Nitrogen-functionalized Carbon Research Articles

Green transformation of biomass-derived Indian gooseberry into fluorescent intrinsic nitrogen-functionalized carbon quantum dots for real-time detection of vitamin B2 in the nanomolar range

Selective and specific detection of vitamin B2 with a fluorescent nanoprobe synthesized using a green methodology.

Alginate based films integrated with nitrogen-functionalized carbon dots and layered clay for active food packaging applications

The applications of alginate derived from seaweed polysaccharide in food packaging are restricted due to their inherent deficient antibacterial, antioxidant and UV barrier properties. In this study, nitrogen-functionalized carbon dots (NCDs) with active functions (0.5–3 %) and layered clay (1 %) with barrier property were introduced to construct alginate based active films via solution casting method. The results showed that the synthesized spherical NCDs had a particle size of 2–3 nm, and the internal structure of NCDs was similar to graphene, with a large number of active groups (-NH2, -OH, etc.) on the surface. Infrared analysis revealed that NCDs could form strong hydrogen bonds with alginate matrix, which slowed down the deterioration of mechanical properties and reduced the surface wettability. With the addition of NCDs, active functions and surface hydrophobicity of the active films were enhanced significantly (P < 0.05). When the amount of NCDs reached 3 %, UV barrier, antioxidant and antibacterial properties of the active films were increased by 50.0 %, 61.1 % and 70.1 %, respectively. The addition of NCDs could enhance the anti-browning ability of alginate based coatings and extend the shelf life of banana significantly. Therefore, a suitable amount of NCDs (1–2 %) and layered clay (1 %) can synergistically improve comprehensive performance of alginate based films and promote their food packaging application used as active films/inner coatings.

Carbon Nanodots as Electron Transport Materials in Organic Light Emitting Diodes and Solar Cells.

Charge injection and transport interlayers play a crucial role in many classes of optoelectronics, including organic and perovskite ones. Here, we demonstrate the beneficial role of carbon nanodots, both pristine and nitrogen-functionalized, as electron transport materials in organic light emitting diodes (OLEDs) and organic solar cells (OSCs). Pristine (referred to as C-dots) and nitrogen-functionalized (referred to as NC-dots) carbon dots are systematically studied regarding their properties by using cyclic voltammetry, Fourier-transform infrared (FTIR) and UV-Vis absorption spectroscopy in order to reveal their energetic alignment and possible interaction with the organic semiconductor's emissive layer. Atomic force microscopy unravels the ultra-thin nature of the interlayers. They are next applied as interlayers between an Al metal cathode and a conventional green-yellow copolymer-in particular, (poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1',3}-thiadiazole)], F8BT)-used as an emissive layer in fluorescent OLEDs. Electrical measurements indicate that both the C-dot- and NC-dot-based OLED devices present significant improvements in their current and luminescent characteristics, mainly due to a decrease in electron injection barrier. Both C-dots and NC-dots are also used as cathode interfacial layers in OSCs with an inverted architecture. An increase of nearly 10% in power conversion efficiency (PCE) for the devices using the C-dots and NC-dots compared to the reference one is achieved. The application of low-cost solution-processed materials in OLEDs and OSCs may contribute to their wide implementation in large-area applications.

Nitrogen-functionalized carbon nanotube based palladium nanoparticles as an efficient catalyst for oxygen reduction and ethanol oxidation reaction

In this report, we have synthesized nitrogen-functionalized carbon nanotube (NCNT) supported palladium nanoparticles (NCNT-Pd) by using facile chemical reduction method at room temperature. This material has been used as electrocatalyst for electrochemical oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR). In the case of ORR, NCNT-Pd shows more positive onset potential, higher current density, as well as superior methanol tolerance and long term durability compared with the 20% commercial Pt/C catalyst. Moreover, NCNT-Pd exhibits enhanced catalytic activity for EOR with more negative onset potential and higher current density. The current density of NCNT-Pd for EOR is 2.54 and 5.2 times higher than that of CNT-Pd and 10% Pd/C, respectively. Due to nitrogen functionalization and synergetic effect between NCNT and Pd, NCNT-Pd exhibits superior catalytic performance in ethanol oxidation and oxygen reduction reactions.

Cellulose nanofiber-based coating film integrated with nitrogen-functionalized carbon dots for active packaging applications of fresh fruit

Carbon dots were synthesized using a hydrothermal method with glucose as the carbon source (GCD) and functionalized with nitrogen. The GCD and N-functionalized carbon dots (NGCD) were used to prepare cellulose nanofiber (CNF)-based composite films. GCD and NGCD provided high UV blocking properties to the CNF film without changing the transparency, reducing the T280 by 91–98 % and T660 by 12−10 %. The addition of GCD and NGCD did not affect the mechanical properties but increased the film's water vapor permeability (WVP) and water contact angle (WCA). The composite films also showed high antioxidant activity with 99−99 % of ABTS and 80–85 % of DPPH radical scavenging activities. The CNF-based films with GCD generated reactive oxygen species (ROS) to exhibit high antimicrobial activity; however, the CNF/NGCD film showed stronger antibacterial and antifungal activity than the CNF/GCD film. In addition, the CNF-based films incorporated with GCDs showed negligible cytotoxicity. When tangerine and strawberry fruit were coated with the CNF-based coating solutions, the fruit coated with CNF/NGCD inhibited fungal growth on the fruit surface, extending their shelf life by more than 10 and 2 d, respectively. The CD-added CNF films with high antioxidant, antimicrobial, and low cytotoxicity are likely to be used for antifungal coating of fresh fruit and active packaging applications.

Nitrogen Tailored Activated Carbon via Microwave Synthesis Method for High Removal of Hydrogen Sulfide

In this work, commercialized palm shell activated carbon was modified into nitrogen-functionalized carbon via urea impregnation method, followed by heat treatment via microwave irradiation at 950 °C.

Physicochemical Properties and Low Relative Humidity Fuel Cell Performance of Pt/ECSTM Catalysts

The maturity of the current polymer electrolyte membrane fuel cells (PEMFCs) has been product of the considerable scientific and industrial effort devoted to developing highly efficient and reliable versions of this technology, resulting in its increased application in the transportation and energy generation sectors. Fuel cells are one of the most advantageous solutions for clean energy applications due to their near-zero-emission, high efficiency, low maintenance cost, and high energy density. PEMFCs produce electricity through the electrochemical reaction of hydrogen and oxygen (or air) taking place in the Membrane Electrode Assembly (MEA) by converting chemical energy of the hydrogen oxidation and oxygen reduction into electrical energy with water as a byproduct. However, producing oxygen reduction reaction (ORR) catalysts with high performance at scale is still a challenge that needs to be tackled to enable an increment in energy generation of this technology. Additionally, tunability of the materials at the core of this technology is essential to meet the demands of the specific application and operating conditions. Here we investigate commercially available ORR catalysts based on platinum nanoparticles (Pt-NPs) supported on nitrogen-functionalized carbon (Engineered Carbon SupportsTM, ECSTM) produced by Pajarito Powder, LLC at scale. The ORR performance of three MEAs made with different Pt/ECS catalysts, by IRD Fuel Cells, LLC was studied under low relative humidity conditions, exhibiting competitive performance, and reaching current densities between 1.8 and 1.3 A/cm2 at 0.6 V, at extremely low loading of Pt – 0.1 mgPt cm-2. The physicochemical properties of these Pt/ECS catalysts alongside their Pt-free ECSTM analogue carbon support materials were comprehensively studied. For this purpose, several characterization techniques were used, such: X-ray diffraction, Raman spectroscopy, and transmission electron microscopy (TEM) to investigate structural and morphological properties, X-ray photoelectron spectroscopy to determine the surface composition and chemical properties, thermogravimetric analysis to evaluate thermal oxidation properties, and nitrogen sorption to determine the surface area and porosity, of the materials. This thorough characterization enabled us to determine that the best performing catalyst in the conditions used in this work have the highest surface area and the highest concentration of surface dopants (nitrogen and oxygen). Although, catalyst supported on lower surface area carbon, but with higher graphitic content, also exhibited competitive performance that can be exploited in applications where more corrosion-resistant carbon is needed. Finally, based on the highly competitive MEA performance for the three Pt/ECS catalysts supported on these carbons, our work demonstrates that these carbon supports (developed by Pajarito Powder, LLC) with engineered morphology and composition fabricated through VariPoreTM synthetic technology can result in tunable properties suitable for a targeted application. We can conclude that these commercially available materials can be adapted through modification of the versatile synthesis platform to tune the physiochemical properties of carbons for other applications and conditions.

Cyan color-emitting nitrogen-functionalized carbon nanodots (NFCNDs) from Indigofera tinctoria and their catalytic reduction of organic dyes and fluorescent ink applications.

The present study reports the synthesis of nitrogen-functionalized carbon nanodots (NFCNDs) by a low-cost hydrothermal method using the leaf extract of Indigofera tinctoria as a novel carbon precursor. The synthesized NFCNDs were characterized by diverse spectroscopic techniques. The optical properties of N-CNDs were analyzed by UV-visible and fluorescence spectroscopic studies. The quantum yield (QY) for the prepared NFCNDs was found to be 12.6%. The surface morphology, functional groups, and crystallinity of NFCNDs were evaluated by HR-TEM, FT-IR, XRD and Raman spectroscopic methods, respectively. The Raman results revealed the moderate graphite structure of NFCNDs, and the calculated ID/IG value was 0.49. The spherical appearance of the synthesized NFCNDs was confirmed by HR-TEM, and the calculated size of the NFCNDs was 4 nm. The XRD and SAED pattern results gives an evidence for the amorphous nature of the prepared NFCNDs. The thermal stability of NFCNDs was studied by TGA analysis. The resulting NFCNDs acted as a green nanocatalyst and thus efficiently improved the reducing capability of sodium borohydride (NaBH4) in the catalytic reduction of methylene blue (MB) and methyl orange (MO) dyes. Furthermore, the bright cyan emission characteristics of synthesized NFCNDs were utilized as a labeling agent in anti-counterfeiting applications.

Nitrogen-functionalized carbon nanotube-supported bimetallic PtNi nanoparticles for hydrogen generation from hydrous hydrazine.

Herein, ultrafine PtNi nanoparticles (NPs) supported on N-functionalized multi-walled carbon nanotubes (N-MWCNTs) were facilely obtained. The N species on N-MWCNTs not only benefit the formation of PtNi NPs but also accelerate the dehydrogenation of hydrous hydrazine, affording a high turnover frequency of 1595 h-1 with 100% H2 selectivity. In addition, the N species can be used as an "anchor" to stabilize the bimetallic NPs and efficiently restrain the aggregation, giving robust stability of the catalysts for decomposition of hydrous hydrazine over PtNi/N-MWCNTs.

Tracking Nafion Evolution in a Humidified Environment through Near-Ambient Pressure X-Ray Photoelectron Spectroscopy

Near ambient pressure X-ray photoelectron spectroscopy (nAP-XPS) affords unparalleled insight into the physicochemical processes that drive electrocatalytic devices.1 Studies featuring nAP-XPS span a broad range of materials and reactions, with many focused on thin films or other well-defined materials. Experiments featuring a water vapor atmosphere, or a humidified atmosphere (often with O2 or H2 as the other vapor component) have been effectively used to study the fundamentals of the electrocatalytic reactions occurring in polymer electrolyte membrane fuel cells and water electrolyzers (PEMFCs and PEMWEs).2,3 However, many of these studies have solely focused on the interaction between gas and catalyst, even if ionomer was also present within the catalyst layer. This talk focuses on the investigation of the evolution of ionomer species, and the catalyst-ionomer interface under conditions relevant to the operation of PEM devices.Analyzing the catalytically relevant surfaces and interfaces present in PEMFC and PEMWE electrodes with nAP-XPS is a complex challenge, due in part to the subtlety of the changes induced in nAP-XP spectra by interactions between the catalyst, ionomer, and gas. Adsorption of a gaseous reactant species onto a catalyst’s surface results in a weak interaction and a small chemical shift in the adsorbent species,5 while ionomer may undergo protonation, re-orientation or degradation upon exposure to reactants, also altering the spectra. Indeed, few studies feature XPS measurements of Nafion, as it has been shown to degrade over the course of standard XPS operation.6 This issue is likely exacerbated through the use of much more intense synchrotron radiation sources most commonly used for nAP-XPS experiments in the literature. Within this work, we present an evaluation of the degree of Nafion degradation during our measurements using a unique Scienta Omicron HiPP-3 nAP-XPS system, and the results of an approach to data collection developed to mitigate the induced damage. This enables the reliable study of both Nafion films and Nafion present within platinum-catalyst based PEMFC cathodes in a water vapor atmosphere using a laboratory-based, commercially available nAP-XPS system. This work lays the foundation for future study of different classes of electrocatalysts at the electrode scale, with the goal of deconvoluting complex changes at the electrode surfaces and interfaces, both in inert and catalytically relevant environments.(1) Starr, D. E.; Liu, Z.; Hävecker, M.; Knop-Gericke, A.; Bluhm, H. Investigation of Solid/Vapor Interfaces Using Ambient Pressure X-Ray Photoelectron Spectroscopy. Chem. Soc. Rev. 2013, 42, 5833–5857.(2) Yamamoto, S.; Bluhm, H.; Andersson, K.; Ketteler, G.; Ogasawara, H.; Salmeron, M.; Nilsson, A. In Situ X-Ray Photoelectron Spectroscopy Studies of Water on Metals and Oxides at Ambient Conditions. J. Phys. Condens. Matter 2008, 20 (18).(3) Casalongue, H. S.; Kaya, S.; Viswanathan, V.; Miller, D. J.; Friebel, D.; Hansen, H. A.; Nørskov, J. K.; Nilsson, A.; Ogasawara, H. Direct Observation of the Oxygenated Species during Oxygen Reduction on a Platinum Fuel Cell Cathode. Nat. Commun. 2013, 4.(4) Saveleva, V. A.; Savinova, E. R. Insights into Electrocatalysis from Ambient Pressure Photoelectron Spectroscopy. Curr. Opin. Electrochem. 2019, 17, 79–89.(5) Dzara, M. J.; Artyushkova, K.; Shulda, S.; Strand, M. B.; Ngo, C.; Crumlin, E. J.; Gennett, T.; Pylypenko, S. Characterization of Complex Interactions at the Gas − Solid Interface with in Situ Spectroscopy : The Case of Nitrogen-Functionalized Carbon. J. Phys. Chem. C 2019, 123 (14), 9074–9086.(6) Paul, D. K.; Giorgi, J. B.; Karan, K. Chemical and Ionic Conductivity Degradation of Ultra-Thin Ionomer Film by X-Ray Beam Exposure. J. Electrochem. Soc. 2013, 160 (4), F464–F469.

Optimization of PGM-free cathodes for oxygen reduction in microbial fuel cells

Iron-nitrogen-carbon catalyst based on iron phthalocyanine supported on nitrogen-functionalized carbon black pearls (FeBP(N)) was integrated into gas diffusion layer electrodes by hot pressing and tested at the cathode side of microbial fuel cells (MFC). As highlighted by I-V characteristics, peak power density decreased over time during MFC functioning. This was caused by an increase of charge and mass transfer resistances of the oxygen reduction reaction due to a biofilm accumulation at the cathode interface, as revealed by electrochemical impedance spectra of the cathodes. Monitoring the peak power density retention over time demonstrated that kinetic and diffusional limitations of ORR at the cathode side of operating MFCs can be minimized by tuning the hot pressing parameters, thus optimizing the cathode interface. In fact, MFCs assembled with cathode obtained by using T = 120 °C and p = 2 MPa as hot pressing parameters allowed achieving the highest performance in terms of peak power density (206.1 ± 10.3 μWcm−2) and peak power retention over 100 days MFC operation (77%), as compared to the cathode prepared with different hot pressing parameters and Pt-based cathodes taken as reference.

(Invited) Ambient Pressure X-Ray Photoelectron Spectroscopy of Electrochemical Systems

Ambient pressure X-ray photoelectron spectroscopy (AP-XPS) enables investigation of surfaces and interfaces under in-situ and in-operando conditions providing improved fundamental understanding of the physicochemical processes that occur during industrially relevant catalytic reactions and operation of electrochemical devices.1–4 Combining traditional ex situ characterization methods, performance testing, and in-situ diagnostics with AP-XPS studies yields a more comprehensive understanding of both catalyst and electrode properties, and their evolution during operation of electrochemical devices. While many AP-XPS studies of electrocatalytically active materials focus on thin films or other model/well-studied materials,5 it is critical to investigate more complex systems.6 This is particularly important to advance the understanding of surfaces and interfaces in low temperature polymer electrolyte membrane devices, such as electrolyzers and fuel cells. In these systems, multiple interfaces exist between the catalyst, support, ionomer, and other additives, in addition to the presence of gas reactant(s). Studies of such complex systems necessitate holistic approaches to data analysis in conjunction with multi-technique studies. Progress has been made on this front,7 however there are still many additional experimental and analytical considerations. This talk will discuss a variety of challenges in collecting and analyzing AP-XPS data towards the goal of better understanding gas-solid interfaces in electrochemical devices. This includes sample preparation and necessary processing steps prior to XPS measurements, conditions during XPS data acquisition, and approaches to data analysis of these complex systems. Additional considerations for experiments on electrodes/composites, as opposed to just a catalyst material will be discussed. (1) Bluhm, H.; Hävecker, M.; Knop-Gericke, A.; Kiskinova, M.; Schlögl, R.; Salmeron, M. In Situ X-Ray Photoelectron Spectroscopy Studies of Gas-Solid Interfaces at near-Ambient Conditions. MRS Bull. 2007, 32 (12), 1022–1030. (2) Crumlin, E. J.; Bluhm, H.; Liu, Z. In Situ Investigation of Electrochemical Devices Using Ambient Pressure Photoelectron Spectroscopy. J. Electron Spectros. Relat. Phenomena 2013, 190, 84–92. (3) Starr, D. E.; Liu, Z.; Hävecker, M.; Knop-Gericke, A.; Bluhm, H. Investigation of Solid/Vapor Interfaces Using Ambient Pressure X-Ray Photoelectron Spectroscopy. Chem. Soc. Rev. 2013, 42, 5833–5857. (4) Stoerzinger, K. A.; Hong, W. T.; Crumlin, E. J.; Bluhm, H.; Shao-Horn, Y. Insights into Electrochemical Reactions from Ambient Pressure Photoelectron Spectroscopy. Acc. Chem. Res. 2015, 48 (11), 2976–2983. (5) Liu, Q.; Han, Y.; Cai, J.; Crumlin, E. J.; Li, Y.; Liu, Z. CO2 Activation on Cobalt Surface in the Presence of H2O: An Ambient- Pressure X-Ray Photoelectron Spectroscopy Study. Catal. Letters 2018, 148 (6), 1686–1691. (6) Artyushkova, K.; Matanovic, I.; Halevi, B.; Atanassov, P. Oxygen Binding to Active Sites of Fe–N–C ORR Electrocatalysts Observed by Ambient-Pressure XPS. J. Phys. Chem. C 2017, 121, 2836–2843. (7) Dzara, M. J.; Artyushkova, K.; Shulda, S.; Strand, M. B.; Ngo, C.; Crumlin, E. J.; Gennett, T.; Pylypenko, S. Characterization of Complex Interactions at the Gas − Solid Interface with in Situ Spectroscopy : The Case of Nitrogen-Functionalized Carbon. J. Phys. Chem. C 2019, 123 (14), 9074–9086.

Pharmaceuticals and personal care products removal from aqueous solution by nitrogen-functionalized carbon adsorbent derived from pomelo peel waste

The aim of this work is to investigate the feasibility of the preparation of nitrogen-functionalized adsorbent material from waste pomelo peel by using diammonium hydrogen orthophosphate (DAP) activation for the removal of Pharmaceuticals and personal care products (PPCPs) such as carbamazepine (CBZ), clofibric acid (CFA) and oxytetracycline (OTC). Our results showed that the adsorbent prepared by chemical activation in the presence of DAP lead to mesoporous material. The adsorbent exhibits acid and basic groups at its porous surface. The kinetic data are found to follow a pseudo-second order kinetic model. The Langmuir model provided a good description of the experimental isotherms for CBZ, whereas CFA and OTC adsorption behavior rather follow the Freundlich model. Moreover, the PPCPs adsorption was found to be strongly dependent on the pH of solution as well as the pKa of both adsorbents and PPCPs. The strong adsorptive interaction between PPCPs and P-DAP was mainly attributed to the combination interactions of electrostatic interaction, hydrogen bonding and π-π interactions.

Characterization of Complex Interactions at the Gas–Solid Interface with in Situ Spectroscopy: The Case of Nitrogen-Functionalized Carbon

Interactions at the gas–solid interface drive physicochemical processes in many energy and environmental applications; however, the challenges associated with characterization and development of these dynamic interactions in complex systems limit progress in developing effective materials. Therefore, structure–property–performance correlations greatly depend on the development of advanced techniques and analysis methods for the investigation of gas–solid interactions. In this work, adsorption behavior of O2 and humidified O2 on nitrogen-functionalized carbon (N–C) materials was investigated to provide a better understanding of the role of nitrogen species in the oxygen reduction reaction (ORR). N–C materials were produced by solvothermal synthesis and N-ion implantation, resulting in a set of materials with varied nitrogen amount and speciation in carbon matrices with different morphologies. Adsorption behavior of the N–C samples was characterized by in situ diffuse reflectance infrared Fourier-transform ...

Improved Oxygen Reduction Activity of Transition Metal-Chelating Ordered Mesoporous Carbon Fuel Cell Catalysts by Milder Template Removal

In the synthesis of iron-chelating ordered mesoporous nitrogen-functionalized carbon (Fe–OMC) catalysts, the removal of the silica template is a crucial and critical step. The silica removal method used today for the Fe–OMCs is based on the very toxic hydrofluoric acid (HF), which usage should be limited where possible. Therefore, the aim of this study is to establish a mild (user-friendly), yet efficient, etch method based on dilute sodium hydroxide (NaOH), which does not impair the catalytic performance of the catalyst, to replace the currently used HF method. A comparison between catalysts etched with HF versus NaOH was performed in order to gain understanding how the two etch methods influence the final catalysts in terms of electrochemical, structural and catalytic properties. The NaOH etch was found to successfully remove the silica template, and interestingly, also improve the catalytic performance. The improved activity is explained by a carbon activation process occurring in the catalyst treated with the NaOH etch. With these findings, we show that it is possible to remove the silica in a more user-friendly way and simultaneously increase the catalysts’ performance by activation of the carbon.Graphical

Ultrafine and monodispersed iridium nanoparticles supported on nitrogen-functionalized carbon: an efficient oxidase mimic for glutathione colorimetric detection.

Ultrafine and monodispersed iridium nanoparticles supported on nitrogen-functionalized carbon materials (Ir/NC) were prepared and served as an efficient oxidase mimic for 3',5,5'-tetramethylbenzidine (TMB) oxidation. Due to the inhibition effect of glutathione (GSH) on TMB oxidation, a sensitive colorimetric GSH detection approach was proposed.

Oxidative Deposition of Manganese Oxide Nanosheets on Nitrogen-Functionalized Carbon Nanotubes Applied in the Alkaline Oxygen Evolution Reaction.

The development of nonprecious catalysts for water splitting into hydrogen and oxygen is one of the major challenges to meet future sustainable fuel demand. Herein, thin layers of manganese oxide nanosheets supported on nitrogen-functionalized carbon nanotubes (NCNTs) were formed by the treatment of NCNTs dispersed in aqueous solutions of KMnO4 or CsMnO4 under reflux or under hydrothermal (HT) conditions and used as electrocatalysts for the oxygen evolution reaction (OER) in alkaline media. The samples were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Our results show that the NCNTs treated under reflux were covered by partly amorphous and birnessite-type manganese oxides, while predominantly crystalline birnessite manganese oxide was observed for the hydrothermally treated samples. The latter showed, depending on the temperature during synthesis, an electrocatalytically favorable reduction from birnessite-type MnO2 to γ-MnOOH. OER activity measurements revealed a decrease of the overpotential for the OER at a current density of 10 mA cm–2 from 1.70 VRHE for the bare NCNTs to 1.64 VRHE for the samples treated under reflux in the presence of KMnO4. The hydrothermally treated samples afforded the same current density at a lower potential of 1.60 VRHE and a Tafel slope of 75 mV dec–1, suggesting that the higher OER activity is due to γ-MnOOH formation. Oxidative deposition under reflux conditions using CsMnO4 along with mild HT treatment using KMnO4, and low manganese loadings in both cases, were identified as the most suitable synthetic routes to obtain highly active MnOx/NCNT catalysts for electrochemical water oxidation.

Catalytic transfer hydrogenation of bio-based furfural by palladium supported on nitrogen-doped porous carbon

Highly porous carbon was prepared via a zeolite hard templating route. Subsequent melamine treatment produced nitrogen-functionalized carbon (NPC), which was used as a support to anchor Pd nanoparticles (Pd/NPC) of sizes 2–4 nm using the chemical reduction method. Various analytical techniques were used to characterize the textural properties, structure, and chemical nature of the catalyst. Pd/NPC was then employed as a catalyst for the transfer hydrogenation of biomass-derived furfural (FF) to furfuryl alcohol (FFA) with alcohol as a hydrogen donor, and the effect of temperature, hydrogen donor species, reaction time, and catalysts loading were investigated. The Pd/NPC catalyst was reusable up to five times without any apparent loss of its activity and selectivity. A possible mechanistic pathway for the catalytic transfer hydrogenation of FF over Pd/NPC catalyst was proposed.

Size and Electronic Modulation of Iridium Nanoparticles on Nitrogen-Functionalized Carbon toward Advanced Electrocatalysts for Alkaline Water Splitting.

Developing efficient catalytic materials for electrochemical water splitting is important. Herein, uniformly dispersed and size-controllable iridium (Ir) nanoparticles (NPs) were prepared using a nitrogen-functionalized carbon as the support (Ir/CN). We found that nitrogen functionalization can simultaneously modulate the size of Ir NPs to substantially enhance the catalytically active sites and adjust the electronic structure of Ir, thereby promoting electrocatalytic activity for water splitting. Consequently, the as-synthesized Ir/CN shows excellent electrocatalytic performance with overpotentials of 12 and 265 mV for hydrogen and oxygen evolution reactions in basic medium, respectively. These findings may pave the way for designing and synthesizing other similar materials as efficient catalysts for electrochemical water splitting.

Removal of Cd2+ and Hg2+ from aqueous solutions by adsorption onto nitrogen-functionalized carbon nanotubes

Removal of Cd2+ and Hg2+ from aqueous solutions by adsorption onto nitrogen-functionalized carbon nanotubes