The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is high...The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is highly intriguing and challenging to promote the selectivity and efficiency of visible-light-responsive photocatalysts that favor the adsorption of CO2 in photoreduction processes.In this work,three-dimensional hierarchical Cd0.8Zn0.2S flowers(C8Z2S-F)with ultrathin petals were successfully synthesized through an in-situ self-assembly growth process using sodium citrate as a morphology director.The flower-like Cd0.8Zn0.2S solid solution exhibited remarkable photocatalytic performance in the reduction of CO2,generating CO up to 41.4μmol g^−1 under visible-light illumination for 3 h;this was nearly three times greater than that of Cd0.8Zn0.2S nanoparticles(C8Z2S-NP)(14.7μmol g^−1).Particularly,a comparably high selectivity of 89.9%for the conversion of CO2 to CO,with a turnover number of 39.6,was obtained from the solar-driven C8Z2S-F system in the absence of any co-catalyst or sacrificial agent.Terahertz time-domain spectroscopy indicated that the introduction of flower structures enhanced the light-harvesting capacity of C8Z2S-F.The in situ diffuse reflectance infrared Fourier transform spectroscopy unveiled the existence of surface-adsorbed species and the conversion of photoreduction intermediates during the photocatalytic process.Empirical characterizations and predictions of the photocatalytic mechanism demonstrated that the flower-like Cd0.8Zn0.2S solid solution possessed desirable CO2 adsorption properties and an enhanced charge-transfer capability,thus providing a highly effective photocatalytic reduction of CO2.展开更多
Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast pho...Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.展开更多
光纤电流互感器(FOCT)易受到各类噪声的影响而导致其测量准确度下降,尤其是在一次电流较小时,因此提高其信噪比是FOCT的关键技术之一。通过全面分析FOCT的光信号噪声、信号检测噪声及外界环境引入的噪声源,给出了FOCT信噪比的计算方法,...光纤电流互感器(FOCT)易受到各类噪声的影响而导致其测量准确度下降,尤其是在一次电流较小时,因此提高其信噪比是FOCT的关键技术之一。通过全面分析FOCT的光信号噪声、信号检测噪声及外界环境引入的噪声源,给出了FOCT信噪比的计算方法,仿真了不同噪声对信噪比的影响,并在此基础上研制了样机。结果表明:通过提高探测器接收光功率、增加传感头敏感光纤圈数以及选择合适的闭环反馈相位调制偏置工作点等方法,可有效提高信噪比;以此为基础设计的FOCT样机,在额定电流为600 A时,可满足0.2S级要求,1%额定电流下信噪比高达30.2 d B,比差<0.61%,相差<12.39′。提出的信噪比优化设计方法,具有较大的实用价值,对FOCT的设计具有指导意义。展开更多
Constructing S-scheme heterojunctions preserves the intrinsic redox capabilities of both semiconductors while promoting the separation of photogenerated electrons and holes,making it a promising approach for enhancing...Constructing S-scheme heterojunctions preserves the intrinsic redox capabilities of both semiconductors while promoting the separation of photogenerated electrons and holes,making it a promising approach for enhancing the properties of semiconductors.In this study,an S-scheme Cd_(0.8)Zn_(0.2)S-CeO_(2)(CZS-CeO_(2))heterojunction was successfully fabricated via the in-situ growth of CZS nanowires on CeO_(2)nanocubes.The S-scheme charge-transfer mechanism of the CZS-CeO_(2)composites during photocatalytic reactions was confirmed through in-situ X-ray photoelectron spectroscopy and density functional theory calculations.These results demonstrate that the interfacial electric field(IEF)significantly facilitates charge separation and transport within the heterojunction.Consequently,the CZS-CeO_(2)composites exhibited excellent photocatalytic hydrogen production performance under simulated sunlight irradiation,surpassing that of blank CZS.Particularly,the optimal photocatalytic hydrogen generation rate for CZS-15%CeO_(2)reached 58 mmol·g^(-1)·h^(-1),approximately 8.8 times higher than that of blank CZS.After five consecutive cycles of testing,CZS-15%CeO_(2)retained a relatively high level of activity.This enhanced stability can be attributed to the fabrication of S-scheme heterojunctions,which effectively suppressed hole-induced photocorrosion of CZS.This investigation provides a beneficial reference for the rational design of S-scheme heterojunction photocatalysts for efficient and stable photocatalytic hydrogen production.展开更多
In recent years,environmental pollution and energy crisis have become increasingly serious issues owing to the burning of fossil fuels.Among the many technologies,decomposition of water to produce hydrogen has attract...In recent years,environmental pollution and energy crisis have become increasingly serious issues owing to the burning of fossil fuels.Among the many technologies,decomposition of water to produce hydrogen has attracted much attention because of its sustainability and non-polluting characteristic.However,highly efficient decomposition of water that is driven by visible light is still a challenge.Herein,we report the large-scale preparation of step-scheme porous graphite carbon nitride/Zn0.2Cd0.8S-diethylenetriamine(Pg-C3N4/Zn0.2Cd0.8S-DETA)composite by a facile solvothermal method.It was found by UV-vis spectroscopy that 15%Pg-C3N4/Zn0.2Cd0.8S-DETA exhibited suitable visible absorption edge and band gap for water decomposition.The hydrogen production rate of 15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite was 6.69 mmol g^-1 h^-1,which was 16.73,1.61,and 1.44 times greater than those of Pg-C3N4,CdS-DETA,and Zn0.2Cd0.8S-DETA,respectively.In addition,15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite displayed excellent photocatalytic stability,which was maintained for seven cycles of photocatalytic water splitting test.We believe that 15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite can be a valuable guide for the development of solar hydrogen production applications in the near future.展开更多
S-scheme heterojunctions have promising applications in photocatalytic CO_(2) reduction due to their unique structure and interfacial interactions,but improving their carrier separation efficiency and CO_(2) adsorptio...S-scheme heterojunctions have promising applications in photocatalytic CO_(2) reduction due to their unique structure and interfacial interactions,but improving their carrier separation efficiency and CO_(2) adsorption capacity remains a challenge.In this work,highly dispersed MOF-BiOBr/Mn_(0.2) Cd_(0.8) S(MOF-BiOBr/MCS)S-scheme heterojunctions with high photocatalytic CO_(2) reduction performance were constructed.The intimate contact between the MCS nano-spheres and the nanosheet-assembled MOF-BiOBr rods,driven by the internal electric field,accelerates the charge transfer along the S-scheme pathway.Moreover,the high specific surface area of MOFs is preserved to provide abundant active sites for reaction/adsorption.The formation of MOF-BiOBr/MCS S-scheme heterojunction is confirmed by theoretical calculations.The optimum MOF-BiOBr/MCS shows excellent activity in CO_(2) reduction,affording a high CO evolution rate of 60.59µmol h^(−1) g^(−1).The present work can inspire the exploration for the construction of effective heterostructure photocatalysts for photoreduction CO_(2).展开更多
文摘The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is highly intriguing and challenging to promote the selectivity and efficiency of visible-light-responsive photocatalysts that favor the adsorption of CO2 in photoreduction processes.In this work,three-dimensional hierarchical Cd0.8Zn0.2S flowers(C8Z2S-F)with ultrathin petals were successfully synthesized through an in-situ self-assembly growth process using sodium citrate as a morphology director.The flower-like Cd0.8Zn0.2S solid solution exhibited remarkable photocatalytic performance in the reduction of CO2,generating CO up to 41.4μmol g^−1 under visible-light illumination for 3 h;this was nearly three times greater than that of Cd0.8Zn0.2S nanoparticles(C8Z2S-NP)(14.7μmol g^−1).Particularly,a comparably high selectivity of 89.9%for the conversion of CO2 to CO,with a turnover number of 39.6,was obtained from the solar-driven C8Z2S-F system in the absence of any co-catalyst or sacrificial agent.Terahertz time-domain spectroscopy indicated that the introduction of flower structures enhanced the light-harvesting capacity of C8Z2S-F.The in situ diffuse reflectance infrared Fourier transform spectroscopy unveiled the existence of surface-adsorbed species and the conversion of photoreduction intermediates during the photocatalytic process.Empirical characterizations and predictions of the photocatalytic mechanism demonstrated that the flower-like Cd0.8Zn0.2S solid solution possessed desirable CO2 adsorption properties and an enhanced charge-transfer capability,thus providing a highly effective photocatalytic reduction of CO2.
基金financial supports pro-vided by the National Natural Science Foundation of China(No.21905279)the Natural Science Foundation of Fujian Province(No.2020J05086).
文摘Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.
文摘光纤电流互感器(FOCT)易受到各类噪声的影响而导致其测量准确度下降,尤其是在一次电流较小时,因此提高其信噪比是FOCT的关键技术之一。通过全面分析FOCT的光信号噪声、信号检测噪声及外界环境引入的噪声源,给出了FOCT信噪比的计算方法,仿真了不同噪声对信噪比的影响,并在此基础上研制了样机。结果表明:通过提高探测器接收光功率、增加传感头敏感光纤圈数以及选择合适的闭环反馈相位调制偏置工作点等方法,可有效提高信噪比;以此为基础设计的FOCT样机,在额定电流为600 A时,可满足0.2S级要求,1%额定电流下信噪比高达30.2 d B,比差<0.61%,相差<12.39′。提出的信噪比优化设计方法,具有较大的实用价值,对FOCT的设计具有指导意义。
文摘Constructing S-scheme heterojunctions preserves the intrinsic redox capabilities of both semiconductors while promoting the separation of photogenerated electrons and holes,making it a promising approach for enhancing the properties of semiconductors.In this study,an S-scheme Cd_(0.8)Zn_(0.2)S-CeO_(2)(CZS-CeO_(2))heterojunction was successfully fabricated via the in-situ growth of CZS nanowires on CeO_(2)nanocubes.The S-scheme charge-transfer mechanism of the CZS-CeO_(2)composites during photocatalytic reactions was confirmed through in-situ X-ray photoelectron spectroscopy and density functional theory calculations.These results demonstrate that the interfacial electric field(IEF)significantly facilitates charge separation and transport within the heterojunction.Consequently,the CZS-CeO_(2)composites exhibited excellent photocatalytic hydrogen production performance under simulated sunlight irradiation,surpassing that of blank CZS.Particularly,the optimal photocatalytic hydrogen generation rate for CZS-15%CeO_(2)reached 58 mmol·g^(-1)·h^(-1),approximately 8.8 times higher than that of blank CZS.After five consecutive cycles of testing,CZS-15%CeO_(2)retained a relatively high level of activity.This enhanced stability can be attributed to the fabrication of S-scheme heterojunctions,which effectively suppressed hole-induced photocorrosion of CZS.This investigation provides a beneficial reference for the rational design of S-scheme heterojunction photocatalysts for efficient and stable photocatalytic hydrogen production.
基金supported by the National Natural Science Foundation of China(51572103,51502106)the Distinguished Young Scholar of Anhui Province(1808085J14)+2 种基金the Foundation for Young Talents in College of Anhui Province(gxyqZD2017051)the Key Foundation of Educational Commission of Anhui Province(KJ2016SD53)Innovation Team of Design and Application of Advanced Energetic Materials(KJ2015TD003)~~
文摘In recent years,environmental pollution and energy crisis have become increasingly serious issues owing to the burning of fossil fuels.Among the many technologies,decomposition of water to produce hydrogen has attracted much attention because of its sustainability and non-polluting characteristic.However,highly efficient decomposition of water that is driven by visible light is still a challenge.Herein,we report the large-scale preparation of step-scheme porous graphite carbon nitride/Zn0.2Cd0.8S-diethylenetriamine(Pg-C3N4/Zn0.2Cd0.8S-DETA)composite by a facile solvothermal method.It was found by UV-vis spectroscopy that 15%Pg-C3N4/Zn0.2Cd0.8S-DETA exhibited suitable visible absorption edge and band gap for water decomposition.The hydrogen production rate of 15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite was 6.69 mmol g^-1 h^-1,which was 16.73,1.61,and 1.44 times greater than those of Pg-C3N4,CdS-DETA,and Zn0.2Cd0.8S-DETA,respectively.In addition,15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite displayed excellent photocatalytic stability,which was maintained for seven cycles of photocatalytic water splitting test.We believe that 15%Pg-C3N4/Zn0.2Cd0.8S-DETA composite can be a valuable guide for the development of solar hydrogen production applications in the near future.
基金supported by the National Natural Science Foundation of China(Nos.22278169 and 51973078)the Excellent scientific research and innovation team of Education Department of Anhui Province(No.2022AH010028)+1 种基金the Major projects of Education Department of Anhui Province(No.2022AH040068)the Key Foundation of Educational Commission of Anhui Province(No.2022AH050396).
文摘S-scheme heterojunctions have promising applications in photocatalytic CO_(2) reduction due to their unique structure and interfacial interactions,but improving their carrier separation efficiency and CO_(2) adsorption capacity remains a challenge.In this work,highly dispersed MOF-BiOBr/Mn_(0.2) Cd_(0.8) S(MOF-BiOBr/MCS)S-scheme heterojunctions with high photocatalytic CO_(2) reduction performance were constructed.The intimate contact between the MCS nano-spheres and the nanosheet-assembled MOF-BiOBr rods,driven by the internal electric field,accelerates the charge transfer along the S-scheme pathway.Moreover,the high specific surface area of MOFs is preserved to provide abundant active sites for reaction/adsorption.The formation of MOF-BiOBr/MCS S-scheme heterojunction is confirmed by theoretical calculations.The optimum MOF-BiOBr/MCS shows excellent activity in CO_(2) reduction,affording a high CO evolution rate of 60.59µmol h^(−1) g^(−1).The present work can inspire the exploration for the construction of effective heterostructure photocatalysts for photoreduction CO_(2).
