为了更加准确地了解地下水中重金属含量,以中卫市地下水为研究对象,介绍一种基于微波消解原子吸收法的地下水重金属测定方法。研究指出,Cu、Zn、Mn、Hg、As检测时,光源波长在212.8~327.0 nm范围内,电流在10~25 m A范围内,乙炔、空气流...为了更加准确地了解地下水中重金属含量,以中卫市地下水为研究对象,介绍一种基于微波消解原子吸收法的地下水重金属测定方法。研究指出,Cu、Zn、Mn、Hg、As检测时,光源波长在212.8~327.0 nm范围内,电流在10~25 m A范围内,乙炔、空气流量分别为2.0、17.0 L/min,原子化器高度为8.0 mm,狭缝宽度为0.7 H;Pb与Cd检测时,光源波长分别为282.2 nm与227.7 nm,电流分别为10 m A与5.0 m A,乙炔、空气流量分别为850、20 L/min与250、20 L/min,原子化器高度为130/30 mm,狭缝宽度为0.7 L。该条件下对地下水重金属含量检测时,可得到精确、可靠的结果,线性回归方程相关系数均高于0.99,回收率高于90%;中卫市地下水重金属含量均未超标,无需加强处理。展开更多
Developing efficient and durable alkaline hydrogen evolution reaction(HER)catalysts is crucial for realizing high-performance,practical anion exchange membrane water electrolyzer(AEMWE)operating at ampere-level curren...Developing efficient and durable alkaline hydrogen evolution reaction(HER)catalysts is crucial for realizing high-performance,practical anion exchange membrane water electrolyzer(AEMWE)operating at ampere-level current densities.Although atomically dispersed Platinum(Pt)catalysts offer significant potential for enhancing atom utilization,their HER performance and durability are limited by the inflexibility in valence electron transfer between Pt and the support.In this study,we utilize asymmetrically single-atom copper(Cu)with tunable valence states as a valence electron reservoir(VER)to dynamically regulate the Pt 5d valence states,achieving efficient alkaline HER.In situ synchrotron radiation and theoretical calculations demonstrate that the dynamic evolution of the Pt 5d valence electron configuration optimizes the adsorption strengths of reaction intermediates.Meanwhile,single-atom Cu accelerates the rate-limiting water dissociation,and Pt facilitates subsequent^(*)H coupling.The catalyst requires only 23.5 and 177.2 mV overpotentials to achieve current densities of 10 and 500 mA cm^(-2)in 1 M KOH.Notably,the PtCu/NC exhibits a~57%lower hydrogen evolution barrier than Pt/NC.Moreover,the PtCu/NC-based AEMWE operates for over 600 h at an industrially relevant current density of 500 mA cm^(-2).展开更多
基金supported by the Ningbo Top-Talent Team Program,Program for the National Natural Science Foundation of China(22106166)the Yongjiang Innovative Individual Introduction of China,and the China Postdoctoral Science Foundation(2022M723253)。
文摘Developing efficient and durable alkaline hydrogen evolution reaction(HER)catalysts is crucial for realizing high-performance,practical anion exchange membrane water electrolyzer(AEMWE)operating at ampere-level current densities.Although atomically dispersed Platinum(Pt)catalysts offer significant potential for enhancing atom utilization,their HER performance and durability are limited by the inflexibility in valence electron transfer between Pt and the support.In this study,we utilize asymmetrically single-atom copper(Cu)with tunable valence states as a valence electron reservoir(VER)to dynamically regulate the Pt 5d valence states,achieving efficient alkaline HER.In situ synchrotron radiation and theoretical calculations demonstrate that the dynamic evolution of the Pt 5d valence electron configuration optimizes the adsorption strengths of reaction intermediates.Meanwhile,single-atom Cu accelerates the rate-limiting water dissociation,and Pt facilitates subsequent^(*)H coupling.The catalyst requires only 23.5 and 177.2 mV overpotentials to achieve current densities of 10 and 500 mA cm^(-2)in 1 M KOH.Notably,the PtCu/NC exhibits a~57%lower hydrogen evolution barrier than Pt/NC.Moreover,the PtCu/NC-based AEMWE operates for over 600 h at an industrially relevant current density of 500 mA cm^(-2).
