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
基于电转氨(power to ammonia,P2A)的综合能源生产单元(integrated energy production unit,IEPU)通过耦合绿电制氢和哈伯反应合成氨工艺,为农业、工业和制造业等行业提供绿氨,对促进可再生能源消纳及氢能储运等行业发展具有重要的意义...基于电转氨(power to ammonia,P2A)的综合能源生产单元(integrated energy production unit,IEPU)通过耦合绿电制氢和哈伯反应合成氨工艺,为农业、工业和制造业等行业提供绿氨,对促进可再生能源消纳及氢能储运等行业发展具有重要的意义。为定量评价IEPU的能效、技术经济性和降碳潜力,该文基于Aspen Plus建立碱性电解水制氢、合成氨及换热网络等关键过程模型,对IEPU进行系统仿真,定量评价各设备全流程之间的能量流、(火用)流、碳足迹及绿氨的平准化成本。热经济性能效评估表明,IEPU系统的设计工况整体能量效率为39.47%,(火用)效率为26.51%。技术经济性评估表明,当可再生能源电价为0.204元/(kW·h),年利用小时数达到6000时,IEPU系统的绿氨成本约为传统煤制氨生产工艺的1.5倍。基于全生命周期碳足迹评价的结果表明,水、核、风和光伏4种能源驱动的IEPU系统碳足迹在0.20~2.39 kg CO_(2.eq)/kg NH3间波动。结果可用于指导氨基IEPU的规划与设计。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.
文摘基于电转氨(power to ammonia,P2A)的综合能源生产单元(integrated energy production unit,IEPU)通过耦合绿电制氢和哈伯反应合成氨工艺,为农业、工业和制造业等行业提供绿氨,对促进可再生能源消纳及氢能储运等行业发展具有重要的意义。为定量评价IEPU的能效、技术经济性和降碳潜力,该文基于Aspen Plus建立碱性电解水制氢、合成氨及换热网络等关键过程模型,对IEPU进行系统仿真,定量评价各设备全流程之间的能量流、(火用)流、碳足迹及绿氨的平准化成本。热经济性能效评估表明,IEPU系统的设计工况整体能量效率为39.47%,(火用)效率为26.51%。技术经济性评估表明,当可再生能源电价为0.204元/(kW·h),年利用小时数达到6000时,IEPU系统的绿氨成本约为传统煤制氨生产工艺的1.5倍。基于全生命周期碳足迹评价的结果表明,水、核、风和光伏4种能源驱动的IEPU系统碳足迹在0.20~2.39 kg CO_(2.eq)/kg NH3间波动。结果可用于指导氨基IEPU的规划与设计。
