Achieving highly selective electrochemical CO_(2) reduction to C_(2)H_(4) on Cu nanosheets

The conversion of CO_(2)into value-added chemicals coupled with the storage of intermittent renewable electricity is attractive.CuO nanosheets with an average size and thickness of~30 and~20 nm have been developed,which are in situ reduced into Cu nanosheets during electrochemical CO_(2)reduction reaction(ECO_(2)RR).The derived Cu nanosheets demonstrate much higher selectivity for C2H4production than commercial CuO derived Cu powder,with an optimum Faradaic efficiency of 56.2%and a partial current density of C_(2)H_(4)as large as 171.0 mA cm^(-2)in a gas diffusion flow cell.The operando attenuated total reflectance-Fourier transform infrared spectra measurements and density functional theory simulations illustrate that the high activity and selectivity of Cu nanosheets originate from the edge sites on Cu nanosheets with a coordinate number around 5(4–6),which facilitates the formation of^(*)CHO rather than^(*)COH intermediate,meanwhile boosting the C-C coupling reaction of^(*)CO and^(*)CHO intermediates,which are the critical steps for C_(2)H_(4)formation.

A new horizontal in C1 chemistry: Highly selective conversion of syngas to light olefins by a novel OX-ZEO process

The most challenging goal of C1 chemistry is the control of C–C coupling to produce chemicals or fuels from C1 feedstocks,in particular syngas（H2/CO）,which can be derived from various carbon resources such as coal,natural gas or shale gas,and biomass.

Highly selective electrosynthesis of 3,4-dihydroisoquinoline accompanied with hydrogen production over three-dimensional hollow CoNi-based microarray electrocatalysts

Electrocatalytic oxidation reaction of biomass-based derivatives is an excellent candidate to replace water oxidation for obtaining both value-added products and hydrogen(H_(2)),but the exploration of competent electrocatalysts is still highly challenging.Herein,two new types of three-dimensional self-supported hollow microarrays containing CoNi layered double hydroxide(CoNi-LDH)and N-doped carbon nanosheets decorated with CoNi alloyed nanoparticles(CoNi-NC)on carbon cloth(CC)are prepared,which are further used as efficient electrocatalysts for tetrahydroisoquinoline(THIQ)electrooxidation and hydrogen evolution reaction(HER),respectively.We demonstrate that the Co-modulated electronic environment for Ni(II)/Ni(Ⅲ)redox-looping in CoNi-LDH is the main factor to boost the selectivity of 3,4-dihydroisoquinoline(DHIQ)for the indirect electrooxidation process of THIQ.Density functional theory(DFT)calculations reveal that the Ni(Ⅲ)/Co(Ⅲ)dual sites of CoNi-LDH exhibit enhanced adsorption for THIQ but poorer adsorption for DHIQ compared to pure Co(Ⅲ)or Ni(Ⅲ).Therefore,the Ni(Ⅲ)/Co(Ⅲ)dual sites can effectively inhibit the peroxidation of DHIQ to isoquinoline(IQ)over CoNi-LDH,thus improving the selectivity of DHIQ to nearly 100%,much higher than that of its pure Ni counterpart.Moreover,CC@CoNi-NC can deliver high HER activity with low overpotential(40 mV@10 mA·cm^(-2))and high exchange current density(3.08 mA·cm^(-2)).Impressively,the assembled flow-cell device with CC@CoNi-LDH anode and CC@CoNi-NC cathode only requires low cell voltage and electricity consumption of 1.6 V and 3.50 kWh per cubic meter of H_(2)(@25 mA·cm^(-2)).

Tunable bismuth doping/loading endows NaTaO_(3)nanosheet highly selective photothermal reduction of CO_(2)

Photothermal CO_(2)reduction with H2O,integrating advantages of photocatalysis driven H2O splitting and thermal catalysis promoted CO_(2)reduction,has drawn sharply increasing attention in artificial synthesis of solar fuels.The photothermal effect of metal nanoparticles facilities CO_(2)hydrogenation and activation of lattice oxygen in oxide photocatalyst promotes H2O oxidation,which is essentially considered for highly efficient photothermal catalysis.However,the large thermal conductivity of most metal nanoparticles induces inevitable heat dissipation,restricting the increase of catalyst temperature.In this work,to minimize the heat dissipation,we employ bismuth nanoparticles as photothermal unit,which is of the lowest thermal conductivity in the metal family.Meanwhile,we adopt bismuth doped NaTaO_(3)as photocatalytic unit because of the bismuth doping induced activation of lattice oxygen.The bismuth nanoparticles are assembled with bismuth doped NaTaO_(3)through one-step tunable transformation from Bi4TaO8Cl.Benefiting from the photothermal effect,thermal insulation caused by bismuth metal,and lattice oxygen activation by bismuth doping,the NaTaO_(3):Bi hybrid exhibits high photothermal catalytic performance.The yield of CO over NaTaO_(3):Bi hybrid at 413 K via photothermal catalysis is 141 times higher than that room temperature photocatalysis.Further,ultraviolet(UV)light irradiation leads to 89.2%selectivity of CO and visible light irradiation leads to 97.5%selectivity of CH4.This work may broaden the photocatalytic application of ABO_(3)perovskite and provides a novel strategy for the development of photothermal catalysts for artificial photosynthesis.

Laparoscopic Partial Nephrectomy by Diode Laser with Highly Selective Clamping of Segmental Renal Arterial

INTRODUCTION The treatment of small renal masses has shifted from radical nephrectomy to partial nephrectomy, in particular, laparoscopic partial nephrectomy. Renal artery clamping is often necessary to minimize hemorrhage during resection in cases of partial nephrectomy. However, renal artery clamping may lead to greater incidence of renal malfunction after partial nephrectomy. Therefore, novel techniques which could both avoid renal artery occlusion and achieve adequate hemostasis are urgently required. Selective renal segmental artery clamping was one of several common methods that could achieve ＂zero ischemia.＂ At the same time, a number of reports about laser-assisted partial nephrectomy on humans using multiple kinds of outstanding coagulative specialties of lasers were published.

Enhanced flow injection analysis for measurements of S-nitrosothiols species in biological samples using highly selective amperometric nitric oxide sensor

A highly selective nitric oxide（NO） sensor is fabricated and applied to devise an enhanced flow injection analysis（FIA） system for S-nitrosothiols（RSNOs） measurement in biological samples.The NO sensor is prepared using a polytetrafluoroethylene（PTFE） gas-permeable membrane loaded with Teflon AF？ solution,a copolymer of tetrafluoroethylene and 2,2-bis（trifluoroethylene）-4,5-difluoro -l,3-dioxole,to improve selectivity.This method is much simpler and possesses good performance over a wide range of RSNOs concentrations.Standard deviation for three parallel measurements of blood plasma is 4.0%.The use of the gas sensing configuration as the detector enhances selectivity of the FIA measurement vs.using less selective electrochemical detectors that do not use PTFE/Teflon type outer membranes.

Pseudo-crown ether having AIE and PET effects from a TPE-CD conjugate for highly selective detection of mercury ions

A new tetraphenylethylene-cyclodextrin (TPE-CD) conjugate with a linkage composed of long triethylene glycol chain and triazole ring on the CD rim has been designed and synthesized. The TPE-CD conjugate exists in a stretched form in DMSO and enhances its fluorescence after addition of a small amount of water due to aggregation-induced emission (AIE) effect. However, in the presence of a large amount of water, the TPE unit will enter the cyclodextrin cavity to form a folded self-inclusion compound. In the self-inclusion compound, not only nitrogen-containing pseudo-crown ether is formed but also arouses photo-induced electron transfer (PET) process from nitrogen atoms of triazole ring to TPE unit and quenches the fluorescence although more aggregation occurs in more water. This is the first finding that TPE-macrocycle conjugate can form pseudo-crown ether and has both the AIE phenomenon and the PET effect. Interestingly, only mercury ion arouses the fluorescence recover of the self-inclusion compound by entering the pseudo-crown ether cavity and blocking the PET process by binding to the nitrogen atoms, while other tested metal ions almost have no effect on the fluorescence. Therefore, the TPE-CD conjugate can be used for the highly selective fluorescence "Turn-On" detection of Hg^(2+).

MoC nanocrystals confined in N-doped carbon nanosheets toward highly selective electrocatalytic nitric oxide reduction to ammonia

Electrochemical nitric oxide reduction reaction(NORR)to produce ammonia(NH3)under ambient conditions is a promising alternative to the energy and carbon-intensive Haber–Bosch approach,but its performance is still improved.Herein,molybdenum carbides(MoC)nanocrystals confined by nitrogen-doped carbon nanosheets are first designed as an efficient and durable electrocatalyst for catalyzing the reduction of NO to NH3 with maximal Faradaic efficiency of 89%±2%and a yield rate of 1,350±15μg·h^(−1)·cm^(−2) at the applied potential of−0.8 V vs.reversible hydrogen electrode(RHE)as well as high stable activity with negligible current density and NH3 yield rate decays over a 30 h continue the test.Moreover,as a proof-of-concept of Zn–NO battery,it achieves a peak power density of 1.8 mW·cm^(−2) and a large NH3 yield rate of 782±10μg·h^(−1)·cm^(−2),which are comparable to the best-reported results.Theoretical calculations reveal that the MoC(111)has a strong electronic interaction with NO molecules and thus lowering the energy barrier of the potential-determining step and suppressing hydrogen evolution kinetics.This work suggests that Mo-based materials are a powerful platform providing great opportunities to explore highly selective and active catalysts for NH3 production.

Highly Selective Fluorescent Recognition towards Th4＋ Based on Coumarin-derivatized Crescent Aromatic Oligoamide

An intramolecularly hydrogen-bonded crescent aromatic oligoamide 1 bearing two coumarin residues was syn- thesized. The results from UV-vis and fluorescent spectra upon metal ions complexation demonstrated that the two fluorophores serving as parts of the shape-persistent backbone provided the molecule with high selectivity and sen- sitivity for recognition of Th4＋ over other lanthanide and uranyl ions. A 48-fold fluorescent enhancement in the in- tensity was observed at 505 nm upon adding Th4＋, while other metal cations failed to induce such a significant change. A visual detection for Th4＋ was achieved by color change. The stoichiometry of the complex formed by 1 and Th4＋ was found to be 1 ： 1 with the stability constant of（2.0±0.6） × 10^6 L·mol^-1.

Highly selective conversion of methane to ethanol over CuFe_(2)O_(4)-carbon nanotube catalysts at low temperature

Conversion of methane into liquid alcohol such as ethanol at low temperature in a straight,selective and low energy consumption process remains a topic of intense scientific research but a great challenge.In this work,CuFe_(2)O_(4)/CNT composite is successfully synthesized via a facile co-reduction method and used as catalysts to selectively oxidize methane.At a low temperature of 150℃,methane is directly converted to ethanol in a single process on the as-prepared CuFe_(2)O_(4)/CNT composite with high selectivity.A mechanism is also proposed for the significant methane selective oxidation performance of the CuFe_(2)O_(4)/CNT composite catalysts.

A Novel Highly Selective“Turn-On”Fluorescence Sensor for Silver Ions Based on Schiff Base

A novel optical chemical sensor L was designed and synthesized for the determination of silver ions.The sensor L was derived from 1-naphthaldehyde and 3,4,5-tris(hexadecyloxy)benzohydrazide.The sensor L shows high sensitivity and selectivity for Ag+detection in comparison to other metal cations(Mg^(2+),Ca^(2+),Al^(3+),Cr^(3+),Fe^(3+),Co^(2+),Ni^(2+),Cu^(2+),Zn^(2+),Cd^(2+),Hg^(2+),Pb^(2+))and has no significant response to other common metal cations.Upon addition of Ag+,the fluorescent emission of the sensor L was enhanced dramatically but other metal cations had no same response.The detection limit for Ag+was 1.2×10^(−7) mol/L.Therefore,the sensor L is useful for Ag+detection with some advantages including sensitivity,selectivity,simplicity and low-cost.

Selective synthesis of nitrate from air using a plasma-driven gas-liquid relay reaction system

The direct oxidation of nitrogen is a potential pathway to achieving the zero-carbon-emission synthesis of nitric acid or nitrate, because it does not involve ammonia synthesis and additional ammonia oxidation processes. However, the slow kinetics of nitrogen oxidation and the difficult selective control of oxidation products hinder the development of this process. In this study, a plasma-driven gas-liquid relay reaction system was developed to overcome these limitations. A typical feature of this reaction system is that it can efficiently generate NO_x under plasma exposure;moreover, the specific anions in the absorption solution can be oxidized to strong oxidants capable of relay oxidation of low-valence nitrogen oxides. This feature allows for the deep oxidation of nitrogen, thus enabling the oxidation products of nitrogen to exist in high-valence states in the absorption solution. For experimental verification, we achieved the 100% selective synthesis of nitrate under plasma exposure, with air as the supply gas and a sodium sulfate solution as the absorption solution.

A robust & weak-nucleophilicity electrocatalyst with an inert response for chlorine ion oxidation in large-current seawater electrolysis

Seawater splitting into hydrogen,a promising technology,is seriously limited by the durability and tolerance of electrocatalysts for chlorine ions in seawater at large current densities due to chloride oxidation and corrosion.Here,we present a robust and weak-nucleophilicity nickel-iron hydroxide electrocatalyst with excellent selectivity for oxygen evolution and an inert response for chlorine ion oxidation which are key and highly desired for efficient seawater electrolysis.Such a weak-nucleophilicity electrocatalyst can well match with strong-nucleophilicity OH-compared with the weak-nucleophilicity Cl^(-),resultantly,the oxidation of OH-in electrolyte can be more easily achieved relative to chlorine ion oxidation,confirmed by ethylenediaminetetraacetic acid disodium probing test.Further,no strongly corrosive hypochlorite is produced when the operating voltage reaches about 2.1 V vs.RHE,a potential that is far beyond the thermodynamic potential of chlorine ion oxidatio n.This concept and approach to reasonably designing weaknucleophilicity electrocatalysts that can greatly avoid chlorine ion oxidation under alkaline seawater environments can push forward the seawater electrolysis technology and also accelerate the development of green hydrogen technique.

High Selective Etching of Aluminum Alloys In High Plasma Density Reactor

An inductively coupled plasma (ICP) discharge and its etching behaviors for aluminum alloys were investigated in this report. A radio frequency power supply was used for plasma generation. The unique hardware configuration enabled one to control ion energy separately from plasma density. Plasma properties were measured with a Langmuir probe. Electron temperature, plasma potential and plasma density were found to be comparable with those reported from Electron Cyclotron Resonance (ECR) and other types of reactors[1].A mixture of HBr and chlorine gases were used for this aluminum etch study. Experimental matrices were designed with Response Surface Methodology (RSM) to analyze the process trends versus etch parameters, such as source power, bias power and gas composition. An etch rate of 8500A to 9000A per minute was obtained at 5 to 15 mTorr pressure ranges. Anisotropic profiles with high photoresist selectivity (5 to 1) and silicon dioxide selectivity greater than 10 were achieved with HBr addition into chlorine plasma.Bromine-containing chemistry for an aluminum etch in a low pressure ICP discharge showed great potential for use in ULSI fabrication. In addition, the hardware used was very simple and the chamber size was much smaller than other high density plasma sources.

Fabrication of oxygen-doped MoSe2 hierarchical nanosheets for highly sensitive and selective detection of trace trimethylamine at room temperature in air

Nano Research volume 13,pages1704–1712(2020)Cite this article 191 Accesses Metrics details Abstract Intelligent gas sensors based on the layered transition metal dichalcogenides(TMDs)have attracted great interest in the field of gas sensing due to their multiple active sites,fast electron,mass transfer capability and large surface-to-volume ratio.However,conventional TMDs-based sensors typically work at elevated temperature in inert atmosphere,which would largely limit the corresponding practical applications.Herein,novel oxygen-doped MoSe2 hierarchical nanostructures composed of ultrathin nanosheets with large specific surface area have been designed and generated typically at 200°C in air for fast and facile gas sensing of trimethylamine(TMA),effectively.Benefited from the gas-accessible hierarchical morphology and high surface area with abundant nanochannels,highly sensitive and selective detection of trace TMA has been achieved under ambient condition,and as detected the theoretical limit of detection(LOD)is 8 ppb,which is the lowest for TMA detection under ambient condition among the reported studies.The mechanism of oxygen doping on the improved gas-sensing performance has been investigated,revealing that the oxygen doping could greatly optimize the electronic structure,thus regulate the Fermi level of MoSe2 as well as the affinity between TMA molecule and sensor surface.It is expected that the oxygen doping strategy developed for the highly efficient gas sensors based on TMDs in present work may also be applicable to other types of gas-sensing semiconductors,which could open up a new direction for the rational design of high-performance gas sensors working under ambient condition.

Berlin Green Framework‑Based Gas Sensor for Room‑Temperature and High‑Selectivity Detection of Ammonia

Ammonia detection possesses great potential in atmosphere environmental protection,agriculture,industry,and rapid medical diagnosis.However,it still remains a great challenge to balance the sensitivity,selectivity,working temperature,and response/recovery speed.In this work,Berlin green(BG)framework is demonstrated as a highly promising sensing material for ammonia detection by both density functional theory simulation and experimental gas sensing investigation.Vacancy in BG framework offers abundant active sites for ammonia absorption,and the absorbed ammonia transfers sufficient electron to BG,arousing remarkable enhancement of resistance.Pristine BG framework shows remarkable response to ammonia at 50–110°C with the highest response at 80°C,which is jointly influenced by ammonia’s absorption onto BG surface and insertion into BG lattice.The sensing performance of BG can hardly be achieved at room temperature due to its high resistance.Introduction of conductive Ti3CN MXene overcomes the high resistance of pure BG framework,and the simply prepared BG/Ti3CN mixture shows high selectivity to ammonia at room temperature with satisfying response/recovery speed.

Bi-Atom Electrocatalyst for Electrochemical Nitrogen Reduction Reactions

The electrochemical nitrogen reduction reaction(NRR)to directly produce NH3 from N_(2) and H_(2)O under ambient conditions has attracted significant attention due to its ecofriendliness.Nevertheless,the electrochemical NRR presents several practical challenges,including sluggish reaction and low selectivity.Here,bi-atom catalysts have been proposed to achieve excellent activity and high selectivity toward the electrochemical NRR by Ma and his co-workers.It could accelerate the kinetics of N_(2)-to-NH_(3) electrochemical conversion and possess better electrochemical NRR selectivity.This work sheds light on the introduction of bi-atom catalysts to enhance the performance of the electrochemical NRR.

Genes for the high life： New genetic variants point to positive selection for high altitude hypoxia in Tibetans

People living on the high plateaus of the world have long fascinated biological anthropologists and geneticists because they live in ＂thin air＂ and epitomize an extreme of human biological adaptation.

Active oxygen center in oxidative coupling of methane on La_(2)O_(3) catalyst

La_(2)O_(3) catalyzed oxidative coupling of methane(OCM) is a promising process that converts methane directly to valuable C_(2)(ethylene and ethane) products. Our online MS transient study results indicate that pristine surface without carbonate species demonstrates a higher selectivity to C_(2) products, and a lower light-off temperature as well. Further study is focused on carbonate-free La_(2)O_(3) catalyst surface for identification of active oxygen species associated with such products behavior. XPS reveals unique oxygen species with O 1 s binding energy of 531.5 e V correlated with OCM catalytic activity and carbonates removal. However, indicated thermal stability of this species is much higher than the surface peroxide or superoxide structures proposed by earlier computation models. Motivated by experimental results,DFT calculations reveal a new more stable peroxide structure, formed at the subsurface hexacoordinate lattice oxygen sites, with energy 2.18 e V lower than the previous models. The new model of subsurface peroxide provides a perspective for understanding of methyl radicals formation and C_(2) products selectivity in OCM over La_(2)O_(3) catalyst.

Visible-light deposition of CrO_(x) cocatalyst on TiO_(2):Cr valence regulation for superior photocatalytic CO_(2)reduction to CH_(4)

Photodeposition is widely adopted for implanting metal/metal oxide cocatalysts on semiconductors.However,it is prerequisite that the photon energy should be sufficient to excite the host semiconductor.Here,we report a lower-energy irradiation powered deposition strategy for implanting CrO_(x) cocatalyst on TiO_(2).Excitingly,CrO_(x)-400 implanted under visible-light irradiation significantly promotes the CH4 evolution rate on TiO_(2)to 8.4μmolg·^(-1)h^(-1) with selectivity of98%from photocatalytic CO_(2)reduction,which is 15 times of that on CrO_(x)-200 implanted under UV-visible-light irradiation.Moreover,CrO_(x)-400 is identified to be composed of higher valence Cr species compared to CrO_(x)-200.This valence states regulation of Cr species is indicated to provide more active sites for CO_(2) adsorption/activation and to modulate the reaction mechanism from single Cr site to Cr-Cr dual sites,thus endowing the superior CH_(4)production.This work demonstrates an alternative strategy for constructing efficient metal oxides cocatalysts on wide bandgap semiconductor.