Carbonaceous Catalyst Research Articles

O- and F-doped porous carbon bifunctional catalyst derived from polyvinylidene fluoride for sulfamerazine removal in the metal-free electro-Fenton process

Heteroatom-doped carbon materials can effectively activate H2O2 into •OH during the metal-free electro-Fenton (EF) process. However, information on bifunctional catalysts for the simultaneous generation and activation of H2O2 is scarce. In this study, O- and F-doped porous carbon cathode materials (PPCs) were prepared by the direct carbonization of polyvinylidene fluoride (PVDF) for sulfamerazine (SMR) removal in a metal-free EF process. The porous structure and chemical composition of the PPCs were regulated by the carbonization temperature. PPC-6 (carbonized at 600 °C) exhibited optimal electrocatalytic performance in terms of electrochemical H2O2 generation and activation owing to its high specific surface area, mesoporous structure, and optimum fractions of doped O and F. Excellent performance of the 2e− oxygen reduction reaction was found with an H2O2 selectivity of 93.5% and an average electron transfer number of 2.13. An H2O2 accumulative concentration of 103.9 mg/L and an SMR removal efficiency of 90.1% were achieved during the metal-free EF process. PPC-6 was able to stably remove SMR over five consecutive cycles, retaining 92.6% of its original performance. Quantitative structure-activity relationship analysis revealed that doped oxygen functional groups contributed substantially to H2O2 generation, and semi-ionic C–F bonds with high electronegativity were the cause of the activation of H2O2 to •OH. These findings suggest that the PVDF-derived carbonaceous catalysts are feasible and desirable for metal-free EF processes.

Cobalt-embedded in ultrahigh boron and nitrogen codoped hierarchically porous carbon nanowires as excellent catalysts toward water splitting

The low heteroatoms doping amount and uncontrollable formation of electrochemically inactive boron (B)–nitrogen (N) bonds have hindered the electrocatalytic activities of B and N codoped carbonaceous catalysts. Herein, the novel three-dimensional (3D) cobalt (Co) nanoparticles (NPs)-embedded and ultrahigh B and N doped hierarchically porous carbon nanowires (denoted as Co@BNPCFs) have been successfully synthesized via pyrolyzing the 3D cobalt acetate/hydroxybenzeneboronic acid/polyvinylpyrrolidone precursor networks woven by electrospinning. After optimizing the pyrolysis temperatures, the optimal Co@BNPCFs-800 owns a large surface area and abundant carbon edges/defects. Especially, 6.86 atom % of B and 6.59 atom % of N atoms are doped into carbon frameworks with affording 13.45 atom % of B/N active centers (i.e. BC3, pyridinic-N, Co-Nx-C, pyrrolic-N, and graphitic-N). In alkaline solution, the hydrogen evolution reaction overpotential at 10 mA cm−2 of the optimal Co@BNPCFs-800 (151.3 mV) is just 82.4 mV larger than 20 wt% Pt/C (68.9 mV). Especially, the oxygen evolution reaction potential at 10 mA cm−2 of the optimal Co@BNPCFs-800 (1.554 V vs. RHE) is even 2 mV more negative than RuO2 (1.556 V vs. RHE). For full water splitting, Co@BNPCFs-800 based electrolysis cell just requires a small voltage of 1.596 V to achieve 10 mA cm−2, which is 19 mV smaller than that of the state-of-the-art 20 wt% Pt/C||RuO2 benchmark (1.615 V). The perfect 3D hierarchically porous structures and fairly abundant electrocatalytic active sites dispersed along Co@BNPCFs-800′s surface are responsible for the outstanding water splitting performances. In addition, as the good structural and chemical stabilities, Co@BNPCFs-800 nanowires based water electrolysis cell also displays excellent water electrolysis stability.

Radical and non-radical cooperative degradation in metal-free electro-Fenton based on nitrogen self-doped biochar

To achieve sustainable metal-free electron-Fenton, N self-doped biochar air-cathode (BCAC) was prepared by pyrolyzing coffee residues. During the pyrolysis process, the endogenous N transformed from edge-doping to graphite-doping. Particularly, N vacancies started to evolve when the peak temperature exceeded 700 °C. A high Tetracycline removal rate of 70.42% was obtained on the BCAC at the current density of 4 mA cm−2. Quenching tests incorporated with ESR spectroscopy were adopted to identify the specific oxidants produced on the cathode. The results showed that •OH (37.36%), •O2- (29.67%) and 1O2 (24.17%) played comparable role in the tetracycline removal, suggesting the coexist of radical and non-radical oxidants in our electro-Fenton system. According to the structure characterization and the DFT calculation, graphitic N was suggested as the critical site for H2O2 generation, and both graphitic N and pyridinic N were electroactive sites for H2O2 activation to •OH. Graphitic N and N vacancies with stronger capabilities in O2 adsorption and electron-trapping were proposed as the electroactive sites for 1O2 and •O2- formation. This work predicts a novel electro-Fenton process with cooperative radical and non-radical degradation on N self-doped carbonaceous catalysts at a mild condition, which is extremely meaningful for boosting sustainable electro-Fenton technology.

Insight into the Transformation Behaviors of Dioxins from Sintering Flue Gas in the Cyclic Thermal Regeneration by the V2O5/AC Catalyst-sorbent.

Dioxins in the sintering flue gas are usually removed through integrated elimination technologies by carbonaceous catalysts. However, the regeneration of the used catalyst is poorly investigated, leading to the risk of leakage of dioxins. Herein, the influences of cyclic regenerations on the dioxin removal performance of a catalyst (V2O5/AC) were investigated systematically with dibenzofuran (DBF) as a model pollutant. It was demonstrated that the adsorption capacity and oxidation activity of catalysts significantly declined after several regeneration cycles due to the decreasing external specific surface area and V5+, respectively. Compared with 79.12% DBF directly emitted from a regenerator during N2 regeneration, the emission of DBF was only 29.93% with the modification of the regeneration process through O2 addition and temperature adjustment. The possible regenerated products were also analyzed to disclose the transformation behaviors of DBF. The regeneration mechanisms of DBF followed the transformation pathway of dibenzofuranol, benzofuran, anhydride species, and ultimately to CO2 and H2O. Moreover, the accumulated heavy aromatics on the surface could be decomposed by introducing O2. This research provides a comprehensive understanding of dioxin transformation behavior and a theoretical basis for efficient control of dioxin removal in the whole integrated removal technologies.

Filter paper membrane based microfluidic fuel cells: Toward next-generation miniaturized and low cost power supply

Micro Fuel cells or microfluidic fuel cells (μMFCs) are one of the most promising power supplies for portable electronics. However, the necessary electrode spacing is required to prevent fuel-crossover and maintain the stable operation, introducing the unavoidable ohmic resistance and retarding the miniaturization. Herein, we propose a novel μMFC device combining the cellulose paper as separator, with selective catalysts at the cathode side to eliminate the unwanted side reactions and increase the system compactness. One single reactant solution containing fuel and electrolyte is applied to keep the device stable operation. The power-generation properties are evaluated in typical alkaline conditions. A great construction simplification makes the device a substantial high-power density of 2.14 W cm−3 and maximum current density of 15.82 A cm−3. The μMFC stacks are arranged in series and parallel manners, which delivers a maximum power output of 23.6 mW and current of 194.6 mA. It is expected that innovative and customizable performance from commercial paper and low-cost carbonaceous catalysts can provide a forum for future advancement in chip-based electrochemical energy generation and storage devices.

Extraordinarily high hydrogen-evolution-reaction activity of corrugated graphene nanosheets derived from biomass rice husks

The metal-free carbonaceous catalysts are one of the promising candidates for efficient electrocatalytic hydrogen production. Aiming at demonstrating the high electrocatalytic activity of the hydrogen evolution reaction (HER), we synthesized the biomass rice husk-derived corrugated graphene (RH-CG) nanosheets via the KOH activation. The 700 °C-activated RH-CG nanosheets exhibited the large specific surface area as well as the high electrical conductivity. When using the RH-CG nanosheets as a HER electrocatalyst in 0.5 M H2SO4, the excellent HER activities with a small overpotential (9 mV at 10 mA/cm2) and a small Tafel slope (31 mV/dec) were achieved. The results provide a new strategy for materializing the superb biomass-derived electrocatalyst for highly efficient hydrogen production.

Morphological modulation of iron carbide embedded nitrogen-doped hierarchically porous carbon by manganese doping as highly efficient bifunctional electrocatalysts for overall water splitting

In the development of water splitting, the sluggish electrocatalytic kinetics of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have restricted their energy conversion efficiencies. Along with the continuous rise in the prices of noble metals and transition metals (such as cobalt and nickel), constructing high-efficiency HER/OER catalysts based on low cost transition metals, such as iron and manganese, is becoming more meaningful in developing industrialized water splitting devices. In this paper, in the absence of a template or active agent, three-dimensional, hierarchically porous FexMny nanoparticles (NPs) were embedded and nitrogen-doped carbon materials (denoted as FexMny@NC; x:y, representing the molar ratio of Fe:Mn) were successfully prepared via pyrolysis of corresponding precursors containing different metallic salt components. Various morphological, structural, and chemical characterization analysis demonstrate that at an Fe:Mn molar ratio of 3:1, the optimal Fe3Mn1@NC material shows high graphitization degree, rich mesoporous structures, a large surface area, and abundant carbon defects/edges, which promote the uniform dispersion of pyridinic-N (pyridinic-N-metal), graphitic-N, carbon oxygen bonds (CO), manganese oxide (MnO) nanocrystals, and Fe3C NPs-embedded, N-doped carbon sheet (Fe3C@NC) active sites. In alkaline conditions, the HER onset potentials (Eonset) and potentials recorded at 10 mA cm−2 (E10) of the optimal Fe3Mn1@NC are just 84.8 and 156 mV more negative than those of 20 wt% platinum carbon (Pt/C). Meanwhile, the OER Eonset and E10 values of the optimal Fe3Mn1@NC are just 8 and 18.7 mV more positive than those of RuO2. Furthermore, optimized Fe3Mn1@NC catalysts were assembled into a water splitting cell, where the catalytic current density achieves 10 mA cm−2 at a low voltage of 1.6287 V (with superior catalytic stability), which is just 24.9 mV higher than that of the (-) 20 wt% Pt/C||RuO2 (+) benchmark (1.6038 V) under the same conditions. This work describes the regulating efficiency of Mn toward growing mesopores and opens new possibilities for the development of novel carbonaceous catalysts with excellent hydroxide catalytic efficiencies based on low cost Mn/Fe elements.

Influence of different Fe doping strategies on modulating active sites and oxygen reduction reaction performance of Fe, N-doped carbonaceous catalysts

Fe/N/C catalysts, synthesized through the pyrolysis of Fe-doped metal–organic framework (MOF) precursors, have attracted extensive attention owing to their promising oxygen reduction reaction (ORR) catalytic activity in fuel cells and/or metal-air batteries. However, post-treatments (acid washing, second pyrolysis, and so on) are unavoidable to improve ORR catalytic activity and stability. The method for introducing Fe3+ sources (anhydrous FeCl3) into the MOF structure, in particular, is a critical step that can avoid time-consuming post-treatments and result in more exposed Fe-Nx active sites. Herein, three different Fe doping strategies were systematically investigated to explore their influence on the types of active sites formed and ORR performance. Fe-NC(Zn2+), synthesized by one-step pyrolysis of Fe doped ZIF-8 (Zn2+) precursor which was obtained by adding the anhydrous FeCl3 source into the Zn(NO3)2•6H2O/methanol solution before mixing, possessed the highest Fe-Nx active sites due to the high-efficiency substitution of Zn2+ ions with Fe3+ ions during ZIF-8 growth, the strong interaction between Fe3+ ions and N atoms of 2-Methylimidazole (2-MIm), and ZIF-8′s micropore confinement effect. As a result, Fe-NC(Zn2+) presented high ORR activity in the entire pH range (pH = 1, 7, and 13). At pH = 13, Fe-NC(Zn2+) exhibited a half-wave potential (E1/2) of 0.95 V (vs. reversible hydrogen electrode), which was 70 mV higher than that of commercial Pt/C. More importantly, Fe-NC(Zn2+) showed superior ORR stability in neutral media without performance loss after 5,000 cycles. A record-high open-circuit voltage (1.9 V) was obtained when Fe-NC(Zn2+) was used as a cathodic catalyst in assembled Mg-air batteries in neutral media. The assembled liquid and all-solid Mg-air batteries with high performance indicated that Fe-NC(Zn2+) has enormous potential for use in flexible and wearable Mg-air batteries.

Mechanism of ozone adsorption and activation on B-, N-, P-, and Si-doped graphene: A DFT study

• Detailed evolution mechanism of O 3 into ROS on the doped graphene was revealed. • O ads produced from O 3 decomposition was a vital intermediate to generate other ROS. • Types and efficiency of the formed ROS from O ads depended on the doped heteroatoms. • CDD was a useful descriptor for carbonaceous catalyst design based on QSAR model. The detailed evolution mechanism of O 3 into Reactive oxygen species (ROS) is of paramount importance but remains elusive in catalytic ozonation. Herein, we report a density functional theory study to comprehensively reveal the specific evolution processes of O 3 into ROS on the B-, N-, P-, and Si-doped graphene, including the adsorption, decomposition and ROS generation. In contrast to some previous reports that O 3 would directly decompose into effective ROS on catalysts, our results indicate that after O 3 adsorption, the decomposition products are ground state O 2 and the adsorbed oxygen species (O ads ). The O ads is more likely to act as a crucial intermediate for generating other ROS instead of directly attacking the organics. The type of the ROS and generation efficiency vary with the doped heteroatoms, and the heteroatoms of B, P and Si, or the neighboring C of N, would serve as active sites for O 3 adsorption and decomposition. The N- and P-doped graphene are predicted to have the superior performance in ROS generation and catalytic stability. Finally, twenty representative descriptors were adopted to build the quantitative structure–activity relationship (QSAR) with the activation energy barrier of O 3 decomposition. The result indicates that condensed dual descriptor (CDD) could be useful for preliminarily selecting the modified graphene catalysts, since it shows a very good linear relation with the activation energy barrier. This contribution provides an alternative way to gain fundamental insights into the mechanism of catalytic ozonation at the molecular level, and could be helpful for designing more-efficient catalysts in environmental remediation.

Catalytic advancements in carbonaceous materials for bio-energy generation in microbial fuel cells: a review.

Microbial fuel cells (MFCs) are a sustainable alternative for wastewater treatment and clean energy generation. The efficiency of the technology is dependent on the cathodic oxygen reduction reaction, where the sluggish reaction kinetics hampers its propensity. Carbonaceous materials with high electrical conductivity have been widely explored for oxygen reduction reaction (ORR) catalysts. Here, incorporating transition metal (TM) and heteroatom into carbon could further enhance the ORR activity and power generation in MFCs. Nitrogen (N)-doped carbons have also been a popular research hotspot due to abundant active sites formed, resulting in superior conductivity, stability, and catalytic activity over carbons. This review summarizes the progress in the carbon-based materials (primary focus on the cathode) for ORR and their utilization in MFCs. Furthermore, we discussed the conceptualization of MFCs and carbonaceous materials to instigate the ORR kinetics and power generation in MFC. Furthermore, prospects of carbon-based materials for actual application in bio-energy generation have been discussed. Carbonaceous catalysts and biomass-derived carbons exhibit good potential to replace precious Pt catalysts for ORR. M-N-C catalysts were found to be the most suitable catalysts. Electrocatalysts with MNx sites are able to achieve excellent activity and high-power output by taking advantage of the active site exposure and rapid mass transfer rate. Moreover, the use of biomass-derived carbons/self-doped carbons could further reduce the overall cost of catalysts. It is anticipated that the research gaps and future perspectives discussed will show new avenues to develop excellent electrocatalysts for better performance and transformation of technology to industrial applications.

MgO/Carbon nanocomposites synthesized in molten salts for catalytic isomerization of glucose to fructose in aqueous media

Isomerization of glucose into fructose has always been an important step in the biorefining process. This study synthesized a novel Mg-decorated carbonaceous catalyst by molten salt method for the application of glucose isomerization. The morphology of carbon microspheres was formed with high specific surface area and pore volume. The effects of Mg loading, catalyst dosage, reaction temperature, and reaction time were investigated and optimized. The highest fructose yield of 34.58% and fructose selectivity of 81.17% were achieved by the catalyst named Mg(100mg)/Carbon at hydrothermal temperature of 100 °C with reaction time of 1.5–2 h, showing the superiority of the catalyst. The results of recycling tests indicated Mg(100mg)/Carbon has good recyclability and can restore its activity after a simple regeneration. And the possible mechanism of glucose isomerization by Mg(100mg)/Carbon was indicated. This study provided a new method for overcoming the difficulty of high energy barrier required for glucose isomerization in the biorefining process.

FeCl3-Modified Carbonaceous Catalysts from Orange Peel for Solvent-Free Alpha-Pinene Oxidation

The work presents the synthesis of FeCl3-modified carbonaceous catalysts obtained from waste orange peel and their application in the oxidation of alpha-pinene in solvent-free reaction conditions. The use of waste orange peel as presented here (not described in the literature) is an effective and cheap way of managing this valuable and renewable biomass. FeCl3-modified carbonaceous materials were obtained by a two-stage method: in the first stage, activated carbon was obtained, and in the second stage, it was modified by FeCl3 in the presence of H3PO4 (three different molar ratios of these two compounds were used in the studies). The obtained FeCl3-modified carbon materials were subjected to detailed instrumental studies using the methods FT-IR (Fourier-transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscope), EDXRF (Energy Dispersive X-ray Fluorescence) and XPS (X-ray Photoelectron Spectroscopy), while the textural properties of these materials were also studied, such as the specific surface area and total pore volume. Catalytic tests with the three modified activated carbons showed that the catalyst obtained with the participation of 6 M of FeCl3 and 3 M aqueous solutions of H3PO4 was the most active in the oxidation of alpha-pinene. Further tests (influence of temperature, amount of catalyst, and reaction time) with this catalyst made it possible to determine the most favorable conditions for conducting oxidation on this type of catalyst, and allowed study of the kinetics of this process. The most favorable conditions for the process were: temperature of 100 °C, catalyst content of 0.5 wt% and reaction time 120 min (very mild process conditions). The conversion of the organic raw material obtained under these conditions was 40 mol%, and the selectivity of the transformation to alpha-pinene oxide reached the value of 35 mol%. In addition to the epoxy compound, other valuable products, such as verbenone and verbenol, were formed while carrying out the process.

Promotion of sulfonic acid groups on biomass carbons loading ultrafine palladium nanoparticles for the efficient hydrodeoxygenation of vanillin in water

Carbonaceous catalysts with sulfonic acid (-SO3H) groups are showing promising performances in the conversion of mono- and poly-saccharides, however, their applications in the hydrodeoxygenation (HDO) of oxygen-rich lignin derivatives are rarely reported. Herein, we report a facile synthetic approach for one-step preparation of porous carbonaceous solid acids with –SO3H groups (OHCA) where monosaccharide, polysaccharide, and raw biomass can be used as carbon precursors. These porous carbonaceous solid acids supported ultrafine palladium nanoparticles (Pd/OHCA) exhibited excellent performances in the HDO of vanillin (VAN) in water. We found that Pd nanoparticles (Pd NPs) were responsible for the hydrogenation of VAN to vanillyl alcohol (VAL) and acidic groups were crucial for the hydrogenolysis of generated VAL to 2-methoxy-4-methylphenol (MMP). Importantly, VAL once generated can be immediately converted to MMP via synergistic catalysis between acidic groups and Pd NPs, avoiding the formation of by-products. Pd/OHCA catalyst also exhibited excellent stability in the HDO of VAN and retained its activities in the six consecutive runs. The findings of this work provide a new thought for the HDO of biomass derivatives over biomass-based carbon catalysts.

Fe, N-doped carbonaceous catalyst activating periodate for micropollutant removal: Significant role of electron transfer

In this study, the performance of periodate (PI) on sulfadiazine (SDZ) degradation was evaluated using coagulation solid waste fabricated catalyst (CWBC), obtained by simple pyrolysis. SDZ effectively underwent 98.94% remove within 90 min in the CWBC/PI system. Electron transfer was the predominant mechanism due to the development of an electronic cycle among SDZ, CWBC and PI, where the O2•−, PFRs, and the reactive iodine species had minor roles. Density functional theory calculations identified that Fe and N could change the electron configuration and break the chemical inertness of carbonaceous material. As a result, electrons on the carbon matrix of CWBC are inclined to travel through the formed Fe–O covalent bond to PI. Further analysis demonstrated that SO42−, humic acid (HA), as well as anoxic conditions greatly facilitated SDZ degradation. This study provides a facile protocol for converting coagulation waste to an efficient catalyst and provides fundamental insights into the degradation mechanisms of micropollutants by activating PI.

Defect-Engineered Graphene Films as Ozonation Catalysts for the Devastation of Sulfamethoxazole: Insights into the Active Sites and Oxidation Mechanism.

Graphene-based catalysts have been widely applied for catalytic ozonation. However, as it is difficult to obtain graphene with high structural precision, it is currently unfeasible to comprehend the relationships between the intrinsic structure of the layered carbon catalysts with its catalytic activities. Here, an advanced plasma-assisted etch strategy was used to fine tune the ozonation activity of monolayered graphene films by tailoring the defect types. Raman mapping indicated that the defects of the as-prepared monolayered graphene films were predominantly sp3, vacancy, and boundary-type defects, respectively. The roles and contributions of these active defects in manipulating the oxidative potential of monolayered graphene films were revealed by quenching experiments, electron paramagnetic resonance results, and density functional theory calculations. The catalytic results showed that the monolayered graphene films with boundary-like defects exhibited the best catalytic performance toward the degradation of sulfamethoxazole. This work contributes new insights into the design of high-efficiency carbonaceous catalysts by structuring additional defective sites.

Electrochemical Characterization and Detection of the Antibiotic Compounds Over Modified Working Electrode

The electrochemical characterization and detection of antibiotic compounds are essential to understand and address the issues of drug-resistance in bacteria. In this work, we have characterized a varieties of antibiotic compounds such as Ciprofloxacin, Tobramycin, and a novel hybrid of both Ciprofloxacin and Tobramycin (Cip-Tob) over modified and unmodified glassy carbon electrodes. The working electrodes were modified using various carbonaceous catalyst support such as Carbon Black and functionalized Carbon Nanotubes, etc. Various electrochemical measurements such as cyclic voltammetry and differential pulse voltammetry were performed and they revealed the ultra-sensitivity of the modified electrodes towards the detection of antibiotics.

Synergistic oxytetracycline adsorption and peroxydisulfate-driven oxidation on nitrogen and sulfur co-doped porous carbon spheres

Metal-free carbonaceous catalysts are receiving increasing attention in wastewater treatment. Here, nitrogen and sulfur co-doped carbon sphere catalysts (N,S-CSs900-OH) were synthesized using glucose and L-cysteine via a hydrothermal method and high temperature alkali activation. The N,S-CSs900-10%-OH exhibited excellent catalytic performance for the degradation of oxytetracycline (OTC). The degradation rate was 95.9% in 60 min, and the reaction equilibrium rate constant was 0.0735 min−1 (k0–15 min). The synergistic effect of adsorption-promoting degradation was demonstrated in the removal process of OTC. The excellent adsorption capacity of N,S-CSs900-10%-OH ensured the efficient oxidation of OTC. N,S-CSs900-10%-OH reduced the activation energy of the OTC degradation reaction (Ea=18.23 kJ/mol). Moreover, the pyrrolic N, thiophene S and carbon skeleton played an important role in the degradation of OTC based on density function theory, and the catalytic mechanism was expounded through radical and nonradical pathways. The active species involved in the reaction were O2•−, 1O2, SO4•− and •OH, of which O2•− was the primary reactive species. This study provides a new insight into the reaction mechanism for efficient treatment of organic pollutants using metal-free doped porous carbon materials.

Highly Efficient Zirconium Based Carbonaceous Solid Acid Catalyst for Selective Synthesis of 5-HMF from Fructose and Glucose in Isopropanol as a Solvent

Highly Efficient Zirconium Based Carbonaceous Solid Acid Catalyst for Selective Synthesis of 5-HMF from Fructose and Glucose in Isopropanol as a Solvent

Magnetic porous nano‐carbon catalysts supported silver nanoparticles derived from chitin and their application in catalytic reduction reactions

AbstractThe exploitation of recycled carbonaceous catalysts from renewable biomass resources such as chitin is a crucial issue for the development of the sustainable society. In this article, the chitin‐based N and O doped carbon microspheres (ChC) were fabricated by a simple dissolution, sol–gel transformation, and the carbonization methods. Subsequently, the novel magnetic Ag‐Fe3O4@chitin‐based carbon microspheres catalyst (MChC) was successfully constructed through the in situ redox reaction. The as‐prepared MChC possessed rich micropores with high‐surface area, and a narrow size distribution (50–120 μm). The Ag‐Fe3O4 nanoparticles were immobilized through the interaction with C, N, and O atoms in the pores of MChC. The reduction of 4‐nitrophenol was applied to evaluate the catalytic activity of MChC. 4‐Nitrophenol (4‐NP) could be fully reduced to 4‐aminophenol (4‐AP) in 5 min with the catalyst MChC‐45. Moreover, MChC could be collected in solution with an external magnet in 8 s and remained relatively high‐catalytic activity after 10 cycle times. This work provided novel ideas for the fabrication of doped carbon material from biomass and promoted its utilization in nanocatalytic applications.

N, P-dual doped carbonaceous catalysts derived from bifunctional-salt activation for effective electro-Fenton degradation on waterborne organic pollutions

To achieve the two-electron governed oxygen reduction reaction (ORR) is the major challenge for carbonaceous catalyst in the electro-Fenton (EF) degradation on the exhaustive stubborn pollutants from industrial wastewater. Herein, a bifunctional salts strategy utilizing EDTA-2K and NaH2PO2.H2O as heteroatom dopants and porogens is proposed to regulate the doping amounts of N, P heteroatoms as well as the content of active species (pyrrolic-N and P-C bonding motifs) to enhance 2e--ORR selectivity for EF degradation. It is found that the generated gaseous substances could serve as soft template to create micro-/meso-pores for the accommodation of highly oxidizing .OH radicals. In addition, thanks to the high N, P doping amounts (both are 2.9 at. %, respectively), large specific surface area (1388 m2 g-1) and appropriate pore sizes (1.5/3.8 nm), the optimized carbonaceous catalyst enables high EF degradation efficiencies up to 98.4 % (60 min) and 97.1 % (150 min), respectively for methyl yellow and mixed dyes with good stability and reusability. The current work paved a new concept to engineer the carbonaceous catalysts for the promoted catalytic activity and selectivity in the electro-degradation of organic pollution.