Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in ac...Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in acidic media,resulting in considerable waste of acid reagents and the following neutralizing agents.In this study,kinetics and mechanisms of Cr(Ⅵ) reduction by sulfite in alkaline conditions(pH:7-10) were investigated.It reveals that Cr(Ⅵ) reduction follows pseudo-zero-order kinetics,where the rate constants increased markedly with an in situ irradiation of Far-UVC(UV_(222)).Decreasing pH levels slightly favored the reduction.Iodide ion displayed a notable accelerating effect,which not only save the energy input but also minimize the reductant usage.Chloride,sulfate,and carbonate ions exhibit little effect on the reduction,whereas nitrate and nitrite ions,dissolved oxygen as well as Cu(Ⅱ) suppressed the reduction significantly,implying that hydrated electrons produced by UV222 played the most important role in the reaction.Compared to the UV254/sulfite/iodide process,UV222/sulfite/iodide demonstrates clear advantages in the reduction kinetics and the sulfite utilization efficiency,underscoring its potential for effective Cr(Ⅵ) remediation in various environmental settings.展开更多
AlGaN-based LEDs with peak wavelength below 240 nm(far-UVC)pose no significant harm to human health,thus highlighting their broader application potential.While,there is a significant Schottky barrier between the n-ele...AlGaN-based LEDs with peak wavelength below 240 nm(far-UVC)pose no significant harm to human health,thus highlighting their broader application potential.While,there is a significant Schottky barrier between the n-electrode and Alrich n-AlGaN,adversely impeding electron injection and resulting in considerable heat generation.Here,we fabricate V-based electrodes of V/Al/Ti/Au on n-AlGaN with Al content over 80%and investigate the relationship between the metal diffusion and contact properties during the high-temperature annealing process.Experiments reveal that decreasing V thickness in the electrode promotes the diffusion of Al towards the surface of n-AlGaN,which facilitates the formation of VN and thus the increase of local electron concentration,resulting in lower specific contact resistivity.Then,increasing the Al thickness inhibits the diffusion of Au to the n-AlGaN surface,suppressing the rise of Schottky barrier.Experimentally,an optimized n-electrode of V(10 nm)/Al(240 nm)/Ti(40 nm)/Au(50 nm)on n-Al_(0.81)Ga_(0.19)N is obtained,realizing an optimal specific contact resistivity of 7.30×10^(−4)Ω·cm^(2).Based on the optimal n-electrode preparation scheme for Al-rich n-AlGaN,the work voltage of a far-UVC LED with peak wavelength of 233.5 nm is effectively reduced.展开更多
细菌、病毒等病原体给人类社会造成巨大危害。化学药剂、热能和紫外线被广泛应用于灭活有害微生物,但这些方法也会对病原体的宿主产生无差别伤害。宿主无损光照消毒技术能够在不损伤宿主细胞的同时灭活病原体,因而受到越来越多的关注。...细菌、病毒等病原体给人类社会造成巨大危害。化学药剂、热能和紫外线被广泛应用于灭活有害微生物,但这些方法也会对病原体的宿主产生无差别伤害。宿主无损光照消毒技术能够在不损伤宿主细胞的同时灭活病原体,因而受到越来越多的关注。目前主流的宿主无损光照消毒技术包括207~222 nm远紫外线(far-ultraviolet C,far-UVC)、抗菌蓝光(antibacterial blue light)和低功率超短脉冲激光消毒。该文综述了这3种技术的基本原理、研究动态、适用场景和优缺点;对比了宿主无损光照消毒技术与传统紫外线消毒技术的技术特点;从理论模型建立和实际应用2方面提出了宿主无损光照消毒技术的研究展望。宿主无损光照消毒技术将有助于阻止大规模疫情中有害病原体的传播,可为食品保鲜和医疗产品消毒提供一种新方案,具有广阔的应用前景。展开更多
基金supported by the National Key R&D Program of China(No.2023YFE0112100)the Science and Technology Planning Project of Fujian Province(No.2023Y4015)the Marine and Fishery Devel-opment Special Fund of Xiamen(No.23YYST064QCB36).
文摘Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in acidic media,resulting in considerable waste of acid reagents and the following neutralizing agents.In this study,kinetics and mechanisms of Cr(Ⅵ) reduction by sulfite in alkaline conditions(pH:7-10) were investigated.It reveals that Cr(Ⅵ) reduction follows pseudo-zero-order kinetics,where the rate constants increased markedly with an in situ irradiation of Far-UVC(UV_(222)).Decreasing pH levels slightly favored the reduction.Iodide ion displayed a notable accelerating effect,which not only save the energy input but also minimize the reductant usage.Chloride,sulfate,and carbonate ions exhibit little effect on the reduction,whereas nitrate and nitrite ions,dissolved oxygen as well as Cu(Ⅱ) suppressed the reduction significantly,implying that hydrated electrons produced by UV222 played the most important role in the reaction.Compared to the UV254/sulfite/iodide process,UV222/sulfite/iodide demonstrates clear advantages in the reduction kinetics and the sulfite utilization efficiency,underscoring its potential for effective Cr(Ⅵ) remediation in various environmental settings.
基金supported by National Key R&D Program of China(2022YFB3605103)National Natural Science Foundation of China(62425408,62121005,U22A2084,12234018)+2 种基金Youth Innovation Promotion Association of the Chinese Academy of Sciences(2023223)Natural Science Foundation of Jilin Province(20230101345JC,20230101360JC,SKL202302026)Young Elite Scientist Sponsorship Program by CAST(YESS20200182).
文摘AlGaN-based LEDs with peak wavelength below 240 nm(far-UVC)pose no significant harm to human health,thus highlighting their broader application potential.While,there is a significant Schottky barrier between the n-electrode and Alrich n-AlGaN,adversely impeding electron injection and resulting in considerable heat generation.Here,we fabricate V-based electrodes of V/Al/Ti/Au on n-AlGaN with Al content over 80%and investigate the relationship between the metal diffusion and contact properties during the high-temperature annealing process.Experiments reveal that decreasing V thickness in the electrode promotes the diffusion of Al towards the surface of n-AlGaN,which facilitates the formation of VN and thus the increase of local electron concentration,resulting in lower specific contact resistivity.Then,increasing the Al thickness inhibits the diffusion of Au to the n-AlGaN surface,suppressing the rise of Schottky barrier.Experimentally,an optimized n-electrode of V(10 nm)/Al(240 nm)/Ti(40 nm)/Au(50 nm)on n-Al_(0.81)Ga_(0.19)N is obtained,realizing an optimal specific contact resistivity of 7.30×10^(−4)Ω·cm^(2).Based on the optimal n-electrode preparation scheme for Al-rich n-AlGaN,the work voltage of a far-UVC LED with peak wavelength of 233.5 nm is effectively reduced.
文摘细菌、病毒等病原体给人类社会造成巨大危害。化学药剂、热能和紫外线被广泛应用于灭活有害微生物,但这些方法也会对病原体的宿主产生无差别伤害。宿主无损光照消毒技术能够在不损伤宿主细胞的同时灭活病原体,因而受到越来越多的关注。目前主流的宿主无损光照消毒技术包括207~222 nm远紫外线(far-ultraviolet C,far-UVC)、抗菌蓝光(antibacterial blue light)和低功率超短脉冲激光消毒。该文综述了这3种技术的基本原理、研究动态、适用场景和优缺点;对比了宿主无损光照消毒技术与传统紫外线消毒技术的技术特点;从理论模型建立和实际应用2方面提出了宿主无损光照消毒技术的研究展望。宿主无损光照消毒技术将有助于阻止大规模疫情中有害病原体的传播,可为食品保鲜和医疗产品消毒提供一种新方案,具有广阔的应用前景。
