Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insuffic...Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insufficien atomic hydrogen(H^(*))supply.Herein,we propose CuO/NiO heterojunction with the assistance of a built-in electric field to enhance mass transfer and H^(*)provision.The built-in electric field in Cu O/Ni O is success fully formed as demonstrated by X-ray photoelectron spectroscopy and ultraviolet photoemission spec troscopy.The results reveal that Cu O/Ni O achieves high NO_(3)^(-)reduction activity(100%)and NH_(4)^(+)selec tivity(100%)under low NO_(3)^(-)concentration conditions(100 mg/L NO_(3)^(-),ca.22.6 mg/L NO_(3)^(-)-N),which i superior to that of many recently reported electrocatalysts.Density functional theory calculations furthe clarify that the built-in electric field triggers the enhanced adsorption of reactants on CuO/NiO hetero junction interface and strong d-p orbital hybridization between reactants and CuO/NiO.Besides,the free energy diagram of hydrogen evolution reaction of CuO/NiO confirms the realization of enhanced H^(*)pro vision.Moreover,coupling experiments and consecutive cycle tests demonstrate the potential of CuO/NiO in practical applications.This work may open up a new path and guide the development of efficien electrocatalysts for electrocatalytic reduction of NO_(3)^(-)at low concentrations to NH_(4)^(+).展开更多
The emerging pseudohalide metal-free perovskite(pseudohalide–MFPs)X-ray detector caters to the demands of timely mobile diagnosis owing to its lightweight,flexibility,and cost-effectiveness.However,the performance of...The emerging pseudohalide metal-free perovskite(pseudohalide–MFPs)X-ray detector caters to the demands of timely mobile diagnosis owing to its lightweight,flexibility,and cost-effectiveness.However,the performance of these devices is severely limited by poor X-ray absorption,ultra-wide band gap,relative instability,and their unknown biotoxicity.Herein,we construct heavy atom covalent bonds(C–Br/Cl)on the A-site organic cation to reinforce component coordination to modulate X-ray absorption and band gap in pseudohalide–MFPs and further enhance its stability.Molecular dynamics simulations demonstrate that the introduction of halogen atoms can strengthen hydrogen bonding interactions,thereby improving the coordination between different components.The resultant(MDABCOBr)–NH_(4)(BF_(4))_(3)(MDABCO=N-methyl-N’-diazabicyclo[2.2.2]octonium)single crystal significantly increases X-ray absorption cross-section and crystalline density(from 1.728 to 1.950 g cm^(−3)),and synergistically realizes the band nature modulation(from 7.4 to 5.5 eV)and enhanced ionic migration inhibition(628 meV)with optimized stability.As such,our X-ray detectors realized a sensitivity of 2377μCGy_(air)^(−1)cm^(−2),an ultralow detection limit of 50.1 nGy_(air)s^(−1),and impressive operation stability.Moreover,cytotoxicity assay confirmed the compatibility of pseudohalide metal-free perovskite.Finally,within this framework,we successfully fabricate the(MDABCOBr)–NH_(4)(BF_(4))_(3)-based flexible device to create an ideal in vitro wearable X-ray detection.展开更多
基金support of the National Natural Science Foundation of China(Nos.52170082,51938007,21906076,and 52300081)the Natural Science Foundation of Jiangxi Province(No.20212ACB203008)。
文摘Electrocatalytic reduction of nitrate(NO_(3)^(-))at low concentrations to ammonia(NH_(4)^(+))still faces chal lenges of low NO_(3)^(-)conversion and NH_(4)^(+)selectivity due to the sluggish mass transfer and insufficien atomic hydrogen(H^(*))supply.Herein,we propose CuO/NiO heterojunction with the assistance of a built-in electric field to enhance mass transfer and H^(*)provision.The built-in electric field in Cu O/Ni O is success fully formed as demonstrated by X-ray photoelectron spectroscopy and ultraviolet photoemission spec troscopy.The results reveal that Cu O/Ni O achieves high NO_(3)^(-)reduction activity(100%)and NH_(4)^(+)selec tivity(100%)under low NO_(3)^(-)concentration conditions(100 mg/L NO_(3)^(-),ca.22.6 mg/L NO_(3)^(-)-N),which i superior to that of many recently reported electrocatalysts.Density functional theory calculations furthe clarify that the built-in electric field triggers the enhanced adsorption of reactants on CuO/NiO hetero junction interface and strong d-p orbital hybridization between reactants and CuO/NiO.Besides,the free energy diagram of hydrogen evolution reaction of CuO/NiO confirms the realization of enhanced H^(*)pro vision.Moreover,coupling experiments and consecutive cycle tests demonstrate the potential of CuO/NiO in practical applications.This work may open up a new path and guide the development of efficien electrocatalysts for electrocatalytic reduction of NO_(3)^(-)at low concentrations to NH_(4)^(+).
基金funded by the National Natural Science Foundation of China(22279049,12374393)the Fundamental Research Funds for the Central Universities(lzujbky-2023-eyt03,lzujbky-2023-it18 and lzujbky-2024-ey02)+1 种基金the Natural Science Foundation of Gansu Province(23JRRA1017 and 23JRRA1160)the calculation workwas supported by Supercomputing Center of Lanzhou University.
文摘The emerging pseudohalide metal-free perovskite(pseudohalide–MFPs)X-ray detector caters to the demands of timely mobile diagnosis owing to its lightweight,flexibility,and cost-effectiveness.However,the performance of these devices is severely limited by poor X-ray absorption,ultra-wide band gap,relative instability,and their unknown biotoxicity.Herein,we construct heavy atom covalent bonds(C–Br/Cl)on the A-site organic cation to reinforce component coordination to modulate X-ray absorption and band gap in pseudohalide–MFPs and further enhance its stability.Molecular dynamics simulations demonstrate that the introduction of halogen atoms can strengthen hydrogen bonding interactions,thereby improving the coordination between different components.The resultant(MDABCOBr)–NH_(4)(BF_(4))_(3)(MDABCO=N-methyl-N’-diazabicyclo[2.2.2]octonium)single crystal significantly increases X-ray absorption cross-section and crystalline density(from 1.728 to 1.950 g cm^(−3)),and synergistically realizes the band nature modulation(from 7.4 to 5.5 eV)and enhanced ionic migration inhibition(628 meV)with optimized stability.As such,our X-ray detectors realized a sensitivity of 2377μCGy_(air)^(−1)cm^(−2),an ultralow detection limit of 50.1 nGy_(air)s^(−1),and impressive operation stability.Moreover,cytotoxicity assay confirmed the compatibility of pseudohalide metal-free perovskite.Finally,within this framework,we successfully fabricate the(MDABCOBr)–NH_(4)(BF_(4))_(3)-based flexible device to create an ideal in vitro wearable X-ray detection.
