High Degree Of Graphitization Research Articles

Reconfiguring the interface charge of Co@Carbon polyhedron for enhanced capacitive deionization

In this work, the Co-metal organic framework (ZIF-67) is employed as the template to prepare 3D mesoporous Co@carbon polyhedron (Co@CP) for capacitive deionization (CDI) anodes with improved salt removal capacity. The as-prepared Co@CP exhibits a novel dodecahedron structure with abundant nanopores and embeds with Co nanoparticles which are uniformly distributing on the carbon skeleton. Such structure not only enhances the conductivity and structural durability of the whole electrode, but also provides a convenient transport channel for ions/electrons and thereby promoting the desalination kinetics. Remarkably, the reversible electrochemical conversion between the Co0 to some extent improves the storage of Na+, accompanied by the desalination/regeneration. Regarding the preparation, as the temperature increased from 600 to 800℃, the dominant particle size rises from 5 to 7 nm to 12–18 nm. The density functional theory calculation features that the conductivity and charge transport ability of Co@CP can be reinforced by optimizing the Co-C interface. Accordingly, the charge density difference simulation demonstrates that the Co doping and the existence of defects benefits to generate great potential active sites, leading to the enhanced adsorption of Na+. As a result, the optimized Co@CP possesses the large pore volume, high degree of graphitization and large specific surface area (515.6 m2/g). Towards the desalination, the highest desalination capacity reaches to 47.8 mg/g in 1000 μS/cm NaCl at 1.2 V with adsorption rate of 3.28 mg/g/min.

Constructing ultra-stable photothermal plastics assisted by carbon dots with photocaged reactivity

Constructing ultra-stable photothermal plastics assisted by carbon dots with photocaged reactivity

High-graphitization, large-surface area, and porous carbon nanofiber: A superior bi-functional electrode for vanadium redox flow battery

In this paper, a vanadium redox flow battery carbon nanofiber electrode (CNF-700–4) with high graphitization, large specific surface area and high porosity was prepared by introducing ferric ammonium citrate (FAC). During carbonization process, FAC was employed to improve the graphitization degree, form microporous structure, and realize heteroatom doping. The effects of FAC content and calcination temperature on the electrochemical properties of carbon nanofiber electrode was systematically studied. CNF-700–4 exhibited excellent electrocatalytic activity and reversibility towards VO2+/VO2+ and V2+/V3+ redox couples among all electrodes. The electrochemical performance was mainly improved from three aspects: electron transport, charge transfer and diffusion processes. The higher degree of graphitization, abundant porous structures, and types of functional groups can improve the conductivity of the electrodes and provide active sites for reactions. The cell using CNF-700–4 exhibited excellent adaptability and good durability during charge–discharge tests. Compared with pristine cell, the cell using CNF-700–4 has a 10% higher energy efficiency and an improved discharge capacity of 224 mA h at 200 mA cm−2.

Porous Ni3S2-Co9S8 Carbon Aerogels Derived from Carrageenan/NiCo-MOF Hydrogels as an Efficient Electrocatalyst for Oxygen Evolution in Rechargeable Zn-Air Batteries.

Herein, we fabricate N-doped porous Ni3S2-Co9S8/carbon aerogels (Ni3S2-Co9S8/NCAs) using carrageenan/NiCo-metal-organic framework (MOF) hydrogels as the precursor via the high-temperature carbonization route with excellent electrocatalytic properties for the oxygen evolution reaction (OER). The electrochemical measurements indicate that the Ni3S2-Co9S8/NCA as a quintessential electrocatalyst exhibits excellent OER performance, which has outperformed most transition metal sulfide (TMS) catalysts in alkaline environments, as attested with a lower overpotential of 337 mV at 10 mA cm-2 and a smaller Tafel slope of 77 mV dec-1. Meanwhile, a Zn-air battery based on Ni3S2-Co9S8/NCA + Pt/C achieves a large power density of up to 256 mW cm-2 (and 193 mW cm-2), small charge/discharge voltage gap, and good cycling stability, notably better than the conventional RuO2 + Pt/C-based Zn-air batteries. These excellent electrocatalytic properties are mainly attributed to the distinct hierarchical porous structure and interfacial synergy between the Ni3S2 and Co9S8 nanoparticle structure with rich defects, facilitating the mass transport and high graphitization degree beneficial for electron mobility. It is envisioned that the research provides a novel approach for the exploration of marine biomass as an electrocatalyst.

Sandwich-type electrochemical aptasensor based on Au-modified conductive octahedral carbon architecture and snowflake-like PtCuNi for the sensitive detection of cardiac troponin I

The cardiac troponin I (cTnI) detection is increasingly significant given its promising value in the clinical acute myocardial infarction diagnosis. Here a sensitive sandwich-type cTnI electrochemical aptasensor was developed by using zirconium-carbon loaded with Au (Au/Zr–C) as electrode-modified material and snowflake-like PtCuNi catalyst as label material. The Au/Zr–C was prepared from a carbonation process and a reduction step. The PtCuNi was synthesized by a one-pot hydrothermal reaction. On the one hand, due to its many merits of large effective area, rich pores, high degree of graphitization, the assistance of Au, the Au/Zr–C exhibited remarkable electronic conductivity but low catalytical capacity, thus improving the electrochemical property but lowing the background signal of electrode. On the other hand, because of its accessible active sites of the special snowflake-like structure and the synergy of three elements, the PtCuNi catalyst presented excellent catalytic activity and improved stability compared to binary alloy. The recognition reactions were achieved by stepwise incubation of aptamer 1, cTnI, and aptamer 2-PtCuNi (denoted as Apt2-label) on the Au/Zr–C-modified electrode. The electrocatalytic signals of the immobilized Apt2-label towards the H2O2 reduction were recorded in all tests for cTnI analysis. Consequently, this cTnI aptasensor exhibited excellent performance involving a wide linear range of 100 ng mL−1 to 0.01 pg mL−1 with a detection limit of 1.24 × 10−3 pg mL−1 (S/N = 3), good selectivity, satisfying reproducibility, outstanding stability, and good recovery.

Experimental study on preparation of oxygen reduction catalyst from coal gasification residual carbon

Coal gasification fine slag (GFS) produced from industrial entrained-flow gasification plants typically contains a large amount of residual carbon. Using the GFS coal flotation residue as a carbon source for the oxygen reduction reaction (ORR) catalyst is therefore an effective recycling method that will further promote utilization of the solid waste generated during coal gasification. In this study, ORR catalysts were prepared by the acid treatment, activation, and heteroatom doping of residual GFS carbon. The specific surface area (SSA) of the nitrogen-doped porous carbon catalyst, calculated using the Brunauer–Emmett–Teller method, was 1657 m2/g. In addition, N and/or Fe are in the composition of ORR-active sites which are uniformly distributed on the catalyst surface. Although the catalyst exhibited a rich porous structure and a high degree of graphitization, several graphite lattice defects were also present. In the ORR test, the Fe-N-C catalyst reached a limiting diffusion current density of 4.86 mA/cm2 and a half-wave potential of 0.76 V in a 0.1 M KOH electrolyte, in addition to giving a high electron transfer number of 3.77 and following a predominant four-electron pathway. In the zinc-air battery test, the power density of the Fe-N-C catalyst reached 124.2 mW/cm2, and the battery maintained a charging voltage of 1.99 V after 250 charge/discharge cycles. This ORR catalytic performance obtained for the Fe-N-C catalyst indicates the feasibility of preparing an ORR catalyst from GFS carbon residue, and paves the way for further research in this area.

Fe3O4/MnO2 co-doping phenolic resin porous carbon for high performance supercapacitors

BackgroundThus, the excellent electrochemical property of PR-Fe@MnO2 composite made it an encouraging electrode material for practical applications like charge storage and in other pseudocapacitors. MethodsUsing phenolic resin (PR) as a carbon source, potassium ferrate (K2FeO4) and manganese acetate (Mn(CH3COO)2·4H2O) as the dopants, a one-step carbonization method was used to prepare a series of Fe3O4 and MnO2 co-doped composites, which are denoted as PR-Fe@MnO2. During high-temperature carbonization (800 °C), partially amorphous carbon forms a multi-layer graphene structure, making PR-Fe@MnO2 exhibit a high degree of graphitization. After doping, the transition metal Mn was investigated theoretically by performing density functional theory calculations. Significant FindingsThe results confirmed that doping of moderate Mn ions in the PR-Fe lattice improved the interactions between OH− in the electrolyte and Mn metal center, consequently, the electrical conductivity (19%) of the electrode according to the equivalent series resistance (Rs). The Mn composition also increased the specific area for more electroactive sites and reduced the charge transfer resistance (decreased by 27.7%). As a result, PR-Fe@MnO2–1.5 had the highest specific capacitance of 601 F/g at 1.0 A/g and superior cycling stability (capacitance retention of 97.8% after 10,000 cycles). Furthermore, the assembled PR-Fe@MnO2–1.5//PR-Fe@MnO2–1.5 symmetric supercapacitor provided a specific energy density of 25.7 Wh/kg at a power density of 384.9 W/kg.

A solvothermal pre-oxidation strategy converting pitch from soft carbon to hard carbon for enhanced sodium storage

Due to its low cost and easy availability, the pitch is considered a promising precursor for soft carbon anodes. However, pitch-derived soft carbon shows a high graphitization degree and small interlayer spacing, resulting in its much lower sodium storage performance than hard carbon. We propose a novel pre-oxidation strategy to introduce additional oxygen atoms into the low-cost soft carbon precursor pitch to fabricate a defect-rich and large-interlayer spacing hard carbon anode (HPP-1100). Compared with the direct pyrolysis of pitch carbon, the sodium storage capacity of HPP-1100 is significantly improved from 120.3 mAh/g to 306.7 mAh/g, with an excellent rate and cycling capability (116.5 mAh/g at 10 C). Moreover, when assorted with an O3-Na(NiFeMn)1/3O2 cathode, the full cell delivers a high reversible capacity of 274.0 mAh/g at 0.1 C with superb cycle life. This work provides a new solution for realizing the application of low-cost pitch anodes in Na-ion batteries.

Evaluation of graphitization and tensile property in microwave plasma treated carbon fiber

Plasma technology can be used as a green and novel method for the graphitization of carbon fiber. The effect of graphitization time on the main element content along with microstructure of carbon fiber in the plasma treatment process was investigated. It took an extremely short time (less than 100 ms) for the temperature of the system to increase until a relatively stable stage was reached. Furthermore, compared with the original carbon fiber, the increase in the carbon content and graphitization degree of carbon fiber was observed after microwave plasma treatment. Moreover, the original imperfect turbostratic graphite-like structure transformed to an ordered graphite structure with the escape of non‑carbon elements from the disordered region of graphite-like crystallites. With the graphitization time of 180 s and microwave power of 800 W, corresponding to the temperature of 2100 °C, a high graphitization degree (R = 0.61) was observed and the crystallite size was as large as 5.10 nm, which are better than that of M40J and T800H. After 5 mins treatment, the average tensile modulus of samples apparently increased by 23% from 189 GPa to 245 GPa. This work demonstrated that the microwave plasma is an alternative approach for the development of carbon fibers with good microstructure and high graphitization degree.

High Graphitic Carbon Derived from Coconut Coir Waste by Promoting Potassium Hydroxide in the Catalytic Graphitization Process for Lithium-Ion Battery Anodes

Graphite is a critical material for lithium-ion battery (LIB) anodes. However, its fabrication using a simple route and sustainable carbon sources still remains a great challenge. In this current work, we fabricate high graphitic carbon from coconut coir waste by combining potassium hydroxide (KOH) and a Ni-based catalyst in a one-pot graphitization process. The graphitic carbon (1200-ANi-KOH) shows good electrochemistry performance as the anode of LIB with a specific capacity of 397.60 mA h/g, exceeding commercial graphite (339.90 mA h/g) and a high graphitic degree of IG/ID (1.99) with a surface area of 162.31 m2/g. The synergistic effect of K and Ni metal interaction with amorphous carbon promotes internal heating and catalytic graphitization, resulting in an ordered carbon structure and a greater area of graphitic structure. Ion diffusion in the graphite interlayer was found to be the dominant ion storage mechanism at 1200-ANi-KOH, which is comparable to the commercial graphite mechanism. Finally, this simple one-pot graphitization process succeeded in converting coconut coir waste into a graphitic material with a high graphitization degree and excellent LIB anode performance.

Highly Graphitized Porous Carbon Microspheres Derived from Copolymer of Glucose and Melamine for Advanced Electrodes

AbstractThe N/O co‐doped hierarchical porous graphitized carbon microspheres (N/O‐PCs) are successfully prepared by condensation polymerization of 5‐hydroxymethylfurfural and melamine, and subsequent KOH activation strategy. The obtained carbon materials have a high specific surface area (1685.58 m2 g–1), rich micro‐ and mesopores, and appropriate pore volume (0.828 cm3 g–1). The degree of graphitization for N/O‐PCs is improved because the ratio of IG and ID increases from 0.88 to 1.03. The layer spacing of the lattice plane (002) for the N/O‐PCs is enlarged, facilitating the transmission of electrolyte ions. The high graphitization degree and enlarged layer spacing bring excellent electrical conductivity and wettability for N/O‐PCs as electrode materials. Besides, owing to the higher N (3.59 at%) and O (12.67 at%) content, the N/O‐PCs show excellent specific capacitances of 412 and 284 F g–1 at the current densities of 1 and 10 A g–1 in 2 m H2SO4 aqueous electrolytes, respectively. Outstanding rate performance (200 F g–1 at 50 A g–1) and ideal cycle stability (>10 000 cycles) are achieved. Moreover, the N/O‐PCs‐based symmetric supercapacitor exhibits an energy density of 9.6 Wh kg–1 at 100.8 W kg–1. Thus, the N/O‐PCs provide the potential for high‐performance supercapacitor electrodes.

Lignin Isolated from Poplar Wood for Porous Carbons as Electrode for High-Energy Renewable Supercapacitor Driven by Lignin/Deep Eutectic Solvent Composite Gel Polymer Electrolyte

The current challenge for supercapacitors based on sustainable materials is the difficulty of elevating energy density while maintaining the power density and capacitance retention. Herein, we demonstrate a strategy to boost the energy density of renewable all-lignin-based supercapacitors via sound design of lignin porous carbon electrodes isolated from poplar wood as well as employing lignin/deep eutectic solvent (DES) gel polymer electrolytes (GPEs) with a wide electrochemical window. The resulting device exhibits a remarkable specific capacitance of 181.5 F g–1 at 1 A g–1 and favorable capacitance retention of 80.2% at 5 A g–1 over 2000 cycles, which is attributed to the large specific surface area of 1125 m2 g–1 as well as a high degree of graphitization possessed by the electrode materials and excellent conductivity of 13.5 S/m held by the DES gel polymer electrolytes. Furthermore, the supercapacitor delivers a maximum energy density of 40.8 Wh kg–1 and it remains 29.0 Wh kg–1 at an ultrahigh power density of 3.2 KW kg–1.

Refurbished carbon materials from waste supercapacitors as industrial-grade electrodes: Empowering electronic waste

Reinstallation of industrial-grade electrode materials by recycling waste electrochemical energy storage devices is the best way to achieve excellent economic and environmental benefits. In this study, we repaired active carbon materials from end-of-life supercapacitors using simple thermal activation and back-integrated them into high-voltage and super-stable supercapacitors. The recovered carbon materials retained their excellent surface and structural features, including a large specific surface area (∼1716 m2/g) with a surface morphology composed of fine nanoparticles and a high degree of graphitization with well-oriented graphitic layers. The repaired carbon was then re-instated in an innovative water-in-salt electrolyte, which can easily be cycled in an extended working voltage range (2 V). Benefiting from the maintained structural and surface characteristics, the renovated supercapacitor delivered exceptional cycling stability over 300,000 cycles, with 99% capacitance retention, achieving a high capacitance of 57 F/g (0.25 A/g), a specific energy of 32 Wh/kg (0.25 A/g), and a rate capability of 85.90%. This ground-breaking performance of recovered materials from waste supercapacitors will encourage future waste-recovery initiatives, aiding sustainable practices and the circular economy.

N-doped low-rank coal based carbon catalysts for heterogeneous activation of peroxymonosulfate for ofloxacin oxidation via electron transfer and non-radical pathway

BackgroundAdvanced oxidation processes based on sulfate radicals were promising technologies for deep wastewater treatment. There was an urgent need of low-cost and green catalytic materials. MethodsIn this study, N-doped low-rank coal based carbon catalysts (NLCs) were prepared under different urea and low-order coal ratios and pyrolysis temperatures, which showed excellent catalytic performance for peroxymonosulfate (PMS) activation. Significant findingsThe NLCs had a high degree of graphitization and electrical conductivity, which leading to a high removal rates as 100% in 45 min. The N-doped structure lead to the formation of electron-rich regions, which favored the adsorption of PMS. Mechanistic studies revealed that the main reactive oxygen species in the NLC/PMS system was singlet oxygen (1O2), and that electron transfer pathways and surface-bound reactive complexes also played an important role in this system. The NLC/PMS system had a wide pH adaptation and good environment adaptation because of the electron transfer mechanism. It could remove 100% OFL in the pH range of 3-9. Therefore, the prepared N-doped coal based carbon catalytic materials had good prospects for application in advanced oxidation processes for wastewater treatment.

Efficient ethanol solvothermal synthesis of high-performance nitrogen-doped carbon quantum dots from lignin for metal ion nanosensing and cell imaging

The preparation of carbon quantum dots (CQDs) with excellent photoluminescence (PL) properties from biomass is a hot research topic. Herein, nitrogen-doped CQDs (N-CQDs) from lignin (C-source) using diethylenetriamine (DETA) as an N-source were synthesized via a facile, green, and large-scale solvothermal approach. The as-synthesized N-CQDs in ethanol (N-CQDs-ET) exhibit unique structures with abundant N-doping (~7.2%), rich functional groups (especially CO and pyrrolic-N), high degree of graphitization, and uniform particle size (~5.0 nm). The N-CQDs-ET have excellent QL properties with high quantum yield, superior fluorescence stability, and long fluorescence lifetime, all of which are much better than N-CQDs obtained from a traditional hydrothermal process. The N-CQDs-ET display excellent sensitivity for Fe3+ and Co2+ detection with a good linear correlation ranging from 0.27 to 250 μM and 0.45–500 μM, respectively. In addition, the N-CQDs-ET exhibit excellent biocompatibility and multicolored cell imaging ability, showing great potential applications in biosensors.

Ganoderma Lucidum-derived erythrocyte-like sustainable materials

The conversion of biomass waste into functional carbon materials is an environmentally friendly solution with diverse applications for a sustainable world. Here, we report an approach to fabricate the Ganoderma Lucidum waste-derived erythrocyte-like N, O self-doped porous biomass carbon (GL800) with a high graphitization degree by a facile carbonization and activation method. The prepared GL800 showed a relatively high specific surface area (2407.5 m2 g−1) and a porous structure like the red blood cell, which affords enough space to accommodate active sites and are easy for electrolytes to infiltrate. Due to the synergistic effect of the rich N, O self-doped elements and porous structures, GL800 shows strong chemical adsorption and physical confinement for polysulfide. Lithium-sulfur batteries using GL800 electrodes exhibited a high discharge capacity of 1367.8 mA g−1 at 0.1C and desirable rate performance. Furthermore, the battery has a capacity retention rate after 300 cycles at 0.5C with high coulombic efficiency (99%). Together with the good biocompatibility and biodegradability of the prepared material, it has a high potential for diverse applications in energy storage, environmental remediation, wearable electronics, biomedicine, and other areas, providing a Nature-derived solution with good sustainability.

Less energy-intensive synthesis of mesoporous multi-oriented graphite microspheres with low defect concentration for advanced potassium-ion battery anodes

Potassium-ion batteries (KIBs) have emerged as prospective alternatives to lithium-ion batteries (LIBs) given the wide availability of K resources and the similar operating voltage. As in the case of LIBs, graphite is regarded as the most promising anode material for KIBs due to high energy density attributed to its low potential plateau and resource abundance. However, the practical use of graphite in KIBs is hindered by poor stability due to huge volume changes during K+ ion insertion-deinsertion. Here, a facile and scalable synthesis method of mesoporous multi-oriented graphite microspheres via pilot-scale spray drying process and less energy-intensive graphitization step is introduced. A high degree of graphitization is achieved even at 1100 °C by virtue of in situ formed Fe nanocrystals within the microsphere that serve as graphitization catalyst. The degree of graphitization can be further improved by selective removal of amorphous carbon by oxidation at 450 °C, which greatly increases the initial Coulombic efficiency and reversible capacity of the graphite microspheres. The synthesized microspheres with the multi-oriented graphite grains and the mesoporous network enable rapid K+ ion insertion-deinsertion, and alleviate stress from volume changes during cycling, thereby exhibiting markedly improved cyclability (247 mA h g−1 after 400 cycles at 0.5C) and rate performance (58 mA h g−1 at 3C) that outperform those of commercial artificial graphite. This study provides a new perspective for designing reliable nanostructured graphite materials for advanced KIB anodes.

N/P/O doped porous carbon materials for supercapacitor with high performance

Owing to the need for new-generation energy storage equipment and industrial application, the development of carbon electrode materials with comprehensive electrochemical performances and convenient production processes has become a top priority. In this study, N/P/O doped carbon materials are prepared using a simple one-step method with 4-(2,4,6-tricarboxylphenyl)-2,2′:6′,2″-terpyridine (TT) as a raw material. Owing to the doping of many heteroatoms, particularly phosphorus atoms, the optimized TT(Zn/P)-700 exhibits a large specific surface area (2164.7 cm2/g), proper pore distribution from micropore to macropore, and high degree of graphitization. These structural and morphological features ensure excellent comprehensive capacitance performance, such as a high specific capacitance (366.25 F/g at 0.5 A/g), and high specific energy (73.25 Wh/kg at 300 W/kg). In addition, the specific capacitance of the symmetric supercapacitor assembled with TT(Zn/P)-700 electrode reaches 143.3 and 121.7 F/g at specific currents of 0.5 and 10 A/g, respectively. The specific current is increased 20 times, and the capacitance retention rate reaches 84.9%, improving the rate performance. When the specific power increases to 150 and 3000 W/kg, the specific energy reaches 7.17 and 6.08 Wh/kg, respectively. After 5000 charge/discharge cycles, the capacitance retention rate is 92.7%. These high-performance N/P/O-doped carbon electrode materials demonstrate great potential in industrial applications and new-generation energy storage equipment.

Preparation of novel N-doped biochar and its high adsorption capacity for atrazine based on π–π electron donor-acceptor interaction

Novel nitrogen (N)-doped cellulose biochar (NC1000–10) with large adsorption capacity (103.59 mg g−1) for atrazine (ATZ) was synthesized through the one-pot method. It has the best adsorption efficiency than N-doped biochars prepared from hemicellulose and lignin. The adsorption behaviors of ATZ by N-doped biochars with different N doping ratios (NC1000–5, NC1000–10, NC1000–20 and NC1000–30) were significantly different, which was attributed to the difference of sp2 conjugate C (ID/IG = 0.99–1.18) and doped heteroatom N (pyridinic N, pyrrolic N and graphitic N). Adsorption performance of ATZ on NC1000–10 conformed to the pseudo-second-order kinetic and Langmuir adsorption isotherm model. Thermodynamic calculations showed that adsorption performance was favorable. Besides, wide pH adaptability (pH = 2–10), good resistance to ionic strength and excellent recycling efficiency make it have extensive practical application potential. Further material characterizations and the density functional theory (DFT) calculations indicated that good adsorption performance of NC1000–10 for ATZ mainly depended on chemisorption, and π-π electron donor-acceptor (EDA) interaction contributed the most due to high graphitization degree. Specifically, pyridinic N and graphitic N further promoted adsorption performance by hydrophobic effect and π-π EDA interaction between ATZ and NC1000–10, respectively. Pyrrolic N and other surface functional groups (-COOH, -OH) facilitated the hydrogen bond effect.

Chromium(VI) removal from synthetic solution using novel zero-valent iron biochar composites derived from iron-rich sludge via one-pot synthesis

In this study, Fe-rich sludge obtained from coagulation–flocculation of swine wastewater was processed into zero-valent iron (ZVI) biochar composites through one-pot pyrolysis at 700 °C under anoxic (MBCN700) and hypoxic (MBCA700) conditions. X-ray diffraction analysis revealed that α-Fe0 and γ-Fe0 were the dominant Fe species in MBCN700 and MBCA700, respectively. The effects of different process parameters, including composite dosage, initial Cr(VI) concentration, pH, dissolved O2 (DO), and contact time on Cr(VI) removal from synthetic solutions were evaluated. The results showed that both the acidic initial pH and DO contributed to Cr(VI) removal; the highest removal rate was observed at pH 3. Based on the Langmuir isotherm model, the predicted maximum removal capacity of MBCA700 was greater than that of MBCN700, primarily because of its core-shell structure, less corrosive ZVI, and higher degree of graphitization. X-ray photoelectron spectroscopy analysis coupled with fitting of the kinetic (pseudo-second-order) and isothermal (Freundlich) data suggested that Cr(VI) removal by MBCN700 occurred via adsorption, FeC micro-electrolysis, and co-precipitation. In contrast, the removal mechanism for MBCA700 included adsorption, reduction, and electrostatic attraction. Thus, ZVI biochar composites can serve as potential remediators of Cr(VI)-contaminated wastewater.