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Zinc sulfide, as an excellent catalyst, has attracted a lot of attention from scholars owing to its photocatalytic hydrogen evolution from water splitting in the ultraviolet (UV) region. In this work, polytype wurtzite-nH ZnS (n = 2 and 8) was synthesized successfully using thiourea (SCN2H4) as the sulfur source by hydrothermal and solvothermal methods. Compared with ZnS nanosheets and ZnS nanowires (2H), the ZnS hollow nanosphere (8H) photocatalysts exhibited the best light capturing ability, longest electric charge lifespan and highest electron (e−) and hole (h+) separation efficiency, which contributed to the superior photocatalytic hydrogen production activity. The photocatalytic hydrogen evolution rate (10.35 mmol h−1 g−1) of ZnS hollow nanospheres (8H) with good photostability was measured under the support of solar-light irradiation, and the highest apparent quantum efficiency (AQE) of 6.4% was recorded. This work not only presents the effects of the morphology and stacking order of crystal forms on the hydrogen production performance of photocatalysts, but also provides new insights into the construction of solar-light-driven catalysts for H2 production from H2O splitting.

Pore structure in shale is an important factor influencing the storage capacity of a shale gas reservoir and the effect of shale gas development. Taking the core and outcrop shale samples from the Lower Cambrian Niutitang Formation and Lower Silurian Longmaxi Formation as the object of the research, combined with the scanning electron microscope, high pressure mercury injection, CO2 and N2 gas adsorption experiments, we investigated the porosity, pore types, pore structure, and pore size distribution of the Lower Paleozoic shale gas reservoirs in northern Guizhou, South China. The results indicated that there are developed various genetic types of micro-nano pores in the Lower Paleozoic marine shale in northern Guizhou, which provide the main reservoir spaces for shale gas. The porosity of the Lower Paleozoic shale in northern Guizhou is 1.30%–13.37% in range, and the average is 4.56%. The inter-granular pore, organic matter pore and intra-granular pore are most common. Micropore (

The weak interactions between anions and common functional groups make it difficult for the development of anion photoluminescence sensors. In this work, we report an ultra-sensitive anion photoluminescence (PL) sensor for F− based on triethylene glycol monomethyl ether modified poly(p-phenylenediamine) dots (TPPDs). Due to the PET process in excited TPPDs, no obvious PL behavior can be observed in TPPDs. Due to the fast photoinduced electron transfer (PET) process in excited TPPDs, no obvious photoluminescence behavior can be observed: however, the PET process can be cut off in the presence of F− and TPPDs show bright red PL. The detection limit of this system is 2 × 10−10 M, which is much lower than most other reported detection methods. Compared with traditional “ON-OFF” PL sensors, such an “OFF-ON” PL detection system shows higher value in practical applications. The detection system exhibits superior photostability and high selectivity for F−. We also demonstrate the successful F− detection in vitro based on TPPDs.

Pure silk fibroin (SF) hydrogel exhibits poor elasticity and low water retention ability, owing to the compact crystalline structure and high content of hydrophobic amino acids. Herein, a composite double-network hydrogel of SF and tyramine-modified hyaluronic acid (mHA) was constructed, via the laccase-catalyzed coupling reactions between the phenolic hydroxyl groups from SF and mHA chains. The obtained hydrogel exhibits improved structural stability and flexibility compared to pure SF hydrogel. Meanwhile, the swelling ratio, mechanical property, drug loading, and release behaviors can be readily regulated by alcoholization, altering pH value, and ionic strength of soaking solutions. Increasing pH values promoted the swelling capacity of SF/mHA hydrogel, resulting in an efficient loading of cationic drugs and sustained release of anionic drugs as well. The addition of inorganic salts reduced electrostatic repulsion in the hydrogel scaffold, accompanying with a noticeable improvement of toughness. Furthermore, alcohol treatment induced conformation changes of fibroin protein, and the composite hydrogel achieved a higher fracture and improved elasticity. The present work provides a biological alternative to regulate the mechanical behavior, drug loading, and sustained release capacity of the SF-based hydrogel.

Although previous research has provided useful insights into unconventional shale gas resources in recent years, the geochemical and geological characteristics of marine–continental transitional shale have not been studied systematically. During the Late Permian, Longtan Formation shales were widely deposited in the Yangtze area of South China. These shales clearly indicate the need to deepen our understanding of marine–continental transitional shales. This study describes the various characteristics of black shales from the Longtan Formation in this area on the basis of a field investigation and relevant laboratory analyses. Longtan shale reservoirs, with a thickness and burial depth range of 20–650 and 800–2400 m, respectively, are usually interbedded with coal and compact sandstone reservoirs due to their special sedimentary environment. Geochemical analysis of the samples of Longtan shales from seven wells in the Yangtze area indicates the presence of high organic matters (OMs), with a total organic carbon content in the range of 0.85%–35.7% (average of 7.33%) but low hydrocarbon genetic potential (S2) with a value below 3 mg HC/g rock. The analysis of carbon isotopes and organic macerals demonstrates that the investigated samples mainly contain type III kerogen. Data from gas chromatography and gas chromatography-mass spectrometry analyses illustrate a weakly oxidizing to a weakly reducing environment, with most organic materials originating from algal-bacterial organisms and terrestrial plants. The terrestrial plants contribute significantly to the OM. The Longtan shales are thermally over-matured, and they have entered the dry-gas generation window according to Ro, production index data, and biomarker maturity ratios. X-ray diffraction analyses show that the content of brittle minerals of the Longtan shales is generally lower than that of marine shales in North America. The Longtan shales show a high clay content averaging 60.32 wt% and low calcite mineral content averaging 3.73 wt%. Field emission scanning electron microscopy shows that various types of nanometer-to micrometer-scale pores, including interparticle and intraparticle pores, OM pores, and microfractures, are well developed in the shales. Generally, high OM abundance, thermal evolution degree, clay mineral content, and pore space (porosity of 0.56%–10.6%) positively influence shale gas content (1.0%–3.8%). However, high clay content and variable reservoir thickness hinder the successful production of shale gas.

Although significant progress has been achieved in characterizing marine shale reservoirs, studies that are associated with marine-continental shale reservoirs, particularly quantitative characterizations of shale pore–fracture, remain rare. In this study, 12 black organic-rich marine-continental shale samples were collected from seven wells that were recently drilled in the Upper Permian Longtan Formation in the Southern Sichuan Basin of southern China. X-ray diffraction revealed that clay minerals are the most prevalent component of shale, followed by quartz and calcite. Various pore types were classified and morphologically characterized from images that were obtained with field emission scanning electron microscopy. Shale total porosity, which was measured via mercury injection porosimetry, was between 3.1% and 7.5%. In addition, a pore-fracture interpretation model was built to calculate fractures and matrix porosity, including organic matter porosity, interparticle porosity of brittle minerals, and intraparticle porosity of clay minerals. The model was highly consistent with the measured porosity. Three key parameters were obtained to characterize the development of different types of matrix pores (VTOC > VBri > VClay). Low-pressure N2 and CO2 gas adsorption experiments were conducted to analyze pore volume, special surface area (SSA), and pore-size diameter. The results of the analyses revealed that micropores and macropores (including micro-fractures) are the dominant pores of the Longtan shale reservoir and that micropores provide the dominant shale gas adsorption space. Furthermore, the effects of shale components on pore development, as well as the correlation among different pore structural parameters, were discussed. The results showed that the enrichment of total organic carbon and clay mineral content will benefit the development of the Longtan shale pore–fracture system. Moreover, a good positive linear relationship existed among matrix porosity, pore volume, SSA, average pore diameter, and surface porosity.

Petroleum bulk properties such as API gravity are important parameters in petroleum system analysis. Three sags (the Bayindulan, Saihantala and Wuliyasitai Sags) in the Erlian rift basin of northern China provide interesting insights into the correlations between organofacies, maturity and oil fluid properties. The API gravity of oils in the three sags shows obvious differences, ranging from 17.0 to 30.9° for Bayindulan oils, 25.7–40.5° for Saihantala oils, and 32.8–41.9° for Wuliyasitai oils. Oil geochemical parameters indicate that the differences in oil fluid properties among the three sags can be attributed to the variations in organofacies and thermal maturity, consistent with the analysis of geochemistry and maceral composition of the source rocks in the three sags. Bayindulan oils were expelled from organofacies C with an extremely high initial hydrogen index (HIo) of 600–900 mg/g TOC in the early mature stage (

Using a high pressure, semi-closed thermal simulation system, two organic-rich lacustrine and marine immature shales from North China were investigated to probe the dynamic processes and potential for the gas generation throughout the oil-gas window. The results identified at least two processes during gas generation, as revealed by changes of the gas dry coefficient (C1/ΣC1-5%) and carbon isotopic composition of methane (δ13Cmethane). The first process is associated with kerogen thermal degradation and occurs during the main phase of oil generation, showing an increasing trend of the dry coefficient and δ13Cmethane. The second process begins during the late phase of oil generation, accompanied by increasing yields of wet gas components and 13C depleted methane. Due to the lack of aliphatic carbon in kerogen in the highly to over mature stage, as demonstrated by FTIR analyses, the second process is mainly related to the cracking of kerogen-generated bitumen which is retained in the shale. The hydrogen content, a key parameter for petroleum generation, is then used to quantitatively evaluate the gas generation potential from kerogen thermal degradation and retained-bitumen cracking. Mass balance calculations show that kerogen-generated bitumen that is retained in lacustrine and marine shales is estimated to contribute 30% of the total gas yields at the stage of 1.5–2.0% Ro. This result is consistent with the theoretical calculations from Xia et al. (2013) and has important implications for the shale gas sources, and further the shale gas resource assessments before exploration in shale-gas petroleum systems.

The porosities of the Lower Cambrian shale and Upper Ordovician-Lower Silurian marine shale from the Sichuan Basin were analyzed using He-Hg porosimetry and field-emission scanning electron microscopy, to discuss the relationship of porosity to the organic matter maturity, total organic carbon (TOC) and free gas volume. Overmature (Ro greater than 2%) shale samples with a TOC less than 5% display a positive correlation between TOC and porosity, but samples with a TOC greater than 5% display a limited increase in porosity with increasing TOC. The porosity of shale decreases generally with increasing maturity in the overmature stage. The free gas in porosity is the key factor for successful development of shale gas, and free gas volumes are controlled by porosity and gas saturation. Higher TOC shale has higher porosity and gas saturation. The Lower Silurian Longmaxi Formation shale has a higher TOC, Ro ranging from 2.0% to 2.3%, its porosity and gas saturation are significantly higher than the Lower Cambrian shale. The high free gas volume results in high production in the Lower Silurian Longmaxi Formation shale pay. Key words: marine shale, porosity, free gas, overmature, Sichuan Basin

Sandstone-hosted roll-type U deposits has recently been found in the Middle Jurassic Zhiluo Formation in the Dongsheng area, north of the Ordos Basin. In order to assess the origin of the uranium mineralization, the host sandstone has been investigated, with emphasis on δ34S values of ore-stage pyrite, δ13C of calcite, fluid inclusion oil biomarkers, X-ray diffraction, ICP-MS, as well as studies by electron microprobe and scanning electron microscope. The mineralization consists mainly of coffinite. Some of the coffinite is intimately intergrown with ore-stage pyrite, indicating co-precipitation. Ore-stage pyrite has δ34S values from − 34 to + 17‰, suggesting the pyrite sulfur originated from bacterial sulfate reduction. In the host sandstone, calcite cement exhibits δ13C values from − 27.6 to − 2.1‰ and fluid inclusion oils show evidence of biodegradation. These lines of evidence indicate petroleum was likely oxidized by sulfate-reducing bacteria (SRB) and thus supplied a source of some of the carbon in the calcite. Microbial degradation of petroleum is partially supported by the low-temperature diagenetic environment (

Six petroleum source beds have been developed in the Kuche Depression (also known as “Kuqa Depression”) of the Tarim Basin, including three lacustrine source rocks (Middle and Upper Triassic Kelamayi and Huangshanjie formations, and Middle Jurassic Qiakemake Formation) and three coal measures (Upper Triassic Taliqike Formation, Lower Jurassic Yangxia Formation, and Middle Jurassic Kezilenuer Formation). While type I–II organic matter occurs in the Middle Jurassic Qiakemake Formation (J2q), other source beds contain dominantly type III organic matter. Gas generation rates and stable carbon isotopic kinetics of methane generation from representative source rocks collected in the Kuche Depression were measured and calculated using an on-line dry and open pyrolysis system. Combined with hydrocarbon generation history modelling, the formation and evolution processes of the Jurassic–Triassic highly efficient gas kitchens were established. High sedimentation rate in the Neogene and the fast deposition of the Kuche Formation within the Pliocene (5 Ma) in particular have led to the rapid increase in Mesozoic source rock maturity, resulting in significant dry gas generation. The extremely high gas generation rates from source kitchens have apparently expedited the formation of highly efficient gas accumulations in the Kuche Depression. Because different Mesozoic source rocks occur in different structural belts, the presence of both lacustrine and coaly gas kitchens during the Cenozoic time can be identified in the Kuche Depression. As shown by the chemical and stable carbon isotope compositions of the discovered gases, the formation of the giant gas pools in the Kela 2, Dina 2, Yaha and Wucan 1 have involved very different geological processes due to the difference in their gas source kitchens.

The molecular compositions and molecular carbon isotopic compositions of gas hydrocarbons produced in the hydrocarbon generation of oil asphaltene from Lunnnan area were investigated by pyrolysis of asphaltene sealed in gold tube in a limited system. The experimental results indicated that oil asphaltene from Lunnan area had relatively high generation potential of methane. However, the molecular compositions and molecular carbon isotopic compositions of gas hydrocarbons in the hydrocarbon generation of oil asphaltene exhibited different characteristics from that of gas hydrocarbons by primary cracking of kerogen and secondary cracking of oil. Based on kinetic simulation with paleo-geothermal data of oil reservoir, the methane produced by cracking of oil asphatene was characterized by relatively light carbon isotopic compositions. This result could not explain relatively heavy carbon isotopic compositions of natural gas from Lunnan area. Pyrolysis of kerogen from source rocks under very high temperature probably made remarkable contributions to natural gas from Lunnan area.

Due to the importance of the Gloeocapsomorpha Prisca (G. prisca)-enriched source rocks, which belong to Kukersite-type source rocks in the Lower Paleozoic Ordovician strata, it has received great attentions during the petroleum exploration as to whether there are the Kukersite-type source rocks developed in the major hydrocarbon source strata of the Upper and Middle Ordovician in the Tarim Basin. Using pyrolysis-gas chromatography-mass spectrography to analyse kerogens from source rocks in the lime- mud mound with moderate maturity, study reveals that there are the Kukersite-type source rocks in the Ordovician strata of the Tarim Basin. The pyrolysis products showed a low content of >n-C19 normal alkanes with a significant odd-even predominance between n-C13 and n-C17, long-chain alky substituted alkylbenzene and alkylthiophene isomers and distinctive distribution of 5-N-alkyl-1, 3-Benzenediol and its homologous. Based on the geographic environment characteristics of G. Prisca, the molecular distributions of crude oil from the Lower Paleozoic petroleum systems in the Tarim Basin and characteristics of kerogen pyrolysis products from the Middle and Upper Ordovician source rocks, the results suggested that it is less possible to develop the G. Prisca-enriched Kukersite-type source rocks in the major hydrocarbon source rocks in the Middle and Upper Ordovician strata in the Tarim Basin. However, the benthic macroalga and planktonic algae-enriched source rocks are the main contributors.

As the number of applications of quantum dots (QDs) grows, the likelihood of exposure increases. Because these metals have the potential for detrimental environmental and health effects, concerns have been raised over our lack of understanding about the fate of these products. Among various types of QDs, cadmium-based quantum dots attract the greatest attention due to their wide applications. To properly assess the potential risk of cadmium-containing QDs, we summarize the current state of academic knowledge on the toxicity of cadmium-based QDs.