Helium Plasma Damage of Low-k Carbon Doped Silica Film:the Effect of Si Dangling Bonds on the Dielectric Constant

The low-k carbon doped silica film has been modified by radio frequency helium plasma at 5 Pa pressure and 80 W power with subsequent XPS, FTIR and optical emission spec- troscopy analysis. XPS data indicate that helium ions have broken Si-C bonds, leading to Si-C scission with C（1s） lost seriously. The Si（2p）, O（ls）, peak obviously shifted to higher binding en- ergies, indicating an increasingly oxidized Si（2p）. FTIR data also show that the silanol formation increased with longer exposure time up to a week. Contrarily, the CHa stretch, Si-C stretching bond and the ratio of the Si-O-Si cage and Si-O-Si network peak sharply decreased upon exposure to helium plasma. The OES result indicates that monovalent helium ions in plasma play a key role in damaging carbon doped silica film. So it can be concluded that the monovalent helium ions besides VUV photons can break the weak Si-C bonds to create Si dangling bonds and free methyl radicals, and the latter easily reacts with O_2 from the atmosphere to generate CO_2 and H_2O. The bonds change is due to the Si dangling bonds combining with H_2O, thereby, increasing the dielectric constant k value.

Cu,N codoped carbon nanosheets encapsulating ultrasmall Cu nanoparticles for enhancing selective 1,2-propanediol oxidation

In the selective oxidation of biomass-based 1,2-propanediol(PDO)with oxygen as the terminal oxidant,it is challenging to improve the lactic acid(LA)selectivity for nonnoble metal nanoparticles(NPs)due to their limited oxygen reduction rate and easy C-C cleavage.Given the high economic feasibility of nonnoble metals,i.e.,Cu,in this work,copper and nitrogen codoped porous carbon nanosheets encapsulating ultrafine Cu nanoparticles(Cu@Cu-N-C)were developed to realize highly selective of PDO oxidation to LA.The carbon-encapsulated ultrasmall Cu^(0)NPs in Cu@Cu-N-C have high PDO dehydrogenation activity while N-coordinated Cu(Cu-N)sites are responsible for the high oxygen reduction efficacy.Therefore,the performance of catalytic PDO conversion to LA is optimized by a proposed pathway of PDO→hydroxylacetone→lactaldehyde→LA.Specifically,the enhanced LA selectivity is 88.5%,and the PDO conversion is up to 75.1%in an O_(2)-pressurized reaction system(1.0 MPa O_(2)),superior to other Cu-based catalysts,while in a milder nonpressurized system(O_(2)flow rate of 100 mL min-1),a remarkable LA selectivity(94.2%)is obtained with 39.8%PDO conversion,2.2 times higher than that of supported Au nanoparticles(1%Au/C).Moreover,carbon encapsulation offers Cu@Cu-N-C with strong leaching resistance for better recycling.

Structure,electronic,and nonlinear optical properties of superalkaline M_(3)O(M=Li,Na)doped cyclo[18]carbon

Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.

Carbon Doping Triggered Efficient Electrochemical Hydrogen Evolution of Cross-Linked Porous Ru-MoO_(2) Via Solid-Phase Reaction Strategy

The defect-free structure of Mo-based materials is a“double-edged sword”,which endows the material with excellent stability,but limits its chemical versatility and application in electrochemical hydrogen evolution reaction(HER).Carbon doping engineering is an attractive strategy to effectively improve the performance of Mo-based catalyst and maintain their stability.Herein,we report a cross-linked porous carbon-doped MoO_(2)(C–MoO_(2))-based catalyst Ru/C–MoO_(2) for electrochemical HER,which is prepared by the convenient redox solid-phase reaction(SPR)of porous RuO_(2)/Mo_(2)C composite precursor.Theoretical studies reveal that due to the presence of carbon atoms,the electronic structure of C–MoO_(2) has been properly adjusted,and the loaded small Ru nanoparticles provide a fast water dissociation rate and moderate H adsorption strength.In electrochemical studies under a pH-universal environment,Ru/C–MoO_(2) electrocatalyst exhibits a low overpotential at a current density of 10 mA cm^(-2) and has a low Tafel slope.Meanwhile,Ru/C-MoO_(2) has excellent stability for more than 100 h at an initial current density of 100 mA cm^(-2).

Template-free synthesis of carbon doped TiO_2 mesoporous microplates for enhanced visible light photodegradation

报道了一种在乙酸蒸汽中蒸发有机钛源(Ti(i-Pr O)_4),无模版合成碳掺杂介孔Ti O_2微板块的方法.该微板块由纳米晶组成,具有统一的介孔结构和微米级厚度.制备过程的副产有机物经炭化后对Ti O_2形成了表面和/或间隙碳掺杂,特别是源于乙酸的羧基最终与Ti O_2形成双齿螯合结构,强吸电子特性使羧基在价带边引入了带尾,导致Ti O_2带隙大幅减小(1.84 e V).独特的形貌和显著缩减的带隙,使该Ti O_2微板块显示出较高的可见光苯酚降解活性和优良的固-液分离性能.

Effect of Reduction Temperature on the Hydrodesulfurization Performance of Carbon-doped Alumina-supported Nickel Phosphide Catalyst

Nickel phosphide-carbon-doped alumina(Ni_(2)P/Al_(2)O_(3)-C)catalysts with 10 wt.%Ni_(2)P loading were successfully prepared via a hydrothermal reduction process and the effect of reduction temperature on the hydrodesulfurization(HDS)performance of the as-prepared Ni_(2)P/Al_(2)O_(3)-C catalysts was investigated.The properties of the support(Al_(2)O_(3)-C)and Ni_(2)P/Al_(2)O_(3)-C catalysts were characterized by transmission electron microscopy,scanning electron microscopy,Brunauer-Emmett-Teller measurements,X-ray diffractometry,and X-ray photoelectron spectroscopy.The results indicated that the incorporation of carbon in the support aided the reduction of Ni_(2)P.With an increase in the reduction temperature,Ni and Ni_(12)P_(5) were first generated and then converted into crystalline Ni_(2)P.Furthermore,a higher reduction temperature enhanced the HDS performance of the catalyst by generating more well-dispersed active-phase crystalline Ni_(2)P.

Nitrogen doped carbon catalyzing acetylene conversion to vinyl chloride

Commercial production of vinyl chloride from acetylene relies on the use of HgCla as the catalyst, which has caused severe environmental problem and threats to human health because of its toxicity. Therefore, it is vital to explore alternative catalysts without mercury. We report here that N-doped carbon can catalyze directly transformation of acetylene to vinyl chloride. Particularly, N-doped high surface area mesoporous carbon exhibits a rather high activity with the acetylene conversion reaching 77% and vinyl chloride selectivity above 98% at a space velocity of 1.0 mL.min-l.g-1 and 200 ~C. It delivers a stable performa℃nce within a test period of 100h and no obvious deactivation is observed, demonstrating potentials to substitute the notoriously toxic mercuric chloride catalyst.

Biomass derived porous nitrogen doped carbon for electrochemical devices

Biomass derived porous nanostructured nitrogen doped carbon(PNC) has been extensively investigated as the electrode material for electrochemical catalytic reactions and rechargeable batteries. Biomass with and without containing nitrogen could be designed and optimized to prepare PNC via hydrothermal carbonization, pyrolysis, and other methods. The presence of nitrogen in carbon can provide more active sites for ion absorption, improve the electronic conductivity, increase the bonding between carbon and sulfur, and enhance the electrochemical catalytic reaction. The synthetic methods of natural biomass derived PNC, heteroatomic co-or tri-doping into biomass derived carbon and the application of biomass derived PNC in rechargeable Li/Na batteries, high energy density Li-S batteries, supercapacitors, metal-air batteries and electrochemical catalytic reaction(oxygen reduction and evolution reactions, hydrogen evolution reaction) are summarized and discussed in this review. Biomass derived PNCs deliver high performance electrochemical storage properties for rechargeable batteries/supercapacitors and superior electrochemical catalytic performance toward hydrogen evolution, oxygen reduction and evolution, as promising electrodes for electrochemical devices including battery technologies, fuel cell and electrolyzer.

Graphitic‐shell encapsulated FeNi alloy/nitride nanocrystals on biomass‐derived N‐doped carbon as an efficient electrocatalyst for rechargeable Zn‐air battery

Oxygen reduction/evolution reactions(ORR/OERs)catalysts play a key role in the metal‐air battery and water‐splitting process.Herein,we developed a facile template‐free method to fabricate a new type of non–noble metal‐based hybrid catalyst which consists of binary FeNi alloy/nitride nanocrystals with graphitic‐shell and biomass‐derived N‐doped carbon(NC)(FexNiyN@C/NC).This novel nanostructure exhibits superior performance for ORR/OER,which can be attributed to the strong interactions between the graphitic‐shell encapsulated FeNi alloy/nitride nanocrystals and the N‐doped porous carbon substrate.The X‐ray absorption spectroscopy technique was employed to reveal the underlying mechanisms for the excellent performance.The assembled Zn‐air battery device exhibits outstanding charging/discharging performance and cycling stability,indicating the great potential of this type of novel catalysts.

Interaction of hydrogen molecules on Ni-doped single-walled carbon nanotube

Adsorption of hydrogen molecules on an Ni-doped （8,0） single-walled carbon nanotube （SWNT） is investigated by using first-principles density functional calculations. The result shows that a single Ni atom adsorbed on the bridge site of the tube could cannot dissociate the H2, however it can chemisorb three H2 at most, with the average binding energy per H2 suitable for the hydrogen storage at the room temperature. More H2 would physisorb around an Ni atom weakly. As for the SWNT with an Ni dimer adsorbed, we find that when the H2 approaches the Ni Ni bond, it dissociates without overcoming any barrier and makes bonds with Ni atom.

Structure and Mechanical Performance of Nitrogen Doped Diamond-like Carbon Films

Nitrogen doped diamond-like carbon （DLC：N） films were prepared by electron cyclotron resonance chemical vapor deposition （ECR-CVD） on polycrystalline Si chips. Film thickness is about 50 nm. Auger electron spectroscopy （AES） was used to evaluate nitrogen content, and increasing N2 flow improved N content from 0 to 7.6%. Raman and X-ray photoelectron spectroscopy （XPS） analysis results reveal CN-sp^3C and N-sp^2C structure. With increasing the N2 flow, sp^3C decreases from 73.74% down to 42.66%, and so does N-sp^3C from 68.04% down to 20.23%. The hardness decreases from 29.18 GPa down to 19.74 GPa, and the Young＇s modulus from 193.03 GPa down to 144.52 GPa.

Modulating the CO methanation activity of Ni catalyst by nitrogen doped carbon

Nitrogen doping has been proved to be an effective way to modify the properties of graphene and other carbon materials. Herein, we explore a composite with nitrogen doped carbon overlayers wrapping Si C substrate as a support for Ni（Ni/CN-Si C） and evaluate its effects on the methanation activity. The results show that both the activity and stability of Ni are enhanced. Characterization with STEM, XRD, XPS, Raman and H2-TPR indicates that nitrogen doping generates more defects in the carbon overlayers, which benefit the dispersion of Ni. Furthermore, the reduction of Ni is facilitated.

Porous carbon materials for CO_(2)capture,storage and electrochemical conversion

Continuous accumulation and emission into the atmosphere of anthropogenic carbon dioxide(CO_(2)),a major greenhouse gas,has been recognized as a primary contributor to climate change associated with the global warming and acidification of oceans.This has led to drastic changes in the natural ecosystem,and hence an unhealthy ecological environment for human society.Thus,the effective mitigation of the ever increasing CO_(2)emission has been recognized as the most important global challenge.To achieve zero carbon footprint,novel materials and approaches are required for potentially reducing the CO_(2)release,while our current fossil-fuel-based energy must be replaced by renewable energy free from emissions.In this paper,porous carbons with hierarchical pore structures are promising for CO_(2)adsorption and electrochemical CO_(2)reduction owing to their high specific surface area,excellent catalytic performance,low cost and long-term stability.Since efficient gas-phased(electro)catalysis involves the access of reactants to active sites at the gas-liquid-solid triple phase,the hierarchical porous carbon materials possess multiple advantages for various CO_(2)-related applications with enhanced volumetric and gravimetric activities(e.g.,CO_(2)uptake and current density)for practical operations.Recent studies have demonstrated that porous carbon materials exhibited notable activities as CO_(2)adsorbents and provided facile conducting pathways and mass diffusion channels for efficient electrochemical CO_(2)reduction even under the high current operation conditions.Herein,we summarize recent advances in porous carbon materials for CO_(2)capture,storage,and electrochemical conversion.Prospectives and challenges on the rational design of porous carbon materials for scalable and practical CO_(2)capture and conversion are also discussed.

MnS–MnO heterogeneous nanocube@N,S-doped carbon as a highly efficient bifunctional water splitting electrocatalyst

A stable,efficient,and economical bifunctional electrolytic catalyst would be incredibly beneficial for the development of hydrogen production by electrocatalytic water splitting.In this study,we synthesized a novel MnS–MnO heterogeneous nanocube@N,S-doped carbon(MnS–MnO@NSC).MnS–MnO nanocubes possess rich heterogeneous interfaces and plentiful catalytic active sites to promote electrochemical reactions,while the N,S-doped carbon shell possesses excellent conductivity and catalytic properties and protects the nanocubes.MnS–MnO@NSC exhibited excellent electrochemical properties as an effective bifunctional electrocatalyst for the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in KOH solution.In the HER,the overpotential was as low as 124 mV at a current density of 10 mA·cm^(-2)while in the OER,it was only 340 mV at 100 mA·cm^(-2)under the same conditions.In addition,a MnS–MnO@NSC||MnS–MnO@NSC electrolyzer exhibited almost comparable activity and higher steadiness than those exhibited by the state-of-the-art Pt/C||RuO_(2)/C system for full water splitting in KOH solution.

Tailoring local structures of atomically dispersed copper sites for highly selective CO_(2) electroreduction

Atomically‐dispersed copper sites coordinated with nitrogen‐doped carbon(Cu–N–C)can provide novel possibilities to enable highly selective and active electrochemical CO_(2) reduction reactions.However,the construction of optimal local electronic structures for nitrogen‐coordinated Cu sites(Cu–N_(4))on carbon remains challenging.Here,we synthesized the Cu–N–C catalysts with atomically‐dispersed edge‐hosted Cu–N_(4) sites(Cu–N_(4)C_(8))located in a micropore between two graphitic sheets via a facile method to control the concentration of metal precursor.Edge‐hosted Cu–N_(4)C_(8) catalysts outperformed the previously reported M–N–C catalysts for CO_(2)‐to‐CO conversion,achieving a maximum CO Faradaic efficiency(FECO)of 96%,a CO current density of–8.97 mA cm^(–2) at–0.8 V versus reversible hydrogen electrode(RHE),and over FECO of 90%from–0.6 to–1.0 V versus RHE.Computational studies revealed that the micropore of the graphitic layer in edge‐hosted Cu–N_(4)C_(8) sites causes the d‐orbital energy level of the Cu atom to shift upward,which in return decreases the occupancy of antibonding states in the*COOH binding.This research suggests new insights into tailoring the locally coordinated structure of the electrocatalyst at the atomic scale to achieve highly selective electrocatalytic reactions.

Core-shell particles of C-doped CdS and graphene: A noble metal-free approach for efficient photocatalytic H_(2) generation

To achieve efficient photocatalytic H_(2) generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reported.The doping effect and the application of graphene as cocatalyst for CdS is studied for photocatalytic H_(2) generation.The most active sample consists of CdS and graphene(CdS-0.15G)exhibits promising photocatalytic activity,producing 3.12 mmol g^-(1) h^-(1) of H_(2) under simulated solar light which is^4.6 times superior than pure CdS nanoparticles giving an apparent quantum efficiency(AQY)of 11.7%.The enhanced photocatalytic activity for H_(2) generation is associated to the narrowing of the bandgap,enhanced light absorption,fast interfacial charge transfer,and higher carrier density(N_(D))in C-doped CdS@G samples.This is achieved by C doping in CdS nanoparticles and the formation of a graphene shell over the C-doped CdS nanoparticles.After stability test,the spent catalysts sample was also characterized to investigate the nanostructure.

Mechanochemical Synthesis of Visible-light Induced Photocatalyst with Nitrogen and Carbon Doping

Nitrogen and/or carbon doped titania photocatalysts were prepared by a novel mechanochemical method. The prepared powders possessed two absorption edges around 400 and 540 nm wavelengths and showed excellent photocatalytic ability for nitrogen monoxide oxidation under visible light irradiation. Under the irradiation of visible light of wavelength >510 nm,37% of nitrogen monoxide could be continuously removed by the carbon and nitrogen co-doped titania prepared by planetary ball milling of P-25 titania–10% hexamethylenetetramine mixture followed by calcination in air at 400-C.

Synergistic effects of carbon doping and coating of TiO_(2) with exceptional photocurrent enhancement for high performance H2 production from water splitting

The"one pot"simultaneous carbon coating and doping of TiO_(2) materials by the hydrolysis of TiCl4 in fructose is reported.The synergistic effect of carbon doping and coating of TiO_(2) to significantly boost textural,optical and electronic properties and photocurrent of TiO_(2) for high performance visible light H2 production from water splitting has been comprehensively investigated.Carbon doping can significantly increase the thermal stability,thus inhibiting the phase transformation of the Titania material from anatase to rutile while carbon coating can suppress the grain aggregation of TiO_(2).The synergy of carbon doping and coating can not only ensure an enhanced narrowing effect of the electronic band gap of TiO_(2) thus extending the absorption of photocatalysts to the visible regions,but also promote dramatically the separation of electron-hole pairs.Owing to these synergistic effects,the carbon coated and doped TiO_(2) shows much superior photocatalytic activity for both degradation of organics and photocatalytic/photoelectro chemical(PEC)water splitting under simulated sunlight illumination.The photocatalytic activity of obtained materials can reach 5,4 and 2 times higher than that of pristine TiO_(2),carbon doped TiO_(2) and carbon coated TiO_(2),respectively in the degradation of organic pollutants.The carbon coated and doped TiO_(2) materials exhibited more than 37 times and hundreds of times photocurrent enhancement under simulated sunlight and visible light,respectively compared to that of pristine TiO_(2).The present work providing new comprehensive understanding on carbon coating and doping effect could be very helpful for the development of advanced TiO_(2) materials for a large series of applications.

Carbon‐based materials for all‐solid‐state zinc–air batteries

Solid‐state Zn–air batteries(ZABs)hold great potential for application in wearable and flexible electronics.However,further commercialization of current ZABs is still limited by the poor stability and low energy efficiency.It is,thus,crucial to develop efficient catalysts as well as optimize the solid electrolyte system to unveil potential of the ZAB technology.Due to the low cost and versatility in tailoring the structures and properties,carbon materials have been extensively used as the conductive substrates,catalytic air electrodes,and important components in the electrolytes for the solid‐state ZABs.Within this context,we discuss the challenges facing current solid‐state ZABs and summarize the strategies developed to modify properties of carbon‐based electrodes and electrolytes.We highlight the metal−organic framework/covalent organic framework‐based electrodes,heteroatom‐doped carbon,and the composites formed of carbon with metal oxides/sulfides/phosphides.We also briefly discuss the progress of graphene oxide‐based solid electrolyte.

Influence of Sodium Carbonate Amount on Crystalline Phase and Structure Stability for Doping Nickel Hydroxide

Alpha nickel hydroxide has better performances than commercial beta nickel hydroxide. However, the main defect is that α-phase is difficult to synthesize and easily transformed to β-phase Ni（OH）2 upon aging in a strong alkaline solution. In this study, the Al-Co, Al-Yb, Yb-Co and Al-Yb-Co multiple doping was used respectively. By controlling the amount of sodium carbonate, the α-Ni（OH）2 was prepared by ultrasonic-assisted precipitation. And the influence of sodium carbonate on the crystalline phase and structure stability for alpha nickel hydroxide was studied. The results demonstrate that, with increasing amount, the biphase nickel hydroxide transforms to pure alpha nickel hydroxide gradually, and the structure stability is also improved. When the amount of sodium carbonate is 2 g, the sample still keeps α-Ni（OH）2 after being aged for 30 days, for Al-Yb-Co-Ni（OH）2. And when the amount is less than 2 g, the phase transformations exist in the samples with different extents. These results demonstrated that the amount of sodium carbonate is a critical factor to maintain the structural stability of α-Ni（OH）2.