The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor ...The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.展开更多
[Objectives]To compare content of proanthocyanidins and polysaccharides in wild Lycium ruthenicum.[Methods]The wild L.ruthenicum collected from different regions such as Qinghai,Inner Mongolia,Ningxia and Gansu Provin...[Objectives]To compare content of proanthocyanidins and polysaccharides in wild Lycium ruthenicum.[Methods]The wild L.ruthenicum collected from different regions such as Qinghai,Inner Mongolia,Ningxia and Gansu Province were taken as the research objects.The conventional indicators such as proanthocyanidins and polysaccharides of the experimental materials were determined,and the proanthocyanidins and polysaccharides of the experimental materials in different regions were compared and analyzed.The difference in content and correlation,and the cluster analysis method were used to divide clusters of the experimental materials.[Results]The absorbance of proanthocyanidins in the fruit of wild L.ruthenicum was No.4>No.1>No.5>No.6>No.3>No.2,among which the absorbance of anthocyanin(2.43)of wild L.ruthenicum variety No.4 was significantly higher than other experimental materials(P<0.05),and proanthocyanidin of No.2 had the lowest absorbance value of 1.35.There was no significant difference between No.3 and No.6(P>0.05),and there were significant differences among other experimental materials(P<0.05).The content of polysaccharides was:No.3>No.7>No.2>No.4>No.5>No.6>No.1;there was no significant difference between No.3 and No.7(P>0.05),but significantly higher than other materials(P<0.05).Besides,proanthocyanidins and polysaccharides showed significant variability,but there was no consistency in the correlation between them.[Conclusions]In terms of the absorbance of proanthocyanidins,the experimental materials No.1 and No.4 can be classified into a cluster;experimental materials No.2,No.3,No.5 and No.6 can be classified into another cluster.This can provide a theoretical basis for the introduction and breeding of fine varieties.展开更多
配电网运行包络将配电网安全运行与分布式能源(distributed energy resource,DER)调控解耦,将配电网安全运行约束映射到DER出力约束空间,为解决配电网和DER分属主体不同、调控目标差异的问题提供有效手段。设计配电网运行包络的关键是...配电网运行包络将配电网安全运行与分布式能源(distributed energy resource,DER)调控解耦,将配电网安全运行约束映射到DER出力约束空间,为解决配电网和DER分属主体不同、调控目标差异的问题提供有效手段。设计配电网运行包络的关键是计算各个节点功率准许波动范围,现有研究主要关注有功运行包络,忽略无功波动范围。该文研究配电网的有功-无功运行包络计算方法。首先,构建有功-无功运行包络的旋转矩形模型,通过引入旋转参数,扩大运行包络中有功-无功区域;其次,建立考虑配电网电压与潮流约束的运行包络鲁棒优化模型,并推导其二次约束规划问题;然后,提出基于网络拓扑参数特征的运行包络快速算法,显著提升优化问题求解速度;最后,采用不同规模配电网进行算例分析,验证所提出的配电网运行包络计算方法的有效性和先进性。展开更多
文摘The efficiency and stability of catalysts for photocatalytic hydrogen evolution(PHE)are largely governed by the charge transfer behaviors across the heterojunction interfaces.In this study,CuO,a typical semiconductor featuring a broad spectral absorption range,is successfully employed as the electron acceptor to combine with CdS for constructing a S-scheme heterojunction.The optimized photocatalyst(CdSCuO2∶1)delivers an exceptional hydrogen evolution rate of 18.89 mmol/(g·h),4.15-fold higher compared with bare CdS.X-ray photoelectron spectroscopy(XPS)and ultraviolet-visible diffuse reflection absorption spectroscopy(UV-vis DRS)confirmed the S-scheme band structure of the composites.Moreover,the surface photovoltage(SPV)and electron paramagnetic resonance(EPR)indicated that the photogenerated electrons and photogenerated holes of CdS-CuO2∶1 were respectively transferred to the conduction band(CB)of CdS with a higher reduction potential and the valence band(VB)of CuO with a higher oxidation potential under illumination,as expected for the S-scheme mechanism.Density-functional-theory calculations of the electron density difference(EDD)disclose an interfacial electric field oriented from CdS to CuO.This built-in field suppresses charge recombination and accelerates carrier migration,rationalizing the markedly enhanced PHE activity.This study offers a novel strategy for designing S-scheme heterojunctions with high light harvesting and charge utilization toward sustainable solar-tohydrogen conversion.
基金Supported by Science and Technology Program of Inner Mongolia(201602083)Special Fund for Scientific Research of Inner Mongolia Agricultural University"Special Program for Breeding(Selection)of Animal and Plant Varieties"(YZGC2017023)
文摘[Objectives]To compare content of proanthocyanidins and polysaccharides in wild Lycium ruthenicum.[Methods]The wild L.ruthenicum collected from different regions such as Qinghai,Inner Mongolia,Ningxia and Gansu Province were taken as the research objects.The conventional indicators such as proanthocyanidins and polysaccharides of the experimental materials were determined,and the proanthocyanidins and polysaccharides of the experimental materials in different regions were compared and analyzed.The difference in content and correlation,and the cluster analysis method were used to divide clusters of the experimental materials.[Results]The absorbance of proanthocyanidins in the fruit of wild L.ruthenicum was No.4>No.1>No.5>No.6>No.3>No.2,among which the absorbance of anthocyanin(2.43)of wild L.ruthenicum variety No.4 was significantly higher than other experimental materials(P<0.05),and proanthocyanidin of No.2 had the lowest absorbance value of 1.35.There was no significant difference between No.3 and No.6(P>0.05),and there were significant differences among other experimental materials(P<0.05).The content of polysaccharides was:No.3>No.7>No.2>No.4>No.5>No.6>No.1;there was no significant difference between No.3 and No.7(P>0.05),but significantly higher than other materials(P<0.05).Besides,proanthocyanidins and polysaccharides showed significant variability,but there was no consistency in the correlation between them.[Conclusions]In terms of the absorbance of proanthocyanidins,the experimental materials No.1 and No.4 can be classified into a cluster;experimental materials No.2,No.3,No.5 and No.6 can be classified into another cluster.This can provide a theoretical basis for the introduction and breeding of fine varieties.
文摘配电网运行包络将配电网安全运行与分布式能源(distributed energy resource,DER)调控解耦,将配电网安全运行约束映射到DER出力约束空间,为解决配电网和DER分属主体不同、调控目标差异的问题提供有效手段。设计配电网运行包络的关键是计算各个节点功率准许波动范围,现有研究主要关注有功运行包络,忽略无功波动范围。该文研究配电网的有功-无功运行包络计算方法。首先,构建有功-无功运行包络的旋转矩形模型,通过引入旋转参数,扩大运行包络中有功-无功区域;其次,建立考虑配电网电压与潮流约束的运行包络鲁棒优化模型,并推导其二次约束规划问题;然后,提出基于网络拓扑参数特征的运行包络快速算法,显著提升优化问题求解速度;最后,采用不同规模配电网进行算例分析,验证所提出的配电网运行包络计算方法的有效性和先进性。
