氮掺杂碳纳米管负载Co_(3)O_(4)氧还原电催化剂的制备与性能

以碳纳米管(CNT)为原料,通过负载维生素B12,简单热解得到了一种氮掺杂碳纳米管(N/CNT)负载低含量Co_(3)O_(4)纳米颗粒的氧还原电催化剂(Co_(3)O_(4)@N/CNT)。得益于均匀分散的Co_(3)O_(4)纳米颗粒以及氮掺杂,Co_(3)O_(4)@N/CNT表现出了优异的氧还原催化性能,其半波电位达到了0.844 V(vs RHE),超越了商业Pt/C(0.820 V(vs RHE))。与Pt/C相比,基于Co_(3)O_(4)@N/CNT组装的锌-空气电池表现出了更优的放电性能和循环稳定性。

Effect of Temperature on the Reaction of 2-(N-acetylamine)-3-(3,5-di-<i>tert</i>-butyl-4-hydroxyphenyl)-propionic Acid with Oxygen in an Alkaline Condition

Results of oxidation 2-(N-acetylamine)-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid oxygen depend on temperature. At 55℃?- 60℃, 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa is formed. The constitution is based on dates of spectrums 1Н and 13С NMR. At 95℃?- 97℃, mixtures of 2,4-di-tert-butylbicyclo(4,3,1)deca-4,6-dien-8-(N-acetylamine)-3,9-dion-1-oxa and of 6,8-di-tert-butyl-3-(N-acetylamine)spiro(4,5)deca-1-oxa-5,8-dien-2,7-dione are produced. Structures are calculated by the method of Hartrii-Foka. Values of enthalpies and of entropies allow to assume dynamic isomerism.

Generation and transformation of ROS on g-C_3N_4 for efficient photocatalytic NO removal:A combined in situ DRIFTS and DFT investigation

Understanding the performance of reactive oxygen species(ROS)in photocatalysis is pivotal for advancing their application in environmental remediation.However,techniques for investigating the generation and transformation mechanism of ROS have been largely overlooked.In this study,considering g‐C3N4 to be a model photocatalyst,we have focused on the ROS generation and transformation for efficient photocatalytic NO removal.It was found that the key to improving the photocatalysis performance was to enhance the ROS transformation from·O2^-to·OH,elevating the production of·OH.The ROS directly participate in the photocatalytic NO removal and tailor the rate‐determining step,which is required to overcome the high activation energy of the intermediate conversion.Using a closely combined experimental and theoretical method,this work provides a new protocol to investigate the ROS behavior on g‐C3N4 for effective NO removal and clarifies the reaction mechanism at the atomic level,which enriches the understanding of ROS in photocatalytic environmental remediation.

Pd nanoparticles embedded in N-Enriched MOF-Derived architectures for efficient oxygen reduction reaction in alkaline media

Developing high efficient Pd-based electrocatalysts for oxygen reduction reaction(ORR) is still challenging for alkaline membrane fuel cell,since the strong oxygen adsorption energy and easy agglomerative intrinsic properties. In order to simultaneously solve these problems, Pd/Co_(3)O_(4)–N–C multidimensional materials with porous structures is designed as the ORR catalysts. In details, the ZIF-67 with polyhedral structure was firstly synthesized and then annealed at high-temperature to prepare the N-doped Co_(3)O_(4)carbon-based material, which was used to homogeneously confine Pd nanoparticles and obtained the Pd/Co_(3)O_(4)–N–C series catalysts. The formation of Co–N and C–N bond could provide efficient active sites for ORR. Simultaneously, the strong electronic interaction in the interface between the Pd and N-doped Co_(3)O_(4)could disperse and avoid the agglomeration of Pd nanoparticles and ensure the exposure of active sites, which is crucial to lower the energy barrier toward ORR and substantially enhance the ORR kinetics. Hence, the Pd/Co_(3)O_(4)–N–C nanocompounds exhibited excellent ORR catalytic performance, ideal Pd mass activity, and durability in 0.1 mol L-1KOH solution compared with Co_(3)O_(4)–N–C and Pd/C. The scalable synthesis method, relatively low cost, and excellent electrochemical ORR performance indicated that the obtained Pd/Co_(3)O_(4)–N–C electrocatalyst had the potential for application on fuel cells.

N‐doped porous carbon nanofibers inlaid with hollow Co_(3)O_(4) nanoparticles as an efficient bifunctional catalyst for rechargeable Li‐O_(2) batteries

Stable and high‐efficiency bifunctional catalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desired for the practical application of Li‐O_(2)batteries with excellent rate performance and cycle stability.Herein,a novel hybrid bifunctional catalyst with carbon nanofibers inlaid with hollow Co_(3)O_(4)nanoparticles and separate active sites for ORR and OER were prepared and applied in Li‐O_(2)batteries.Benefiting from the synergistic effect of unique porous structural features and high electrocatalytic activity of hollow Co3O4 intimately bound to N‐doped carbon nanofibers,the assembled Li‐O_(2)batteries with novel catalyst exhibited high specific capacity,excellent rate capability,and cycle stability up to 150 cycles under a capacity limitation of 500 mAh g^(–1)at a current density of 100 mA g^(–1).The facile synthesis and preliminary results in this work show the as‐prepared catalyst as a promising bifunctional electrocatalyst for applications in metal‐air batteries,fuel cells,and electrocatalysis.

Introducing B–N unit boosts photocatalytic H_(2)O_(2) production on metal-free g-C_(3)N_(4)nanosheets

Metal-free catalyst for photocatalytic production of H_(2)O_(2)is highly desirable with the long-term vision of artificial photosynthesis of solar fuel.In particular,the specific chemical bonds for selective H_(2)O_(2)photosynthesis via 2e–oxygen reduction reactions(ORR)remain to be explored for understanding the forming mechanism of active sites.Herein,we report a facile doping method to introduce boron-nitrogen(B–N)bonds into the structure of graphitic carbon nitride(g-C_(3)N_(4))nanosheets(denoted as BCNNS)to provide significant photocatalytic activity,selectivity and stability.The theoretical calculation and experimental results reveal that the electron-deficient B–N units serving as electron acceptors improve photogenerated charge separation and transfer.The units are also proved to be superior active sites for selective O_(2)adsorption and activation,reducing the energy barrier for*OOH formation,and thereby enabling an efficient 2e–ORR pathway to H_(2)O_(2).Consequently,with only bare loss of activity during repeated cycles,the optimal H2O2 production rate by BCNNS photocatalysts reaches 1.16 mmol·L^(–1)·h^(–1)under 365 nm-monochrome light emitting diode(LED365nm)irradiation,increasing nearly 2–5 times as against the state-of-art metal-free photocatalysts.This work gives the first example of applying B–N bonds to enhance the photocatalytic H_(2)O_(2)production as well as unveiling the underlying reaction pathway for efficient solar-energy transformations.

2D nanoplate assembled nitrogen doped hollow carbon sphere decorated with Fe3O4 as an efficient electrocatalyst for oxygen reduction reaction and Zn-air batteries

Designing a highly efficient non-precious based oxygen reduction reaction(ORR)electrocatalyst is critical for the commercialization of various sustainable energy storage and conversion devices such as metal-air batteries and fuel cells.Herein,we report a convenient strategy to synthesis Fe3O4 embedded in N doped hollow carbon sphere(NHCS)for ORR.What's interesting is that the carbon microsphere is composed of two-dimensional(2D)nanoplate that could provide more exposed active sites.The usage of solid ZnO nanowires as zinc source is crucial to obtain this structure.The Fe3O4@NHCS-2 exhibits better catalytic activity and durability than the commercial PtC catalyst.Moreover,it further displays high-performance of Zn-air batteries as a cathode electrocatalyst with a high-power density of 133 mW·cm^-2 and high specific capacity of 701 mA·h·g^-1.The special hollow structure composed 2D nanoplate,high surface area,as well as synergistic effect between the high active Fe3O4 nanoparticles and N-doped matrix endows this outstanding catalytic activity.The work presented here can be easily extended to prepare metal compounds decorated carbon nanomaterials with special structure for a broad range of energy storage and conversion devices.

Enhanced CH4 selectivity in CO2 photocatalytic reduction over carbon quantum dots decorated and oxygen doping g-C3N4

Graphitic carbon nitride(g-C3N4,CN)exhibits inefficient charge separation,deficient CO2 adsorption and activation sites,and sluggish surface reaction kinetics,which have been recognized as the main barriers to its application in CO2 photocatalytic reduction.In this work,carbon quantum dot(CQD)decoration and oxygen atom doping were applied to CN by a facile one-step hydrothermal method.The incorporated CQDs not only facilitate charge transfer and separation,but also provide alternative CO2 adsorption and activation sites.Further,the oxygen-atom-doped CN(OCN),in which oxygen doping is accompanied by the formation of nitrogen defects,proves to be a sustainable H^+ provider by facilitating the water dissociation and oxidation half-reactions.Because of the synergistic effect of the hybridized binary CQDs/OCN addressing the three challenging issues of the CN based materials,the performance of CO2 photocatalytic conversion to CH4 over CQDs/OCN-x(x represents the volume ratio of laboratory-used H2O2(30 wt.%)in the mixed solution)is dramatically improved by 11 times at least.The hybrid photocatalyst design and mechanism proposed in this work could inspire more rational design and fabrication of effective photocatalysts for CO2 photocatalytic conversion with a high CH4 selectivity.

Sonochemical Synthesis of Two Dimensional C3N4 Nanosheets Supported Palladium Composites and Their Electrocatalytic Activity for Oxygen Reduction and Methanol Oxidation Reaction

The preparation of highly active electrocatalysts with good durability and low cost for fuel cells is highly desir- able but still remains a significant challenge. Here we synthesized two dimensional （2D） C3N4 nanosheets supported palladium composites （C3N4/Pd） via a simple and convenient sonochemical approach. We have systematically stud- ied the electrocatalytic performance of as-prepared catalysts. We found that the prepared C3N4/Pd composites pos- sessed excellent catalytic activity and stability for oxygen reduction reaction （ORR） in alkaline media. Encourag- ingly, the C3N4/Pd catalysts exhibit the excellent electrocatalytic activity for methanol oxidation reaction （MOR） in alkaline media, even better than that of the commercial Pt/C catalyst, The excellent electrocatalytic performance of the 2D C3N4 nanosheets supported palladium composites catalysts results from their synergy effect between the ul- trathin substrate material with large surface area and excellent dispersion of palladium nanoparticles. This study demonstrates that sonochemical method opens up a new avenue for the preparation of electrocatalysts for fuel cells. We expect these materials are likely to find uses in a broad range of applications, for example, fuel cells, solar cells, batteries and other electrochemical analysis.

Synthesis of graphitic carbon nitride through pyrolysis of melamine and its electrocatalysis for oxygen reduction reaction

Received 2 December 2012 Received in revised form 26 December 2012 Accepted 31 December 2012 Available online 4 February 2013

Visible-light-driven enhanced antibacterial and biofilm elimination activity of graphitic carbon nitride by embedded Ag nanoparticles

Semiconductor nanomaterials with photocatalytic activity have potential for many applications. An effective way of promoting photocatalytic activity is depositing noble metal nanoparticles （NPs） on a semiconductor, since the noble metal NPs act as excellent electron acceptors which inhibit the quick recombination of the photoexcited electron-hole pairs and thereby enhance the generation of reactive oxygen species （ROS）. Herein, a highly effective platform, graphitic carbon nitride （g-C3N4） nanosheets with embedded Ag nanopartides （Ag/g-C3N4）, was synthesized by a facile route. Under visible light irradiation, the ROS production of Ag/g-C3N4 nanohybrids was greatly improved compared with pristine g-C3N4 nanosheets, and moreover, the nanohybrids showed enhanced antibacterial efficacy and ability to disperse bacterial biofilms. We demonstrate for the first time that the Ag/g-C3N4 nanohybrids are efficient bactericidal agents under visible light irradiation, and can also provide a new way for biofilm elimination. The enhanced antibacterial properties and biofilm-disrupting ability of Ag/g-C3N4 nanohybrids may offer many biomedical applications.

Chlorine doped graphitic carbon nitride nanorings as an efficient photoresponsive catalyst for water oxidation and organic decomposition

Rationally engineering the microstructure and electronic structure of catalysts to induce high activity for versatile applications remains a challenge. Herein, chlorine doped graphitic carbon nitride(Cl-doped g-C3N4) nanorings have been designed as a superior photocatalyst for pollutant degradation and oxygen evolution reaction(OER). Remarkably, Cl-doped g-C3N4 nanorings display enhanced OER performance with a small overpotential of approximately 290 m V at current density of 10 m A cm^-2 and Tafel slope of 83 m V dec-1, possessing comparable OER activity to precious metal oxides RuO2 and IrO2/C. The excellent catalytic performance of Cl-doped g-C3N4 nanorings originates from the strong oxidation capability,abundant active sites exposed and efficient charge transfer. More importantly, visible light irradiation gives rise to a prominent improvement of the OER performance, reducing the OER overpotential and Tafel slope by 140 m V and 28 m V dec^-1, respectively, demonstrating the striking photo-responsive OER activity of Cl-doped g-C3N4 nanorings. The great photo-induced improvement in OER activity would be related to the efficient charge transfer and the·OH radicals arising spontaneously on CN-Cl100 catalyst upon light irradiation. This work establishes Cl-doped g-C3N4 nanorings as a highly competitive metal-free candidate for photoelectrochemical energy conversion and environmental cleaning application.