Showing papers by "Henan Normal University published in 2015"
TL;DR: Visible light-responsive photocatalytic technology holds great potential in water treatment to enhance purification efficiency, as well as to augment water supply through the safe usage of unconventional water sources as mentioned in this paper.
Abstract: Visible light-responsive photocatalytic technology holds great potential in water treatment to enhance purification efficiency, as well as to augment water supply through the safe usage of unconventional water sources. This review summarizes the recent progress in the design and fabrication of visible light-responsive photocatalysts via various synthetic strategies, including the modification of traditional photocatalysts by doping, dye sensitization, or by forming a heterostructure, coupled with π-conjugated architecture, as well as the great efforts made within the exploration of novel visible light-responsive photocatalysts. Background information on the fundamentals of heterogeneous photocatalysis, the pathways of visible light-responsive photocatalysis, and the unique features of visible light-responsive photocatalysts are presented. The photocatalytic properties of the resulting visible light-responsive photocatalysts are also covered in relation to the water treatment, i.e., regarding the photocatalytic degradation of organic compounds and inorganic pollutants, as well as photocatalytic disinfection. Finally, this review concludes with a summary and perspectives on the current challenges faced and new directions in this emerging area of research.
759 citations
TL;DR: In this paper, the authors established the multi-year comprehensive atmospheric emission inventories of 12 typical toxic heavy metals (Hg, As, Se, Pb, Cd, Cr, Ni, Sb, Mn, Co, Cu, and Zn) from primary anthropogenic activities in China for the period of 1949-2012 for the first time.
Abstract: . Anthropogenic atmospheric emissions of typical toxic heavy metals have caused worldwide concern due to their adverse effects on human health and the ecosystem. By determining the best available representation of time-varying emission factors with S-shape curves, we establish the multiyear comprehensive atmospheric emission inventories of 12 typical toxic heavy metals (Hg, As, Se, Pb, Cd, Cr, Ni, Sb, Mn, Co, Cu, and Zn) from primary anthropogenic activities in China for the period of 1949–2012 for the first time. Further, we allocate the annual emissions of these heavy metals in 2010 at a high spatial resolution of 0.5° × 0.5° grid with ArcGIS methodology and surrogate indexes, such as regional population and gross domestic product (GDP). Our results show that the historical emissions of Hg, As, Se, Cd, Cr, Ni, Sb, Mn, Co, Cu, and Zn, during the period of 1949–2012, increased by about 22–128 times at an annual average growth rate of 5.1–8.0 %, reaching about 526.9–22 319.6 t in 2012. Nonferrous metal smelting, coal combustion of industrial boilers, brake and tyre wear, and ferrous metal smelting represent the dominant sources of heavy metal emissions. In terms of spatial variation, the majority of emissions are concentrated in relatively developed regions, especially for the northern, eastern, and southern coastal regions. In addition, because of the flourishing nonferrous metal smelting industry, several southwestern and central-southern provinces play a prominent role in some specific toxic heavy metals emissions, like Hg in Guizhou and As in Yunnan. Finally, integrated countermeasures are proposed to minimize the final toxic heavy metals discharge on account of the current and future demand of energy-saving and pollution reduction in China.
349 citations
TL;DR: In this paper, an improved CH3NH3PbI3−xClx perovskite quality is demonstrated with good crystallization and stability by using water as an additive during crystal perovsite growth.
Abstract: A key issue for perovskite solar cells is the stability of perovskite materials due to moisture effects under ambient conditions, although their efficiency is improved constantly. Herein, an improved CH3NH3PbI3−xClx perovskite quality is demonstrated with good crystallization and stability by using water as an additive during crystal perovskite growth. Incorporating suitable water additives in N,N-dimethylformamide (DMF) leads to controllable growth of perovskites due to the lower boiling point and the higher vapor pressure of water compared with DMF. In addition, CH3NH3PbI3−xClx · nH2O hydrated perovskites, which can be resistant to the corrosion by water molecules to some extent, are assumed to be generated during the annealing process. Accordingly, water additive based perovskite solar cells present a high power conversion efficiency of 16.06% and improved cell stability under ambient conditions compared with the references. The findings in this work provide a route to control the growth of crystal perovskites and a clue to improve the stability of organic–inorganic halide perovskites.
322 citations
TL;DR: In this article, a cost-effective approach to dispose of amaranthus waste (the discarded leaves and stalks of Amaranthus and the extract remains of natural AMaranthus red) to yield nitrogen-doped carbon is presented.
Abstract: We present a cost-effective approach to dispose of amaranthus waste (the discarded leaves and stalks of amaranthus and the extract remains of natural amaranthus red) to yield nitrogen-doped carbon. Amaranthus waste is a natural, abundantly available, and yearly renewable source, acting as a single precursor for nitrogen (mainly from the lysine-rich amino acids) as well as carbon. It therefore eliminates the need for multiple hazardous chemicals including organic precursors for similar synthesis processes. Our facile experimental strategy without any activation supports reasonable nitrogen doping in porous carbon along with a high surface area and excellent conductivity, which leads to a superior electrocatalytic oxygen reduction activity and proves to be a promising alternative for costly Pt-based electrocatalysts in fuel cells in terms of excellent electrocatalytic performance, high selectivity, and long durability. This judicious transformation of organic-rich waste not only addresses the disposal issue, but also generates valuable functional carbon materials from the discard. Our as-synthesized carbon will certainly be believed to be a trend setter and have greater economic ramifications by creating value-added materials from waste.
295 citations
TL;DR: PT-symmetry-breaking chaos is demonstrated in an optomechanical system, which features an ultralow driving threshold and offers the prospect of exploring ultralowing-power-laser-triggered chaos and its potential applications in secret communication.
Abstract: We demonstrate $\mathcal{P}\mathcal{T}$-symmetry-breaking chaos in an optomechanical system, which features an ultralow driving threshold. In principle, this chaos will emerge once a driving laser is applied to the cavity mode and lasts for a period of time. The driving strength is inversely proportional to the starting time of chaos. This originally comes from the dynamical enhancement of nonlinearity by field localization in the $\mathcal{P}\mathcal{T}$-symmetry-breaking phase. Moreover, this chaos is switchable by tuning the system parameters so that a $\mathcal{P}\mathcal{T}$-symmetry phase transition occurs. This work may fundamentally broaden the regimes of cavity optomechanics and nonlinear optics. It offers the prospect of exploring ultralow-power-laser-triggered chaos and its potential applications in secret communication.
295 citations
TL;DR: This proposal offers an alternative approach to control the OMS using a squeezed cavity mode, which should allow single-photon quantum processes to be implemented with currently available optomechanical technology.
Abstract: We investigate the nonlinear interaction between a squeezed cavity mode and a mechanical mode in an optomechanical system (OMS) that allows us to selectively obtain either a radiation-pressure coupling or a parametric-amplification process. The squeezing of the cavity mode can enhance the interaction strength into the single-photon strong-coupling regime, even when the OMS is originally in the weak-coupling regime. Moreover, the noise of the squeezed mode can be suppressed completely by introducing a broadband-squeezed vacuum environment that is phase matched with the parametric amplification that squeezes the cavity mode. This proposal offers an alternative approach to control the OMS using a squeezed cavity mode, which should allow single-photon quantum processes to be implemented with currently available optomechanical technology. Potential applications range from engineering single-photon sources to nonclassical phonon states.
277 citations
TL;DR: This work studies OMIT in parity-time (PT)-symmetric microresonators with a tunable gain-to-loss ratio and shows that by tuning the pump power at a fixed gain- to- Loss ratio, one can switch from slow to fast light and vice versa.
Abstract: Optomechanically-induced transparency (OMIT) and the associated slowing of light provide the basis for storing photons in nanoscale devices. Here we study OMIT in parity-time (PT)-symmetric microresonators with a tunable gain-to-loss ratio. This system features a sideband-reversed, non-amplifying transparency , i.e., an inverted-OMIT. When the gain-to-loss ratio is varied, the system exhibits a transition from a PT-symmetric phase to a broken-PT-symmetric phase. This PT-phase transition results in the reversal of the pump and gain dependence of the transmission rates. Moreover, we show that by tuning the pump power at a fixed gain-to-loss ratio, or the gain-to-loss ratio at a fixed pump power, one can switch from slow to fast light and vice versa. These findings provide new tools for controlling light propagation using nanofabricated phononic devices.
251 citations
TL;DR: A thin-film, flexible, and rechargeable zinc-air battery having high energy density is reported particularly for emerging portable and wearable electronic applications.
Abstract: A thin-film, flexible, and rechargeable zinc-air battery having high energy density is reported particularly for emerging portable and wearable electronic applications. This freeform battery design is the first demonstrated by sandwiching a porous-gelled polymer electrolyte with a freestanding zinc film and a bifunctional catalytic electrode film. The flexibility of both the electrode films and polymer electrolyte membrane gives great freedom in tailoring the battery geometry and performance.
244 citations
TL;DR: In this paper, the results of back trajectory analysis indicated that the elevated concentration of aerosol and its chemical components during haze days might be caused by the integrated effects of accumulation under a stagnant meteorological condition and the transport emissions of pollutants from anthropogenic sources surrounding Beijing city.
233 citations
TL;DR: In this paper, the first-cycle coulombic efficiency strongly depends on the sodium content in NaxFeFeFe(CN)6, and first-principle calculations demonstrate that sodium cations in the large cavities of PBs have a priority to occupy the 8c site, while in the Na-rich samples, Na+ ions can be pushed into other 24d site.
221 citations
TL;DR: In this paper, a symmetric supercapacitor based on a-PFC 3, which is synthesized at the mass ratio of KOH to PF derived carbon (PFC) to be 3 during activation step, offers a specific capacitance of 297 ǫg −1 at current density of 1ǫ g −1 within potential range of #2-3#1ǫV using 1ǒ H 2 SO 4 electrolyte.
TL;DR: In this article, the potential of graphyne as substrate materials for noble-metal (Au, Pt, Ir, Pd, Rh, and Ru) single-atom catalysts have been systematically investigated.
TL;DR: MFe2O4 (M=Mg, Ni, Cu) magnetic nanoparticles (MNPs) were found to have catalytic activities similar to those of biological enzymes such as catalase and peroxidase, which could catalyze the decomposition reaction of H2O2 into water and oxygen directly in the same condition through theCatalase-like activity.
TL;DR: In this paper, an efficient ORR catalyst based on nitrogen doped porous graphene foams (PNGFs) using a hard templating approach was developed, which exhibits both remarkable ORR activity and long term stability in both alkaline and acidic solutions.
Abstract: Nitrogen-doped graphene materials have been demonstrated as promising alternative catalysts for the oxygen reduction reaction (ORR) in fuel cells and metal–air batteries due to their relatively high activity and good stability in alkaline solutions. However, they suffer from low catalytic activity in acid medium. Herein, we have developed an efficient ORR catalyst based on nitrogen doped porous graphene foams (PNGFs) using a hard templating approach. The obtained catalyst exhibits both remarkable ORR activity and long term stability in both alkaline and acidic solutions, and its ORR activity is even better than that of the Pt-based catalyst in alkaline medium. Our results demonstrate a new strategy to rationally design highly efficient graphene-based non-precious catalysts for electrochemical energy devices.
TL;DR: In this article, a three-dimensional porous sulfur, nitrogen co-doped carbon is synthesized using honeysuckles as the single precursor, which has a graphene-like structure and exhibits excellent ORR activity in 0.1m KOH medium with superior tolerance to methanol and stability to those of Johnson Matthey Pt/C catalyst.
TL;DR: In this paper, the density function theory (DFT) calculations were used to investigate the mechanisms for oxygen reduction on the metal-free phosphorus doped graphene (P-Gra) support, and it was found that all ORR species can be strongly adsorbed on the P-Gra except for the H2O molecule.
TL;DR: In this paper, the detailed paths of ORR on MnN4 embedded graphene have been investigated by using the dispersion-corrected density functional theory (DFT-D) method.
TL;DR: In this paper, the authors extend some classes of structured matrices to higher-order tensors and discuss their relationships with positive semi-definite tensors, and some other structured tensors.
Abstract: In this paper, we extend some classes of structured matrices to higher-order tensors. We discuss their relationships with positive semi-definite tensors and some other structured tensors. We show that every principal sub-tensor of such a structured tensor is still a structured tensor in the same class, with a lower dimension. The potential links of such structured tensors with optimization, nonlinear equations, nonlinear complementarity problems, variational inequalities and the non-negative tensor theory are also discussed.
TL;DR: The results indicated that the growth performance significantly increased in the groups HDP, LPP, HPP and HDE, compared with the control, indicating that the feasibility of Rehmannia glutinosa as a fish-feed additive is viable.
TL;DR: Tetrasodium of N,N-bis(carboxymethyl) glutamic acid (GLDA), a novel readily biodegradable chelating ligand, was employed for the first time to remove heavy metals from industrial sludge generated from a local battery company under various conditions.
TL;DR: In this paper, the surface plasmon absorption band of Ag/ZnO composites is distinctly broadened and the PL intensity varies with the increase of Ag loading, which can effectively decrease the recombination of electron-hole pairs, lead to a prolonged lifetime of the electron-holes pairs that promotes the degradation efficiency.
TL;DR: HMs emissions from specified anthropogenic sources under three different control scenarios for the target year 2015 are projected, and collaborative and specialized control strategies are proposed to meet the demand of emission reduction goals of different regions.
Abstract: A bottom-up inventory of atmospheric emissions of five precedent-controlled toxic heavy metals (HMs), including mercury (Hg), arsenic (As), lead (Pb), cadmium (Cd), and chromium (Cr), from primary anthropogenic sources in China is established for the period 2000–2010. Total emissions of HMs demonstrate a gradually ascending trend along with the increase of coal consumption and industrial production, which are estimated at approximately 842.22 t for Hg, 4196.31 t for As, 29272.14 t for Pb, 795.29 t for Cd, and 13715.33 t for Cr for 2010. Coal combustion is found to be the primary source of HMs emissions. Owing to the dramatic differences of coal use by industrial and power sectors among provinces, spatial allocation performs remarkably uneven characteristics, and spatial distribution features are demonstrated by allocating the emissions into 0.5° × 0.5° grid cells with GDP and population as surrogate indexes. Further, HMs emissions from specified anthropogenic sources under three different control scenarios for the target year 2015 are projected, and collaborative and specialized control strategies are proposed to meet the demand of emission reduction goals of different regions. In the future, a whole processes control management system will be the most effective way for control of HMs.
TL;DR: In this article, a waste-to-resource strategy to convert fallen ginkgo leaves into a new kind of ORR electrocatalyst, nitrogen-doped fullerene-like carbon shell (NDCS), is presented.
TL;DR: In this paper, the electronic characteristics of arsenene-graphene van der Waals (vdW) heterostructures were studied by using first-principles methods.
Abstract: The electronic characteristics of arsenene-graphene van der Waals (vdW) heterostructures are studied by using first-principles methods. The results show that a linear Dirac-like dispersion relation around the Fermi level can be quite well preserved in the vdW heterostructures. Moreover, the p-type Schottky barrier (0.18 eV) to n-type Schottky barrier (0.31 eV) transition occurs when the interlayer distance increases from 2.8 to 4.5 A, which indicates that the Schottky barrier can be tuned effectively by the interlayer distance in the vdW heterostructures.
TL;DR: The excellent capacitive and photovoltaic performances highlight the potential of a-NCs in sustainable energy devices.
Abstract: Activated N-doped porous carbons (a-NCs) were synthesized by pyrolysis and alkali activation of graphene incorporated melamine formaldehyde resin (MF). The moderate N doping levels, mesopores rich porous texture, and incorporation of graphene enable the applications of a-NCs in surface and conductivity dependent electrode materials for supercapacitor and dye-sensitized solar cell (DSSC). Under optimal activation temperature of 700 °C, the afforded sample, labeled as a-NC700, possesses a specific surface area of 1302 m2 g(-1), a N fraction of 4.5%, and a modest graphitization. When used as a supercapacitor electrode, a-NC700 offers a high specific capacitance of 296 F g(-1) at a current density of 1 A g(-1), an acceptable rate capability, and a high cycling stability in 1 M H2SO4 electrolyte. As a result, a-NC700 supercapacitor delivers energy densities of 5.0-3.5 Wh kg(-1) under power densities of 83-1609 W kg(-1). Moreover, a-NC700 also demonstrates high electrocatalytic activity for I3- reduction. When employed as a counter electrode (CE) of DSSC, a power conversion efficiency (PCE) of 6.9% is achieved, which is comparable to that of the Pt CE based counterpart (7.1%). The excellent capacitive and photovoltaic performances highlight the potential of a-NCs in sustainable energy devices.
TL;DR: In this article, the authors presented a general mechanism to amplify nonlinearity using parity-time symmetric structures, and showed that an on-chip microscale phonon diode can be fabricated using a π-mathcal{PT}$-symmetric mechanical system.
Abstract: Nonreciprocal devices that permit wave transmission in only one direction are indispensible in many fields of science including, e.g., electronics, optics, acoustics, and thermodynamics. Manipulating phonons using such nonreciprocal devices may have a range of applications such as phonon diodes, transistors, switches, etc. One way of achieving nonreciprocal phononic devices is to use materials with strong nonlinear response to phonons. However, it is not easy to obtain the required strong mechanical nonlinearity, especially for few-phonon situations. Here we present a general mechanism to amplify nonlinearity using parity-time ($\mathcal{PT}$)-symmetric structures, and show that an on-chip microscale phonon diode can be fabricated using a $\mathcal{PT}$-symmetric mechanical system, in which a lossy mechanical resonator with very weak mechanical nonlinearity is coupled to a mechanical resonator with mechanical gain but no mechanical nonlinearity. When this coupled system transits from the $\mathcal{PT}$-symmetric regime to the broken-$\mathcal{PT}$-symmetric regime, the mechanical nonlinearity is transferred from the lossy resonator to the one with gain, and the effective nonlinearity of the system is significantly enhanced. This enhanced mechanical nonlinearity is almost lossless because of the gain-loss balance induced by the $\mathcal{PT}$-symmetric structure. Such an enhanced lossless mechanical nonlinearity is then used to control the direction of phonon propagation, and can greatly decrease (by over three orders of magnitude) the threshold of the input-field intensity necessary to observe the unidirectional phonon transport. We propose an experimentally realizable lossless low-threshold phonon diode of this type. Our study opens up perspectives for constructing on-chip few-phonon devices and hybrid phonon-photon components.
TL;DR: In this paper, a cost-effective synthesis of carbon materials as highly durable ORR electrocatalyst, produced by carbonizing the wasted sweet potato vines, was presented, and the specific capacitance of the as-prepared heteroatoms-doped porous carbon material is as high as 265 F g−1, with a superior cycling stability for electric double-layer supercapacitor at a current density of 1 ǫg−1 after 10,000 cycles.
TL;DR: A solution-processed PSC device with a superior CH3NH3PbI(3-x)Cl(x) crystalline film with large-scale domains and good film uniformity shows a remarkable improvement in PCE, compared with the reference pristine PEDOT PSS based device.
Abstract: Planar structure has been proven to be efficient and convenient in fabricating low-temperature and solution-processing perovkite solar cells (PSCs). Interface control and crystal film growth of organometal halide films are regarded as the most important factors to obtain high-performance PSCs. Herein, we report a solution-processed PEDOT:PSS-GeO2 composite films by simply incorporating the GeO2 aqueous solution into the PEDOT:PSS aqueous dispersion as a hole transport layer in planar PSCs. Besides the merits of high conductivity, ambient stability and interface modification of PEDOT:PSS-GeO2 composite films, the formed island-like GeO2 particles are assumed to act as growing sites of crystal nucleus of perovskite films during annealing. By the seed-mediation of GeO2 particles, a superior CH3NH3PbI3–xClx crystalline film with large-scale domains and good film uniformity was obtained. The resulting PSC device with PEDOT:PSS-GeO2 composite film as HTL shows a best performance with 15.15% PCE and a fill facto...
TL;DR: Based on data samples collected with the BESIII detector at the BEPCII collider at nine center of mass energies from 4.21 to 4.42 GeV, the production of e^{+}e^{-}→ωχ_{cJ} (J=0, 1, 2) is observed for the first time and the upper limits on the cross sections are determined.
Abstract: Based on data samples collected with the BESIII detector at the BEPCII collider at nine center of mass energies from 4.21 to 4.42 GeV, we search for the production of e(+)e(-) -> omega chi(cJ) (J = 0, 1, 2). The process e(+)e(-) -> omega chi(c0) is observed for the first time, and the Born cross sections at root s = 4.23 and 4.26 GeV are measured to be (55.4 +/- 6.0 +/- 5.9) and (23.7 +/- 5.3 +/- 3.5) pb, respectively, where the first uncertainties are statistical and the second are systematic. The omega chi(c0) signals at the other seven energies and the e(+)e(-) -> omega chi(c1) and omega chi(c2) signals are not significant, and the upper limits on the cross sections are determined. By examining the omega chi(c0) cross section as a function of center of mass energy, we find that it is inconsistent with the line shape of the Y(4260) observed in e(+)e(-) -> pi(+)pi(-) J/psi Assuming the omega chi(c0) signals come from a single resonance, we extract the mass and width of the resonance to be (4230 +/- 8 +/- 6) MeV/c(2) and (38 +/- 12 +/- 2) MeV, respectively, and the statistical significance is more than 9 sigma.
TL;DR: Anode modification by doping silver nano-particles (Ag NPs) into poly(3,4-ethylene dioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and cathode interfacial modification by inserting solution-processed bathophenanthroline (sBphen) in CH3NH3PbI3−xClx based planar perovskite solar cells are investigated as discussed by the authors.
Abstract: Anode modification by doping silver nano-particles (Ag NPs) into poly(3,4-ethylene dioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and cathode interfacial modification by inserting solution-processed bathophenanthroline (sBphen) in CH3NH3PbI3−xClx based planar perovskite solar cells are investigated. Prior to the optical effect such as localized surface plasmon resonance, the Ag-NPs distributed in PEDOT:PSS mainly cause an improvement in the electrical property of PEDOT:PSS–Ag NPs composite films. The sBphen interfacial layer modified the surface morphology of perovskite/phenyl-C61-butyric acid methyl ester (PC61BM) films by filling the voids on the surface of perovskite/PC61BM effectively, which led to an obvious improvement in the fill factor. Accordingly, an efficient device with a power conversion efficiency of 15.75% was achieved due to the simultaneous cathode and anode interfacial modification.