Improvement In Emission Intensity Research Articles

Carbon emissions embodied in investment: Assessing emissions reduction responsibility through multi-regional input-output analysis

Investment makes an outstanding contribution to the global economy while significantly impacting on global carbon emissions. However, few attempts have been made to analyze temporal changes in historical emissions induced by investment, and it is difficult to determine which countries are responsible for emissions reductions. Here we investigate the evolution in the carbon emissions embodied in investment (ECI) at global and national levels with the Global Multi-regional input-output (GMRIO) model, aiming to address the question of “Who should be responsible for how much, when it comes to emissions reductions?”. Our results show that global ECI increased by 72.4% from 1990 to 2021, with intermediate input structure being the key driver. Specifically, China, the United States and India had the highest ECI, and domestic investment level was responsible for promoting the growth of investment-related emissions. Improvements in emission intensity were the primary contributor to reductions. The construction, electrical and machinery, and transport equipment sectors were the leading sectors in shaping national investment-related emissions. To enable more effective reduction policies measures of ECI reduction, serious consideration should be given to technology cooperation and sharing.

China's economic restructuring reduced emissions of polycyclic aromatic hydrocarbons (PAHs) in the post-global financial crisis era

Polycyclic aromatic hydrocarbons (PAHs) emissions driven by transboundary supply-chain activities across Chinese provinces are largely unknown. In this study, we comprehensively assessed the dynamics of production-, consumption-, and income-based PAHs emissions from individual Chinese provinces in China from 2007 to 2017. We also examined the critical supply-chain paths and socioeconomic drivers behind the changes in PAHs emissions and explored their correlations with China's economic restructuring during this period. We found that production-, consumption-, and income-based PAHs emissions have decreased to lower levels in 2017 (45.6, 36.2, and 40.1 kt, respectively) than those (52.8, 37.5, and 43.6 kt, respectively) in 2007. The dominant contributors of trade-driven PAHs emissions were located in the northern inland provinces with rich coal resources and the southeastern coastal provinces with dense populations and developed economies. China's economic restructuring reduced PAHs emissions in these provinces in the post-global financial crisis era, benefiting from improvements in emission intensity and trade structure. Concurrently, migrating energy- and emission-intensive industries into less affluent provinces (e.g., Xinjiang, Jiangxi, Henan, Anhui, and Yunnan) changed the roles of emission factors (from the demand side), primary input structure and energy mix (from the supply side) from driving down to driving up PAHs emissions. These changing drivers exerted a greater upward influence on PAHs emissions than the overall downward influence exerted by other drivers, thereby causing emissions outsourcing and leakage. This study explored the effects of economic structural transition on interprovincial trade-driven PAH emission transfer, offering valuable insights for policymakers to formulate policies for mitigating PAHs emissions.

Improving Strain-localized GaSe Single Photon Emitters with Electrical Doping.

Exciton localization through nanoscale strain has been used to create highly efficient single-photon emitters (SPEs) in 2D materials. However, the strong Coulomb interactions between excitons can lead to nonradiative recombination through exciton-exciton annihilation, negatively impacting SPE performance. Here, we investigate the effect of Coulomb interactions on the brightness, single photon purity, and operating temperatures of strain-localized GaSe SPEs by using electrostatic doping. By gating GaSe to the charge neutrality point, the exciton-exciton annihilation nonradiative pathway is suppressed, leading to ∼60% improvement of emission intensity and an enhancement of the single photon purity g(2)(0) from 0.55 to 0.28. The operating temperature also increased from 4.5 K to 85 K consequently. This research provides insight into many-body interactions in excitons confined by nanoscale strain and lays the groundwork for the optimization of SPEs for optoelectronics and quantum photonics.

Improvement of emission intensity of PbS quantum dots in thick silica shell by initial coating in organic solvent

Abstract Positioning of colloidal quantum dots (QDs) by nanoholes is applicable to fabricating quantum devices such as quantum circuits. A silica coating technique that facilitates the positioning manages the effective size of QDs while preserving the quantum state inside. In the reverse micelle method, which is commonly used for the silica coating, optical properties deteriorate due to the exposure of QD surface to moisture within the reverse micelle. We studied a thin silica coating on the surface of PbS QDs by pyrolyzing tetraethyl orthosilicate in an organic solvent before forming a thick silica shell by the reverse micelle method. As a result, highly luminous silica-coated PbS QDs with a diameter of about 110 nm were realized.

Tunable emission, energy transfer and cation substitution in the Li2Sr2Al(PO4)3:Dy3+, Eu3+, Na+ phosphor for WLEDs application

The current investigation deals with the synthesis and characterization of the singly, double and triple ions (Dy3+, Eu3+, Na+) co-doped Li2Sr2Al(PO4)3 phosphors. The entire series of suggested phosphors has been successfully synthesized using a straightforward combustion method and their XRD and Rietveld refinement pattern confirms the phase formation and successful synthesis of material. The morphological behaviour, elemental composition, vibrational features, thermal stability and luminescence properties were carried out by SEM-EDAX analysis, FT-IR, TG-DTA and photoluminescence techniques. The single Dy3+ doped Li2Sr2Al(PO4)3 phosphors exhibits blue and yellow emission band around at 482 nm and 572 nm monitored at 350 nm, 365 nm, 388 nm excitation. While, Eu3+ doped Li2Sr2Al(PO4)3 phosphors exhibits orange and red emission band around at 592 nm and 615 nm under 395 nm and 466 nm excitation. According to Froster and Dexter theory, the PL excitation spectrum Dy3+ doped Li2Sr2Al(PO4)3 phosphor and Eu3+ doped Li2Sr2Al(PO4)3 phosphor are overlapped to each other. Consequently, an investigation was conducted to study the transfer of energy between Dy3+ and Eu3+. In addition, to improvement in emission intensity and color tunning host cation (Li+) replaced with another cation (Na+) and their impact was studied. The photometric characterization like CRI Chromaticity coordinate, CRI and CCT values are also estimated using color calculator. The host cation substitution revealed that performance of Dy3+/Eu3+ doped Li2Sr2Al(PO4)3 phosphors were improved with doping of Na+ ions. The overall study and their estimated results suggested that Dy3+, Eu3+, Na+ ions doped Li2Sr2Al(PO4)3 phosphors have huge ability for WLEDs application and their future investigation.

Improvement in luminescence of thermally stable CaMoO4:Tb3+ green phosphor by Bi3+ ions

The growing optoelectronic industries have prompted researchers to develop a single-component green phosphor for diverse applicability. It is well known that Tb3+ doped phosphors emit green light due to strong 5D4→7F5 transition. The green emission of Tb3+ ion can be enhanced by using sensitizers such as Bi3+ ion, which creates intermediate energy levels between the host and Tb3+, thereby, achieving efficient energy transfer between the host and Tb3+. In this article, we have reported a substantial improvement in the green emission of Tb3+ doped CaMoO4 by Bi3+ co-doping. The phosphors have been successfully prepared via a lucrative self-combustion process. The XRD patterns reveal an impurity-free tetragonal crystalline structure of all the phosphors. The Tb3+ doped CaMoO4 gives three major emissions at 489 nm, 544 nm and 621 nm corresponding to the Tb3+ transitions from 5D4 to 7F6, 7F5, and 7F3, respectively. The maximum emission has been achieved for 5% Tb3+ doped CaMoO4, which is further enhanced by 47% via co-doping of Bi3+. The improvement in emission intensity for Bi3+ co-doped phosphors is attributed to improved crystalline nature and transfer of energy from Bi3+ to Tb3+ levels. The energy transfer process from [MoO4]2- to Bi3+ and Tb3+ is explained in detail and maximum improvement is obtained upon co-doping of 4% Bi3+ ions. The incorporation of Bi3+ ions also results in shifting of CIE coordinates and color purity towards green color. The activation energy required for the thermal quenching is 0.25 eV, much better than already reported green phosphors. There is no change in the CIE coordinates of the overall emission with temperature indicating the better emission color stability of the phosphor. Hence with optimum concentration of Bi3+ and Tb3+ ion in CaMoO4 they can be used as potential green emitting phosphors.

CAVITATION FUSION BY ENERGY-INTENSIVE MULTIFUNCTION CAVITATION IN A STRONG MAGNETIC FIELD WITH LASER LIGHT EXCITATION

This paper introduces an experimental apparatus capable of producing cavitation fusion based on laser-assisted high-magnetic-field energy-intensive multifunction cavitation. Combining water jet, ultrasonic and magnetic field energy sources has been shown to increase the luminescence intensity in this system such that the threshold required for deuterium-tritium fusion can be exceeded. The incorporation of a laser provides a further improvement in emission intensity based on an increase in the internal temperature of bubbles. Multiphoton excitation induced by the laser irradiation raises the pressure generated during collisions between bubbles. Consequently, the probability of achieving cavitation fusion is greatly enhanced.

Enhancement of Emission and Negative Thermal Quenching Effect of Na2TiF6:Mn4+,TEAH+ by Antenna Effect of TEAH+

AbstractIn order to develop new red‐emitting phosphors, in this work, a series of organic‐inorganic hybrid Na2TiF6 : Mn4+, (CH3CH2)3NH+ (NTF : Mn4+, TEAH+) red‐emitting phosphors have been prepared. Due to the antenna effect of TEAH+, double improvement in emission intensity and luminous thermal stability of the optimal sample are obtained: (a) The integrated emission intensity of the hybrid NTF : Mn4+,TEAH+ sample is 150 % of the un‐doping one (NTF : Mn4+), (b) The luminescent thermal stability of the hybrid NTF : Mn4+,TEAH+ sample is obviously increased because of strong negative thermal quenching (NTQ) effect. The integrated emission intensity at 150 °C is 176.2 % of the initial value at 30 °C, and the intensity at 178 °C is still 100 % of the initial one. The strong NTQ effect is attributed to the driving of the antenna effect of TEAH+. The above double improvements make the optimal sample has extensive application prospects for daily lighting white light‐emitting diodes (WLEDs).

Drivers and critical paths of carbon emissions in India: a structural path decomposition analysis

ABSTRACT As a fast-growing economy with over 1.35 billion people, India will be critical to achieving future climate targets. The country implemented many policies to limit its carbon emissions. To make targeted policies, it is imperative to evaluate the mutually opposing effects of fast development and climate policies on carbon emissions. We apply environmentally extended input-output analysis, and structural path and decomposition analysis to calculate key emission statistics and drivers of change in critical sectors and production paths. Results reveal that India is a net exporter of emissions and its production and consumption-based emissions have more than doubled between 2000 and 2016. Two sectors, ‘Electricity, gas, and water’ and ‘petroleum, chemical, and non-metallic mineral products,’ function as supplying sectors in most of the critical paths. Although improvements in emission intensity and production structure have helped in reducing emissions, household consumption and investments have increased them.

Investigations on the effect of NH4Cl flux on the structural and optical properties of CdSiO3:Eu3+ nanophosphor

ABSTRACT In this work, NH4Cl flux-assisted solution combustion synthesis of Eu3+-doped CdSiO3 phosphor has been reported. The prepared phosphor has been characterised using XRD, SEM, FTIR, UV–Vis and PL techniques. The influence of NH4Cl flux on the structural, morphological and photoluminescence (PL) properties has been thoroughly investigated. The PL spectra of 5 mol% Eu3+-doped CdSiO3 nanophosphor monitored at Eu3+ emission wavelength of 613 nm, consists of four broad excitation peaks centred at 362 nm, 381 nm, 393 nm and 414 nm ascribed to Eu3+ ion transitions from its 7F0 ground state energy level to different excited energy states 5H3, 5L7, 5L6 and 5D3, respectively. CdSiO3:Eu3+ samples prepared by using 6 wt% flux showed appreciable improvement in emission intensity in the studied concentration limit. The observed improvement in the orange-red photoluminescence is due to effective substitution of Eu3+ ions in the CdSiO3 lattice.

Carbon prices and emission intensity: role of autonomous improvements and price-driven changes

ABSTRACT An improvement in emission intensity for a production process can be achieved either by technological improvements that support lower carbon footprint or by fuel substitution. The prevailing prices of carbon emission allowances motivate the emitters’ decision. In this paper, we examine the interrelationship between the prices of carbon emission allowances and the expected emission intensity in future periods after accounting for common factors representing business cycle innovations. Using data from phase three of the emission trading system in the European Union, we provide evidence that improvements in emission intensity driven by higher prices of carbon emission allowances have low persistence. We also report that the autonomous technological improvements have a durable effect on emission intensity in the future periods. Our findings have important policy implications. Our results highlight the importance of technological improvements for sustained improvements in emission intensity.

Enhanced photoluminescence and energy transfer behavior in Ba3Lu4O9:Bi3+,Eu3+ for flexible lighting applications

In this work, we report a color-tunable green-orange-emitting phosphor by introducing Bi3+ and Eu3+ into Ba3Lu4O9 host lattice. The emission spectra of Ba3Lu4O9:Bi3+,Eu3+ cover the whole visible spectral region, and present both the typical emissions from 3P1 – 1S0 transitions of Bi3+ and 5D0,1 – 7FJ transitions of Eu3+. The energy transfer behavior in the phosphor has been verified, based on which the emitting color of Ba3Lu4(0.98-y)O9:0.08Bi3+,4yEu3+ (y = 0–0.08) can be tuned from yellowish green (0.3188, 0.4491) to orange (0.5304, 0.3871). The phosphor Ba3Lu3.6O9:0.08Bi3+,0.32Eu3+ shows 33.3% improvement in emission intensity of Eu3+ compared with that of Ba3Lu3.92O9:0.32Eu3+. Moreover, soft polydimethylsiloxane/phosphor composite films were prepared utilizing the Ba3Lu4O9:Bi3+,Eu3+. Intense green-orange emissions suggest that the phosphors and corresponding s-PDMS-based films can be considered as promising candidates for near-UV pumped lighting and flexible devices.

Hetero-valent substitution strategy toward orange-red luminescence in Bi3+ doped layered perovskite oxide phosphors for high color rendering index white light-emitting diodes

Controllable efficient emission tuning from 553 nm (yellow) to 609 nm (orange-red) in novel Sr 1- x La 1+ x ZnO 3.5+ x /2 :Bi 3+ (0 ≤ x ≤ 0.4) phosphors with layered perovskite structure is first designed for high color rendering index pc-WLEDs via a hetero-valent cation substitution and controlling over site selective excitation strategies. • Hetero-valent substitution strategy is designed in novel yellow SrLaZnO 3.5 :Bi 3+ . • Luminescence tuning from 558 nm (yellow) to 585 nm (orange) is achieved. • Orange-red luminescence (609 nm) is achieved by site-selective excitation strategy. • White LED shows a superior color rendering index (Ra = 97.1, R9 = 98). The equivalent or hetero-valent substitution strategy is an efficient method for stimulating photoluminescence tuning or optimizing the photoluminescence performances of phosphor materials. A new K 2 NiF 4 -type layered perovskite SrLaZnO 3.5 :Bi 3+ phosphor with broad-band yellow emission (558 nm) is first explored. Based on an efficient hetero-valent substitution strategy, a series of Sr 1- x La 1+ x ZnO 3.5+ x /2 :Bi 3+ (0 ≤ x ≤ 0.4) solid solution phases are successfully constructed. The different Bi 3+ local environments at two crystallographic sites and vacancy oxygen make the various distributions of emission and excitation spectra. Consecutive emission tuning from yellow (558 nm) to orange (585 nm), and improvement of emission intensity and internal quantum efficiency (IQE = 45%-64%) are achieved through La 3+ hetero-valent substitution for Sr 2+ in Sr 1- x La 1+ x ZnO 3.5+ x /2 :Bi 3+ (0 ≤ x ≤ 0.4). The structural stability and Bi 3+ occupation distribution in solid solution have been revealed by structural elaboration and crystal field regulation. Based on the both hetero-valent substitution and site-selective excitation strategies, a novel orange-red luminescence can be observed peaking at ~609 nm under near-ultraviolet light (~390 nm) excitation without visible absorption. The fabricated full-spectrum phosphor-converted white light-emitting diodes (pc-WLEDs) show outstanding warm white light, and a high color rendering index (Ra = 97.1, R9 = 98) is achieved, implying that the as-prepared Sr 1- x La 1+ x ZnO 3.5+ x /2 :Bi 3+ (0 ≤ x ≤ 0.4) phosphors can used as yellow/orange-red components in pc-WLED lighting. These results indicate that hetero-valent substitution can predict and control site preference of luminescent centers, providing a new way for optimizing phosphor materials for solid-state lighting.

Demand contributors and driving factors of Singapore’s aggregate carbon intensities

Singapore is an island city state. It lacks conventional energy resources and is alternative energy disadvantaged. Yet its aggregate carbon intensity, given by the ratio of carbon emissions to GDP, dropped by 30% from 2005 to 2014. Currently it has a relatively low carbon intensity. Using I–O analysis, we study Singapore’s aggregate carbon intensity and the factors contributing to its changes at different levels, i.e. final demand, sector, and transmission levels. It is found that domestic exports accounted for nearly two-thirds of Singapore’s aggregate carbon intensity, followed by private consumption and investment. At the sectoral level, the top three contributors were the petroleum, petrochemical, and land transport sectors. Improvements in emission intensity and final demand structure were major factors contributing to reductions in carbon intensity. Our study contributes to the literature in two aspects. Methodologically, it deals with embodied emission intensity and analyzes its changes from the demand perspective. This differs from most studies in the literature from the production perspective. Empirically, the findings and policy implications are unique as they are applicable to a major city. With urbanization taking place in many developing countries, cites’ role in emissions and environmental sustainability are growing in importance but not many in-depth analyses similar to our study have been reported.

Simultaneous improvement in emission intensity and spectral purity of red photon upconversion in Gd2O3:Yb3+/Er3+ phosphors under 1550 nm excitation

Upconversion luminescent nano-materials with both excitation and emission peaks in the “optical window” is of significant importance for application in deeper bio-imaging, due to the weak effects of light absorption, light scattering, and auto-fluorescence. This paper reports an Er3+ self-sensitized red up-converting nanophosphors with improved emission intensity and spectral purity. The influence of Yb3+ concentration on upconversion luminescence properties is investigated comprehensively. Compared with the sample without Yb3+ doping, the luminescence intensity in the sample with 10% Yb3+ is increased by 12.9 times. Moreover, the dominant wavelength at 1550 nm excitation is about 60 nm larger than that excited at 980 nm. It has been demonstrated that Yb3+ co-doping can not only improve the photon absorption at 1550 nm and the probability of red emission, but also suppress other light emissions and phonon emission through the selective population of red-emitting level.

One-pot synthesis of water-soluble Cu–In–Zn–S/ZnS core/shell quantum dots for efficient white light-emitting devices

I–III–VI quantum dots (QDs), as a new class of light-emitting materials, have aroused a great of attention for an impressive variety of applications. A facile one-pot approach was employed to synthesize highly luminescent Cu–In–Zn–S/ZnS (CIZS/ZnS) core/shell QDs. It was found that the CIZS/ZnS QDs prepared using sodium sulfide as sulfur source exhibited the strongest emission due to its highest chemical reactivity as compared to thiourea and thioacetamide. The combination of GSH content and pH value played a crucial role in the growth of ZnS shell, which was responsible for the bright emission of QDs. The surface defects of QDs could be effective passivated by GSH, which exhibited a significant improvement of emission intensity. The optimum pH value of 7 was also established due to the fact that the deprotonized sulfhydryl group of GSH molecule strongly coordinated with Zn2+ at neutral pH value. Moreover, the particle size and composition of the CIZS/ZnS QDs can be well adjusted by tuning the nZn/nCuInZn ratios. The maximum quantum yield (QY) of CIZS/ZnS QDs increased from 5.95% to 26.12%, accompanying by the improvement of the radiative decay rate from 1.90 × 105 to 5.64 × 105 s−1. Furthermore, a blue LED-pumped white light-emitting diode (WLED) device was realized by combining yellow-orange CIZS/ZnS QDs with green Lu3Al5O12:Ce3+ phosphor, achieving a luminous efficacy (LE) of 66.9 lm/W, and color rendering index (CRI) of 87.2, which demonstrated their great application potential in solid-state lighting field.

Designing High‐Performance LED Phosphors by Controlling the Phase Stability via a Heterovalent Substitution Strategy

AbstractPhosphor‐converted white light‐emitting diodes (LEDs) are currently playing key roles in the lighting and display industries and trigger urgent demands for the discovery of “good” phosphors with high quantum efficiency, improved thermal stability, and controllable excitation/emission properties. Herein, a general and efficient heterovalent substitution strategy is demonstrated in K2HfSi3O9:Eu2+achieved by Ln3+(Ln = Gd, Tb, Dy, Tm, Yb, and Lu) doping to optimize luminescence properties, and as an example, the Lu3+substitution leads to improvement of emission intensity and thermal stability, as well as tunable emission color from blue to cyan. The structural stability and Eu2+occupation via Lu3+doping have been revealed by the structural elaboration and density functional theory calculations, respectively. It is shown that heterovalent substitution allows predictive control of site preference of luminescent centers and therefore provides a new method to optimize the solid‐state phosphors for LEDs.

Survival of the cleanest? Evidence from a plant-level analysis of pollutant emissions in Canadian pulp and paper industry, 2005–2013

We capitalize on access to plant-level data in examining the changes in emissions of biochemical oxygen demand (BOD), total suspended solids (TSS), and greenhouse gas (GHG) for a set of Canadian pulp and paper mills from 2005 to 2013. In particular, we investigate the roles played by changes in output, emission intensity, allocation of production among surviving plants, and plant closures. Output change is the main factor and improvement of emission intensity by surviving plants—the so-called technique effect—brings a small, yet positive contribution. However, there are no indications that market operations determining plant output and plant survival lead to lower emissions.

Complete Decomposition Analysis of CO2 Emissions in the Health Sector in Portugal

This study uses the “Complete Decomposition” technique to examine the intensity of CO2 emissions in the health sector in Portugal over the period 1997–2014. Our results suggest that improvements in emission intensity in the health sector depend on the design of incentives of replacing fossil fuels with fuels from renewable energy sources and adopting measures to save energy. In addition, capital investment may also contribute to the reduction of the emission intensity in the sector, if the investment is applied to the acquisition of more efficient equipment. We identify areas for action and recommend that public and private sector health professionals should elevate energy efficiency to a top priority. Our results also highlight the importance of the Kyoto protocol.

Influence of sol–gel-derived ZnO:Al coating on luminescent properties of Y2O3:Eu3+ phosphor

This study deposited transparent and conductive Al-doped ZnO (AZO) thin coating on the surface of Y2O3:Eu3+ phosphor particle via a sol–gel method and analyzed the influence of soaking pretreatment, sol concentration, stabilizers, and coating temperature on the microstructure and luminescent properties of AZO-coated Y2O3:Eu3+ phosphors with the aid of SEM, TEM, cathodoluminescence (CL), and photoluminescence (PL) measurements. A water soaking pretreatment was found to effectively improve the coverage and uniformity of the AZO coating, resulting in a continuous and coherent coating. This result is attributed to the presence of adsorbed water and hydroxyl groups on the Y2O3:Eu3+ particle surface after water soaking. Monoethanolamine as a stabilizer agent and higher sol concentration led to a thicker coating on the phosphors. At 800 V or lower, the CL intensity of AZO coated Y2O3:Eu3+ phosphors is significantly greater than that of the uncoated particles and increases with coating thickness. In addition, the PL emission intensity also rises with increasing coating thickness and is even higher than bare phosphors. Further increases in coating thickness beyond the optimum value led to a decrease in PL intensity. This study thus proposes that AZO coatings with sufficient thickness and surface coverage bring about in a higher electron/UV light transport and less surface defects, resulting in an improvement in emission intensity.