Porous Activated Carbon Research Articles

CO2 methanation: a bibliometric analysis and review of activated carbon-based materials (2014–24)

Abstract This study highlights the significant potential of activated carbon (AC)-based materials in environmental remediation and energy production, particularly in converting carbon dioxide (CO2) and hydrogen (H2) into methane (CH4) and water (H2O) using transition metal-based catalysts. It emphasizes the role of porous AC in waste reduction and resource utilization, examining various applications of CO2 and evaluating environmental impacts. The research explores commercialization opportunities and specifically investigates CO2 methanation using AC-based materials. Using bibliometric analyses of 4196 articles from the Web of Science database, the study identifies a growing research interest in porous AC-related CO2 methanation from 2014 to 2024. The top three journals in this field are Environment Development and Sustainability, Biomass Conversion and Biorefinery, and Journal of Environment Science and Pollution. However, there is limited inter-institutional collaboration in this field, suggesting room for development towards commercializing sustainable CH4 production pathways. CH4 is highlighted as a crucial intermediate in industrial processes, and research directions are identified through co-occurring author keywords analysis. The study suggests the need for a comprehensive approach integrating AC materials into carbon-neutral energy processes while addressing the potential adverse effects of AC nanoparticles on biological and environmental factors. Ultimately, it clarifies the potential uses and commercialization prospects for porous AC materials, especially in conjunction with carbon capture and utilization technologies, promoting sustainable practices in energy production and environmental management.

Porous activated carbon integrated carbon nitride nanosheets as functionalized separators for the efficient polysulfide entrapment in Li[sbnd]S batteries

Electrification of vehicles, hybrid aircraft and the advancement of portable electronics are exacting the deployment of high energy-dense batteries. The high theoretical capacity of sulfur (1675 mAh g−1), cost-effectiveness and environmental benignity of the lithium‑sulfur batteries (LSBs) are propitious for electrochemical energy storage beyond Li-ion battery technology. In this work, we described a simple, scalable preparation and electrochemical performance of porous activated carbon (PC)-infused graphitic carbon nitride (GCN) nanosheets with various ratios (PC@GCN 11, PC@GCN 12 and PC@GCN 21) as a polysulfide anchoring functionalized separator for LSBs. The high specific area (822 m2/g), hetero porosity, conductive carbon framework, surface functionalities and enriched N-doping of the PC@GCN synergistically induce mitigation of polysulfides via chemical and physical adsorption pathways in LSBs. The PC@GCN 21 modified separator demonstrates a high initial discharge capacity of 1389 mAh g−1 at a 0.1C rate and exhibits better capacity retention over 500 cycles at a 1C rate (655 mAh g−1) with sulfur loading of 3.8 mg/cm2 accompanied by high coulombic efficiency (94 %). The assembled cell with high S-loading (5.12 mg/cm2) shows a high initial discharge capacity of 712 mAh g−1 at 0.1C rate conditions. High Li-ion transference number (0.714), stable shuttle current, minimal coulombic efficiency loss (0.84 %), low shuttle factor and negligible self-discharge behaviour support the superior performance of the PC@GCN 21 coated cells. This report demonstrates that combining the high surface area, non-polar porous carbon with polar graphitic carbon nitride is a practical approach for designing metal-free functionalized separators for energy-dense LSBs.

THE X-BAND MICROWAVE ABSORPTION CHARACTERISTICS OF POROUS ACTIVATED CARBON FROM NATURAL RESOURCES

Porous activated carbon (PAC) from bamboo, sisal, and coconut coir fibres with two carbonization steps were prepared and the microwave absorbing characteristics in the frequency range of 8 GHz to 12 GHz were investigated. The PAC based on bamboo, sisal and coconut coir had BET surface areas of 354.79, 141.91, and 25.70 m2/g, respectively. The return loss of -27.3, -25.6 and -16.4 dB was achieved for PAC from bamboo, sisal, and coconut fiber at 10.46, 11.08 and 11.00 GHz, respectively. The microwave absorption of more than 99% for porous activated carbon of bamboo and sisal, and more than 90% for porous activated carbon of coconut coir fiber, is indicated by these return loss values. It is shown by these results that biomass resources can be considered a promising lightweight, cost-effective, and eco-friendly microwave absorber material.

Hydrothermal assisting biomass into a porous active carbon for high-performance supercapacitors

Biomass contained significant amounts of lignin, cellulose and hemicellulose and these high crystallinity results in sub-optimal electrochemical properties. Herein, a hydrothermal method was employed to intentionally weaken the structural integrity of hemp fibers and eliminate cellulose impurities. After undergoing KOH activation, the resulting product achieved a maximum specific surface area of 1644.3 m2 g−1. In a three-electrode test, the specific capacitance of this electrode material was 255.6 F g−1 at a current density of 1 A g−1, representing a nearly double enhancement over the non-hydrothermally treated sample. Furthermore, the assembled symmetric supercapacitor has a specific capacitance of 56.9 F g−1 at 1 A g−1 and a capacitance retention of 102 % after 10,000 charge/discharge cycles (10 A g−1). Its maximum power density was 725 W kg−1 at an energy density of 16.6 Wh kg−1. The desirable capacitive properties indicated that the hydrothermal pretreatment method was expected to have wider applications in the preparation of other biomass-based electrode materials.

Polyacrylonitrile-based 3D N-rich activated porous carbon synergized with Co-doped MoS2 for promoted electrocatalytic hydrogen evolution

MoS2 is a promising electrocatalyst for the hydrogen evolution reaction (HER), but it is limited by its own agglomeration, low conductivity, and surface inertness. In this study, we report a well-organized 3D hybrid structure of N-rich active porous carbon (CN) synergized with Co-doped molybdenum disulfide (Co-MoS2@CN) for promoted electrocatalytic hydrogen evolution. MoS2 nanosheets were grown vertically on CN and the pore structure was improved, which exposed abundant edge active sites. The N-rich graphite structure and abundant pore structure of CN enhanced the electron transfer ability and stability of the 3D hybrid structure. Meanwhile, doping of Co atoms optimized the catalytic activity of the in-plane sulfur sites and induced a partial transition from 2H-MoS2 to 1 T-MoS2. The resulting Co-MoS2@CN 3D hybrid structure exhibited excellent HER electrocatalytic performance, had a current density of 10 mA cm−2 in a 0.5 M H2SO4 aqueous solution by an overpotential of 137 mV, and showed excellent stability in a 24 h HER test. DFT calculations confirmed that the heterogeneous interface constructed by CN and Co-MoS2 effectively optimized Gibbs free energy (ΔGH*) of the MoS2 hydrogen adsorption site and enhanced the interfacial electron transfer capacity, which ensured rapid HER kinetics during the electrocatalytic process.

Highly conductive, mechanically robust and multi-purpose carbon aerogel composites derived from waste bread enable high-performance symmetric supercapacitors

Sustainable biomass-based carbon aerogels have attracted extensive concerns in the area of energy storage and wearable sensory electronics. However, the pristine porosity and low weight of aerogels result in unsatisfactory mechanical and electrical properties, limiting their practical applications. Herein, activated porous carbon (APC), reduced graphene oxide (rGO) and carbon nanoparticles (CNP) are utilized as raw materials to develop a novel type of hierarchically waste bread-derived carbon aerogel via a stepwise activation/calcination strategy. The obtained bread-derived carbon aerogels, named APC-rGO/CNP, exhibits an outstanding electrical conductivity (∼3.23 S cm−1) and a high compressive modulus (∼124.60 MPa) by the synergistic bonding interactions. As a supercapacitor electrode, the APC-rGO/CNP composite manifests an excellent capacitance of 474.8 F g−1 (1.0 A g−1). Furthermore, an all-solid-state symmetric APC-rGO/CNP//APC-rGO/CNP supercapacitor with polyvinyl alcohol/potassium hydroxide (PVA/KOH) gel electrolyte realizes an energy density of 17.4 Wh kg−1 at 895 W kg−1. Notably, even under large compressive stress of 20 kPa, the supercapacitor still achieves a high energy density of 25.6 Wh kg−1 at a power density of 822.8 W kg−1, as well as an excellent capacitance retention of 93.8 % over 10,000 cycles. Finally, we demonstrate the potential of the APC-rGO/CNP composite as a responsive pressure sensor with an ultra-wide detecting span of 0–3 MPa and a moderate sensitivity of 0.22 kPa−1, which can detect keyboard pressing and fist clenching movements distinctively. Overall, the desirable mechanical performances and electrical conductivity of the APC-rGO/CNP composites facilitate the development of versatile nanomaterials to exploit state-of-the-art wearable electronics.

KHCO3 chemical-activated hydrothermal porous carbon derived from jackfruit inner skin for supercapacitor applications

The reuse of waste biomass resources had become a hot spot in the sustainable development of human society. Due to the complexity of biomass composition and microstructure, the quality reproducibility of biomass porous carbon was poor. Therefore, it was of great significance to develop a reliable method for preparing porous carbon from biomass. In this paper, a combination of hydrothermal carbonization treatment and mild activation of KHCO3 was used to prepare iron-modified porous carbon with carbon spheres/nanoplates structure, which promoted ion/electrolyte diffusion and increased the accessibility between surface area and electrolyte ions. Therefore, the active porous carbon from the Jackfruit inner skin has good specific capacitance (273.2 F/g at 1 A/g) and good cycle stability, and the capacitance loss is only 6.6 % after 10,000 charge discharge cycles. The above results showed that hydrothermal treatment and mild activation methods provided an effective way to transform waste biomass into high-performance electrode material.

In Situ Fabricated Poly(1,8‐naphthalenediamine)/Active Carbon Composite Cathodes for Aqueous Zinc‐Ion Batteries with High Active Sites Utilization and Ultralong Life Span of 50 000 Cycles

AbstractPolymers with redox activity are one type of promising candidates of cathode materials for aqueous Zn‐ion batteries due to their potential low‐cost, high safe, and renewable features. Unfortunately, suboptimal polymer electrode structure often results in unsatisfactory electrochemical performance. Herein, poly(1,8‐diaminonaphthalene)/active carbon composite electrodes are prepared via nanoconfined in situ electropolymerization within porous active carbon, which have ultrahigh specific surface area (1035.0 m2 g−1) and unique nano‐porous structure, thereby highly enhancing the utilization of the active site up to 91.6%. The as‐prepared cathodes deliver ultrahigh reversible capacity of 479.5 mAh g−1, ultrafast rate capability of up to 60 A g−1 and an ultralong life span of 50,000 cycles. Storage mechanism investigation indicates that the cathode material involves a bipolar‐type behavior. These encouraging results demonstrate that nanoconfined in situ electropolymerization in active carbon is a brand‐new strategy for the design of advanced polymer electrodes for high‐performance aqueous Zn‐organic batteries.

Production of Porous Biochar from Cowdung and its Application

Porous activated carbon (PAC) powder is prepared from solid bio-waste - cow dung samples (CD). UV- Spectroscopy confirms the absorption rate of activated porous biochar at different concentration solutions(in ppm).The activation process is carried out by phosphoric acid and sodium hydroxide treatment followed by calcination at different temperature condition. XRD pattern confirms the amorphous phase formation with graphitic nature for different precursor utilization. SEM analysis shows the uniform and hierarchical porous network formation and aggregated particle with tiny. X- ray analysis confirms the formation of graphitic carbon and porous morphology for sample activated at increased calcination temperature. The elemental composition of as prepared carbon samples is determined by SEM and confirms the formation major carbon content existence. The obtained product is observed for the dye removal process wherein the specific amount of PAC is added to the Methylene Blue(MB) dye solutions and the absorption rate is observed through uv-spectroscopy.

Bimetal-organic frameworks derived redox-type composite materials for high-performance energy storage

Electrodes and electroactive materials are crucial components in the development of supercapacitors due to their geometric properties. In this study, bimetal-organic frameworks (Bi-MOFs, ZIF-8@ZIF-67) were utilized as electrode materials for a high-performance hybrid supercapacitor (HSC) by designing a novel synthesis of metallic carbonate hydroxide/oxides. In particular, the Bi-MOFs function as a sacrificial precursor in the synthesis of hollow NiMn(CO3)0.5·0·.11H2O/ZnO@Co3O4 CNCs (NM-CH/ZnO@Co3O4 CNCs) cubic composite materials by a straightforward low-temperature treatment. The NM-CH/ZnO@Co3O4 CNCs exhibited exceptional electrochemical performance with high specific capacity of 196.3 ± 0.08 mAh/g, specific capacitance of 1179 ± 0.10 F g−1 at 0.5 A g−1, and outstanding cycling stability of 98% after 25,000 cycles compared to the other electrode materials. The porous and hollow structure, along with a large surface area, contributed to the enhanced electrochemical properties of the composite material. An HSC was constructed using NM-CH/ZnO@Co3O4 CNCs as the cathode and activated porous carbon (APC) as the anode, resulting in a device with a specific energy of 33 ± 0.12 Wh kg−1 and a power density of 19354 ± 0.07 W kg−1. The use of Bi-MOF electrodes presents new avenues for the development of high-performance energy storage materials, with the potential for industrial energy storage application demonstrated though the successful powering of portable lightbulbs.

Ultrafast dyeing wastewater purification by high-performance and reusable lignin-derived activated porous carbon filter

Achieving ultrafast purification during filtration while maintaining high adsorption capacity and low-cost filter production is a critical challenge that must be addressed immediately to promote large-scale water filter applications, particularly in remote areas without wastewater purification plants. Herein, low-cost, renewable lignin was used as a carbon source precursor to produce a high-performance, reusable activated porous carbon filter for ultrafast dye wastewater purification. Lignin-derived active porous carbon (LAPC) can achieve a high specific surface area (2276 m2/g) by using a lower amount of KOH (a mass ratio of 0.4 KOH to precursor) during the activation process, which not only meets the requirements of water transport and dye adsorption, but also reduces manufacturing costs. Owing to the pore-filling effect and electrostatic interaction, the LAPC particles displayed a high removal capacity of 1800 mg/g in the static adsorption, higher than most of the reported porous carbon. Furthermore, LAPC filters assembled from a flow of LAPC particles achieve significant dye removal (99.82 % in 30 s) during the dynamic adsorption process. Both anionic and cationic dyes can be removed and clean water can be produced simultaneously by simple dynamic filtration. Moreover, the LAPC filter could be reused for wastewater purification with a high removal efficiency (more than 95 % after 7 cycles of regeneration and use). This continuous operation, strong absorption versatility, and high efficiency of LAPC filter device for complex hybrid dyes system make it have a bright prospect in industrial dyeing wastewater treatment fields.

Asymmetric supercapacitors based on biomass-derived porous activated carbon (PAC)/1D manganese oxide (MnO2) electrodes with high power and energy densities

In this study, we present the electrochemical performance of an asymmetric supercapacitor (ASC) composed of one-dimensional manganese oxide (MnO2) nanorods embedded in porous activated carbon sheets (MnO2/PAC) as the positive electrode (positrode), and renewable porous activated carbon (PAC) as the negative electrode (negatrode). This configuration facilitates a high rate of charge/discharge while maintaining substantial specific capacity. The MnO2/PAC composite was successfully synthesized using a hydrothermal technique, while the PAC material was produced through pyrolysis reaction. The MnO2/PAC composite exhibited a maximum specific capacitance of 208.75F g−1 at 0.5 A/g and demonstrated a cyclic stability of 87.43 % in neutral aqueous electrolytes. This notable electrochemical performance is attributed to the significant contribution of the high pseudo-capacitance offered by dense MnO2 nanorods, in addition to the expansive surface area of the activated carbon sheets with closely packed structures. The ASC constructed as PAC//MnO2/PAC displayed a high energy density of 23.3 Wh kg−1 and a power density of 350.4 W kg−1 at a current density of 0.5 A/g. Furthermore, the device showcased exceptional cycling stability, retaining 90.3 % at a current density of 4 A/g. These results underscore the substantial untapped potential of ASC devices for innovative applications in advanced energy storage.

The NaClO4-water eutectic electrolyte for environmentally friendly electrical double-layer capacitors operating at low temperature

Herein, owing to its remarkable ionic conductivity, the 8.84 mol kg−1 NaClO4 water-in-salt (WIS) eutectic electrolyte is suggested for the low temperature operation of electrical double-layer capacitors down to -35 °C. Molecular dynamic simulations reveal that the local structure of the solution remains relatively stable from RT to -35 °C, with distinct channel-like domains formed by hydrogen-bonded water molecules, which facilitate the ionic diffusion within the bulk of the electrolyte. Interestingly, on activated carbon (AC) electrodes, the electrolyte demonstrates an electrochemical stability window (ESW) increasing from 1.8 V to 2.1 V as temperature decreases from 25 °C to -35 °C. The high ESW of this electrolyte is due to i) pH close to neutrality enabling high overpotential of water reduction on porous AC electrodes; ii) WIS characteristics with a reduced amount of free water in the Stern layer under positive polarization of AC; iii) higher oxidation potential at low temperature ascribed to the enhanced immobilization of the ClO4− anions in the Stern layer as well as reduced diffusion of water molecules in the AC electrode porosity. The electrochemical investigations on laminate AC//AC cells in the NaClO4-water electrolyte demonstrate low values of their resistive components down to -30 °C, while the devices can operate with rated voltage of 2.0 V and 1.7 V at -30 °C and RT, respectively. At -30 °C and under discharge power as high as 10 kW kg−1, the AC//AC capacitor in the NaClO4-water electrolyte outperforms the specific output energy of a traditional AC//AC cell in the 1 M TEABF4/ACN electrolyte. Hence, for sub-ambient temperatures, the presented environmentally friendly EDLC holds promise to compete with traditional devices implementing an organic electrolyte.

Elaeis guineensis Jacq.waste-derived as an supercapacitor electrode material with low cost and environmentally friendly

The increasingly rapid development of environmentally friendly porous activated carbon (AC) materials has attracted the attention of researchers. Moreover, the material can be produced from organic waste which is abundantly available. This time, porous active carbon based on green material (palm frond waste) has been successfully prepared and characterized. The application of more efficient, environmentally friendly and cost-effective, methods and production instrument has been optimized in this research. Integrated pyrolysis with carbonization (N2; 600 °C) and physical activation (H2O; 800 °C) produces activated carbon with a high purity level of up to 80 %. Through reviewing N2 gas absorption, it was confirmed that palm frond AC has a specific surface area of 356 m2 g−1, with a rough morphological structure and very rich surface nanopores. Furthermore, XRD characterization confirmed the purity of carbon through good amorphorosity properties with the presence of two wide peaks at diffraction angles of 22-24° and 42-44°. These findings show that the development and innovation of activated carbon production that is more environmentally friendly and cost-effective from palm frond waste is capable of producing active carbon with extraordinary physical characteristics. This palm tree AC has high potential for developing applications such as as an absorption material in air purifiers and water purifiers. Apart from that, these extraordinary characteristics also make palm frond AC suitable for use as electrode material in components of energy storage devices, supercapacitors with specific capacitance 86 F g−1.

Inspired by the Seeking Knowledge Strategy for Analects of Confucius to Screen Highly Electrochemically Active Porous Carbon: The Critical Source of Electroactive Sites

In this work, the forestry wastes are converted into a series of porous carbons using H3PO4 activation. These porous carbons feature a large specific surface area (1045.20 m2 g−1) and porosity that combines micro‐, meso‐, and macropores in various amounts depending on the fuel properties recorded for precursors used. Importantly, the C content recorded for forestry waste is one of the crucial factors in defining the specific surface area of the derived porous carbons. In addition, the total capacitance of the pine‐sawdust‐based porous carbon (PS‐C) sample is the highest, such as 220.55 F g−1 upon 5 mV s−1. Notably, the electrical double‐layer capacitance recorded for the samples remains essentially constant with increasing scan rates, such as ≈91.50 F g−1 for the olive‐shell‐based porous carbon, ≈123.70 F g−1 for PS‐C, and ≈105.66 F g−1 for the pine‐needle‐based porous carbon. Encouragingly, the pore‐associated sp3 site holds significant roles in the electrochemical application of the porous carbons. More importantly, the O/C value recorded for the precursor can be employed as a universal predictor of electrochemically active sites produced in porous carbons. In the findings, crucial insights are exhibited into the optimized fabrication of porous carbon with target electrochemically active sites for other applications such as catalysis.

Sustainable synthesis of activated porous carbon from lignin for enhanced CO2 capture: A comparative study of physicochemical activation routes

A sustainable and readily available material-lignin protobind 2400 was upcycled to activated porous carbon (APC) compatible with post-combustion CO2 capture. The effectiveness of the novel two-step physicochemical activation using KOH...

Sustainable oil palm trunk fibre based activated carbon for the adsorption of methylene blue

Activated carbon (AC) is becoming the limelight due to its widespread application as an adsorbent for wastewater treatment, gases, and catalysis. However, its high consumption and price have drawn more attention to the sustainable use of natural resources as precursor for AC production. This study focuses on synthesising AC from two types of oil palm trunk (OPT) fibres, a significant agricultural waste products produced by Malaysia's thriving palm oil industries. The BET surface area of about 2057.9 m2 g−1 was achieved by chemical activation with phosphoric acid (H3PO4). The efficiency of the synthesised AC was critically analysed based on the adsorption experiments with methylene blue (MB) by varying several parameters (dosage of adsorbent, pH, initial dye concentration, and temperature of the solution) to elucidate the adsorption mechanism(s). A maximum adsorption capacity of 320.4 mg g−1 at 50 °C was achieved, and the Temkin (r2 = 0.98, 0.95, 0.95) and Langmuir (r2 = 0.94, 0.93, 0.95) isotherm models fitted the adsorption process better than the Freundlich (r2 = 0.95, 0.90, 0.86) model. Besides, the pseudo-second-order model (r2 > 0.90) best described the adsorption process, favouring chemisorption over physisorption. Thermodynamics showed MB adsorption on AC was spontaneous except at the highest dye concentration. It was exothermic at lower dye concentrations (50 and 100 mg L−1) and endothermic at higher ones (300, 500, and 700 mg L−1). In a nutshell, this study reveals that OPT fibre is a promising precursor for synthesising highly porous AC for the adsorption of MB dye.

Design of Hierarchical Nickel-Cobalt Phosphide/Nickel Oxide with Tunable Electronic Structure and Strong Chemical Interface for Advanced Supercapacitors

The design of a reasonable heterostructure electrode to achieve enhanced areal performance for supercapacitors remains a great challenge. Here, we constructed hierarchical porous NiCoP/NiO nanocomposites anchored on Ni foam with tunable electronic and structural properties, as well as robust interfacial interaction. In NiCoP/NiO, the interconnected NiO nanosheets serve as a carrier with enriched anchoring sites to confine the NiCoP and improve its stability. Meanwhile, the ultrathin NiCoP nanosheets with bimetallic centers are connected with porous NiO nanosheets to form a reliable heterojunction, enhancing the electrochemical reaction kinetics. Taking advantage of the synergistic contribution of bimetallic centers, phosphides and unique structure, the NiCoP/NiO delivers a high areal specific capacitance (1860 mF cm−2 at 5 mA cm−2), good rate performance of 78.5% at six times the increased current density, and remarkable durability (11.0% decrease after 10,000 cycles). Furthermore, the assembled hybrid supercapacitor NiCoP/NiO//porous-activated carbon (PAC) delivers a high areal energy density of 173.7 μWh cm−2 (116.4 μWh cm−2) at 1.6 mW cm−2 (32 mW cm−2). The results indicate that the design of the heterostructure interface with strong chemical interface and tunable electronic structure is an effective and promising approach to boost the electrochemical performance for advanced supercapacitors.

Simultaneous Electrochemical Determination of Hydroquinone and Catechol by Lignocellulose Biopolymers Derived Porous Carbon

AbstractHemicellulose and lignin, which are main components of wood biomass with different structures, were carbonized and activated by KOH to prepare wood biomass‐derived porous carbons (WBM‐PCs). The resulting WBM‐PCs were characterized by SEM, XRD, Raman, FI‐IR, and N2‐adsorption/desorption isotherms, and successfully utilized as an effective modifier on the glassy carbon electrode surface (GCE) for simultaneous electrochemical determination of dihydroxybenzene isomers, i. e. hydroquinone (HQ) and catechol (CC), which are highly toxic and non‐degradable. The resulting WBM‐PCs‐modified GCEs allowed simultaneous determination of HQ and CC with cyclic voltammetry and constant‐potential amperometry. The linear range for determination of HQ by hemicellulose‐derived carbon (HC) was from 1.0 to 3000 μmol/L with the limit of detection (LOD) of 1.05 μmol/L, and that for CC was from 1.0 to 5000 μmol/L with LOD of 0.4 μmol/L. For lignin‐derived carbon (LC), the linear range for HQ was from 0.5 to 1000 μmol/L with LOD of 0.095 μmol/L, and that for CC was from 0.5 to 3000 μmol/L with LOD of 0.15 μmol/L. These results imply that wood biomass (hemicellulose and lignin), which is sustainable, renewable and environment‐friendly material, have potential as an effective precursor of electrochemically active porous carbon materials applicable to various electrochemical sensors.

K-buserite manganese oxide nanosheets enabling high-efficiency energy storage in aqueous Zn-ion batteries and hybrid supercapacitors

Mn-based cathode materials are promising for aqueous Zn-ion batteries (AZIBs) and hybrid supercapacitors (AZHSCs) because of their high theoretical capacity, low costs, and environmental benignity. However, sluggish reaction kinetics and robust electrostatic interaction often weaken their electrochemical performances, limiting their widespread application. Herein, novel potassium buserite manganese oxide nanosheets (MnOx NSs) are reported as a cathode material for AZIBs and AZHSCs. In-/Ex-situ characterizations and theoretical calculations demonstrate that MnOx NSs consist of K-buserite units which are irreversibly transformed into Zn-buserite units during the first cycle. In subsequent cycles, Zn-buserite serves as an active material with high activity/stability, enabling excellent energy storage. Notably, in full cells of MnOx NSs//PrGO-PTCDI (Perylene-3,4,9,10-tetracarboxylic diimide), a desirable capacity is achieved at 3.0 A g−1, and 103 mAh g−1 is retained at 0.5 A g−1 after 2000 cycles. Meanwhile, hybrid supercapacitors of MnOx NSs//PAC (porous activated carbon) achieve a capacitance of 212.9 F g−1 at 3.0 A g−1 with an energy (power) density of 180.3 Wh kg−1 (2094.2 W kg−1), and surprisingly long stability of 235 F g−1 remains after 53,000 cycles at 2.0 A g−1 with 88 % capacitance retention. This work offers new insights into deep understanding and creative designing of Mn-based materials for high-efficiency Zn-storage.