2D Carbon Nanosheets Research Articles

Confined pyrolysis to transfer MXene-like MOF into 2D carbon nanosheet boosting the ozone oxidation of antibiotic: Degradation behavior and intrinsic mechanism

Ozone oxidation as a means of water treatment has received great attention in recent years, but ozone has low solubility and utilization, which hinders their efficient treatment of refractory pollutants. Herein, a dopamine-encapsulated 2D MOF strategy is proposed, where different metal salts including (acetylacetone iron, manganese, copper, etc.) are doped in it as active site precursors. After pyrolysis, 2D hollow porous carbon nanosheet catalysts such as Mn-HCNSs, Fe-HCNSs, Cu-HCNSs and Co-HCNSs are formed due to the rigid interface-induction of dopamine. Mn-doped Mn-HCNSs exhibits the best catalytic degradation performance when the antibiotic tetracycline is used as the target pollutant, and the degradation efficiency reached 90 % within 25 min (k = 0.213 min−1). This excellent catalytic performance can be attributed to several advantages: (i) the hollow porous 2D structure facilitates mass transfer and enhances the reaction kinetic constants; (ii) the confinement effect of dopamine wrapping facilitates the generation of more dispersed active sites and accelerates its ozone decomposition efficiency. This study expands the application of 2D MOF-derived porous carbon materials in ozone oxidation.

Ru-M (Fe, Co, Ni) onto Nitrogen-doped Two-dimensional Carbon Nanosheets through Microwave Approach with Strong Metal-support Interactions for overall Water-splitting

Developing Ru-based catalysts with strong metal-support interactions (SMSI) is a significant approach to achieve highly-efficient catalytic activity and satisfactory stability. Nevertheless, the current strategies to construct SMSI are generally time-consuming and tedious, and then leading to aggregation. In this research, ultrafast microwave (45 s) is employed to affix small Ru-M (Fe, Co, Ni) nanoparticles onto nitrogen-doped two-dimensional (2D) carbon nanosheets (NCN, Ru-M/NCN), leading to robust metal-support interactions that enhance reaction kinetics and boost stability. Furthermore, the electronic interplay between Ru and M is pivotal in augmenting catalytic efficacy. The small size of the Ru-M nanoparticles and high specific surface area also favor exposing active sites and abundant interconnected channels to accelerate mass transport. Subsequent low-temperature oxidation process, to prepare RuM@RuOx/NCN, which is conducted to achieve oxygen evolution reaction (OER) performance. Thus, the as-synthesized RuCo/NCN only requires 65 mV, 58 mV, and 98 mV to achieve 10 mA cm-2 for hydrogen evolution reaction (HER) in 0.5 M H2SO4, 1 M KOH and alkaline seawater. RuM@RuOx/NCN is obtained by low-temperature oxidation to achieve excellent oxygen reduction reaction performance in 1 M KOH, the low overpotential of only 273 mV, 256 mV and 284 mV can reach 10 mA cm-2 and satisfactory stability. Moreover, the prepared electrocatalysts also achieve satisfactory electrocatalytic activity for overall water-splitting in alkaline freshwater/seawater electrolytes. This work provides a superior pathway for multifunctional nanomaterials for sustainable energy storage and conversion.

N-doped three-dimensional carbon nanosheets: Facile synthesis and high-concentration dye adsorption

Purification of dye-contaminated wastewater has always been a research hotspot, yet also a challenge, due to high concentration and species diversity of pollutants. The present study designs an efficient nitrogen-doped 3D carbon nanosheets (N-3DCNs) adsorbent with 2592.50 m2 g−1 of specific surface area and 2.68 m3/g of average pore volume based on nitrilotriacetic acid trisodium salt by combining calcination and activation techniques. Microstructure and surface potential of N-3DCNs indicate that a large number of N heteroatoms in the lattice of main material can effectively optimize Zeta potential from 1.53 to −31.08 mV with solution pH increases from 3 to 11. So, as-prepared N-3DCNs possesses necessary conditions for efficient and selective adsorption of cationic dyes due to the abundant adsorption sites and strong electrostatic interactions. When 700 mg/L of cationic rhodamine and anionic methyl orange are respectively used as high concentration industrial dye-contaminated wastewater, N-3DCNs shows 97.97 % and 89.13 % of removal efficiency within 60 min. Furthermore, the adsorption capacity of N-3DCNs displays a wider pH tolerance at 1000 mg/L of cationic concentration, with a maximum adsorption capacity of 4888.70 mg/g at pH = 7 and a minimum value of 4203.77 mg/g at pH = 3, only 14 % of attenuation rate. The kinetics mechanism of dye adsorption could be well explained by pseudo-second-order kinetic model, suggesting chemisorption behavior, while fitting better with the linear Langmuir isothermal model. The groundbreaking and exceptional adsorption performances of N-3DCNs can be attributed primarily to the high specific surface area and negatively charged active sites, facilitating synergistic adsorption.

Supercapacitive behavior of two-dimensional carbon nanosheets with oxygen-induced interfacial modification

Biomass-derived carbon typically contains abundant heteroatomic defects and interfacial functional groups, which can contribute to additional pseudocapacitance. However, the type of interfacial functional groups in biomass-derived carbon is uncontrollable and variable, reducing their homogeneity. In this work, recyclable boric acid was employed as an activator to convert bioaerogels into carbon nanosheets. Subsequently, low-temperature air oxidation was utilized to modulate their thickness and microstructure. Notably, the multiple and uncontrollable functional groups at the carbon interface were uniformly transformed into oxygen-containing functional groups under oxygen induction, resulting in 2D carbon nanosheet materials with enhanced stability properties. Meanwhile, the introduction of more oxygen-containing functional groups, such as carbonyl (C=O) and carboxyl (-COOH) groups, improves material wettability and capacitive properties. In addition, the boron and nitrogen elements doping introduced by activators and precursors enhances its pseudocapacitive properties and electrical conductivity from the carbon lattice perspective. Moreover, the rich electron/deficient effect of BN valence bond can effectively boost their conductivity and rate performance. In fact, the materials present good capacitive properties (high specific capacitance of 298.5 F g−1 in KOH three-electrode system) and CDI (capacitive deionization) performance (good desalting capacity of 35.2 mg g−1 in CDI system).

WO2–N co-doped 2D Carbon nanosheets as multifunctional additives for enhancing the electrochemical hydrogen storage performance of Co2B

Co2B, with its high theoretical hydrogen storage capacity, is a potential solid-state hydrogen storage material. However, its poor cycling life limits its practical application. In this work, in order to improve the cycling stability and reversibility of hydrogen absorption and desorption of Co2B, we propose to use WO2–N–C nanosheets as dopants to mix with Co2B, thereby enhancing its practical performance. Two-dimensional tungsten oxide-nitrogen-carbon (WO2–N–C) nanosheets was syntheized via a liquid-phase approach, using a tungstenate-polydopamine precursor followed by thermal treatment. Subsequently, these WO2–N–C nanosheets were compounded with cobalt boride (Co2B) particles through ball milling at various ratios of 1%, 3%, and 5%, which were confirmed by XRD (X-ray diffraction) and SEM (Scanning Electron Microscope) methods. Employing a comprehensive suite of electrochemical analyses, including corrosion potential measurements, polarization curves, step voltammetry, and electrochemical impedance spectroscopy (EIS), we found that the incorporation of WO2–N–C significantly enhances the corrosion resistance and electrochemical activity of Co2B. Furthermore, cyclic life tests revealed that the WO2–N–C-doped Co2B composites exhibit superior discharge capacities and capacity retention rates compared to pristine Co2B. Notably, the 3% WO2–N–C-doped Co2B composite demonstrated the optimal electrochemical performance, achieving a maximum discharge specific capacity of 555 mAh g−1 and maintaining 82% of its initial capacity after 50 cycles. Our findings underscore the dual role of WO2–N–C in not only augmenting the surface electrochemical activity of Co2B but also providing a protective surface layer, thereby enhancing its overall electrochemical performance.

3D Co-doped carbon nanosheets as high-performance electrodes for Li-S batteries

3D petal-shaped Cobalt-doped carbon nanosheets (PCoCNS) were synthesized as excellent sulfur hosts for lithium-sulfur (Li-S) batteries. Co doping enhanced the affinity of the carbon surface for lithium polysulfides (LiPSs), inhibiting the shuttle effect. The electrocatalytic effect of the PCoCNS electrode exhibited enhanced polysulfide conversion kinetics, thereby promoting Li2S formation. Owing to the above advantages, the PCoCNS cathode exhibited satisfactory reversibility of 841 mAh/g with a high capacity retention of 91 %. Additionally, it displayed high coulombic efficiency (CE) values exceeding 97 % over 100 cycles at a current rate of 0.5C. Furthermore, the electrode demonstrated low polarization and exhibited an excellent rate performance, delivering a capacity of 575 mAh/g at the high rate of 3C. This study synthesized a promising sulfur cathode for enhancing the electrochemical performance of Li-S batteries.

RETRACTED: Fe–Co co-doped 1D@2D carbon-based composite as an efficient catalyst for Zn-air batteries

A Fe-Co dual-metal co-doped nitrogen-containing carbon composite (FeCo-HNC) was prepared by adjusting the ratio of iron to cobalt as well as the pyrolysis temperature with the assistance of functionalized silica template. Fe1Co-HNC, which was made from 1D carbon nanotubes and 2D carbon nanosheets with a rich mesoporous structure, presented exceptional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activity. The ORR half-wave potential is 0.86 V (vs. reversible hydrogen electrode, RHE), and the OER overpotential is 0.76 V at 10 mA cm−2 with the Fe1Co-HNC catalyst, which can be applied to zinc-air batteries with superior performance. It is worth noting that the zinc-air batteries with Fe1Co-HNC-1000 as the cathodic catalyst achieved the highest power density of 94.9 mW cm−2 under a current density of 159.8 mA cm−2. This method provides a promising strategy for fabricating efficient transition metal-based carbon catalysts.

CoSe2-Modified multidimensional porous carbon frameworks as high-Performance anode for fast-Charging sodium-Ion batteries

Transition metal selenides (TMSs) possess relatively high theoretical capacity and unique structures emerge as promising anode materials for sodium-ion batteries (SIBs). However, TMSs anode materials suffer from challenges such as substantial volume expansion, undesired side reactions, and poor active reaction dynamics. Herein, we propose a novel synthesis method that integrates metal salt-assisted polymer-blowing technique with in situ selenization strategy to fabricate multidimensional porous 3D carbon nanosheet frameworks modified by cobalt diselenide nanoparticles (CoSe2-CNF). Such unique architecture bestows intimate structural interconnectivity with high mechanical strength and abundant ion diffusion channels on CoSe2-CNF, exhibiting remarkable reversible capacity and fast-charging capability within diverse electrolyte systems. For instance, the CoSe2-CNF anode in ether electrolyte exhibits prominent rate performance of 349 mAh/g at 15 A/g. Sodium storage mechanism and fast electrochemical kinetics in the discharge/charge processes are investigated by in situ XRD and in situ EIS techniques. Additionally, DFT calculations are utilized to analyze the electrochemical differences observed in various electrolyte systems. When coupled with Na3V2(PO4) (NVP) cathodes, the full batteries also afford enhanced reversible capacity of 105 mAh/g over 100 cycles. The proposed structural engineering for CoSe2-CNF is beneficial for designing fast-charging energy storage devices.

Mo2C-Co heterostructure with carbon nanosheets decorated carbon microtubules: Different means for high-performance lithium-sulfur batteries

The practical applications of lithium sulfur batteries (LSBs) are hindered by notorious shuttle effect and sluggish conversion kinetics of intermediate polysulfides. Herein, Mo2C-Co heterogeneous particles decorated two-dimensional (2D) carbon nanosheets grown on hollow carbon microtubes (CCC@MCC) are synthesized. Three-dimensional (3D) carbon framework with Mo2C-Co heterogeneous particles combines the conductivity, adsorption and catalysis, effectively trapping and accelerating the conversion of polysulfides. As evidenced experimentally, the hetero-structured Mo2C-Co with high Li+ diffusion coefficient enables uniform precipitation and complete oxidation of Li2S. Meanwhile, CCC@MCC is found to have multiple application possibilities for lithium-sulfur batteries. As an interlayer, the cells deliver an excellent capacity of 881.1 mAh/g at 2C and still retain 438.2 mAh/g after 500 cycles under the low temperature of 0 ℃. As a sulfur carrier, the cell with a sulfur loading of 7.0 mg cm−2 exhibits a high area capacity of 5.3 mAh cm−2. This work provides an effective strategy to prepare heterostructured material and imaginatively exploit the application potential of it.

Scalable Production of 2D Non‐Layered Metal Oxides through Metal–Organic Gel Rapid Redox Transformation

Two‐dimensional (2D) nonlayered metal compounds with porous structure show broad application prospects in electrochemistry‐related fields due to their abundant active sites, open ions/electrons diffusion channels, and faradaic reactions. However, scalable and universal synthesis of 2D porous compounds still remains challenging. Here, inspired by blowing gum, a metal‐organic gel (MOG) rapid redox transformation (MRRT) strategy is proposed for the mass production of a wide variety of 2D porous metal oxides. Adequate crosslinking degree of MOG precursor and its rapid redox with NO3‐ are critical for generating gas pressure from interior to exterior, thus blowing the MOG into 2D carbon nanosheets, which further act as self‐sacrifice template for formation of oxides with porous and ultrathin structure. The versatility of this strategy is demonstrated by the fabrication of 39 metal oxides, including 10 transition metal oxides, one II‐main group oxide, two III‐main group oxides, 22 perovskite oxides, four high‐entropy oxides. As an illustrative verification, the 2D transition metal oxides exhibit excellent capacitive deionization (CDI) performance. Moreover, the assembled CDI cell could act as desalting battery to supply electrical energy during electrode regeneration. This MRRT strategy offers opportunities for achieving universal synthesis of 2D porous oxides with nonlayered structures and studying their electrochemistry‐related applications.

Scalable Production of 2D Non-Layered Metal Oxides through Metal-Organic Gel Rapid Redox Transformation.

Two-dimensional (2D) nonlayered metal compounds with porous structure show broad application prospects in electrochemistry-related fields due to their abundant active sites, open ions/electrons diffusion channels, and faradaic reactions. However, scalable and universal synthesis of 2D porous compounds still remains challenging. Here, inspired by blowing gum, a metal-organic gel (MOG) rapid redox transformation (MRRT) strategy is proposed for the mass production of a wide variety of 2D porous metal oxides. Adequate crosslinking degree of MOG precursor and its rapid redox with NO3 - are critical for generating gas pressure from interior to exterior, thus blowing the MOG into 2D carbon nanosheets, which further act as self-sacrifice template for formation of oxides with porous and ultrathin structure. The versatility of this strategy is demonstrated by the fabrication of 39 metal oxides, including 10 transition metal oxides, one II-main group oxide, two III-main group oxides, 22 perovskite oxides, four high-entropy oxides. As an illustrative verification, the 2D transition metal oxides exhibit excellent capacitive deionization (CDI) performance. Moreover, the assembled CDI cell could act as desalting battery to supply electrical energy during electrode regeneration. This MRRT strategy offers opportunities for achieving universal synthesis of 2D porous oxides with nonlayered structures and studying their electrochemistry-related applications.

Amine-Functionalized Metal-Free Nanocarbon to Boost Selective CO2 Electroreduction to CO in a Flow Cell.

Highly efficient electrochemical CO2-to-CO conversion is a promising approach for achieving carbon neutrality. While nonmetallic carbon electrocatalysts have shown potential for CO2-to-CO utilization in H-type cells, achieving efficient conversion in flow cells at an industrial scale remains challenging. In this study, we present a cost-effective synthesis strategy for preparing ultrathin 2D carbon nanosheet catalysts through simple amine functionalization. The optimized catalyst, NCNs-2.5, demonstrates exceptional CO selectivity with a maximum Faradaic efficiency of 98% and achieves a high current density of 55 mA cm-2 in a flow cell. Furthermore, the catalyst exhibits excellent long-term stability, operating continuously for 50 h while maintaining a CO selectivity above 90%. The superior catalytic activity of NCNs-2.5 is attributed to the presence of amine-N active sites within the carbon lattice structure. This work establishes a foundation for the rational design of cost-effective nonmetallic carbon catalysts as sustainable alternatives to metals in energy conversion systems.

Fe-Co Co-Doped 1D@2D Carbon-Based Composite as an Efficient Catalyst for Zn-Air Batteries.

A Fe-Co dual-metal co-doped N containing the carbon composite (FeCo-HNC) was prepared by adjusting the ratio of iron to cobalt as well as the pyrolysis temperature with the assistance of functionalized silica template. Fe1Co-HNC, which was formed with 1D carbon nanotubes and 2D carbon nanosheets including a rich mesoporous structure, exhibited outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activities. The ORR half-wave potential is 0.86 V (vs. reversible hydrogen electrode, RHE), and the OER overpotential is 0.76 V at 10 mA cm-2 with the Fe1Co-HNC catalyst. It also displayed superior performance in zinc-air batteries. This method provides a promising strategy for the fabrication of efficient transition metal-based carbon catalysts.

Interfaces Engineering of Ultrafine Ni@Ni2P/C Core-Shell Heterostructure for High Yield Hydrogen Peroxide Electrosynthesis.

Developing cost-effective and sustainable catalysts with exceptional activity and selectivity is essential for the practical implementation of on-site H2O2 electrosynthesis, yet it remains a formidable challenge. Metal phosphide core-shell heterostructures anchored in carbon nanosheets (denoted as Ni@Ni2P/C NSs) are designed and synthesized via carbonization and phosphidation of the 2D Ni-BDC precursor. This core-shell nanostructure provides more accessible active sites and enhanced durability, while the 2D carbon nanosheet substrate prevents heterostructure aggregation and facilitates mass transfer. Theoretical calculations further reveal that the Ni/Ni2P heterostructure-induced optimization of geometric and electronic structures enables the favored adsorption of OOH* intermediate. All these features endow the Ni@Ni2P/C NSs with remarkable performance in 2e ORR for H2O2 synthesis, achieving a top yield rate of 95.6mgL-1h-1 with both selectivity and Faradaic efficiency exceeding 90% under a wide range of applied potentials. Furthermore, when utilized as the anode of an assembled gas diffusion electrode (GDE) device, the Ni@Ni2P/C NSs achieve in situ H2O2 production with excellent long-term durability (>32h). Evidently, this work provides a unique insight into the origin of 2e ORR and proposes optimization of H2O2 production through nano-interface manipulation.

A synthesis strategy of 3D carbon nanosheet anode with adsorption/intercalation-filling hybrid mechanism for high-performance sodium/potassium-ion batteries

Hard carbons are significant in sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). However, the structural defects of hard carbons lead to poor rate performance and cycling stability, which need further improvement. The waste cooking oil was used as the precursor to synthesize 3D carbon nanosheets (NWCOC) with amino nitrogen functional groups, multi-layered pores, and expanded interlayer spacing. The excellent electrochemical properties of NWCOC were investigated and it was demonstrated that NWCOC can significantly improve the adsorption of Na+/K+ on hard carbons, substantially enhancing the embedding/de-embedding of Na+/K+, reducing the diffusion distance of ions and electrons, and improving their adaptability to volume changes. In situ XRD and Raman characterization reveal that the Na storage mechanism of NWCOC is mainly based on adsorption/intercalation-filling. Combined with density functional theory, it is shown that the porous structures doped with nitrogen have a greater propensity for ion adsorption, resulting in increased ion capture and storage. As expected, NWCOC650 exhibits high capacities of 489.4 and 388.3 mAh/g in SIBs and PIBs. NWCOC650 displays superior performance in the Na3V2(PO4)3/NWCOC650 full cell, achieving a capacity of 107.84 mAh/g. This work presents a new perspective on the synthesis and mechanisms of high-performance anodes for SIBs and PIBs.

Allying interfacial engineering of 2D carbon nanosheet‐, graphene‐, and graphdiyne‐based heterostructured electrocatalysts toward hydrogen evolution and overall water splitting

AbstractElectrochemical hydrogen evolution reaction (HER) and overall water splitting (OWS) for renewable energy generation have recently become a highly promising and sustainable strategy to tackle energy crisis and global warming arising from our overreliance on fossil fuels. Previously, tremendous research breakthroughs have been made in 2D carbon‐based heterostructured electrocatalysts in this field. Such heterostructures are distinguished by their remarkable electrical conductivity, exposed active sites, and mechanical stability. Herein, with fundamental mechanisms of electrocatalytic OWS summarized, our review critically emphasized on state‐of‐the‐art 2D carbon nanosheet‐, graphene‐, and graphdiyne‐based heterostructured electrocatalysts in HER and OWS since 2018. Particularly, the three emerging carbonaceous substrates tend to be incorporated with metal carbides, phosphides, dichalcogenides, nitrides, oxides, nanoparticles, single atom catalysts, or layered double hydroxides. Meanwhile, fascinating structural engineering and facile synthesis strategies were also unraveled to establish the structure–activity relationship, which will enlighten future electrocatalyst developments toward ameliorated HER and OWS activities. Additionally, computational results from density functional theory simulations were highlighted as well to better comprehend the synergistic effects within the heterostructures. Finally, current stages and future recommendations of this brand‐new electrocatalyst type were concluded and discussed for advanced catalyst designs and future practical applications.

Dual Activation for Tuning N, S Co-Doping in Porous Carbon Sheets Toward Superior Sodium Ion Storage.

Porous carbon has been widely focused to solve the problems of low coulombic efficiency (ICE) and low multiplication capacity of Sodium-ion batteries (SIBs) anodes. The superior energy storage properties of two-dimensional(2D)carbon nanosheets can be realized by modulating the structure, but be limited by the carbon sources, making it challenging to obtain 2D structures with large surface area. In this work, a new method for forming carbon materials with high N/S doping content based on combustion activation using the dual activation effect of K2SO4/KNO3 is proposed. The synthesized carbon material as an anode for SIBs has a high reversible capacity of 344.44mAhg-1 at 0.05Ag-1. Even at the current density of 5Ag-1, the capacity remained at 143.08mAhg-1. And the ICE of sodium-ion in ether electrolytes is ≈2.5 times higher than that in ester electrolytes. The sodium storage mechanism of ether/ester-based electrolytes is further explored through ex-situ characterizations. The disparity in electrochemical performance can be ascribed to the discrepancy in kinetics, wherein ether-based electrolytes exhibit a higher rate of Na+ storage and shedding compared to ester-based electrolytes. This work suggests an effective way to develop doubly doped carbon anode materials for SIBs.

1D hollow tubular/2D nanosheet hybrid dimensional porous carbon prepared by one-step carbonization using natural minerals as templates for supercapacitors.

The reasonable construction of one-dimensional (1D)/two-dimensional (2D) hybrid dimensional porous carbon materials with complementary advantages and disadvantages is an important approach to addressing the structural and performance deficiencies of single carbon materials, while also significantly improving the electrochemical performance of super-capacitors. In this study, 1D hollow tubular/2D nanosheet hybrid dimensional porous carbon was synthesized through one-step carbonization using 1D fibrous brucite and 2D layered magnesium carbonate hydroxide as templates. By adjusting the feed ratio of 1D fibrous and 2D layered templates, the morphology, pore structure and specific surface area (SSA) of the prepared 1D hollow tubular/2D nanosheet hybrid dimensional porous carbon were controlled. The prepared hybrid dimensional porous carbons were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption. And their electrochemical performance was also studied by cyclic voltammograms (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results show that the use of templates with different dimensions significantly influences the morphology, pore structure, SSA and electrochemical performance of the synthesized hybrid dimensional porous carbon. The hybrid dimensional porous carbon (3F) exhibits a high specific capacitance and excellent cycling stability. 3F demonstrates the specific capacitance of 245.3 F g-1 at 1 A g-1. Furthermore, the capacity retention rate remains as high as 93.4% after 8000 cycles at 10 A g-1. This work reveals that hybrid dimensional porous carbon composed of 1D hollow carbon tubes and 2D carbon nanosheets has great potential for use in supercapacitor electrode materials.

A nanoelectrode of hybrid nanomaterials of palladium oxide with cadmium sulfide based on 2D-carbon nanosheets for developing electron transfer efficiency for supercapacitor applications

A layered nanoelectrode design was based on the high surface area of graphene oxide and reduced graphene oxide; these layers were decorated with n/p-type palladium oxide nanoparticles (NPs) and cadmium sulfide NPs.

The synergy of Co-MoN-MgO on 2D carbon sheets for effective catalytic hydrogenation

The Co-based materials are the promising catalysts for the catalytic hydrogenation reactions. The optimization of the electronic structure and micro-morphology to achieve like-noble-metal catalysis is a current research hotspot. Here, the Co-MoN-MgO heterojunctions embedded on 2D carbon nanosheets (Co-MoN-MgO/C) were designed in a melt-salt system for efficient catalytic hydrogenation of the nitro-compounds. The tests show the intimate contact of Co with MoN, realizing effective synergy for promoting the electrons transfer from Co to MoN. The transfer optimizes the electronic structure of Co components, being favorable for the adsorption/desorption of intermediates and catalytic hydrogenation reaction. The 2D porous structure gives enhanced mass-transfer ability and large accessible surface for better contact with the reactants. Above features endow Co-MoN-MgO/C with good catalytic activity for p-nitrophenol (4-NP) hydrogenation, with a reaction rate constant k of 0.41 min−1 (10 °C), which is 2.73 times greater than Co-MgO/C catalyst (0.15 min−1) and even better than some reported noble-metal catalysts. Furthermore, the catalyst shows good cycling stability with no obvious deactivation after 10 cycles and obvious catalytic activity for a series of nitro-compounds. This work has important implications for the design of efficient non-noble-metal synergistic catalyst for the effective catalytic hydrogenation.