B/N-Enriched Semi-Conductive Polymer Film for Micro-Supercapacitors with AC Line-Filtering Performance

Anion-Exchange Strategy for Ru/RuO2-Embedded N/S-Co-Doped Porous Carbon Composites for Electrochemical Nitrogen Fixation

Ionic porous polymers have been widely utilized efficiently to anchor various metal atoms for the preparation of metal-embedded heteroatom-doped porous carbon composites as the active materials for electrocatalytic applications. However, the rational design of the heteroatom and metal elements in HPC-based composites remains a significant challenge, due to the tendency of the aggregation of metal nanoparticles during pyrolysis. In this study, a nitrogen (N)- and sulfur (S)-enriched ionic covalent organic framework (iCOF) incorporating viologen and thieno[3,4-b] thiophene (TbT) was constructed via Zincke-type polycondensation. The synthesized iCOF possesses a crystalline porous structure with a pore size of 3.05 nm, a low optical band gap of 1.88 eV, and superior ionic conductivity of 10-2.672 S cm-1 at 333 K, confirming the ionic and conjugated nature of our novel iCOF. By applying the iCOF as the precursor, a ruthenium and ruthenium(IV) oxide (Ru/RuO2) nanoparticle-embedded N/S-co-doped porous carbon composite (NSPC-Ru) was prepared by using a two-step sequence of anion-exchange and pyrolysis processes. In the electrochemical nitrogen reduction reaction (eNRR) application, the NSPC-Ru achieves an impressive NH3 yield rate of 32.0 μg h-1 mg-1 and a Faradaic efficiency of 13.2% at -0.34 V vs. RHE. Thus, this innovative approach proposes a new route for the design of iCOF-derived metal-embedded porous carbon composites for enhanced NRR performance.

Carbon Nanostructures Derived from In Situ Grown ZIF Nanocages within Bacterial Cellulose for AC-Filtering Electrochemical Capacitors

Electrochemical capacitors (ECs) offer superior specific capacitance for energy storage compared to traditional electrolytic capacitors but face limitations in alternating current (AC) filtering due to the need for balancing fast response and high capacitance. This study addresses these challenges by developing a freestanding nanostructured carbon electrode, derived from the rapid carbonization of bacterial cellulose (BC) embedded with zeolitic imidazolate framework 8 (ZIF-8) and in situ formed carbon nanotubes (CNTs). The electrode exhibits an exceptionally low area resistance of 9.8 mΩ cm2 and a high specific capacitance of 2.1 mF cm-2 at 120 Hz, maintaining performance even at high frequencies. Stacking these electrodes enhances the capacitance to 5.3 mF cm-2, with the phase angle degrading to -74.4° at 120 Hz; however, they retain a phase angle below -45° up to ≈50 kHz, demonstrating excellent high-frequency performance. Furthermore, connecting three aqueous units in series as an integrated cell or utilizing organic electrolytes extends the voltage window to 2.4 V, enhancing their suitability for high-voltage applications. Ripple voltage analysis under various loads and frequencies indicates effective filtering capabilities, highlighting the potential of these nanostructured ECs for next-generation electronic applications.

Enabling Multi-Chemisorption Sites on Carbon Nanofibers Cathodes by an In-situ Exfoliation Strategy for High-Performance Zn-Ion Hybrid Capacitors

Carbon nanofibers films are typical flexible electrode in the field of energy storage, but their application in Zinc-ion hybrid capacitors (ZIHCs) is limited by the low energy density due to the lack of active adsorption sites. In this work, an in-situ exfoliation strategy is reported to modulate the chemisorption sites of carbon nanofibers by high pyridine/pyrrole nitrogen doping and carbonyl functionalization. The experimental results and theoretical calculations indicate that the highly electronegative pyridine/pyrrole nitrogen dopants can not only greatly reduce the binding energy between carbonyl group and Zn²⁺ by inducing charge delocalization of the carbonyl group, but also promote the adsorption of Zn²⁺ by bonding with the carbonyl group to form N-Zn-O bond. Benefit from the multiple highly active chemisorption sites generated by the synergy between carbonyl groups and pyridine/pyrrole nitrogen atoms, the resulting carbon nanofibers film cathode displays a high energy density, an ultralong-term lifespan, and excellent capacity reservation under commercial mass loading (14.45 mg cm^‒2). Particularly, the cathodes can also operate stably in flexible or quasi-solid devices, indicating its application potential in flexible electronic products. This work established a universal method to solve the bottleneck problem of insufficient active adsorption sites of carbon-based ZIHCs.Imoproved should be changed into Improved.

N-confused porphyrin-based conjugated microporous polymers

Metal porphyrins, which possess metal-N coordination centers, are important building blocks for the construction of porous organic materials with catalytic performance. However, most of the previous work has focused on controlling the metal elements instead of the metal-N coordinations. Here, Pt(II) N-confused porphyrin and Pt(II) porphyrin based conjugated microporous polymers were synthesized by Yamamoto coupling reaction. The structural and property differences of Pt-N₃C and Pt-N₄ were studied. Calculations demonstrate that the Pt-N₃C-based porous polymer exhibits broader photoabsorption and narrower bandgap than conventional Pt-N₄-based porous polymers.

Laser-Induced Interdigital Structured Graphene Electrodes Based Flexible Micro-Supercapacitor for Efficient Peak Energy Storage

The rapidly developing demand for lightweight portable electronics has accelerated advanced research on self-powered microsystems (SPMs) for peak power energy storage (ESs). In recent years, there has been, in this regard, a huge research interest in micro-supercapacitors for microelectronics application over micro-batteries due to their advantages of fast charge–discharge rate, high power density and long cycle-life. In this work, the optimization and fabrication of micro-supercapacitors (MSCs) by means of laser-induced interdigital structured graphene electrodes (LIG) has been reported. The flexible and scalable MSCs are fabricated by CO₂-laser structuring of polyimide-based Kapton ^® HN foils at ambient temperature yielding interdigital LIG-electrodes and using polymer gel electrolyte (PGE) produced by polypropylene carbonate (PPC) embedded ionic liquid of 1-ethyl-3-methyl-imidazolium-trifluoromethansulphonate [EMIM][OTf]. This MSC exhibits a wide stable potential window up to 2.0 V, offering an areal capacitance of 1.75 mF/cm² at a scan rate of 5.0 mV/s resulting in an energy density (E_a) of 0.256 µWh/cm² @ 0.03 mA/cm² and power density (P_a) of 0.11 mW/cm² @0.1 mA/cm². Overall electrochemical performance of this LIG/PGE-MSC is rounded with a good cyclic stability up to 10,000 cycles demonstrating its potential in terms of peak energy storage ability compared to the current thin film micro-supercapacitors.

Preparation of nickel-bound porous carbon and its application in supercapacitors

In this study, nickel-bound porous carbon (Ni-PC) was prepared by introducing Ni2+ into dipotassium ethylenediaminetetraacetate (EDTA-2K) derived nitrogen-doped porous carbon (PC) using the ball milling method.

A Terpyridine-Fe2+-Based Coordination Polymer Film for On-Chip Micro-Supercapacitor with AC Line-Filtering Performance

The preparation of redox-active, ultrathin polymer films as the electrode materials represents a major challenge for miniaturized flexible electronics. Herein, we demonstrated a liquid–liquid interfacial polymerization approach to a coordination polymer films with ultrathin thickness from tri(terpyridine)-based building block and iron atoms. The as-synthesized polymer films exhibit flexible properties, good redox-active and narrow bandgap. After directly transferred to silicon wafers, the on-chip micro-supercapacitors of TpPB-Fe-MSC achieved the high specific capacitances of 1.25 mF cm⁻² at 50 mV s⁻¹ and volumetric energy density of 5.8 mWh cm⁻³, which are superior to most of semiconductive polymer-based micro-supercapacitor (MSC) devices. In addition, as-fabricated on-chip MSCs exhibit typical alternating current (AC) line-filtering performance (−71.3° at 120 Hz) and a short resistance–capacitance (RC) time (0.06 ms) with the electrolytes of PVA/LiCl. This study provides a simple interfacial approach to redox-active polymer films for microsized energy storage devices.