Carbon-based Catalysts Research Articles

Efficient activation of peroxyacetic acid by cobalt-iron alloy/oxide heterojunctions anchored in defect-rich biochar for pesticide degradation in water: Unravelling the radical-unradical mechanism

The activation processes of peracetic acid (PAA-AOPs) have garnered significant attention in wastewater treatment. In this study, an amorphous carbon-modified bimetallic CoFe alloy/oxide catalyst (CoFe@DBCx-y, where x represents biomass mass and y represents pyrolysis temperature) was developed to activate PAA for the degradation of organochlorine pesticides (OCPs). Due to the size effect, biochar dynamically regulates the particle size of metal species, which is influenced by the pyrolysis temperature. Among these systems, the CoFeDBC2.0–700/PAA oxidation system effectively removed 95.7 % of 2,4-dichlorophenoxyacetic acid (2,4-D), exhibiting a kinetic constant 1.7 times higher than that of the Nano/PAA system. Furthermore, quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that high-valent metal oxides (MIV = O) and singlet oxygen (1O2) are the primary active species responsible for the removal of 2,4-D, whereas organic radicals (RO·) and hydroxyl radicals (·OH) play a secondary role. Electrochemical and Raman spectroscopy tests revealed the formation of a metastable surface complex (≡Co(III)–OO(O)CCH3) between PAA and the catalyst, which acted as an intermediate oxidant to generate reactive oxygen species (ROS) through a chain reaction. Carbon defects in the biochar functioned as an electron source, continuously replenishing the electrons consumed in the reaction and facilitating the valence cycling between Co and Fe. This study provides new insights into the remediation of pesticide-contaminated wastewater using PAA-AOPs with heterogeneous bimetallic carbon-based catalysts.

Rigid Ligand Confined Synthesis of Carbon Supported Dimeric Fe Sites with High-Performance Oxygen Reduction Reaction Activity for Quasi-Solid-State Rechargeable Zn-Air Batteries.

Dimeric metal sites (DiMSs) in carbon-based single atom catalysts (SACs) offer distinct advantages in optimizing the adsorption energies of the catalytic intermediates and reaction pathways over single atom sites, which inspires the investigations on the rational design of DiMSs-based SACs and the accurate discernment of catalytic mechanisms. Here, dimeric Fe sites on carbon blacks (DiFe-N/CBs) are prepared using the precursor of metal-organic complex with a controlled structure, and the rigid ligand confinement secures the preservation of dimeric Fe sites during the thermal treatment. DiFe-N/CBs shows excellent electrocatalytic performance for oxygen reduction reaction (ORR) with a high half-wave potential of 0.917 V, and excellent durability with negligible activity decay. Theoretical studies reveal that the dimeric Fe sites have an optimal adsorption of OOH* with the Yeager-type binding, illustrating the advantages of DiMSs over SAs in catalyzing ORR. The rechargeable aqueous and quasi-solid-state Zn-air batteries assembled using DiFe-N/CBs-based air cathodes achieve small voltage gaps after long term charge/discharge test, showing great promises for practical applications. This synthetic strategy serves a novel platform to produce a scope of catalysts incorporating multimeric metal sites, and studies on the catalytic mechanism lay the foundation for establishing cooperative effect for multidentate adsorption reactions.

Recent advances in electrocatalytic C-N coupling for urea synthesis.

Urea, one of the most widely used nitrogen-containing fertilizers globally, is essential for sustainable agriculture. Improving its production is crucial for meeting the increasing demand for fertilizers. Electrocatalytic co-reduction of CO₂ and nitrogenous compounds (NO₂⁻/NO₃⁻) has emerged as a promising strategy for green and energy-efficient urea synthesis. However, challenges such as slow reaction kinetics and complex multi-step electron transfers have hindered the development of efficient urea synthesis methods. This review explores recent advances in the electrocatalytic C-N coupling process, focusing on bimetallic catalysts, metal oxide/hydroxide catalysts, and carbon-based catalysts. The review also discusses the future prospects of designing effective catalysts for electrocatalytic C-N coupling to improve urea synthesis.

Efficient conversion of xylose and corncob to furfural using a novel carbon-based solid acid derived from black liquor lignin-tin complexes

The novel carbon-based solid acid catalyst was prepared by carbonizing the mixture of metal salts and black liquor, followed by sulfonating. The physicochemical properties of the catalysts were characterized by SEM, FTIR, BET, NH3-TPD, Py-IR, XPS, ICP, and elemental analysis. The catalytic ability of the catalyst was explored by converting xylose and corncob to furfural via a one-step process. The effects of solvent types and water contents, catalyst dosage, substrate concentration, reaction temperature, and reaction time on furfural yield were evaluated. 93.4 % of furfural yield was achieved using 200 mg xylose at 170 °C for 120 min with 150 mg catalysts. Moreover, the furfural yields of 82.5 % were obtained from corncob. This work provides a promising strategy for synthesizing carbon-based solid acid catalysts from pulp waste black-liquid resources, which has a potential application for producing furfural from hemicellulose.

Role of Trap Optimization in a Heterostructure Carbon Nitride as a Methodology to Enhance Photocatalytic Hydrogen Production.

Carbon-based catalysts hold significant promise for photocatalytic hydrogen evolution. A critical challenge lies in optimizing the balance between electron longevity and its accumulation to avoid bottlenecks in photocatalytic efficiency. In this study, we introduce an innovative and efficient strategy for the rapid extraction (<100 fs) of photoinduced free electrons from a carbon-based catalyst without forming additional metal-based heterojunction hybrids. This method effectively prevents excessive accumulation of free carriers within the catalyst. The rapidly extracted electrons are then utilized for photocatalytic hydrogen production, resulting in a 10-fold increase in activity compared to the pristine catalyst, with platinum (3 wt%) used as a cocatalyst. Our strategy significantly enhances the performance of a state-of-the-art catalyst, offering a clean and cost-effective method for producing clean energy. This work demonstrates how a fundamental understanding of molecular-level phenomena and their optimization can pave the way for delivering clean and affordable energy to society.

Recent Advances in Bonding Regulation of Metalloporphyrin-Modified Carbon-Based Catalysts for Accelerating Energy Electrocatalytic Applications.

Metalloporphyrins modified carbon-based materials, owing to the excellent acid-base resistance, optimal electron transfer rates, and superior catalytic performance, have shown great potential in energy electrocatalysis. Recently, numerous efforts have concentrated on employing carbon-based substrates as platforms to anchor metalloporphyrins, thereby fabricating a diverse array of composite catalysts tailored for assorted electrocatalytic processes. However, the interplay through bonding regulation of metalloporphyrins with carbon materials and the resultant enhancement in catalyst performance remains inadequately elucidated. Gaining an in-depth comprehension of the synergistic interactions between metalloporphyrins and carbon-based materials within the realm of electrocatalysis is imperative for advancing the development of innovative composite catalysts. Herein, the review systematically classifies the binding modes (i.e., covalent grafting and non-covalent interactions) between carbon-based materials and metalloporphyrins, followed by a discussion on the structural characteristics and applications of metalloporphyrins supported on various carbon-based substrates, categorized according to their binding modes. Additionally, this review underscores the principal challenges and emerging opportunities for carbon-supported metalloporphyrin composite catalysts, offering both inspiration and methodological insights for researchers involved in the design and application of these advanced catalytic systems.

Comparison between endogenous and exogenous nitrogen of nitrogen-doped carbon catalyst in the process of activating PMS

BackgroundAdvanced oxidation processes (AOPs) based on sulfate radicals (SO4•–) have proven to be highly effective in degrading organics in wastewater. Carbon-based materials have emerged as promising catalysts for activating persulfate, which generates environmentally friendly sulfate radicals (SO4•–), for remediation purposes. The nitrogen doping technique is an effective method for site-specific regulation and can significantly enhance the performance of carbon-based catalysts, which could promote the application of carbon-based catalysts in the future. Endogenous and exogenous nitrogen sources can provide nitrogen sources for N doping. However, there are few reports on the comparison of the structure and catalytic mechanism of these two types of N-doped biochar. It is also of great significance to reveal the mechanisms of constructing catalytic sites using endogenous and exogenous nitrogen. MethodsHerein, the preparation of endogenous nitrogen-doped biochar (BC) was achieved by using soybean as the precursor material, which is rich in natural nitrogen-containing components of proteins. Subsequently, the BC was doped by mixing it with urea and pyrolysis, resulting in the preparation of exogenous nitrogen-doped biochar (NBC). Significant findingsThe characterization of XRD and HRTEM showed that g-C3N4 formed in NBC. The results of catalytic degradation and quenching experiments demonstrate that the exogenous nitrogen-doped catalysts have a better performance than endogenous nitrogen-doped catalysts. The OFL removal rate in BC/PMS was higher than that in the BC/PMS system (71.68% vs. 61.83 %). The kobs in NBC/PMS are also higher than that in BC/PMS (0.00943 min−1vs. 0.01369 min−1). The NBC could be a promising catalyst for PMS activation in practical application. DFT results showed that the g-C3N4 generated from exogenous nitrogen can improve PMS activation performance in the g-C3N4/graphene bilayer structure. The influence on the charge distribution of surrounding carbon materials makes endogenous nitrogen doping a good choice for optimizing the local performance of the material in the absence of natural nitrogen components.

Balanced adsorption and oxidation in a porous P, N-doped carbon prepared by melt-salt-mediated strategy for enhanced fenton-like reaction

The activation of persulfate oxidation processes using carbon-based catalysts is attractive for eliminating persistent aromatic organic pollutants in wastewater treatment. Herein, N and P co-doped carbonaceous (NPC) catalysts with an ultrahigh surface area were synthesized using a melt-salt-mediated strategy, employing Zeolitic Imidazolate Framework-8 as a self-sacrificing template. The NPC(1:1) carbon, prepared under optimized conditions, exhibited the highest surface area of 2001.5 m2/g, characterized by the highest number of defects and a high dispersion of N (1.89 %) and P (0.30 %) atoms on the carbon. This carbon catalyst exhibited a high capacity for adsorption and potential for activating persulfates in the removal of p-Nitrophenol (p-NP). Experimental data indicate a balance between adsorption and oxidation in the NPC(1:1)/PDS/p-NP system, with the highest catalytic removal rate achieved through moderate pre-adsorption of p-NP. Evidence from quenching, electron paramagnetic resonance (EPR), and amperometric i-t experiments suggests that the NPC(1:1)/PDS system primarily degrades p-NP through an electron transfer pathway. Defects in carbon and graphitic N were identified as catalytic sites. These defects resulted in an electron-deficient state, which leads to the activation of PDS and graphitic N was more reactive than both pyridinic and pyrrolic N in the adsorption of PDS molecules. Additionally, P-containing groups such as C-P-O, C-O-P, and C3-P were pinpointed as active sites on the carbons through DFT calculations. The intermediates during p-NP degradation were identified, and possible degradation pathways were proposed. A toxicity analysis indicated a significant reduction in overall toxicity following the oxidation treatment. This study provides innovative insights into the balance between adsorption and catalytic activity in porous carbon-activated persulfate oxidation reactions, thereby aiding in the development of enhanced oxidation catalysts for environmental remediation.

Electrolytic conversion of CO2 to proportionally tunable syngas using nickel-nitrogen doped carbon materials derived from Chlorella sp.

Chlorella sp., a common type of algae found in global surface waters, is prone to causing "blooms" and can accumulate significant amounts of nutrients such as nitrogen, phosphorus, and carbon. While carbon materials derived from Chlorella sp. are widely used in the field of adsorption, there are relatively few reports focused on electrocatalysis. This study utilized Chlorella sp. as a raw material to synthesize functional carbon materials, and prepared nitrogen-doped (CN), nickel-doped (CNi), and nitrogen-nickel co-doped (CNNi) carbon-based catalysts with both metal and non-metal elements. The results showed that the CN, CNi and CNNi catalysts possessed certain electrocatalytic properties, among which the CNNi material had the best electrocatalytic activity towards CO2 reduction (CO2RR). In 1.0 M KHCO3, the CNNi catalyst exhibited an instantaneous current density of 15.4 mA/cm2 under the potential of -0.82V (vs. RHE). In terms of product selectivity, the Faraday efficiency of CO on the CNNi electrode was up to 90% when the electrode potential was -0.62 V (vs. RHE), while the selectivity of the CN and CNi catalysts for CO was only 59% under the optimal conditions. The co-doping of nitrogen and nickel significantly enhanced the electrocatalytic activity and the selectivity towards CO of Chlorella-based carbon materials.

Effect of structure of metal-free nitrogen-doped coal-based carbon on catalytic oxygen reduction

In carbon-based oxygen reduction reaction (ORR) catalysts, metal-free nitrogen-doped carbon-based materials generally have higher catalytic stability compared to metal catalysts with reduced catalytic activity due to the occurrence of metal agglomeration during the catalytic reaction. In this paper, a metal-free nitrogen-doped carbon-based ORR catalyst NCOH5-900 with a half-wave potential of 0.846 V and onset potential of 0.94 V was prepared using coal as the carbon source, dicyandiamide as the nitrogen source and KOH as the activator. The material has good ORR catalytic performance with half-wave potential and onset potential comparable to Pt/C catalyst with the same mass loading, with better resistance to methanol toxicity and catalytic stability. The physical and chemical properties of the prepared catalyst were controlled by adjusting the amount of nitrogen doping and activation temperature to establish the relationship between the material structure and the ORR performance. The results suggest that for the metal-free nitrogen-doped carbon-based material, the good ORR catalytic performance is attributed to the abundant edge defects, high graphitization, good mixed structure of micro/mesopores, large nitrogen content, and high ratio of pyridine to graphitic nitrogen. Finally, the catalytic mechanism of NCOH5-900 for ORR is investigated using in-situ attenuated total reflection Fourier infrared (ATR-FTIR) and in-situ Raman, confirming the four-electron reduction process of O2 via a continuous dual step of two-electron transfer process.

Rare-earth metal neodymium anchored into graphene as a promising CO2 reduction electrocatalyst by regulating the coordination environment

Carbon-based single atom catalysts (SACs) are promising electrocatalysts in the field of carbon dioxide reduction reactions (CO2RR) due to their high efficiency and environmental friendliness, in which the coordination environment is the key factor determining their intrinsic catalytic activity. Furthermore, rare-earth-based SACs have shown great potential on CO2RR in recent years. Meanwhile, various studies have focused on combining metals with N-doped graphene, which together form potential Mx-Ny-C active sites. This work systematically investigates the impact of varying N/C coordination numbers on Nd atoms in graphene (Nd-NxC6-x, x = 0–5) on the CO2RR reaction mechanism and catalytic performance through density functional theory methods. Detailed Gibbs free energy calculation results indicate that most catalysts undergo a two-electron reduction pathway. For Nd-N3C3, Nd-N3C3–1, Nd-N3C3–2, Nd-N4C2, Nd-N4C2–1, Nd-N4C2–2, and Nd-N5C, HCOOH is the main product, with low UL values of -0.18, -0.17, -0.03, -0.10, -0.11, -0.09, and -0.10 V, respectively. In summary, our research results not only indicate that N atoms with different coordination numbers can improve the product selectivity and catalytic activity of catalysts, but also may provide valuable theoretical insights for studying the application of rare-earth-based SACs.

Formation and evolution of coke of pyrolytic volatiles of low-rank coal on the carbon-based catalysts

The catalytic upgrading of coal pyrolysis volatiles is an effective technique to achieve clean and efficient conversion of low-rank coal. However, a major problem in this process is catalyst deactivation caused by coke deposition. This study investigated the catalytic cracking effect of activated carbon and metal-modified activated carbon on coal pyrolysis volatiles. It also explained the physical and chemical properties of coke and its formation mechanism related to volatile cracking. The results indicate that phenolic oils, pitch, oxygen-containing compounds, and polycyclic aromatics are linearly related to the coke deposited on the surface of carbon-based catalysts. These compounds act as precursors and are easily transformed into coke via cracking, deoxidation, crosslinking, and polycondensation reactions when the cracking rate of volatiles does not match the hydrogen supply rate. The micro-morphology of coke is primarily composed of amorphous carbon, which is mainly found in pores ranging from 0.50 to 5.00 nm and on the outer surface of carbon-based catalysts. The chemical structure of coke primarily consists of large aromatic clusters containing at least six benzene rings and oxygen-containing cross-linking compounds with a high degree of graphitization and a low number of carbon structural defects. This results in an increase in radical concentration of carbon-based catalysts, as well as a decrease in combustion reactivity. The outcomes will aid in controlling coke deposition during catalytic cracking of pyrolytic volatiles of low-rank coal.

Petroleum Pitch-Derived Porous Carbon Materials as Metal-Free Catalyst for Dry Reforming of Methane.

Porous carbon materials have gained increasing attention in catalysis applications due to their tailorable surface properties, large specific surface area, excellent thermal stability, and low cost. Even though porous carbon materials have been employed for thermal-catalytic dry reforming of methane (DRM), the structure-function relationship, especially the critical factor affecting catalytic performance, is still under debate. Herein, various porous carbon-based samples with disparate pore structures and surface properties are prepared by alkali (K2CO3) etching and the following CO2 activation of low-cost petroleum pitch. Detailed characterization clarifies that the quinone/ketone carbonyl functional groups on the carbon surface are the key active sites for DRM. Density functional theory (DFT) calculations also show that the C=O group have the lowest transition state energy barrier for CH4* cleavage to CH3* (2.15 eV). Furthermore, the cooperative interplay between the specific surface area and quinone/ketone carbonyl is essential to boost the cleavage of C-H and C-O bonds, guaranteeing enhanced DRM catalytic performance. The MC-600-800 catalyst exhibited an initial CH4 conversion of 51% and a reaction rate of 12.6 mmolCH4 gcat.-1 h-1 at 800 °C, CH4:CO2:N2= 1:1:8, and GHSV = 6000 mL gcat.-1 h-1. Our work could pave the way for the rational design of metal-free carbon-based DRM catalysts and shed new light on the high value-added utilization of heavy oils.

Study on the synthesis of CoFe/CoFe2O4@NCNTs derived from ZnFeCo-ZIF with abundant heterostructures and oxygen vacancies as bifunctional catalyst for ORR/OER in zinc-air batteries

The rational design of bifunctional catalysts for oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) in alkaline electrolyte is of great significance for zinc-air batteries (ZABs). In this study, different types of Fe/Co compounds and nitrogen-doped carbon-based composite catalysts from trimetallic zeolitic-imidazole-framework-derived (ZnFeCo-ZIF) were synthesized by adjusting the ratio of Zn/Fe/Co. Among them, the synthesized CoFe/CoFe2O4-N-doped carbon nanotubes (CoFe/CoFe2O4@NCNTs) have abundant Fe-Nx and Co-Nx activity sites, heterostructures and oxygen vacancies. The experimental results reveal that the electrons of CoFe are transferred to CoFe2O4 at the interface of CoFe/CoFe2O4, which not only enhances the electron transfer ability, but also induces oxygen vacancies to improve the adsorption/desorption capacity of O2 and intermediates. Meanwhile, metal atoms are uniformly dispersed in the N-doped carbon nanotubes to form metal–N sites with high catalytic activity. Therefore, the CoFe/CoFe2O4@NCNTs exhibit excellent electrocatalytic performance, possessing a half-wave potential (E1/2) of 0.878 V and a prominent limiting-current densities (JL) of 6.281 mA cm−2 for ORR, and a low overpotential of 344 mV at 10 mA cm−2 for OER. In particular, the CoFe/CoFe2O4@NCNTs-equiped ZAB possesses a higher open-circuit voltage (1.50 V), a greater maximum power density (193.42 mW cm−2) and a longer cycling performance (160 h). The density functional theory (DFT) calculations show that the CoFe/CoFe2O4 heterostructure can induce the rapid transfer of electrons at the CoFe/CoFe2O4 interface, which promotes the change of the surface electronic structure of the catalyst, and thus helps to enhance the ability of the catalyst to transfer electrons.

Catalytic methane decomposition process on carbon-based catalyst under contactless induction heating

Hydrogen obtained from decomposition of natural gas with direct sequestration of carbon in solid form could be an attractive and cost-effective alternative for large-scale hydrogen production. We report here the use of a carbon-based catalyst to achieve the catalytic decomposition of methane (CMD) at medium temperature, 800 °C, under induction heating (IH). Analyses of the catalytic results and characterizations of the spent catalyst have shown that the carbon deposited during the reaction acts as the active phase for the reaction and can, therefore, be recycled infinitely. This autocatalytic effect can only be observed when the carbon catalyst operates under IH because the same catalyst operating under Joule heating (JH) deactivates rapidly in the same way as that already reported in the literature and no autocatalytic effect has been observed. The carbon formed is in the form of a graphene layer with a high degree of graphitization and is completely different from the carbon black powder obtained in other processes. These promising results could lay the groundwork for the development of an industrially and economically viable way to convert natural gas into turquoise hydrogen, using renewable energy and low-cost catalysts, with better resistance to poisoning by impurities present in the processing load. The combination of a carbon-based catalyst and non-contact IH could also lead to combined catalytic processes for many challenging reactions.

Selective synthesis of oxygenated fuel derivative from microwave assisted acetalization of glycerol: Optimization and mechanistic investigations

Glycerol contains 52 wt% oxygen content, therefore unable to be directly used as fuel due to its poor combustion ability. Thus, the catalytic conversion of glycerol into various oxygen-containing fuel additives is grabbing more attention nowadays. This work provides a novel, sustainable, and eco-friendly method for synthesizing heterogeneous acid carbon catalysts from pearl millet cob (PMC) waste. The hydrothermal carbonization process was carried out at different temperatures to fabricate the series of sulfonated pearl millet cob (SPMC) catalysts. XRD, FT-IR, SEM-EDS, XPS, BET, TGA, and CHNSO analyses were performed to characterize fabricated catalysts. The synthesized catalyst, SPMC-70 (catalyst synthesized at 70 °C temperature), possesses OH, COOH, and SO3H functional groups and a significant total acid density (2.03 mmol/g) with 37 m2/g surface area. The SPMC catalysts were employed for the microwave-assisted acetalization reaction of glycerol with acetone for solketal production. The optimization process was carried out using various reaction parameters, including catalyst dosage (2–6 wt.%), reaction temperature (30–60 °C), glycerol to acetone (GL to AC) molar ratio (1:3–1:9), and reaction time (4–13 min). The SPMC-70 catalyst showed the highest catalytic activity among all the synthesized catalysts and provided 99.11 ± 0.3 % GL conversion with 100 % selectivity of solketal under optimal reaction conditions. Additionally, the recyclability test was performed, and it found that the best catalyst was reusable for up to five reaction cycles. These results showed the effectiveness of carbon-based heterogeneous acid catalysts in deriving a fuel additive, solketal.

Mn and P co-doped biochar catalyst for persulfate efficient degradation of tetracycline hydrochloride：Process and mechanism

A novel manganese/phosphorus-doped biochar (Mn/P-C) catalyst was prepared for the degradation of tetracycline hydrochloride (TCH) by activating peroxymonosulfate (PMS). Characterization of the catalyst revealed that Mn/P-C possessed stacked, complex pleated sheets and surface oxygen-containing functional groups, providing abundant active sites. Mn/P-C exhibited superior adsorption and catalytic properties. Nearly complete removal of TCH was achieved under optimal conditions: a PMS concentration of 2 mM, pH 6.51, and catalyst dosage of 0.5 g/L within 120 minutes of reaction time. The reaction rate constant of the system was 0.060 min−1, which was 13.79 times higher than that of pure biochar. XPS characterization before and after the reaction, quenching experiment, and electron paramagnetic resonance (EPR) experiment comprehensively verified the reaction pathway mechanisms. The primary radicals involved were SO4•- and O2•-, while the 1O2 non-radical transfer pathway was also generated on the catalyst surface, enhancing electron transfer and accelerating catalytic degradation. UPLC-MS/MS was used to investigate the main degradation intermediates and the possible transformation pathways were proposed. The toxicity of TCH and its intermediates was evaluated by the quantitative structure-activity relationship (QSAR) method. Theoretical calculations provided deeper insights into TCH degradation pathways through DFT computational analysis. This study confirms that doping biochar with transition metals and nonmetals can synergistically enhance the degradation efficacy of PMS-activated biochar catalysts, providing a novel approach for the application of carbon-based material catalysts in persulfate activation.

Boosting Suzuki coupling reaction by multiscale porous Pd/carbon nanofibers photothermal catalyst

Carbon-based photothermal catalysts represent a novel, energy-saving, and eco-friendly paradigm in catalysis. In this work, multiscale porous Pd/carbon nanofibers catalyst (Pd/MPCF) was synthesized by electrospinning, CO2 thermal activating and atomic layer deposition (ALD) method. The multiscale pores of MPCF enable uniform Pd deposition on the carbon support, which showed better catalytic performance in Suzuki coupling reaction than commercial Pd/C catalyst through harnessing solar heat, resulting in a zero fossil energy consumption reaction process.

Dynamic Reconstruction of Yttrium Oxide-Stabilized Cobalt-Loaded Carbon-Based Catalysts During Thermal Ammonia Decomposition.

Hydrogen production from the decomposition of ammonia is considered an effective approach for addressing challenges associated with hydrogen storage and transportation. However, their relatively high energy consumption and low efficiency hinder practical multi-scenario applications. In this study, Y2O3-stabilized catalysts with Co-loaded onto porous nitrogen-doped carbon (Y2O3-Co/NC) are synthesized by pyrolysis of Y(NO3)3-modified ZIF-67 under an inert atmosphere, followed by annealing in a reducing environment. The introduction of Y2O3 enhanced the recombination and desorption of N atoms and facilitated the gradual dehydrogenation of NHx on the catalyst surface, resulting in improved catalytic activity for the thermal decomposition of ammonia. Benefitting from the electron-donating properties of Y2O3 and N-doped carbon, the optimized catalyst achieved a remarkable NH3 conversion efficiency of 92.3% at a high gas hourly space velocity of 20000 cm3· ·h-1 with an encouraging H2 production rate of 20.6 mmol· ·min-1 at 550°C. Moreover, the synthesized catalyst undergoes a fast-dynamic reconstruction process, resulting in exceptionally stable catalytic activity during the thermal decomposition of ammonia, rendering it a promising candidate for carbon-free energy thermocatalytic conversion technology.

Boosting the activity of nitrogen-doped carbon catalyst by the guided formation of active sites and enhanced scavenging on reactive oxygen species under the regulation of cerium

The design of nitrogen-doped carbon materials with high density of active sites is of paramount importance for catalysis of the oxygen reduction reaction (ORR). Herein, an efficient oxygen reduction electrocatalyst (CL-Fe/(Fe,Ce)xOy-NC) is developed by planting carbon nanotubes with encapsulated Fe/(Fe,Ce)xOy particles on porous carbon polyhedron particles derived from calcinated ZIF-8 framework. The introduction of Ce evidently promotes the formation of pyridinic nitrogen, graphitic nitrogen and metal nitrogen species in carbon matrix, enhancing the catalytic activity towards the ORR. The Ce oxide in the catalyst effectively scavenges the active oxygen species in ORR process. Under the synergistic effect of high specific surface area with Ce species, the CL-Fe/(Fe,Ce)xOy-NC has a better half-wave potential (0.861 V vs. RHE), faster kinetics (44.13 mV dec−1) and is more stable than the commercial Pt/C catalyst. The zinc-air battery assembled with CL-Fe/(Fe,Ce)xOy-NC has the highest power density of 195 mW cm−2, energy density of 858 Wh kg−1, and better durability. This work presents a novel approach to enhance the efficacy of nitrogen-doped carbon-based catalysts, paving a possible way to substitute the precious platinum catalysts for a variety of electrochemical energy devices.