutes a significant step toward real-life application of soft actuators in chemical sensing and reaction technology.
Precise Micropatterning of a Porous Poly(ionic liquid) via Maskless Photolithography for High-Performance Nonenzymatic H2O2 Sensing
2018. Ming-Jie Yin (et al.). ACS Nano 12 (12), 12551-12557Article
Porous poly(ionic liquid)s (PILs) recently have been serving as a multifunctional, interdisciplinary materials platform in quite a few research areas, including separation, catalysis, actuator, sensor, and energy storage, just to name a few. In this context, the capability of photopatterning PIL microstructures in a porous state on a substrate is still missing but is a crucial step for their real industrial usage. Here, we developed a method for in situ rapid patterning of porous PIL microstructures via a maskless photolithography approach coupled with a simple electrostatic complexation treatment. This breakthrough enables design of miniaturized sensors. As exemplified in this work, upon loading Pt nanoparticles into porous PIL microstructures, the hybrid sensor showed outstanding performance, bearing both a high sensitivity and a wide detection range.
Three birds, one stone - photo-/piezo-/chemochromism in one conjugated nanoporous ionic organic network
2018. Jian-Ke Sun (et al.). Journal of Materials Chemistry C 6 (34)Article
A nanoporous material bearing a high ion density and inherent organic radical character was synthesized by a facile one-pot process, which exhibits photo-, piezo- and chemochromism, driven by the diverse electron transfer processes between the acceptor framework and different electron donors. The responsive behavior is useful for its sensing application, as demonstrated here for pressure, anion and gas sensing.