Due to its lead-free composition and a unique double polarization hysteresis loop with a large maximum polarization(Pmax)and a small remnant polarization(Pr),AgNbO_(3)-based antiferroelectrics(AFEs)have attracted exte...Due to its lead-free composition and a unique double polarization hysteresis loop with a large maximum polarization(Pmax)and a small remnant polarization(Pr),AgNbO_(3)-based antiferroelectrics(AFEs)have attracted extensive research interest for electric energy storage applications.However,a low dielectric breakdown field(Eb)limits an energy density and its further development.In this work,a highly efficient method was proposed to fabricate high-energy-density Ag(Nb,Ta)O_(3) capacitor films on Si substrates,using a two-step process combining radio frequency(RF)-magnetron sputtering at 450℃and post-deposition rapid thermal annealing(RTA).The RTA process at 700℃led to sufficient crystallization of nanograins in the film,hindering their lateral growth by employing short annealing time of 5 min.The obtained Ag(Nb,Ta)O_(3) films showed an average grain size(D)of~14 nm(obtained by Debye-Scherrer formula)and a slender room temperature(RT)polarization-electric field(P-E)loop(Pr≈3.8 mC·cm^(−2) and P_(max)≈38 mC·cm^(−2) under an electric field of~3.3 MV·cm^(−1)),the P-E loop corresponding to a high recoverable energy density(W_(rec))of~46.4 J·cm^(−3) and an energy efficiency(η)of~80.3%.Additionally,by analyzing temperature-dependent dielectric property of the film,a significant downshift of the diffused phase transition temperature(T_(M2-M3))was revealed,which indicated the existence of a stable relaxor-like AFE phase near the RT.The downshift of the T_(M2-M3) could be attributed to a nanograin size and residual tensile strain of the film,and it led to excellent temperature stability(20-240℃)of the energy storage performance of the film.Our results indicate that the Ag(Nb,Ta)O_(3) film is a promising candidate for electrical energy storage applications.展开更多
Ta3N5 is regarded as a promising photocatalyst for solar water splitting because of its excellent visible light absorption characteristics and simple composition.Conventional Ta3N5 photocatalysts prepared from oxide p...Ta3N5 is regarded as a promising photocatalyst for solar water splitting because of its excellent visible light absorption characteristics and simple composition.Conventional Ta3N5 photocatalysts prepared from oxide precursors typically comprise aggregated polycrystalline particles with defects and grain boundaries that reduce the water oxidation activity of the material.In the present work,well-dispersed Ta3N5 nanoparticulate single crystals were synthesized via a mild nitridation process using pure Ta metal nanopowder or Ta nanopowder mixed with NaCl.The resulting high-quality Ta3N5 nanoparticles,after loading with an oxygen evolution cocatalyst,exhibited impressively high photocatalytic performance during O_(2)evolution from a sacrificial AgNO3 solution,with an apparent quantum yield of 9.4%at 420 nm.Our findings suggest a new approach to the facile fabrication of nanostructured single-crystal photocatalysts for efficient solar water splitting,based on the use of metal nanopowders.展开更多
基金support from the National Natural Science Foundation of China (Grant Nos.51772175,52072218,and 52002192)Natural Science Foundation of Shandong Province (Grant Nos.ZR2020QE042,ZR2022ZD39,and ZR2022ME031)+6 种基金the Science,Education and Industry Integration Pilot Projects of Qilu University of Technology (Shandong Academy of Sciences) (Grant Nos.2022GH018 and 2022PY055)support from the Jinan City Science and Technology Bureau (Grant No.2021GXRC055)the Education Department of Hunan Province/Xiangtan University (Grant No.KZ0807969)funding for top talents at Qilu University of Technology (Shandong Academy of Sciences)support from the Jiangsu Province NSFC (Grant No.BK20180764)support from the National Key R&D Program of China (Grant No.2021YFB3601504)Natural Science Foundation of Shandong Province (Grant No.ZR2020KE019).
文摘Due to its lead-free composition and a unique double polarization hysteresis loop with a large maximum polarization(Pmax)and a small remnant polarization(Pr),AgNbO_(3)-based antiferroelectrics(AFEs)have attracted extensive research interest for electric energy storage applications.However,a low dielectric breakdown field(Eb)limits an energy density and its further development.In this work,a highly efficient method was proposed to fabricate high-energy-density Ag(Nb,Ta)O_(3) capacitor films on Si substrates,using a two-step process combining radio frequency(RF)-magnetron sputtering at 450℃and post-deposition rapid thermal annealing(RTA).The RTA process at 700℃led to sufficient crystallization of nanograins in the film,hindering their lateral growth by employing short annealing time of 5 min.The obtained Ag(Nb,Ta)O_(3) films showed an average grain size(D)of~14 nm(obtained by Debye-Scherrer formula)and a slender room temperature(RT)polarization-electric field(P-E)loop(Pr≈3.8 mC·cm^(−2) and P_(max)≈38 mC·cm^(−2) under an electric field of~3.3 MV·cm^(−1)),the P-E loop corresponding to a high recoverable energy density(W_(rec))of~46.4 J·cm^(−3) and an energy efficiency(η)of~80.3%.Additionally,by analyzing temperature-dependent dielectric property of the film,a significant downshift of the diffused phase transition temperature(T_(M2-M3))was revealed,which indicated the existence of a stable relaxor-like AFE phase near the RT.The downshift of the T_(M2-M3) could be attributed to a nanograin size and residual tensile strain of the film,and it led to excellent temperature stability(20-240℃)of the energy storage performance of the film.Our results indicate that the Ag(Nb,Ta)O_(3) film is a promising candidate for electrical energy storage applications.
基金supported by the Artificial Photosynthesis Project of the New Energy and Industrial Technology Development Organization(NEDO).Part of this work was conducted at the Advanced Characterization Nanotechnology Platform of the University of Tokyo,supported by the“Nanotechnology Platform”of the Ministry of Education,Culture,Sports,Science and Technology(MEXT),Japan(No.JPMXP09A-19-UT-0023).
文摘Ta3N5 is regarded as a promising photocatalyst for solar water splitting because of its excellent visible light absorption characteristics and simple composition.Conventional Ta3N5 photocatalysts prepared from oxide precursors typically comprise aggregated polycrystalline particles with defects and grain boundaries that reduce the water oxidation activity of the material.In the present work,well-dispersed Ta3N5 nanoparticulate single crystals were synthesized via a mild nitridation process using pure Ta metal nanopowder or Ta nanopowder mixed with NaCl.The resulting high-quality Ta3N5 nanoparticles,after loading with an oxygen evolution cocatalyst,exhibited impressively high photocatalytic performance during O_(2)evolution from a sacrificial AgNO3 solution,with an apparent quantum yield of 9.4%at 420 nm.Our findings suggest a new approach to the facile fabrication of nanostructured single-crystal photocatalysts for efficient solar water splitting,based on the use of metal nanopowders.
