Recent advances in graphitic carbon nitride-based photocatalysts for solar-driven hydrogen production

Due to the abundance and sustainability of solar energy,converting it into chemical energy to obtain clean energy presents an ideal solution for addressing environmental pollution and energy shortages stemming from the extensive combustion of fossil fuels.In recent years,hydrogen energy has emerged on the stage of history as the most promising clean energy carrier of the 21st century.Among the current methods of producing hydrogen,photocatalytic hydrogen production technology,as a zero-carbon approach to producing high calorific value and pollution-free hydrogen energy,has attracted much attention since its discovery.As the core of photocatalysis technology,semiconductor photocatalysts are always the research hotspots.Among them,graphite-phase carbon nitride(g-C_(3)N_(4)),an organic semiconductor material composed of only C and N elements,possesses physicochemical properties incomparable to those of traditional inorganic semiconductor materials,including suitable energy band positions,easy structural regulation,inexpensive raw materials and abundant reserves,simple preparation,high thermal/mechanical/chemical stability,etc.Therefore,g-C_(3)N_(4) has attracted extensive attention in the field of photocatalytic hydrogen production in the last two decades.This review comprehensively outlines the research trajectory of g-C_(3)N_(4) photocatalytic hydrogen production,encompassing development,preparation methods,advantages,and disadvantages.A concise introduction to g-C_(3)N_(4) is provided,as well as an analysis of the underlying mechanism of the photocatalytic system.Additionally,it delves into the latest techniques to enhance performance,including nanostructure design,elemental doping,and heterojunction construction.The applications of g-C_(3)N_(4) based photocatalysts in hydrogen production are surveyed,underscoring the significance of catalyst active sites and g-C_(3)N_(4) synthesis pathways.At length,concluded are insights into the challenges and opportunities presented by g-C_(3)N_(4) based photocatalysts for achieving heightened hydrogen production.

具有超快电子传输能力的金/薄层氮化碳等离子光催化剂用于光催化产氢（英文）

光催化产氢可以直接将太阳能转化为化学能,是非常有前景的产氢技术之一.然而,光催化产氢的瓶颈在于如何提高光催化产氢效率和光催化剂的稳定性,以及降低产氢成本.因此,开发廉价、易于制备的产氢光催化剂引起人们广泛关注.作为一种非金属半导体光催化剂,石墨相氮化碳(g-C_3N_4)具有良好的物理化学性质,如良好的化学和热稳定性、极佳的光电性能、强的抗氧化能力等.更为重要的是,g-C_3N_4具有合适的能带结构,能够利用可见光.因此,g-C_3N_4已广泛应用于光催化降解、空气净化、光解水和光催化CO2还原等领域.然而,体相g-C_3N_4仍然暴露出一些缺点,例如比表面积小、光生电子-空穴对的复合率高和反应动力学差等.将体相g-C_3N_4剥离成g-C_3N_4纳米薄片是提高光催化效率的有效方法.薄层g-C_3N_4纳米片具有较高的比表面积,比体相的g-C_3N_4有更好的光生电子-空穴对分离效率.为了进一步提高g-C_3N_4的光催化性能,本文通过在薄层g-C_3N_4表面均匀分散Au纳米颗粒来控制电荷载流子的流动.并通过光催化产氢和污染物降解来评估金/薄层氮化碳(Au/monolayer g-C_3N_4)复合材料的光催化性能.所有的Au/薄层g-C_3N_4复合材料均显示出优于体相g-C_3N_4的光催化性能,其中1%Au/薄层g-C_3N_4复合光催化剂具有最高的产氢速率(565μmol g.1h.1),且具有最佳的污染物降解能力.这主要归结于热电子的注入,而不是肖特基结.Au纳米颗粒的成功引入带来了表面等离子共振(SPR)效应,SPR效应不仅能够提高光吸收效率,而且能够带来高效的热电子转移途径.热电子是从Au纳米颗粒表面注入到薄层g-C_3N_4纳米片的导带上.因此,Au/薄层g-C_3N_4复合光催化剂具有更高的光生电子-空穴对迁移和分离效率,以及更低的光生电子-空穴对复合几率.采用紫外可见光谱(UV-Vis)、光致发光光谱(PL)、光电流和阻抗等表征手段研究了Au/薄层g-C_3N_4复合光催化剂性能提升的原因.结果表明,相比于薄层g-C_3N_4纳米片,Au/薄层g-C_3N_4复合光催化剂具有更好的光电性能,因而光催化活性更高.此外,与薄层g-C_3N_4纳米片的光电流强度相比,Au/薄层g-C_3N_4复合光催化剂的光电流强度没有发生改变,这表明薄层g-C_3N_4纳米片导带上的光生电子不可能转移到Au纳米颗粒的表面.也就是说,肖特基结并没有参与到电子转移过程中。

Hierarchical hybrid testability modeling and evaluation method based on information fusion

In order to meet the demand of testability analysis and evaluation for complex equipment under a small sample test in the equipment life cycle, the hierarchical hybrid testability model- ing and evaluation method （HHTME）, which combines the testabi- lity structure model （TSM） with the testability Bayesian networks model （TBNM）, is presented. Firstly, the testability network topo- logy of complex equipment is built by using the hierarchical hybrid testability modeling method. Secondly, the prior conditional prob- ability distribution between network nodes is determined through expert experience. Then the Bayesian method is used to update the conditional probability distribution, according to history test information, virtual simulation information and similar product in- formation. Finally, the learned hierarchical hybrid testability model （HHTM） is used to estimate the testability of equipment. Compared with the results of other modeling methods, the relative deviation of the HHTM is only 0.52%, and the evaluation result is the most accu rate.

Late Paleozoic to Mesozoic extension in southwestern Fujian Province, South China： Geochemical, geochronological and Hf isotopic constraints from basic-intermediate dykes

The tectonic evolution of SE China block since late Paleozoic remains debated. Here we present a new set of zircon U-Pb geochronological, Lu-Hf isotopic data and whole-rock geochemistry for two stages of basicintermediate dykes from the southwestern Fujian. The samples were collected from the NE-trending （mainly diabases） and NW-trending （mainly diabasic diorites） dykes and yielded zircon U-Pb ages of 315 and 141 Ma, with eHf（t） values of -8.90 to 7.49 and -23.39 to -7.15 （corresponding to TDM2 values of 850 to 1890 Ma and 737 to 2670 Ma）, respectively. Geochemically these rocks are characterized by low TiO2 （0.91-1.73 wt.%） and MgO （3.04-7.96 wt.%）, and high A1203 （12.5-16.60 wt.%） and K20 （0.60-3.63 wt.%）. Further they are enriched in LREEs and LILEs （Rb, Ba, Th and K）, but depleted in HFSEs （Nb, Ta and Zr）. The tectonic discrimination analysis revealed that the dykes were formed in an intraplate extensional envi- ronment. However, the NW trending dykes show crust-mantle mixed composition, which indicate an extensional tectonic setting with evidence for crustal contamination. The SE China block experienced two main stages of extensional tectonics from late Carboniferous to early Cretaceous. The tectonic evolution of the SE China block from late Devonian to Cretaceous is also evaluated.

浅蓝霉素H的发酵优化与浅蓝苷K的化学合成

浅蓝霉素H (2)及其4-基α-L-吡喃鼠李糖苷[即浅蓝苷K (1)]是从海洋来源的浅蓝异壁放线菌WH1-2216-6的发酵产物中分离获得的天然产物,浅蓝苷K(1)具有良好的肿瘤细胞增殖抑制活性,但其产率低,合成未见报道.因此,首先对浅蓝霉素H(2)的主产菌株浅蓝异壁放线菌WH1-2216-6突变株CRM05进行发酵优化,采用放线菌5号与玉米配制的固体培养基发酵培养CRM05菌株,将浅蓝霉素H (2)的产量提高到272 mg/L(提高了5倍),获得了足量的浅蓝霉素H(2).接着,通过脱肟、鼠李糖苷化、成肟及脱乙酰保护等6步反应,以25.6%的总收率从浅蓝霉素H(2)合成了浅蓝苷K (1).通过高分辨质谱、核磁共振和比旋光等数据确认了浅蓝苷K (1)的结构,与报道的天然产物为同一化合物.浅蓝苷K (1)具有较强的肿瘤细胞抗增殖活性,对肿瘤细胞株PATU8988T、786-O、5673、DU145、A-375、FaDu和SF126的半数抑制浓度(IC50)为1.07~1.78μmol/L.

Tempospatial Pattern of Surface Wind Speed and the “Urban Stilling Island” in Beijing City

An hourly-resolution dataset from observations at the automatic weather stations(AWSs) is developed and applied to study the characteristics of weakening surface wind in the urban areas of Beijing City in 2008–2017. The "Urban Stilling Island(USI)" is defined and quantified to depict the surface wind speed(WS) differences between rural and urban regions. The urban(rural) sites are represented by 45(6) stations within(outside) the 6th Ring Road(RR). The results demonstrate remarkable smaller annual and seasonal average WS values in urban areas than in rural areas, indicating significant USI, especially in the central urban areas(within the 4th RR) in spring and winter. Further analysis reveals that the surface roughness effect dominates and enhances the USI intensity(USII) under the stronger large-scale background wind in spring and winter, whereas the Urban Heat Island(UHI) effect may dominate and decrease the USII under weaker large-scale wind in summer and autumn. The diurnal USII variations are characterized by a steady low-value phase from 1900 to 0800 Beijing Time(BT) and a high-value phase from 1100 to 1500 BT,with rapid shifts of USII in between. Long-term variation of hourly USII shows large mean USII in 2008–2012 but decreased USII in 2013–2017, possibly attributed to the change of urbanization level around the rural observation sites.

Nanomaterials for neurodegenerative diseases:Molecular mechanisms guided design and applications

Successful treatment of neurodegenerative diseases(NDDs),including Alzheimer’s disease(AD),Parkinson’s disease(PD),and Huntington’s disease(HD),remains a significant challenge for neurologists due to the undesirable curative outcomes.Apart from surgeries,most drugs are only used to relieve the patients’symptoms without a permanent cure of the disease.The development of novel biomaterials targeting NDDs is greatly hindered by the limited understanding of underlying molecular mechanisms.Considering the difficulties in NDD drug development and clinical trials,a comprehensive and up-to-date review of disease pathogenesis and related novel therapies are needed.In the current article,the basic concepts and pathogenic characteristics of NDDs are firstly illustrated.Following the detailed description of molecular mechanisms underlying three common NDDs,recent advances of drug development based on targeting different pathogenic mechanisms are clarified.Hopefully,this review will be beneficial to address the gap between materials and targeted mechanisms while simultaneously provide suggestions for the future design of precise NDD medicine.

Exploitation of a photoelectrochemical sensing platform for bisphenol A quantitative determination using Cu/graphitic carbon nitride nanocomposites

A simple and effective photoelectrochemical sensor was fabricated by Cu/graphitic carbon nitride （Cu/g- CN） composites for detecting bisphenol A. The Cu/g-CN composites were obtained via a solvothermal process in the presence of the copper-based ionic liquid. In view of localized surface plasmon resonance ofCu nanoparticles, Cu nanoparticles can promote light absorbance and rapid electron transport ofg-CN. As a result, the Cu/g-CN composites obtained greatly enhancement of photocurrent, when compared to the pure g-CN. In addition, the introduction of bisphenol A can hinder electron-hole recombination, resulting in sensitive photoelectrochemical monitoring of bisphenol A. The detection limit of the bisphenol A photoelectrochemical sensor was below 0.012 μmol/L. The bisphenol A photoelectrochemical sensor exhibited an excellent stability and acceptable anti-interference. The photoelectrochemical sensor provided the promising platform to monitor bisphenol A at low concentration in water environment.