Ionic thermoelectrics (iTEs) offer a sustainable route for harvesting low-grade heat, but their advancement is hindered by the difficulty of achieving both large thermopower and controllable carrier polarity. Here we introduce a synergistic ionic doping strategy that endows poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) with giant thermopower and reversible p-n switching. Sequential incorporation of lithium tetrafluoroborate (LiBF4) and copper chloride (CuCl2) drives a continuous transition from p-type (+12.23 mV K-1) to n-type (-18.83 mV K-1), yielding one of the broadest thermopower windows reported for a single iTE system (31 mV K-1). Mechanistic analysis reveals that tetrahedral [CuCl4](2-) complexes, identified by synchrotron X-ray absorption and Raman spectroscopy, promote anion-dominated thermodiffusion and boost the power factor to 23.77 mW m(-1) K-2, among the highest for iTEs. Leveraging this dual-doping design, we fabricate a solution-processed ionic thermoelectric generator with integrated p- and n-type legs that delivers 18.66 mW m(-2) under a 2 K gradient, surpassing state-of-the-art devices without post-treatment. This work establishes a universal design principle for polarity-switchable iTEs, bridging molecular engineering with scalable thermal-to-electric energy conversion for wearable electronics and industrial waste-heat recovery.

Electrocatalysis enables the industrial transition to sustainable production of chemicals using abundant precursors and electricity from renewable sources.De-centralized production of hydrogen peroxide(H2O2)from water and oxygen of air is highly desirable for daily life and industry.We report an effective electrochemical refinery(e-refinery)for H2O2 by means of electrocatalysis-controlled comproportionation reaction(2HO+o → 2HO),feeding pure water and oxygen only.Mesoporous nickel(Ⅱ)oxide(NiO)was used as electrocatalyst for oxygen evolution reaction(OER),producing oxygen at the anode.Conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)drove the oxygen reduction reaction(ORR),forming H2O2 on the cathode.The reactions were evaluated in both half-cell and device configurations.The performance of the H2O2 e-refinery,assembled on anion-exchange solid electrolyte and fed with pure water,was limited by the unbalanced ionic transport.Optimization of the operation conditions allowed a conversion efficiency of 80％.

Hydrogen peroxide (H2O2) is a highly useful and green liquid chemical for daily life and industry. It is traditionally employed in wood industry, food packaging, fine chemicals synthesis and environmental depollution. Moreover, it is recently considered in the context of energy storage and conversion such as metal–hydrogen peroxide batteries since the world is trying to find high energy density batteries to replace lithium-ion batteries for electric vehicles and electrified aircraft [1]. Electrochemical production of H2O2 driven by cheap renewable electricity has emerged recently as an alternative to non-sustainable anthraquinone oxidation (AO) process. The recent surge of H2O2 electrosynthesis studies is mainly focused on advanced H2O2 production catalyst design aiming at achieving high activity and selectivity during the last couple of years [2]. As an essential part of H2O2 electrochemical reactors, anode reaction/process is given very little attention among investigators until recently. Water oxidation is the most used anodic reaction, but it suffers from high energy input, the use of expensive catalyst, and low-priced oxygen gas generation. This problem might be mitigated by using alternative organics oxidation processes with the possible generation of value-added products [3]. In order to be economically viable for these systems above, the organics in anode reservoir should not transport to the cathode part through the membrane. However, organic molecules crossover has already been identified in direct alcohol fuel cells and CO2 electrolyzers. Such organics crossover, to the best of our knowledge, has never been considered in previous reports on hydrogen peroxide electrosynthesis devices. We use conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) for ORR via a two-electron pathway to H2O2. 4,5-Dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate (BQDS) was used as a model organic molecule since its oxidation process does not require catalysts as a typical electrolyte used in redox flow batteries. We investigated electrolyte and electric field effects on crossover and H2O2 production. [1] Chem Catal. 2023, 3, 100568 [2] Nat. Rev. Chem.2019, 3, 442 [3] Nat. Energy 2021, 6, 904

Internet-of-Everything (IoE) is defined as networked connections of things, people, data, and processes. IoE nodes, preferably shaped as printed flexible systems, serve as the frontier outpost of the Internet and comprise devices to record and regulate states and functions. To power distributed IoE nodes in an ecofriendly manner, a technology to scavenge energy from ambience and self-powered devices is developed. For this, piezoelectricity is regarded as a key property; however, the current technology typically based on polyvinylidene difluoride (PVDF) copolymers is expensive and produced via toxic protocols. We report piezoelectric characteristics of electrochemically poled cellulose nanofiber (CNF) thin films processed from water dispersions. Poling these films under humid conditions causes breaking and reorientation of CNF segments, which results in enhanced crystal alignment rendering the resulting material piezoelectric. Generators based on poled CNF show similar piezoelectric voltage and coefficient, here measured as d(33) = 46 pm V-1, to devices including PVDF copolymer layers of similar thickness. Our findings promise low-cost and printable ecofriendly piezoelectric-powered IoE nodes.

Zn-ion batteries are considered to be a promising option for low-cost and sustainable secondary batteries. However, one of the current challenges facing this technology is hydrogen evolution and dendritic growth during Zn deposition. To address these issues, a new strategy is to use "water-in-salt" electrolyte (WISE), which refers to super concentrated aqueous electrolytes. This helps to broaden the electrochemical stability window (ESW), suppress the hydrogen evolution reaction (HER), and impede dendritic growth. In this paper, we propose the idea of using "water-in-polymer salt" electrolyte (WIPSE) to address the challenges facing Zn-ion batteries and move this technology towards becoming one of the most affordable, environmentally friendly, and sustainable options. Specifically, we suggest using a lignin-carbon electrode, which is highly promising and has great potential for achieving these goals. The findings suggest reversible Zn deposition and dissolution, leading to dendrite free Zn deposition. The sustainable Zn-lignin battery exhibited remarkable performance, with a maximum energy of 23 Wh/Kg and a maximum power of 610 W/kg, low self-discharge and 82% retention in capacity after 8000 cycles. Given its improved environmental impact and cost-effectiveness, the Zn-lignin battery holds a promising position in the battery market. References: Kumar et al., Advanced Sustainable Systems, 7, 2023, 2200433. Khan et al., Journal of Power Sources, 524, 2022, 231103. Khan et al, Advanced Energy and Sustainability Research 3, 2022, 2100165.

Sustainable production of hydrogen gas, a green energy carrier of high density, is possible only by electrolysis of water based on the hydrogen evolution reaction (HER). Here, we report the effect of oxygen poisoning on the efficiency of hydrogen production and the consumption by the HER and the hydrogen oxidation reaction (HOR), respectively, on the interface of platinum group metal-free electrocatalyst TaS2 in pristine form and intercalated by the organic Lewis base hexylamine. The state of the surface probed by photoelectron spectroscopy was significantly altered by both Lewis base doping and oxygen poisoning. This alteration dramatically affects the hydrogen production efficiency in the HER, while the back process by the HOR was less sensitive to the changes in the surface states of the electrocatalysts. The oxygenated and intercalated electrocatalyst shows more than 2 x 10(5) times lower exchange current density of the HER compared to pristine oxygenated materials.

A plant-based, stretchable organic battery was developed by formulating a quaternary biocomposite electrode that possesses high electrical and ionic conductivities, charge storage capacity of 6.8 mA h cm −3 , and tensile stretchability over 300%.

Lignin, a byproduct from the pulp industry, is one of the redox active biopolymers being investigated as a component in the electrodes for sustainable energy storage applications. Due to its insulating nature, it needs to be combined with a conductor such as carbon or conducting polymer for efficient charge storage. Herein, the lignin/carbon composite electrodes manufactured via mechanical milling (ball milling) are reported. The composite formation, correlation between performance and morphology is studied by comparison with manual mixing and jet milling. Superior charge storage capacity with ≈70% of the total contribution from the Faradaic process involving the redox functionality of lignin is observed in a mechanically milled composite. In comparison, manual mix shows only ≈30% from the lignin storage participation while the rest is due to the electric double layer at the carbon–electrolyte interface. The significant participation of lignin in the ball milled composite is attributed to the homogeneous, intimate mixing of the carbon and the lignin leading the electronic carrier transported in the carbon phase to reach most of the redox group of lignin. A maximum capacity of 49 mAh g−1 is obtained at charge/discharge rate of 0.25 A g−1 for the sample milled for 60 min.

Zn‐ion batteries are one of the hot candidates for low‐cost and sustainable secondary batteries. The hydrogen evolution and dendritic growth upon zinc deposition are today's challenges for that technology. One of the new strategies to cope with these issues is to use “water‐in‐salt” electrolyte (WISE), that is, super concentrated aqueous electrolytes, to broaden its electrochemical stability window (ESW), suppressing hydrogen evolution reaction (HER), and perturbing the dendritic growth. Herein, this work proposes to use “water‐in‐polymer salt” electrolyte (WIPSE) concept to mitigate the challenges with Zn ion batteries and bring this technology toward one of the cheapest, greenest, and most sustainable electrodes: Lignin‐carbon (L‐C) electrode. Potassium polyacrylate (PAAK) as WISE bears out as better electrolyte for L‐C electrodes in terms of self‐discharge, cyclic stability, and specific capacity compared to conventional electrolyte based on chemically cousin molecule potassium acetate. Zinc bis(trifluoromethanesulfonyl) imide (Zn(TFSI) 2 ) added into WIPSE shows deposition and dissolution of Zn in Zn//Zn symmetric cell suggesting that Zn 2+ are moving into the polyanionic network. Furthermore, the added bis (trifluor omethanesul fonyl) imide (TFSI − ) metal salts trigger a ≈40% enhancement of the capacity of L‐C electrode. These results show a new promising direction toward the development of cost‐effective and sustainable Zn‐lignin batteries.

Desalination by capacitive deionization (CDI) is a promising technique to combine desalination and energy storage. The efficiency of charge storage process, which is equivalent to the desalination process, depends strongly on the presence of Faradic side reactions on the electrode. Herein, the performance of a new low‐cost designed flow‐through electrode with porous carbon nanoparticles (CP) coating on carbon‐fiber paper (CFP) is evaluated. The CP layer enables high capacitance while the CFP core makes fluid dynamics along and across the electrode. The electrodes are evaluated by studying the effective operational CDI parameters, such as operational voltage, degassing of electrolyte, and salt concentration. The Faradic side reaction and its effect on charge efficiency (CE) are evaluated which are estimated to decrease to 46% by liquid flow bringing dissolved oxygen from the air‐electrolyte interface to the electrode. The CE enhances to 59% with a salt concentration of 1 m. By purging N2 gas, CE is much higher (>85%) with a maximum efficiency of 97% at 0.6 V. Three regimes of the complex kinetic of side reactions are found involving various species such as O2, H2O2, H2, and carbon oxidation and the implication of those regimes for real applications are discussed.

"Water-in-polymer salt" electrolytes (WiPSEs) based on potassium polyacrylate (PAAK) belong to a new family of "water-in-salt" electrolytes that is envisioned as a potential solution for large-scale supercapacitors to balance the electric grid at short time scales. The WiPSEs display a broad electrochemical stability window up to 3 V, yet they are nonflammable and provide high ionic conductivity (100 mS/cm) as required in high-power devices. However, the transport of matter in PAAK-based WiPSEs has not been studied. In this work, we have extensively characterized PAAK by spectroscopic methods such as Raman spectroscopy and NMR diffusometry to determine the state of water and elucidate the mechanism of ionic transport as well as its interplay with water and polymer chain dynamics, which reveals that a significant proportion of the transport in WiPSEs is attributed to hydrated cations. The results are further supported by molecular dynamics (MD) simulations. Finally, the potential of WiPSEs based on PAAK is demonstrated in an activated carbon-based supercapacitor operating up to 2 V with reasonable self-discharge. This proof of concept shows promise for low-cost and large-scale supercapacitors.

Practical interest in oxygen reduction reaction (ORR) has traditionally been due to its application at fuel cells' cathode following its complete 4e route to the water. In search of new electrode materials, it was discovered that conducting polymers (CPs) also are capable of driving ORR, though predominantly halting the process at 2e reduction leading to hydrogen peroxide generation. As alternative ways to produce this "green oxidant" are attracting increasing attention, a detailed study of the ORR mechanism at CP electrodes gains importance. Here, we summarize our recent theoretical work on the topic, which underscores the fundamental difference between CP and electrocatalytic metal ORR electrodes. Our insights also bring to us the attention of outer-sphere electron transfer, not unknown but somewhat ignored in the field. We also put the action of CP electrodes in a more general context of chemical ORR and redox mediation responsible for the electrocatalytic ORR mechanism.

Polyvinylidene difluoride (PVDF) derivatives in metal/PVDF/metal (MPM) sandwich structures have been studied extensively since 1969. Cousin copolymers of the same family have been discovered with fascinating piezoelectric, pyroelectric, electrocaloric, and ferroelectric properties. Solution processing, flexibility, lightweight, and thermal stability make this class of materials complementary to inorganics. Thus, PVDF based polymers potentially compete with inorganic materials for a broad range of technologies such as energy generators, loudspeakers, coolers, and memories. However, the stable non-electroactive α-phase and hydrophobic nature of PVDF are the main barriers for developoing high performing and robust MPM devices in electronic applications. In this review, we present an up-to-date overview on different methods to induce the electroactive β-phase and improve the adhesion strength with metals to ensure robust and durable MPM devices. We go through advantages and disadvantages of several methods and pinpoint future opportunities in this research area. A special attention is paid to wearable piezoelectric nanogenerators for energy harvesting from human body motion, where flexible PVDF derivatives are compared with rigid piezoelectric ceramics. While the piezoelectric coefficient of PVDF (d33 ~ 24–34 pm/V) is one order lower than ceramic materials, novel co-polymers of PVDF display d33 > 1000 pm/V upon bias. This shows promise to bring piezoelectrics to flexible and large-area applications such as smart textiles. We also discussed challenges to improve wearability, such as light weight, breathability, and flexibility.

The quest for eco‐friendly materials with anticipated positive impact for sustainability is crucial to achieve the UN sustainable development goals. Classical strategies of composite materials can be applied on novel nanomaterials and green materials. Besides the actual technology and applications also processing and manufacturing methods should be further advanced to make entire technology concepts sustainable. Here, they show an efficient way to combine two low‐cost materials, cellulose and zinc oxide (ZnO), to achieve novel functional and “green” materials via paper‐making processes. While cellulose is the most abundant and cost‐effective organic material extractable from nature. ZnO is cheap and known of its photocatalytic, antibacterial, and UV absorption properties. ZnO nanowires are grown directly onto cellulose fibers in water solutions and then dewatered in a process mimicking existing steps of large‐scale papermaking technology. The ZnO NW paper exhibits excellent photo‐conducting properties under simulated sunlight with good ON/OFF switching and long‐term stability (90 minutes). It also acts as an efficient photocatalyst for hydrogen peroxide (H 2 O 2 ) generation (5.7 × 10 −9 m s −1 ) with an envision the possibility of using it in buildings to enable large surfaces to spontaneously produce H 2 O 2 at its outer surface. Such technology promise for fast degradation of microorganisms to suppress the spreading of diseases.

Ionic thermoelectric supercapacitors (ITESCs) produce orders of magnitude higher voltages than those of con-ventional thermoelectrics (TEs) based on the thermo-diffusion of electrons/holes and are therefore attractive for converting low-grade heat into electricity. The stretchability and stability of the whole ITESC are important for wearable heat harvesting applications. Recent studies on ITESC have focused on stretchable ionic TE electrolytes with a giant Seebeck coefficient, but there are no reports of fully stretchable ITESCs for wearable heat harvesting devices due to the lack of stretchable electrodes and stretchable ionic TE electrolytes with stability. Herein, we present a fully stretchable ITESC composed of stable high-performance ionic thermoelectric elastomer (ITE) electrolyte and stretchable gold nanowire (AuNW) electrodes. The ITE shows excellent air stability (> 60 d) in comparison to hydrogel-based electrolytes that are susceptible to dehydration in ambient conditions. Further-more, the ITE exhibits an apparent thermopower up to 38.9 mV K-1 and ionic conductivity of 3.76 x 10-1 mS cm-1, which both are maintained up to a tensile strain of 250%. Finally, a fully stretchable ITESC with AuNW electrodes is developed which can harvest energy from thermal gradients during deformations.

Lignin, obtained as a waste product in huge quantities from the large‐scale cellulose processing industries, holds a great potential to be used as sustainable electrode material for large‐scale electroactive energy storage systems. The fixed number of redox‐active phenolic groups present within the lignin structure limits the electrochemical performance and the total energy storage capacity of the lignin‐based electrodes. Herein, the way to enhance the charge storage capacity of lignin by incorporating additional small catechol molecules into the lignin structure is demonstrated. The catechol derivatives are covalently attached to the lignin via aromatic electrophilic substitution reaction. The increased phenolic groups in all functionalized lignin derivatives notably increase the values of capacitance compared to pristine lignin. Further, solvent fractionation of lignin followed by functionalization using catechol boosts three times the charge capacity of lignin electrode.

Carbonyls, and quinones among them in particular, occupy a place of choice among organic reversible redox systems for electrocatalysis [1] and energy storage [2]. Their electrochemical behavior is marked by coupled proton and electron transfer (CPET) [3-5]. We have studied this subject in the context of flow batteries [6] and hydrogen carriers [7]. On the other hand, metal ion – catecholate (o-dioxolene) binding [8] attracts attention in different and rather independent domains, including active materials for metal-ion and redox flow batteries [2]. Redox transformations of o-dioxolene-metal complexes are therefore coupled to competitive binding with metal ion and proton at the electrochemical timescale, raising the complexity in the system above that of CPET. These effects have not received proper attention e.g. in aqueous metal-ion battery research. The subject of this communication is the electrochemistry of Al3+ - catechol system in aqueous solution. We discuss the conditions and measurable electrochemical signatures of complex formation, as well as the role of buffer. We explain why our observations are contrasting those on catechol containing polymers proposed for universal metal-ion batteries [9, 10] by considering which reactions attain equilibrium and which are obeying kinetics only. [1] K. Tammeveski et al. J. Electroanal. Chem. 2001, 515 , 101; DOI: 10.1016/S0022-0728(01)00633-7 [2] B. Häupler et al. Adv. Energy Mater. 2015, 5 , 1402034; DOI: 10.1002/aenm.201402034 [3] M. Quan et al. J. Am. Chem. Soc. 2007, 129 , 12847; DOI: 10.1021/ja0743083 [4] J. Wang et al. J. Electroanal. Chem. 2007, 601 , 107; DOI: 10.1016/j.jelechem.2006.10.036 [5] Q. Lin et al. J. Phys. Chem. C 2015, 119 , 1489; DOI: 10.1021/jp511414b [6] H. Ghorbani Shiraz et al. J. Energy Chem. 2022, 73 , 292; DOI: 10.1016/j.jechem.2022.06.015 [7] M. Vagin et al. Adv. Funct. Mat. 2020, 30 , 2007009; DOI: 10.1002/adfm.202007009 [8] R. Maskey et al. Encycl. Inorg. Bioinorg. Chem.; DOI: 10.1002/9781119951438.eibc2810 [9] N. Patil et al. ACS Appl. Energy Mater. 2019, 2, 3035; DOI: 10.1021/acsaem.9b00443 [10] K. Pirnat et al. Macromolecules 2019, 52, 8155; DOI: 10.1021/acs.macromol.9b01405

The interfacial energetics are known to play a crucial role in organic diodes, transistors, and sensors. Designing the metal-organic interface has been a tool to optimize the performance of organic (opto)electronic devices, but this is not reported for organic thermoelectrics. In this work, it is demonstrated that the electrical power of organic thermoelectric generators (OTEGs) is also strongly dependent on the metal-organic interfacial energetics. Without changing the thermoelectric figure of merit (ZT) of polythiophene-based conducting polymers, the generated power of an OTEG can vary by three orders of magnitude simply by tuning the work function of the metal contact to reach above 1000 µW cm-2 . The effective Seebeck coefficient (Seff ) of a metal/polymer/metal single leg OTEG includes an interfacial contribution (Vinter /ΔT) in addition to the intrinsic bulk Seebeck coefficient of the polythiophenes, such that Seff  = S + Vinter /ΔT varies from 22.7 µV K-1 [9.4 µV K-1 ] with Al to 50.5 µV K-1 [26.3 µV K-1 ] with Pt for poly(3,4-ethylenedioxythiophene):p-toluenesulfonate [poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate)]. Spectroscopic techniques are used to reveal a redox interfacial reaction affecting locally the doping level of the polymer at the vicinity of the metal-organic interface and conclude that the energetics at the metal-polymer interface provides a new strategy to enhance the performance of OTEGs.

Soft vibrotactile devices have the potential to expand the functionality of emerging electronic skin technologies. However, those devices often lack the necessary overall performance, sensing-actuation feedback and control, and mechanical compliance for seamless integration on the skin. Here, we present soft haptic electromagnetic actuators that consist of intrinsically stretchable conductors, pressure-sensitive conductive foams, and soft magnetic composites. To minimize joule heating, high-performance stretchable composite conductors are developed based on in situ-grown silver nanoparticles formed within the silver flake framework. The conductors are laser-patterned to form soft and densely packed coils to further minimize heating. Soft pressure-sensitive conducting polymer-cellulose foams are developed and integrated to tune the resonance frequency and to provide internal resonator amplitude sensing in the resonators. The above components together with a soft magnet are assembled into soft vibrotactile devices providing high-performance actuation combined with amplitude sensing. We believe that soft haptic devices will be an essential component in future developments of multifunctional electronic skin for future human-computer and human-robotic interfaces.

Zn-metal batteries (ZnBs) are safe and sustainable because of their operability in aqueous electrolytes, abundance of Zn, and recyclability. However, the thermodynamic instability of Zn metal in aqueous electrolytes is a major bottleneck for its commercialization. As such, Zn deposition (Zn2+ → Zn(s)) is continuously accompanied by the hydrogen evolution reaction (HER) (2H+ → H2 ) and dendritic growth that further accentuate the HER. Consequently, the local pH around the Zn electrode increases and promotes the formation of inactive and/or poorly conductive Zn passivation species (Zn + 2H2 O → Zn(OH)2 + H2 ) on the Zn. This aggravates the consumption of Zn and electrolyte and degrades the performance of ZnB. To propel HER beyond its thermodynamic potential (0 V vs standard hydrogen electrode (SHE) at pH 0), the concept of water-in-salt-electrolyte (WISE) has been employed in ZnBs. Since the publication of the first article on WISE for ZnB in 2016, this research area has progressed continuously. Here, an overview and discussion on this promising research direction for accelerating the maturity of ZnBs is provided. The review briefly describes the current issues with conventional aqueous electrolyte in ZnBs, including a historic overview and basic understanding of WISE. Furthermore, the application scenarios of WISE in ZnBs are detailed, with the description of various key mechanisms (e.g., side reactions, Zn electrodeposition, anions or cations intercalation in metal oxide or graphite, and ion transport at low temperature).