Encapsulation of Co single sites in covalent triazine frameworks for photocatalytic production of syngas

The photocatalytic production of syngas using a noble-metal-free catalytic system is a promising approach for renewable energy and environmental sustainability.In this study,we demonstrate an efficient catalytic system formed by integrating Co single sites,which act as the active sites,in covalent triazine frameworks(CTFs),which act as the photoabsorber,for the photocatalytic production of syngas from CO2 in aqueous solution.The enhanced light absorption of the CTFs,which contain intramolecular heterojunctions,in conjunction with 0.8 mmol L^‒1 of the Co complex enables excellent syngas production with a yield of 3303μmol g‒1(CO:H2=1.4:1)in 10 h,which is about three times greater than that achieved using CTF without a heterojunction.In the photocatalytic reaction,the coordinated single Co centers accept the photogenerated electrons from the CTF,and serve as active sites for CO2 conversion through an adsorption-activation-reaction mechanism.Theoretical calculations further reveal that the intramolecular heterojunctions highly promote photogenerated charge separation,thus boosting photocatalytic syngas production.This work reveals the promising potential of CTFs for single-metal-site-based photocatalysis.

Copper-ceria solid solution with improved catalytic activity for hydrogenation of CO to CHOH

A copper-ceria solid solution and ceria-supported copper catalysts were prepared and used for the catalytic hydrogenation of CO2 to CH3OH.According to site-specific classification and quantitative analyses(X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,H2 temperature-programmed reduction,and CO adsorption),the interfaces of the prepared catalysts were classified as Cu incorporated into ceria(Cu-Ov-Cex),dispersed Cu O(D-Cu O-Ce O2),and bulk Cu O(B-Cu O-Ce O2)over the Ce O2 surface.These results,together with those of activity tests,showed that the Cu-Ov-Cex species was closely related to the CO2 hydrogenation activity and resulted in a much higher turnover frequency of CH3OH production than that observed with the D-Cu O-Ce O2 and B-Cu O-Ce O2 species.Thus,the copper-ceria solid solution exhibited improved activity due to the higher Cu-Ov-Cex fraction.

Synthesis of poly (vinyl acetate) oligomersand their phase behavior in supercritical carbon dioxide

Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the reaction temperature and the added amount of initiator of the PVAc polymerization are discussed.In addition,the phase behavior of the prepared PVAc in pressured CO2 is determined via the cloud point method.The results indicate that the cloud point of PVAc increases with the increase in the molecular weight,the PVAc concentration,and the temperature.The cloud point pressures for the PVAc mass concentration of 0.12%with the molecular weight of 1 550,2 120,and 2 960 g/mol are 13.48,13.83 and 15.43 MPa,respectively,at the temperature of 35℃.It reveals that the solubility of PVAc in ScCO2 at relatively low pressure is remarkably limited.

Carbon Reduction Policies: A Regional Comparison of Their Contributions to CO_2 Abatement in Six Carbon Trading Pilot Schemes in China

The contributions of carbon reduction policies were evaluated and compared for six carbon trading pilot schemes in China, in four municipalities(Beijing, Shanghai, Tianjin, and Chongqing) and two provinces(Guangdong and Hubei). The carbon emissions accounting method of the Intergovernmental Panel on Climate Change was used to calculate the actual CO2 and the support vector machine model was used to predict CO2. Chinese carbon reduction policies abated CO2 in the six carbon trading pilot schemes after the comprehensive policies came into force. However, the contribution of policies to CO2 abatement varied among regions, and the effect of carbon reduction policy on municipality pilot schemes was greater than on provincial pilot schemes. The largest contribution of carbon reduction policy to CO2 abatement was 28.3%, for the pilot carbon trading scheme in Beijing, and the smallest contribution was 3.7%, for that in Hubei. It is crucial to consider "carbon leakage" and a carbon trading linking program in order to evaluate the effects of carbon reduction policies.

Wetting between molten iron and prereduced ilmenite with carbon

An interfacial study between molten iron and the prereduced ilmenite with carbon was conducted at different melting temperatures by the sessile droplet method.The wetting characteristics between molten iron and the prereduced ilmenites with carbon were investigated by measuring contact angle of the droplet of molten iron on the prereduced ilmenite substrate.The images of the interface were also examined by the optical microscope and SEM equipped with EDS.The volume of molten iron increased with the melting temperature increasing when titania or high-content titania slag was used as the substrate.The contact angle decreased with the melting temperature increasing and it was independent on time at constant temperature.The contact angle was positively correlated with the reduction degree of the ilmenite,but the work of adhesion was negatively correlated with it.Higher smelting temperature was beneficial to the separation of iron and Ti oxides.The permeability of molten iron into the prereduced ilmenite with carbon was more obvious with reduction degree increasing owing to the high porosity of prereduced ilmenite.

黄金微针射频治疗面部痤疮瘢痕的疗效评估

目的评价黄金微针射频治疗面部痤疮瘢痕的有效性及安全性。方法广州市皮肤病防治所2016年6月至2017年6月采用黄金微针射频治疗的42例痤疮瘢痕患者（观察组）和CO：点阵激光治疗的47例痤疮瘢痕患者（对照组），分别用疗效四级单盲法和临床痤疮瘢痕评估量表（ECCA）权重评分对两组治疗前后照片分析统计，评估疗效。统计方法采用r检验，两独立样本t检验及配对资料Wilcoxon秩和检验。结果治疗后，观察组和对照组总体有效率分别为92．9％（39例）和89．4％（42例），两组差异无统计学意义（χ^2=0．042，P〉0．05）。治疗前观察组ECCA权重评分为46．7±16．3，对照组为45．7±15．8，两组差异无统计学意义（t=0．271，P〉0．05）。治疗后，观察组ECCA权重评分降低为29．5±15．1，前后比较差异有统计学意义（z=-5．713，P〈0．05）；对照组降低为31,3±14．9，前后比较差异有统计学意义（Z=-6．086，P〈0．05）。结论黄金微针治疗面部痤疮瘢痕疗效确切，安全性高且创伤小。

Black phosphorus quantum dot/g-C_3N_4 composites for enhanced CO_2 photoreduction to CO

The development of low cost, metal free semiconductor photocatalysts for CO2 reduction to fuels and valuable chemical feedstocks is a practically imperative for reducing anthropogenic CO2 emissions. In this work, black phosphorus quantum dots（BPQDs） were successfully dispersed on a graphitic carbon nitride（g-C3N4） support via a simple electrostatic attraction approach, and the activities of BP@g-C3N4 composites were evaluated for photocatalytic CO2 reduction. The BP@g-C3N4 composites displayed improved carrier separation efficiency and higher activities for photocatalytic CO2 reduction to CO（6.54 μmol g^-1h^-1 at the optimum BPQDs loading of 1 wt%） compared with pure g-C3N4（2.65 μmol g^-1h^-1）. This work thus identifies a novel approach towards metal free photocatalysts for CO2 photoreduction.

The effects of EGR and ignition timing on emissions of GDI engine

The effects of EGR and ignition timing on engine emissions and combustion were studied through an experiment carried out on an air-guided GDI engine.The test results showed that the ignition timing significantly affected the GDI engine emissions,that the NOx emissions significantly reduced when the ignition timing was retarded,and that NOx emissions decreased with the EGR level increasement.A higher EGR rate could reduce CO emissions while the CO emissions were less affected by the ignition timing.The HC emissions decreased at a lower EGR rate.At 2500 r/min,an appropriate EGR rate could cut down CO emissions.The exhaust gas temperature could significantly decrease with improving the EGR rate,and the exhaust gas temperature at 2500 r/min was clearly higher than that at 1850 r/min.The nucleation mode particles increased clearly,the accumulation mode particle number decreased gradually with the increase of EGR rate,and the typical particle size of nucleation mode particle was in the range of 10–25 nm.