H2O CO2 Research Articles

Integrating polyarylether-COFs with TiO2 nanofibers for enhanced visible-light-driven CO2 reduction in artificial photosynthesis

Artificial photosynthesis is considered a promising strategy to mitigate environmental issues and energy crises. Herein, one-dimensional oxide–semiconductor (TiO2-nanofiber, TNF) and polyarylether-based covalent organic framework (COF-318) were composed to form a visible-light responsive heterojunction (COF-318/TNF) for artificial photosynthesis by simultaneously triggering CO2 reduction and H2O oxidation. Without additional sacrificial agents, photosensitizers or cocatalysts, the optimal sample COF-318/TNF-15 exhibited CO2-to-CO conversion efficiency of 70.1 ± 0.7 µmol∙g−1∙h−1, 12.7 times higher than that of COF-318. The molar ratio of produced CO to O2 was about 2:1, suggesting H2O was the electron donor in the photocatalytic process. Photoelectrochemical measurements and time-resolved transient absorption spectra illustrated the high separation/transfer efficiency of photo-generated charges in COF-318/TNF-15, which was attributed to the construction of heterojunction and the specific one-dimensional property of TiO2 nanofibers. During the CO2 photoreduction, HCOO* was detected as the key intermediate for CO production according to the in-situ FT-IR analysis. This work provides a new route for the rational design of organic–inorganic heterogeneous photocatalysts for visible-light-driven CO2 reduction.

Linking oxidative and reductive clusters to prepare crystalline porous catalysts for photocatalytic CO2 reduction with H2O

Mimicking natural photosynthesis to convert CO2 with H2O into value-added fuels achieving overall reaction is a promising way to reduce the atmospheric CO2 level. Casting the catalyst of two or more catalytic sites with rapid electron transfer and interaction may be an effective strategy for coupling photocatalytic CO2 reduction and H2O oxidation. Herein, based on the MOF ∪ COF collaboration, we have carefully designed and synthesized a crystalline hetero-metallic cluster catalyst denoted MCOF-Ti6Cu3 with spatial separation and functional cooperation between oxidative and reductive clusters. It utilizes dynamic covalent bonds between clusters to promote photo-induced charge separation and transfer efficiency, to drive both the photocatalytic oxidative and reductive reactions. MCOF-Ti6Cu3 exhibits fine activity in the conversion of CO2 with water into HCOOH (169.8 μmol g−1h−1). Remarkably, experiments and theoretical calculations reveal that photo-excited electrons are transferred from Ti to Cu, indicating that the Cu cluster is the catalytic reduction center.

Ore Genesis of the Toudaochuan Gold Deposit in Central Jilin Province, NE China: Constraints from Fluid Inclusions and C–H–O–S–Pb Isotopes

The Toudaochuan gold deposit is a recently discovered lode gold deposit in Central Jilin Province. Gold ore bodies are dominantly controlled by NE-trending fault. The major hydrothermal period can be further divided into the quartz–pyrite stage (stage I), quartz–gold–polymetallic sulfides stage (stage II, major gold mineralization stage), and quartz–carbonate stage (stage III). Primary fluid inclusions (FIs) identified in quartz at different hydrothermal stages include liquid-rich aqueous FIs (L-type), CO2 FIs (C-type, including CO2-bearing C1-type FIs and CO2-rich C2-type FIs), and minor vapor-rich aqueous FIs (V-type). Microthermometry studies on different fluid inclusions indicate that the original ore-forming fluids belonged to the CO2–H2O–NaCl system characterized by a moderate–low temperature and low salinity in stages I and II, and they finally evolved into a H2O–NaCl system characterized by low temperature and low salinity in stage III. Fluid immiscibility is considered to be the key ore-forming mechanism. The initial ore-forming fluid was originated from magmatic water and was mixed with meteoric water in the later stage. The S and Pb isotope data suggest that the ore metal materials were derived from the mixed source of mantle and crust. Based on all the above data, therefore, it can be proposed that the Toudaochuan gold deposit is a mesothermal magmatic–hydrothermal gold deposit.

Fluid Inclusions and Stable Isotope Geochemistry of Gold Mineralization Associated with Fine-Grained Granite: A Case Study of the Xiawolong Gold Deposit, Jiaodong Peninsula, China

The Xiawolong gold deposit, located in the Muping–Rushan gold metallogenic belt (eastern Jiaodong Peninsula), is a newly discovered deposit that developed in the late Early Cretaceous as fine-grained granite. Gold mineralization, which mainly occurs in the middle of fresh fine-grained granite dikes, consists of stockwork-style and disseminated ores. They are characterized by middle-high-temperature mineral assemblages, such as molybdenite and magnetite, associated with gold-bearing pyrite. Four types of primary fluid inclusions, contained within the quartz grains from the gold-bearing disseminated and stockwork-style fine-grained granitic ores, were identified based on microthermometry and Raman spectroscopy. The types identified were type 1 aqueous inclusions with middle-high temperature (201 to 480 °C) and middle-low salinity of 0.18 to 17.00 wt.% NaCl equiv.; type 2 H2O–CO2 inclusions, which show middle-high temperatures (218 to 385 °C), middle-low salinities (1.23 to 13.26 wt.% equiv. NaCl), and variable XCO2 (0.031 to 0.044); type 3 daughter mineral-bearing inclusions with high temperature (416 to 446 °C) and relatively constant and high salinity (28.59 to 32.87 wt.% NaCl equiv.); and type 4 CO2 fluid inclusions, which possess a bulk density of 0.405 to 0.758 g/cm3 and a constant XCO2 (0.952 to 0.990) (according to the decreasing abundance of fluid inclusions). The δ18Owater range is between 3.4 and 5.9‰, and the range of the δD is from −97.1 to −77.4‰, which indicates that the ore-forming process is of a magmatic water origin. The δ34S values possess a narrow range between 4.5 and 9.3‰, indicating the source of the Mesozoic Kunyushan granitoids. The Pb isotopic compositions of pyrite show that the Mesozoic Kunyushan granitoids are the main lead source for pyrites. Types 1, 2, and 3 fluid inclusions coexist in the same view field of the quartz grain, which are suggested to occur as the result of fluid immiscibility because of the boiling of a single homogeneous NaCl-CaCl2-KCl-CO2-H2O system. The fluid immiscibility, rather the fluid mixing and wall-rock sulfidation, is the mechanism of gold precipitation in the Xiawolong deposit. Compared with both the “Linglong-type” and “Jiaojia-type” gold deposits in the Jiaodong Peninsula in terms of geological–petrographic evidence and all of the available geochemical data, it can be concluded the Xiawolong gold deposit is of magmatic hydrothermal origin, having a genetic relation to the fine-grained granite.

Synergistic effects of CO2 density and salinity on the wetting behavior of formation water on sandstone surfaces: Molecular dynamics simulation

Reservoir wettability is very important to predict the structure and residual capture capacity, potential CO2 leakage accidents and improve the risk assessment and sequestration safety during CO2 geological sequestration. The wetting behavior of fluid on reservoir rock surface is actually an interface phenomenon caused by the interaction of different fluid molecules on rock surface. At present, it is difficult for laboratory experiments to observe the microscopic interface phenomena at the molecular scale under reservoir conditions, while molecular dynamics simulations can characterize the microscopic changes in wetting behavior and analyze the interaction between the fluid and the rock surface. In this study, molecular dynamics simulations are used to study the effects of different CO2 densities and different salinities on the wetting behavior of formation water on the sandstone surface during CO2 geological sequestration. The results show that both salinity and CO2 density have significant effects on the wettability of quartz surfaces. However, the increase in salinity can only weaken the wettability, while the increase in CO2 density can transform the wettability of the quartz surface. Both CO2 molecules and H2O molecules form two adsorption layers at 3.5 Å and 6.9 Å away from the quartz surface. CO2 molecules will replace the positions originally occupied by water molecules on the quartz surface, reducing the contact area between water droplets and the quartz surface. The CO2 density mainly affects the interface behavior between the components in the system, while the NaCl concentration mainly affects the interaction between H2O molecules and ions in the system. The research results can further improve the understanding of the wettability of fluid on the pore surface of reservoir rocks during CO2 geological sequestration.

Molecular-level insight into photocatalytic CO2 reduction with H2O over Au nanoparticles by interband transitions

Achieving CO2 reduction with H2O on metal photocatalysts and understanding the corresponding mechanisms at the molecular level are challenging. Herein, we report that quantum-sized Au nanoparticles can photocatalytically reduce CO2 to CO with the help of H2O by electron-hole pairs mainly originating from interband transitions. Notably, the Au photocatalyst shows a CO production rate of 4.73 mmol g−1 h−1 (~100% selectivity), ~2.5 times the rate during CO2 reduction with H2 under the same experimental conditions, under low-intensity irradiation at 420 nm. Theoretical and experimental studies reveal that the increased activity is induced by surface Au–O species formed from H2O decomposition, which synchronously optimizes the rate-determining steps in the CO2 reduction and H2O oxidation reactions, lowers the energy barriers for the *CO desorption and *OOH formation, and facilitates CO and O2 production. Our findings provide an in-depth mechanistic understanding for designing active metal photocatalysts for efficient CO2 reduction with H2O.

As-Doped h-BN Monolayer: A High Sensitivity and Short Recovery Time SF6 Decomposition Gas Sensor.

SF6 is a common insulating medium of gas-insulated switchgear (GIS). However, it is inevitable that SF6 will be decomposed due to partial discharge (PD) in GIS, which will cause hidden dangers to the safe and stable operation of equipment. Based on the DFT method, the two-dimensional nano-composite As-doped h-BN (As-BN) monolayer was proposed. By modeling and calculating, the ability of an As-BN monolayer as a specific sensor for SO2F2 (compared with an H2O adsorption system and CO2 adsorption system) was evaluated by parameters such as the binding energy (Eb), adsorption energy (Eads), transfer charge (ΔQ), geometric structure parameters, the total density of states (TDOS), band structure, charge difference density (CDD), electron localization function (ELF), sensitivity (S), and recovery time (τ). The results showed that an As-BN monolayer showed strong adsorption specificity, high sensitivity, and short recovery time for SO2F2 gas molecules. Therefore, the As-BN monolayer sensor has great application potential in the detection of SF6 decomposition gases.

Metasomatized mantle lithosphere and altered ocean crust as a fluid source for orogenic gold deposits

Whether auriferous hydrothermal fluid is generated during crustal metamorphism or by subcrustal processes to form orogenic gold deposits is hotly debated. Noble gas isotope and halogen abundance ratios can provide important constraints to help resolve this controversy. The Danba gold deposit is a rare example of a Jurassic age hypozonal orogenic gold deposit on the western margin of the Yangtze Craton, China. It is characterized by thick barren quartz veins with fractures infilled by thin auriferous quartz veinlets. The syn-gold quartz veinlets are associated with plagioclase and pyrrhotite and are distinguished from the barren quartz vein hosts on the basis of cathodoluminescence, trace-element content and Raman spectroscopy and microthermometry of fluid inclusions. The dominant fluid inclusions in the gold-bearing quartz and plagioclase are H2O–CH4 with vapor fill of ∼ 15–45 vol% and high pressure-corrected trapping temperatures of ∼ 500 °C, low salinities (<4 wt% NaCl equiv.) and high Mg/Fe ratios. Crushing syn-gold quartz and plagioclase released fluid inclusions with 40Ar/36Ar ratios of between 490 and 710, molar Br/Cl ratios of (0.3–0.7) × 10−3 and molar I/Cl ratios of (18–60) × 10−6. Crushing syn-gold pyrrhotite released fluid inclusions with 3He/4He ratios of 0.21–0.38 Ra (Ra = air value, 1.39 × 10−6) that are higher than typical crustal values of < 0.1 Ra, and 40Ar/36Ar of 330–640 that are similar to the gold-related quartz-hosted inclusions. The combined noble gas and halogen data do not favor an auriferous fluid derived from K- and U-rich Proterozoic granitic basement, which is expected to have radiogenic 40Ar/36Ar and 3He/4He ratios. Instead, the data are more consistent with a fluid source from underlying mantle lithosphere containing a high proportion of altered ocean crust (AOC). The auriferous fluid that formed the Danba gold deposit is thus considered to have been derived from a source comprising both metasomatized mantle lithosphere that had been fertilized in a Neoproterozoic subduction event and a portion of relict AOC beneath the western margin of the Yangtze Craton. In contrast with syn-gold fluid inclusions, those in pre-gold barren quartz are H2O–CO2 dominated. Crushing pre-gold quartz released fluid inclusions with 40Ar/36Ar ratios of 2410–5450, Br/Cl ratios of (1.2–1.5) × 10−3 and I/Cl ratios of (60–80) × 10−6 that are distinctly different to the gold-ore stage. The higher 40Ar/36Ar ratios of the pre-gold fluids are consistent with a source for the barren host quartz veins from prograde greenschist- to amphibolite-facies metamorphism of the Proterozoic granitic basement.

Reflectance study of ice and Mars soil simulant associations—II. CO[formula omitted] and H[formula omitted]O ice

We measure the visible and near-infrared reflectance of icy analogues of the Martian surface made of CO2 ice associated in different ways with H2O ice and the regolith simulant JSC Mars-1. Such experimental results obtained with well-controlled samples in the laboratory are precious to interpret quantitatively the imaging and spectral data collected by various Mars orbiters, landers and rovers. Producing and maintaining well-characterised icy samples while acquiring spectro-photometric measurements is however challenging and we discuss some of the difficulties encountered in preparing and measuring our samples. We present the results in the form of photometric and spectral criteria computed from the spectra and plotted as a function of the composition and physical properties of the samples. Consistent with previous studies, we find that when intimately mixed with other materials, including water ice, CO2 ice becomes rapidly undetectable due to its low absorptivity. As low as 5 wt% of fine-grained H2O ice is enough to mask entirely the signatures of CO2. Similarly, sublimation experiments performed with ternary mixtures of CO2 ice, H2O ice and JSC Mars-1 show that water, even when present as a minor component (3 wt%), determines the texture and evolution of the mixtures. We assess the ability of various combinations of spectral parameters to identify samples with H2O, CO2, JSC Mars-1, or various mixtures from their reflectance and orient our study to helping interpret ice and soil reflectance spectra from the Martian surface. From the laboratory spectra, we simulate the colour signal generated by the CaSSIS instrument to allow for direct comparisons with results from this instrument and provide to databases the necessary spectral data to perform the same operations with other instruments.

Oxide-Derived Core-Shell Cu@Zn Nanowires for Urea Electrosynthesis from Carbon Dioxide and Nitrate in Water.

Urea electrosynthesis provides an intriguing strategy to improve upon the conventional urea manufacturing technique, which is associated with high energy requirements and environmental pollution. However, the electrochemical coupling of NO3- and CO2 in H2O to prepare urea under ambient conditions is still a major challenge. Herein, self-supported core-shell Cu@Zn nanowires are constructed through an electroreduction method and exhibit superior performance toward urea electrosynthesis via CO2 and NO3- contaminants as feedstocks. Both 1H NMR spectra and liquid chromatography identify urea production. The optimized urea yield rate and Faradaic efficiency over Cu@Zn can reach 7.29 μmol cm-2 h-1 and 9.28% at -1.02 V vs RHE, respectively. The reaction pathway is revealed based on the intermediates detected through in situ attenuated total reflection Fourier transform infrared spectroscopy and online differential electrochemical mass spectrometry. The combined results of theoretical calculations and experiments prove that the electron transfer from the Zn shell to the Cu core can not only facilitate the formation of *CO and *NH2 intermediates but also promote the coupling of these intermediates to form C-N bonds, leading to a high faradaic efficiency and yield of the urea product.

The Ulug-Sair Gold Occurrence (Western Tuva, Russia): Mineralogy, Ore Genesis, and S-O Isotope Systematics

Ulug-Sair Au-Bi-Te-Se mineralization is one prospect for native Au in the Western Tuva, and its origin remains debated. Mineralization consists of gold–sulfide–quartz veins in the host sedimentary rocks (conglomerates, siltstones, shales), quartz–tourmaline, and quartz–carbonate–sericite–altered rocks. To determine its origin, we examined the mineralogical–geochemical features, formation conditions, and fluid sources of the Ulug-Sair ore. A mineralogical–geochemical investigation outlines two substages with Au: an early gold–sulfide–quartz with pyrite, chalcopyrite, galena, gold, and electrum; and a late gold–telluride–sulfide–quartz, characterized by the presence of Bi-bearing minerals (AgBiTe, Bi2Te2Se, Cu3BiS3, Bi), tellurides (Au and Ag), Se-tellurides (Ag and Bi), and selenides (Au, Ag, and Hg). The paragenesis of Au–Ag tellurides, and fluid inclusion study data (microthermometry, Raman spectroscopy, LA-ICP-MS, and crush leach analysis (gas and ion chromatography, ICP-MS) in quartz showed that quartz–tourmaline-altered rocks were formed by an aqueous Mg–Na–K-chloride fluid with a salinity of 8–10 wt % NaCl eq. at 325–370 °C, whereas the host quartz–carbonate–sericite-altered rocks were formed from CO2–H2O fluid containing CH4 and N2, with a salinity of 0.18–6.1 wt % NaCl eq. at 200–400 °C. Gold-bearing mineral assemblages were formed at P ~ 0.75–1.0 kbar (~2.3–3 km) due to CO2–H2O chloride (Na–K ± Fe, Mg) fluid with CH4, Na2SO4, and Na2B2O5, and salinities 1.7–12.5 wt % NaCl eq. at temperatures decreasing from 360 up to 115 °C (gold–sulfide–quartz veins—360–130 °C, and gold–telluride–sulfide–quartz veins—330–115 °C), and variable fO2, fS2, fSe2, and fTe2. Results of the investigation of the isotope composition of S in pyrites indicates the magmatic origin of the fluid (δ18SH2S fluid from −0.4 to +2.5‰). The stable O isotope data in quartz indicates that, at an early substage, the formation of ore involved a fluid of magmatic and metamorphic origin (from +8.2 to +11.6‰), and, in the later substage, multiple sources of hydrothermal fluids (from +3.1 to +10.4‰), including magmatic-derived, metamorphic-derived, and meteoric waters. These data, in conjunction with structurally controlled mineralization, point towards similarities of the Ulug-Sair ore system with orogenic gold deposits.

Tectonic setting, fluid inclusion and gold mineralization of the southwest Poli region (northern Cameroon Domain)

This paper documents original petrographic and structural data on metamorphic and magmatic rocks as well as the occurrence of gold mineralization in the Dourou Tchaga area (SW Poli) in the northwestern Cameroon domain. The study area is dominated by high-grade gneisses derived from a volcanic-sedimentary series alternating with orthogneiss and magmatic rocks. Four main deformation stages were distinguish comprising the early D1 and D2 deformations showing ductile behavior under amphibolite to granulite facies, followed by retrogression into greenschist facies. D3 and D4 are characterized by ductile-brittle and late brittle structures. Gold mineralization is hosted in laminated quartz veins in steeply dipping, ENE–WSW-trending, sinistral shear zone developed during D3. Host rocks are high-grade metamorphic paragneiss and orthogneiss. Ore minerals include native gold, galena, sphalerite, pyrite and chalcopyrite; wall rock alteration assemblage includes stable pyrite, magnetite and hematite. This assemblage together with specific quartz microstructures indicate gold mineralization at lower greenschist facies conditions. Gold is disseminated in quartz veins and wall rock alteration zones, where it occurs as free grains but also as inclusions in pyrite and sphalerite. Two types of fluid inclusions are distinguished: aqueous-carbonic CO2–H2O and aqueous (H2O), both with low to moderate (2.0–13.9 wt% NaCleq) salinity and variable CO2 content of 13–23 mole% for the aqueous-carbonic fluid inclusions. Fluid inclusions data and alteration assemblage provide evidence that gold precipitation in quartz veins occurred in response to an increase in fO2 caused by fluid pressure fluctuations in the shear zone. Gold mineralization in the northern Cameroon domain was formed during post-collisional stage and retrograde exhumation of the terrane in the greenschist facies toward the end of the Panafrican Orogeny.

Origin of pegmatitic melts from granitic magmas in the formation of the Jiajika lithium deposit in the eastern Tibetan Plateau

Granitic pegmatites may be genetically related to granites. However, it is still debatable how pegmatitic melts originated from granitic magmas. For example, a possible mechanism of melt–melt immiscibility for the origin of pegmatitic melt has not been well documented. The Jiajika Li deposit in the eastern Tibetan Plateau is a world-class deposit and is hosted in pegmatites, which occurred as dikes surrounding their source granite (two-mica granite). This paper concerns melt inclusions (MIs) in quartz from the granite–marginal pegmatite (GMP) at the roofward contact of the two-mica granite with the country-rock schist, as the MIs from such pegmatite are considered to represent the original pegmatitic melt and hence are ideal for investigating the origin of pegmatitic melts from granitic magmas. The MIs can be classified into H2O–CH4- and H2O–CO2-bearing types, both containing solid phases, including muscovite, albite, and apatite; the H2O–CO2-bearing MIs are usually associated with the H2O–CO2 fluid inclusions. To prevent leakage or decrepitation of these MIs during heating, external pressures were applied by using a hydrothermal diamond-anvil cell. The compositions of muscovite inside the unheated MIs and glass inside the MIs, which was quenched from a homogenous state, were analyzed using electron microprobe analysis (EMPA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). During heating, the H2O–CH4-bearing MIs were homogenized into an H2O-saturated melt mostly at 750–800 °C, while the H2O–CO2-bearing MIs, when similarly treated, showed H2O–CO2-oversaturated entrapment features. The H2O–CH4-bearing MIs are considered to be trapped from the original pegmatitic melt containing ∼12 wt% H2O with up to ∼1000 ppm Li, ∼1500 ppm Rb, and ∼1800 ppm Cs, at pressures of ∼550–700 MPa. Based on previous MI-homogenization experiments, it has been reported that the microthermometry features and compositions (e.g., H2O contents) of the H2O–CH4-bearing MIs in the GMP quartz are similar to those in an H2O-rich melt, which was immiscible with an H2O-poor melt inside the heated MIs in quartz from the two-mica granite. Accordingly, in this study, we demonstrate that pegmatitic melts could be originated via melt–melt immiscibility of granitic magma, and that the initial exsolution of the pegmatitic melt from granitic magma can occur on a very small scale, as tiny droplets whose sizes may be similar to those of the observed MIs in granite. In addition to the enrichment of Li, B, and P, the enhanced H2O content under low oxygen fugacity condition in the granitic magma, as well as the decrease in pressure following the magma emplacement, could promote the melt–melt immiscibility.

Absolute OH density measurements in a CO2–H2O glow discharge by laser-induced fluorescence spectroscopy

Time-resolved absolute OH density measurements in a millisecond-pulsed DC glow discharge from carbon dioxide with water admixture, by laser-induced fluorescence (LIF) spectroscopy, are presented. For this purpose, a novel technique is suggested to calibrate the OH LIF setup by means of two-photon absorption LIF spectroscopy measurements on a CO-filled gas cell. OH densities in the order of 1 × 1018 m−3 are reported at a pressure of 6.67 mbar with a water admixture of 20% and a discharge current of 50 mA. Furthermore, the time evolution of the CO2 conversion is determined from collision energy transfer LIF and validated against the literature. The time-dependent rotational temperature of OH is obtained with LIF thermometry.

A novel route to synthesize metal titanium phosphate ceramic pigments: Co, Ni, and Cu-incorporated α-Ti(HPO4)2⋅H2O from ilmenite

Solid-state reaction of α-Ti(HPO4)2·H2O (α-TiP) and acetates of Co, Ni, or Cu at 500 °C and 800 °C produce a number of different metal titanium phosphate (MTiP) inorganic pigments with different colors and shades. At a given metal to α-TiP ratio and calcination temperature, the reaction produces several types of pigments such as phosphates M0.5TiO(PO4), M0.5Ti2(PO4)3, M2P2O7, and M3(PO4)3 (M = Co, Ni, and Cu) with a unique color. α-TiP, an iron free base material was prepared by digestion of high-grade natural ilmenite beach sand (FeTiO3) with 85 wt% H3PO4 at 120 °C. TGA, XRD, SEM/EDX, Diffuse reflectance UV–vis, and Raman spectroscopy techniques were used for characterization. Synthesized MTiP pigments after enameling at a single fire glazing at 1100 °C for 45 min exhibit vivid colors, ranging from purple, yellow, and green with different shades.

A Compact WSGG Formulation to Account for Inhomogeneity of H2O–CO2 Mixtures in Combustion Systems

Abstract An alternative weighted-sum-of-gray-gases (WSGG) model is proposed with a single set of constant pressure-based absorption coefficients that accounts for different mole fraction ratios (MRs) of H2O–CO2. The method requires no further interpolation, which in turn brings not only less uncertainty into the model but also simplifies its use. The hitemp2010 spectral database along with the line-by-line (LBL) integration is employed to generate a set of accurate total emissivities from which the WSGG coefficients are fitted. The fitting procedure employs a novel formulation to account for the MR dependence, leading to a more compact set of WSGG correlations when compared to the alternatives available in the literature. The new formulation takes advantage of the weak interdependence of temperature and molar fraction ratio in the weight factors and therefore separates their effects by two independent correlations. As oxy-fired combustion usually occurs in two distinct scenarios, dry- and wet-flue gas recirculation (FGR), the paper also proposes two other sets of coefficients intended to support the MR ranges corresponding to these specific conditions. Comparisons made against the benchmark LBL integration and other WSGG models, for one- and three-dimensional calculations, show the satisfactory level of accuracy of the proposed sets of correlations. In particular, the three-dimensional test case illustrates that the new model is also applicable to conditions observed in air–fuel combustion.

Near Infrared Spectroscopy As an Effective Way of Studying Hydrogen Bonding in a LiCl–H2O–CO2 Ternary Mixture

Abstract The possibility of using near IR spectroscopy to analyze the effect isobaric heating has on hydrogen bonding in an aqueous solution of LiCl in equilibrium with supercritical carbon dioxide (a LiCl–H2O–scCO2 ternary mixture) is demonstrated in a wide range of electrolyte concentrations. It is shown that this approach is highly efficient when studying ion and molecular systems with different types of interparticle interactions. The use of near IR spectroscopy allows distinguishing spectral contributions from hydrogen bonded n-mers of bulk water and water molecules in the solvation shells of ions or in ion–water chains like those formed in solutions with extremely high electrolyte concentrations that do not contain bulk water. It is shown for the studied ternary mixture that raising the concentration of electrolyte completely neutralizes the destructive effect of carbon dioxide on the formation of a hydrogen bonded structure of water. The latter is stabilized under the influence of an ion field, which also substantially weakens the temperature effect.

Genesis of the Talate Pb–Zn (–Fe) deposit in the Altay, Xinjiang, NW China: Evidence from fluid inclusions and stable isotopes

The Talate Pb–Zn (–Fe) deposit, located in the Kelan volcanic-sedimentary Basin, Chinese Altay (part of Central Asian Orogenic Belt, NW China), is hosted in the second unit of the lower member of the Lower Devonian Kangbutiebao Formation. This deposit has undergone two periods, including submarine exhalative-sedimentary period (I), and magmatic hydrothermal (skarn) period (II), and period II can be further divided into three stages: prograde skarn stage (II-1), retrograde skarn stage (II-2), and quartz–sulfide stage (II-3). Electron microprobe analyses data show that garnet from II-1 stage is consists of solid solutions of almandine, spessartine, pyrope, and grossularite, with small fraction of andradite and uvarovite. Chlorite forming temperature ranging from 163 to 169 °C. L-type fluid inclusions in period I sphalerite has two total homogenizing temperature of 259 °C and 286 °C, respectively. The ore-forming fluids in the II-1 and II-2 stage belong to the H2O–NaCl system with moderate to high temperatures (mainly at 206–368 °C and 202–416 °C, respectively) and moderate–low salinities (7.17–17.34 wt% NaCl eqv. and 6.45–19.21 wt% NaCl eqv., respectively). The II-3 stage ore-forming fluids belong to H2O–CO2 (±CH4/N2)–NaCl system, their temperature and salinity varies widely (193–445 °C, 0.42–37.40 wt% NaCl eqv., respectively). The garnet and quartz samples from II-1 and II-3 stages yield δDV-SMOW and δ18Ofluid values (–79.8 to –64.9‰ and 4.14 to 6.17‰, respectively) and (–80.7 to –67.0‰ and –0.15 to 3.05‰). The microthermometry data combined with stable isotope data indicate ore-forming fluids in II-1 and II-3 stages are derived from primary magmatic water, but in II-3 stage is mixed with more meteoric water. In addition to meteoric water, it is supplied by carbon-rich, high-temperature and high-salinity fluid in II-3 stage. The δ34S values of the period I sulfides range from –11.7‰ to 2.4‰. Sulfur source in Talate deposit derived from the deep magmatic hydrothermal fluid. The Talate Pb–Zn (–Fe) deposit belongs to the volcanogenic massive sulfide (VMS) + skarn type, thus a genetic model is proposed to explain the metallogenic process of the Talate deposit.

Selective photocatalytic CO2 reduction in aerobic environment by microporous Pd-porphyrin-based polymers coated hollow TiO2

Direct photocatalytic CO2 reduction from primary sources, such as flue gas and air, into fuels, is highly desired, but the thermodynamically favored O2 reduction almost completely impedes this process. Herein, we report on the efficacy of a composite photocatalyst prepared by hyper-crosslinking porphyrin-based polymers on hollow TiO2 surface and subsequent coordinating with Pd(II). Such composite exhibits high resistance against O2 inhibition, leading to 12% conversion yield of CO2 from air after 2-h UV-visible light irradiation. In contrast, the CO2 reduction over Pd/TiO2 without the polymer is severely inhibited by the presence of O2 ( ≥ 0.2 %). This study presents a feasible strategy, building Pd(II) sites into CO2-adsorptive polymers on hollow TiO2 surface, for realizing CO2 reduction with H2O in an aerobic environment by the high CO2/O2 adsorption selectivity of polymers and efficient charge separation for CO2 reduction and H2O oxidation on Pd(II) sites and hollow TiO2, respectively.

Electrochemically Driven Interfacial Transformation For High‐Performing Solar‐To‐Fuel Electrocatalytic Conversion

AbstractThe carbon dioxide reduction reaction (CO2RR) suffers from poor selectivity with low Faradaic efficiency and limited current density due to the lack of advanced electrocatalysts. Herein, it is demonstrated that the electrochemically driven interfacial transformation of bismuth sulfide (Bi2S3) nanorods enables the in situ formation of a 3D bismuth nanosheet network (BiNN) on functionalized carbon fibers (BiNN‐CFs). Notably, the formation of an ideal heterojunction with self‐driven charge migration facilitates the composition conversion with rapid reduction of Bi2S3 nanorods in seconds. The functionalization of CFs via Joule heating of the polytetrafluoroethylene coating induces an interfacial interaction for the simultaneous morphology evolution into the hierarchical BiNN via the recrystallization process. More importantly, the hierarchical BiNN‐CFs display improved performance for the CO2RR, including reasonable selectivity for formate generation (≈92%) in the broad potential range, a large partial current density of 419 mA cm–2, and good long‐term stability. Theoretical understanding elucidates that the lattice distortion tunes the p‐band center for optimizing the intermediate adsorption, and thus improving the electrocatalytic activity. Of particular note, the solar‐driven CO2–H2O full cell also demonstrates a promising energy conversion efficiency of 13.3%. These advances demonstrate the large space to optimize electrocatalysis that stems from the rational regulation of interfacial structure and properties.