Porous Carbonaceous Materials Research Articles

Renewable Musa Sapientum derived porous nano spheres for efficient energy storage devices

Biomass-based carbonaceous materials derived from Musa Sapientum have gained much attention in recent years for their application in energy storage devices, especially supercapacitors. In the present work, we synthesized carbonaceous material from banana peel as the biomass precursor by using a pyrolysis method carried out at various temperatures (600, 800, and 1000 °C). The characterization of the prepared carbonaceous materials BP600, BP800 and BP1000 was done by using different characterization techniques such as FTIR, XRD, FE-SEM, and TEM, studies. The electrochemical study of the synthesized material was carried out by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) electrochemical impedance spectroscopy (EIS). The supercapacitive performance of the material was studied using a 3-electrode system with 3M KOH as an electrolyte. As a result, the BP600 exhibited a better specific capacitance with higher energy and power densities along with a maximum cyclic stability of 16,000 cycles. To show the practical applicability of the material BP 600, two electrode system studies were carried out as well, which showed preferentially good values for specific capacitance with appreciable power and energy density values. The study provides us with a green approach for the fabrication of non-toxic, low-cost, and environmentally friendly potential porous carbonaceous electrode materials by converting bio-waste into a clean and renewable source of energy.

Synthesis of an ion-imprinted starch phosphate porous carbonaceous material removing U(VI) from wastewater: Kinetics and mechanism

Uranium enrichment and separation are important for the sustainable development of nuclear energy. In this study, reverse-phase emulsion crosslinking polymerization was used to synthesize spherical hollow porous carbon materials (II-CLSPC) with a “red blood cell” morphology after roasting. The soft template method was used to modify II-CLSPC to obtain an open pore structure, which increased its contact area. Based on this, ion imprinting was conducted to improve the selective adsorption of U(VI). A spatial site matching the size of U(VI) was formed after ion template removal, which played a crucial role in this process. Multifaceted and multilevel improvements of II-CLSPC facilitated rapid adsorption, reaching equilibrium at 40 min and a removal rate of 94.6 % (pH 5, 298 K). The pseudo-second-order kinetic model and Langmuir isothermal model indicated that the adsorption process of uranyl ions by II-CLSPC involved via monolayer chemisorption with a theoretical saturation adsorption capacity of 653.6 mg g−1. In addition, II-CLSPC exhibited excellent selectivity (KdU = 3.7 × 104 mL g−1), cyclic stability, and salt tolerance, making it a promising candidate for uranium removal from wastewater.

Dual activated carbon derived from Keekar leaves as an excellent symmetric supercapacitor material

Porous carbonaceous materials derived from biomass, which are both cost-effective and obtained from sustainable resources, have emerged as appealing electrode materials for energy storage devices. These materials have received great interest as active electrode materials due to their ample, low-cost, sustainable nature and excellent electrochemical stability. In the present work, porous activated carbon (AC) was synthesized from Keekar leaves by dual activation using H2SO4 and KOH. This Keekar leaves derived AC (KLAC) possesses a surface area of ~1677m2g−1 with a combination of micro and mesoporosity displaying a specific capacitance of 411F/g in 6 M KOH and 219.55F/g for 1 M H2SO4 electrolytic solution at a current density of 1 A/g. Further, the symmetric devices were fabricated using both aqueous (aq.) and polymer gel electrolytes for practical evaluation of the material. The aq. and gel device are capable of delivering a specific capacitance of 108.34 F/g and 88.45 F/g, respectively, at a current density of 0.5 A/g. The aq. device offers a maximum energy density of 33.85 Whkg−1 at a power density of 562.5 Wkg−1. The outstanding capacitance retention of 89.5 % is demonstrated by the aq. device at a higher scan rate of 20 A/g after continuous 10,000 charging-discharging cycles. Such high performance and stability make KLAC a potential candidate as an affordable and sustainable electrochemical energy storage application.

Investigation of characteristics and application of food waste-derived bone char on plant growth

Waste bone, a by-product originating from animal husbandry and food industry, primarily ends up in landfills and may cause soil pollution if no treatment method is applied. In this article, pork bone char (PBc), a porous carbonaceous material, was manufactured by pyrolyzing waste pork bones collected from food waste sources. The investigation covered temperatures from 400 to 800 °C in limited oxygen conditions. The prepared PBc samples were characterized and applied as an alternative source of phosphorus fertilizer by evaluating the growth of Ipomoea aquatica planted on the PBc/soil mixture and assessing the properties of SPBc.As a result, the PBc materials exhibit a clear hydroxyapatite mineral structure along with an abundance of micro-mesoporous features. The SPBc samples demonstrate a significant change in phosphorus concentration (up to 1.6 %) compared to PBc non-amended soil, and the growth of the Ipomoea aquatica plant differed significantly from the plant not fertilized by PBc. The results after four weeks indicate that samples added with PBc synthesized at temperatures of 500, 600, and 700 °C promoted its vigorous growth corresponding to the ratio of Ca/P of hydroxyapatite. The specific surface area, pore volume, and average pore size by various pyrolysis temperatures can impact the release of phosphorus from the PBc into the soil, significantly influencing the growth of Ipomoea aquatica. The achieved outcome not only presents a promising substance for reducing reliance on conventional phosphorus fertilizers derived from apatite minerals but also establishes a means to pursue the objectives of sustainable development and a circular economy.

Theoretical insight into NO formation and reduction at biochar N-sites: Influence of different oxygen-containing functional groups

Biochar is a cost-efficient and promising porous carbonaceous material for the efficient removal of flue gas NOx. The N-site located at the edge of biochar can be a crucial gateway for NO reduction to N2 or for NO formation by oxidation, which can be significantly affected by the oxygen-containing functional groups (OFGs) on the biochar edge. However, the roles of different OFGs in N-site-involved reactions remain elusive. Based on the biochar characterization results, reasonable theoretical models of biochar with different N-sites and OFGs were constructed. Subsequently, the effects of distinct OFGs on the interaction between NO and N-sites as well as the NO liberation from N-sites were elucidated, by employing density functional theory (DFT) and electronic structure analysis. The results reveal that all OFGs, encompassing -CHO, -COOH, and -OH, manifest their roles through the direct inherent electrostatic properties of O/H in OFGs (O*/H*) or altering the reactivity of edge atoms indirectly. For pyridinic nitrogen (N-6) at the zigzag edge, unsaturated (-CHO, -COOH)/saturated (-OH) OFGs inhibit/enhance NO reduction with N-6 by electrostatic properties of O*/H*, and all OFGs inhibit NO generation from N-6. Besides, all OFGs enhance the NO reduction with pyrrolic nitrogen (N-5) at the armchair edge while inhibiting the release of NO, by influencing the edge activity. The present study gives a mechanism insight into the roles of distinct OFGs in reactions involving biochar N-sites.

Promoting the circular economy: Valorization of a residue from industrial char to activated carbon with potential environmental applications as adsorbents

Pyrolysis of residues enriched with carbon, such as in agroforestry or industrial activities, has been postulated as an emerging technology to promote the production of biofuels, contributing to the circular economy and minimizing waste. However, during the pyrolysis processes a solid fraction residue is generated. This work aims to study the viability of these chars to develop porous carbonaceous materials that can be used for environmental applications. Diverse chars discharged by an industrial pyrolysis factory have been activated with KOH. Concretely, the char residues came from the pyrolysis of olive stone, pine, and acacia splinters, spent residues fuel, and cellulose artificial casings. The changes in the textural, structural, and composition characteristics after the activation process were studied by N2 adsorption-desorption isotherms, scanning electron microscopy, FTIR, elemental analysis, and XPS. A great porosity was developed, SBET within 776–1186 m2 g−1 and pore volume of 0.37–0.59 cm3 g−1 with 70–90% of micropores contribution. The activated chars were used for the adsorption of CO2, leading to CO2 maximum uptakes of 90–130 mg g−1. There was a good correlation between the CO2 uptake with microporosity and oxygenated surface groups of the activated chars. Moreover, their ability to adsorption of contaminants in aqueous solution was also evaluated. Concretely, there was studied the adsorption of aqueous heavy metals, i.e., Cd, Cu, Ni, Pb, and Zn, and organic pollutants of emerging concern such as caffeine, diclofenac, and acetaminophen.

Sonocatalytic Activity of Porous Carbonaceous Materials for the Selective Oxidation of 4-Hydroxy-3,5-dimethoxybenzyl Alcohol.

Selective oxidation, which is crucial in diverse chemical industries, transforms harmful chemicals into valuable compounds. Heterogeneous sonocatalysis, an emerging sustainable approach, urges in-depth exploration. In this work, we investigated N-doped or non-doped carbonaceous materials as alternatives to scarce, economically sensitive metal-based catalysts. Having synthesized diverse carbons using a hard-template technique, we subjected them to sonication at frequencies of 22, 100, 500, and 800 kHz with a 50% amplitude. Sonochemical reaction catalytic tests considerably increased the catalytic activity of C-meso (non-doped mesoporous carbon material). The scavenger test showed a radical formation when this catalyst was used. N-doped carbons did not show adequate and consistent sonoactivity for the selective oxidation of 4-Hydroxy-3,5 dimethoxybenzyl alcohol in comparison with control conditions without sonication, which might be associated with an acid-base interaction between the catalysts and the substrate and sonoactivity prohibition by piridinic nitrogen in N-doped catalysts.

Study of carbon materials using X-ray diffraction method, qualitative and quantitative analysis of adsorption

Active carbons are porous industrial adsorbents and carbonaceous materials derived from various organic raw materials and used to treat drinking and waste water. This study aimed to X-ray analyzes the structure of the sorbent based on coal and the efficiency of ion extraction from solutions by this sorbent. The diffraction patterns of the sorbents were obtained on a powder diffractometer. The qualitative and quantitative composition of the sorbents was determined by X-ray fluorescence method. The sorbent surface was imaged using scanning electron microscopy. It was found that the isotherms of the studied systems are satisfactorily described by the Langmuir and Freundlich models. The constants of the Freundlich equation were 0.31, 0.004, and 0.029 for adsorption of iron ions, manganese ions, and nitritions, respectively. The maximum adsorption of Langmuir iron ions was 3.61 mg/g, manganese ions 2.49 mg/g, and nitrite ions 0.33 mg/g. The Gibbs energy during adsorption of iron ions, manganese ions and nitrite ions were −17.93 kJ/mol, −30.5 kJ/mol and −20.5 kJ/mol, respectively. It is shown that effective extraction of ions can occur due to ion exchange and complexation processes for metal ions with active centers on the sorbent surface. Development of the technology of treatment of open-pit and surface wastewater of coal mining enterprises using sorbents based on coal will allow to solve environmental problems of resource-oriented regions and will contribute to the restoration and ecological rehabilitation of water bodies.

Influence of carbon structure/porosity on the electrochemical performance in Li–sulfur batteries

The porous structure of three different, commercially available porous carbonaceous materials is investigated by the αS-plot method and by the t-plot method. Subsequently, the electrochemical properties of sulfur-free porous carbon electrodes from inspected materials are studied by cyclic voltammetry. The comparison of double-layer capacitances with the corresponding adsorption isotherms of N2 reveals the role of micropores during the capacitive charging of carbons by Li+. The studied carbons are added to the sulfur cathodes and evaluated. The cyclic voltammograms show no contribution of micropores in the carbon structure to the electrochemical processes taking place in the lithium–sulfur coin cell. The highest specific capacity of 816 mAh/g is observed for material with the lowest content of micropores in the structure (14%). The partially mesoporous and partially microporous (65%) sample and the predominantly microporous one (87%), show specific capacities of 664 mAh/g and 560 mAh/g, respectively. The galvanostatic cycling of lithium–sulfur coin cells with carbonaceous additives reveals that the mesopores and macropores in the carbon structure increase the specific charge capacity of the lithium–sulfur batteries and that the micropores improve the cycling stability of these batteries.Graphical abstract

Tannin Industry Waste-Derived Porous Carbon: An Effective Adsorbent from Black Wattle Bark for Organic Pollutant Removal

In Brazil, a significant part of the biomass is unused, contributing to environmental pollution. The tannin industry commonly extracts tannins from the bark of Acacia mearnsii or black wattle, leaving a significant residue of 70% (w w−1). This study investigates the conversion of black wattle bark into a porous carbonaceous material to efficiently remove organic pollutants. Using ZnCl2 as a chemical activation reagent, the experiments varied the impregnation time, carbonization rates, and temperatures. Additional experiments aimed to increase the specific surface area (SSA). X-ray diffraction (XRD) analysis showed the formation and removal of ZnO, which increased porosity. Scanning electron microscopy (SEM) showed an irregular morphology with pores. Fourier-transform infrared (FTIR) spectroscopy indicated characteristic bands, and electron paramagnetic resonance (EPR) detected organic free radicals. The SSAs exceeded 1000 m2 g−1, averaging 1360 m2 g−1, with a maximum of 1525 m2 g−1. Micropores (1.4 nm) were consistent. The structure of the material and the high SSA suggest a potential for efficient removal of aromatic impurities by π–π interactions. This approach addresses the issue of biomass waste, provides a solution for environmental remediation, and represents a transformative strategy for biomass utilization.

In Situ Synthesis of Rare-Earth Hybridized Functional Core-Shell Architectures from Microporous Salt Templates and Capacitance-Adsorption Correlation Mechanisms.

Biochar Porous Carbon (BPC) has become a research hotspot in the fields of energy storage, conversion, catalysis, adsorption, and separation engineering. However, the key problem of pore structure liable to collapse has not yet been addressed effectively. Here, an innovative salt ionic coordination modulation technique is reported to synthesize a new core-shell structure of BPC (Dual-doped porous carbonaceous materials, RHPC3@LaYO3) by the asymmetric load of the f orbital ion, which prevents pore structural collapse. The result shows that the novel asymmetric supercapacitors (ASCs) with an excellent energy density (193.11Wh·kg-1) and capacitance (267.14F·g-1) by assembling the prepared porous BPC carrier and RHPC3@LaYO3, which surpass the typical supercapacitor. In order to elucidate the association between adsorption and capacitance, the adsorption coexistence equation (MACE) is constructed with the aim of providing a comprehensive explanation for the mechanism of single-multilayer adsorption. Furthermore, a specific linkage mechanism is discovered using adsorption/ desorption properties to validate the pros/cons of capacitive properties. These results demonstrate the potential of renewable biomass materials as ASCs, which can provide new ideas for the construction of an evaluation approach for the performance of future efficient multi-reaction energy storage devices.

Porous carbonaceous materials simultaneously dispersing N, Fe and Co as bifunctional catalysts for the ORR and OER: electrochemical performance in a prototype of a Zn-air battery.

Infiltration of the mesoporous structure of SBA-15 silica as a hard template with phenanthroline complexes of Fe3+ and Co2+ allowed the simultaneous dispersion of nitrogen, iron and cobalt species on the surface of the obtained carbonaceous CMK-3 silica replica, with potential as bifunctional heterogeneous catalysts for the cathodic oxygen reduction and evolution reactions (ORR and OER). The textural properties and mesopore structure depended on the composition of the material. The carbonaceous FeCoNCMK-3 (1/1), obtained with an Fe/Co molar ratio of 1/1, exhibited an ordered cylindrical mesoporous structure with a high mesopore volume, a rather homogeneous composition in terms of total and surface concentrations of iron and cobalt, and a balanced presence of pyridinic-, pyrrolic- and graphitic-N species. FeCoNCMK-3 (1/1) could improve the ORR kinetics by adsorption and reduction of O2 through the 4-electron mechanism with a current density of -17.37 mA cm-2, Eonset of 1.13 V vs. RHE and E1/2 of 0.75 V when compared to metal-free, monometallic or bimetallic electrocatalysts with a higher amount of cobalt than that of iron. In addition, FeCoNCMK-3 (1/1) exhibited activity for the OER, presenting lower values of Eonset (1.52 V), Ej10 (1.78 V) and the Tafel slope (76.3 mV dec-1) with respect to other catalysts. When evaluated as a cathode in a prototype of a Zn-air battery, FeCoNCMK-3 (1/1) exhibited a high open circuit voltage of 1.41 V, a peak power density of 66.84 mW cm-2, a large specific capacity of 818.88 mA h gZn-1, and cycling for 20 h but with deactivation upon cycling.

Graphene-like materials supported on sepiolite clay synthesized at relatively low temperature

The preparation of solids with graphitic structure usually requires synthesis procedures using very high temperatures. In this work, a comparative study involving different experimental strategies of synthesis at relatively low temperature was carried out to obtain graphene-like materials supported on microporous sepiolite (SEP) clay. The final objective was the optimization of the development of new clay-graphitic nanostructured materials to achieve porous solids while saving energy and time during the preparation stages. The pyrolysis of sucrose (SUC), used as carbon precursor, was accomplished by microwave (MW) pyrolysis or tube furnace (TF) pyrolysis at 200 or 500 °C followed by a hydrothermal carbonization (HTC) step. The resulting carbon-clay nanoarchitectures were characterized by Raman and Infrared spectroscopy, X-ray diffraction, elemental analysis, electron microscopy, and nitrogen adsorption-desorption isotherms. The MW200 and TF200 treatments caramelized SUC and the post-HTC step was fundamental to obtain porous carbonaceous materials. The TF500 pyrolysis produced predominantly crystalline carbon, while the MW500 pyrolysis formed an amorphous material. Moreover, the high-resolution transmission electron microscopy observations of TF500 sample revealed a crystalline material with a d-spacing of 0.33 nm, matching the graphitic lattice. All the treatment conditions performed at 500 °C i.e., MW or TF followed or not by HTC, resulted in mesoporous carbons with a specific surface area above 200 m2 g−1. The MW pyrolysis saved 100 min of the reaction time in comparison to TF pyrolysis to obtain the carbonaceous porous materials.

Modified Solid Electrolyte Interphases with Alkali Chloride Additives for Aluminum-Sulfur Batteries with Enhanced Cyclability

Al-S batteries are promising energy storage devices, employing high-capacity and low-cost Al (2980 mA h g-1, 8050 mAh cm-3) and sulfur (1672 mAh g-1) as the anode and cathode, respectively. However, Al-S batteries suffer from the notorious shuttle effect of polysulfides as other intensively investigated metal-sulfur batteries. Up to now, several strategies have been proposed to improve the poor reversibility and lifespan of Al-S batteries. At the cathode side, materials that can adsorb polysulfides have been employed as the host material of sulfur to reduce the dissolution of polysulfides,1,2 e.g., heteroatom-functionalized and/or hierarchical porous carbonaceous materials, metal-organic frameworks (MOFs), boron nitrides, and Mxenes.3,4 Nonetheless, AMAs, which also play an important role in the shuttle process, have received little attention up to now. Suitable engineering of electrolytes enabling an electronically insulating solid electrolyte interphase (SEI) on AMAs may suppress the deposition of low-solubility Al2S3 and/or short-chain polysulfides further promoting the cell cycling performance.Herein, alkali chlorides are, for the first time, proposed as electrolyte additives to modify the SEI on AMAs and suppress the polysulfide shuttle in Al-S batteries.5 It is demonstrated that adding NaCl to the conventional [AlCl3]1.3[EmimCl]1 electrolyte can enhance the cyclability of Al-S batteries by forming a thicker, NaxAlyO2-containing SEI layer on AMAs. In addition to NaCl, LiCl and KCl as electrolyte additives also lead to improvement of Al-S batteries’ lifespan. These findings provide a new path to suppress the detrimental polysulfides shuttle effect in Al-S batteries, resulting in their improved cycle performance. References (1) Smajic, J.; Wee, S.; Simoes, F. R. F.; Hedhili, M. N.; Wehbe, N.; Abou-Hamad, E.; Costa, P. M. F. J. Capacity Retention Analysis in Aluminum-Sulfur Batteries. ACS Appl. Energy Mater. 2020, 3 (7), 6805–6814.(2) Zhang, Y.; Ma, L.; Tang, R.; Zheng, X.; Wang, X.; Dong, Y.; Kong, G.; Zhao, F.; Wei, L. The Host Hollow Carbon Nanospheres as Cathode Material for Nonaqueous Room-Temperature Al–S Batteries. Int. J. Hydrogen Energy 2021, 46 (7), 4936–4946.(3) Guo, Y.; Jin, H.; Qi, Z.; Hu, Z.; Ji, H.; Wan, L. J. Carbonized-MOF as a Sulfur Host for Aluminum–Sulfur Batteries with Enhanced Capacity and Cycling Life. Adv. Funct. Mater. 2019, 29 (7), 1–6.(4) Wang, Z.; Zheng, X.; Chen, A.; Han, Y.; Wei, L.; Li, J. Unraveling the Anchoring Effect of MXene-Supported Single Atoms as Cathodes for Aluminum−Sulfur Batteries. ACS Mater. Lett. 2022, 4, 8, 1436-1445.(5) Xu, C.; Diemant, T.; Liu, X.; Passerini, S. Modified Solid Electrolyte Interphases with Alkali Chloride Additives for Aluminum–Sulfur Batteries with Enhanced Cyclability. Adv. Funct. Mater. 2023. 2214405.

Electrophoretically Deposited Na3V2(PO4)3 and its Carbonaceous Composites as Promising Cathode for Sodium-ion Batteries

Sodium vanadium phosphate (NVP), a sodium ion super ionic conductor (NASICON), is one of the most attractive cathode materials for sodium ion batteries (SIBs). Electrophoretic deposition (EPD) is demonstrated to be an efficient synthesis tool to deposit strongly adhered and porous NVP carbonaceous material (viz. carbon nano tube (CNT) and reduced graphene oxide (rGO)) on aluminum current collector. EPD grown NVP delivers a stable reversible capacity ∼53.7 mAhg−1 at 0.1Ag−1 current density after 250 cycles. The introduction of CNT and rGO in the electrode significantly improves the electrochemical properties of NVP by providing better conduction pathways. Consequently, reversible capacities of 87 mAhg−1 and 70 mAhg−1 were obtained after 250 cycles at 0.1Ag−1 for NVP/RGO-CB and NVP/CNT-CB electrodes, respectively. These electrodes are able to deliver specific capacities of ∼70 mAhg−1 at a current density of 5Ag−1. Moreover, these electrodes were able to retain more than 80% of its initial capacity even after 2000 cycles at a high current density of 3Ag−1.

Preparation and Characterization of a Hierarchically Porous Zeolite-Carbon Composite from Economical Materials and Green Method

A hierarchically porous structured zeolite composite was synthesized from NaX zeolite supported on carbonaceous porous material produced by thermal treatment for plum stones which is an agro-waste. This kind of inorganic-organic composite has an improved performance because bulky molecules can easily access the micropores due to the short diffusion path to the active sites which means a higher diffusion rate. The composite was prepared using a green synthesis method, including an eco-friendly polymer to attach NaX zeolite on the carbon surface by phase inversion. The synthesized composite was characterized using X-ray diffraction spectrometry, Fourier transforms infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis, thermogravimetric analysis, N2-adsorption/desorption isotherm, and point of zero charges. The results showed that the composite had a surface area of 208.463 m2/g, a pore volume of 0.122 cm3/g, distinct morphology, and functional groups. Also, its pHpzc was 6.9 above which its surface has a positive charge and below 6.9 it is charged negatively. This property determines the composite sorption property in the removal of pollutants from wastewater.

A new 1,2,4-triazine-n-oxide compound: Synthesis, crystal structure, Hirshfeld surface analysis and supercapacitor applications

In this paper, we report the one-step, metal catalyst-free synthesis of 6-(4-chlorophenyl)-3,3-dimethyl-4-(N-oxide)-1,2,3,4-tetrahydro-1,2,4-triazine using 2,4-dihydroxyacetophenone and p‑chloro isonitrosophenyl hydrazine and its full characterization including single crystal X-ray analysis. A simple and straightforward method for the synthesis is presented and the compound is obtained in a moderate yield and high purity. It's molecular and crystal structures were determined and found that It belongs to triclinic system P -1 space group with a = 5.9173 (2) Å, b = 13.3113 (4) Å, c = 14.3963 (4) Å, α = 97.583 (2) °, β = 93.207 (2) °, γ = 91.378 (2) °, Z = 4 and V = 1121.71 (6) Å3. In the crystal structure, the intermolecular NH⋯O hydrogen bonds link the molecules into infinite chains along the a-axis direction. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (48.4 %), H⋯C/C⋯H (16.6 %), H⋯O/O⋯H (13.7 %) and H⋯CI/CI⋯H (11.0 %) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. The electrochemical characterizations and the supercapacitor performances of the compound were also investigated. Although, the pretreated porous carbonaceous materials or nanostructures provide superior surface enhancement properties in terms of the electrode modifications for a wide range of electrochemical applications, here we found a better performance for the proposed single crystal hydrazone as an electrode modifier.

Development of a novel biochar-made porous monolith for enhanced C1 and H2 fermentation

Biochar is a carbonaceous porous material that is produced through the thermal processing of biomass under oxygen-limited environment. Nevertheless, biochar is known to be an inexpensive and sustainable raw material with a wide range of possible applications. Recently, biochar has been discovered as an efficient biological catalyst for anaerobic conversion, mainly due to its highly porous structure with micro and macro channels, which procures a viable living area for attached-grown microorganisms. Whereas it is never applied to improve the biological conversion of gas substances such as C1 (e.g., CO, CO2) and H2, which is a promising research area with increasing commercial interest. However, considering that biological reaction is limited by the target water solubility of gas substrates, special attention is required when combining biochar for gas fermentation. The goal was to create a novel gas sparger where the biofilm grows on biochar, thus improving the interaction with the gaseous substrate. For this purpose, polystyrene foam and powdered biochar were compounded to form a mouldable composite, which was then cast as a porous monolith.•Biochar-made sparger (BS) was investigated for the homoacetogenic conversion of H2 gas via microbial mixed cultures as opposed to a control test equipped with a stone sparger.•BS showed a significantly better performance in terms of biological gas fixation rate (36% more than control) and productivity (8.5 gCOD L−1 d−1).

Boosted persulfate activation by hierarchically porous carbonaceous materials: Pivotal role of pore structure and electron-accepting capacity

Porous carbonaceous materials (CMs) have been praised as superior candidates in activating persulfate for antibiotic wastewater decontamination. Whereas, as one of the frequently reported nonradical pathways, the formation mechanism of the reactive complexes and their correlation with physicochemical properties of CMs have not been comprehensively unveiled. Herein, a series of carbonaceous materials (CMs) with different specific surface area (SSA) and defect structures were fabricated by using KCl, MgCl2, KHCO3 and K2C2O4 as porogenic agents to activate peroxydisulfate (PDS) for sulfadiazine (SDZ) degradation. Results showed that the total pore volume of CMs exhibited a good linearity with degradation rate, attributing to the combined effect of SSA, defect degree and oxygen-containing functional groups according to multiple regression model. The reactive complexes (CM/PDS*) were proved as the foremost active species for SDZ oxidation via a suite of solid evidences. Compared with that after PS addition, the current direction was reversed after SDZ addition in i-t curves shedding light on the sharp enhanced potential of CM/PDS* and much low potential of SDZ. Furthermore, the inner-sphere CM/PDS* originating from the formation of new covalent bonds between CMs and PDS was inferred due to the poor dependence between electron-donating capacity and SDZ degradation result. The CM/PDS* with considerably higher potential can extract electron from SDZ based on the excellent positive relationship between electron-accepting capacity of CMs and SDZ degradation effect. This study advances the mechanistic comprehension of nonradical PDS activation, and provides a multiple regression model to predict degradation effects of carbon materials.

Nitrogen functionalities in mesoporous carbons and their impact on the sulfur infiltration efficiency and in the electrochemical performance of Li[sbnd]S cells

The cyclability of LiS batteries depends strongly on electrochemical cell stability, which is affected by the dilution of lithium polysulfides in the electrolyte. One of the proposed solutions is the use of porous carbonaceous materials in the cathode that trap lithium polysulfide species and prevent them from reaching the electrolyte. This is possible by using dopant heteroatoms in the carbon framework such as nitrogen to generate anchoring sites reducing the shuttle effect. To understand how the sulfur infiltration process in carbonaceous materials is affected by the inclusion of nitrogen in the carbon structure and its effect on the electrochemical performance of LiS batteries, in this study N-doped mesoporous carbons were prepared by varying the carbonization temperature, focusing on the structural and compositional variations. At the highest carbonization temperature (850 °C), a carbonaceous material with the lowest nitrogen content was obtained mainly prevailing the N-quaternary functionality over N-pyrrolic and N-pyridinic. The sulfur infiltration into the pores of the material was improved due to the moderate polarity obtained under the carbonization temperature used (850 °C). Given the distribution of nitrogen functionalities, it was possible to obtain a material with a high degree of graphitization reflected in the electrochemical performance where after 100 cycles a discharge capacity of 422.3 mA h g−1 was reached with a Coulombic efficiency of 99%.