The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resu...The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resulting in a low photocatalytic H_(2) evolution activity.Herein,a cobalt-induced asymmetric electronic distribution is justified as an effective strategy to optimize the electronic configuration of catalytic S sites in NiCoS cocatalysts for highly active photocatalytic H_(2) evolution.To this end,Co atoms are uniformly incorporated in NiS nanoparticles to fabricate homogeneous NiCoS cocatalyst on TiO_(2) surface by a facile photosynthesis strategy.It is revealed that the incorporated Co atoms break the electron distribution symmetry in NiS,thus essentially increasing the electron density of S atoms to form active electron-enriched S^(2+δ)–sites.The electron-enriched S^(2+δ)–sites could interact with Had via an increased antibonding orbital occupancy,which weakens S–Had bonds for efficient H_(ad) adsorption and desorption,endowing the NiCoS cocatalysts with a highly active H_(2) evolution process.Consequently,the optimized NiCoS/TiO_(2)(1:2)photocatalyst displays the highest H_(2) production performance,outperforming the NiS/TiO_(2) and CoS/TiO_(2) samples by factors of 2.1 and 2.5,respectively.This work provides novel insights on breaking electron distribution symmetry to optimize catalytic efficiency of active sites.展开更多
CONSPECTUS:Over the past decade,solution-processed organic−inorganic hybrid perovskite solar cells(PSCs)have emerged as a viable alternative to traditional crystalline silicon photovoltaics,with power conversion effic...CONSPECTUS:Over the past decade,solution-processed organic−inorganic hybrid perovskite solar cells(PSCs)have emerged as a viable alternative to traditional crystalline silicon photovoltaics,with power conversion efficiency(PCE)increasing notably from 3.8%to over 26%.This remarkable advancement is attributed to the unique band structures and exceptional defect tolerance of the hybrid perovskites.The bandgaps in perovskites derive from their antibonding orbitals at both the valence band maximum and conduction band minimum.Consequently,bond breaking creates states away from the bandgap,resulting in either shallow defects or states within the valence band.Despite defect densities up to 106 times higher than single-crystal silicon,polycrystalline perovskite films(<1μm thick)can still achieve comparable device performance due to their high defect tolerance.Superior photovoltaic performance in perovskite films depends on an efficient wetchemical process,offering a notable advantage over silicon-based photovoltaic technology.Evidently,solvent characteristics and their potential interaction with perovskites significantly impact crystal growth from precursor inks,subsequent polycrystalline film quality,and the ultimate performance of devices.Understanding solvent properties in relation to film formation processes is essential for informing solvent selection in the emerging perovskite photovoltaics and its future commercialization.In this Account,we present a thorough analysis of solution-processed perovskite films,encompassing the crystallization process and phase transition of perovskiterelated solvated complexes,and structure passivation of perovskite phase.We systematically categorize the prevalent solvents utilized in film preparation and outline a solvent roadmap for producing high-quality perovskite films from a chemical perspective,considering their interaction with the perovskite structure.We also address often-overlooked factors in solvent selection in current research.First,middle-polarity dispersion solvents fundamentally govern nucleation and growth kinetics of perovskite solvated films in the solution phase,thereby significantly shaping film morphology.However,control over the solvation interaction between dispersion solvent and perovskite structure for morphology regulation remains insufficient.Second,high-polarity binding solvents interact with the perovskite structure via solvent-involved intermediates,optimizing crystallization kinetics in the solution phase(sol−gel state)and controlling phase-transition kinetics of the intermediate phase.This interaction influences the crystal and structural properties of the resultant perovskite phase though managing the intermediate phase remains challenging.Third,lowpolarity modification solvents,combined with functional passivation molecules,are employed to modulate interface energetics of perovskite films by enabling both chemical defect passivation and physical field-effect passivation.However,achieving optimal interface energetics by forming heterojunctions or homogeneous interfaces through solvent selection is still difficult.By integrating fundamental solvent mechanisms and design criteria,comprehensive strategies can be formulated to achieve high PCE and stability in photovoltaics.Finally,we discuss key challenges and future perspectives in commercializing solution-processed perovskite photovoltaics,with the goal of inspiring innovative material designs and solvent engineering approaches.展开更多
The crystal structure,mechanical stability,phonon dispersion,electronic transport properties and thermoelectric(TE)performance of the Bi_(2)Sn_(2)Te_(6)monolayer are assessed with the first-principles calculations and...The crystal structure,mechanical stability,phonon dispersion,electronic transport properties and thermoelectric(TE)performance of the Bi_(2)Sn_(2)Te_(6)monolayer are assessed with the first-principles calculations and the Boltzmann transport theory.The Bi_(2)Sn_(2)Te_(6)monolayer is an indirect semiconductor with a band gap of 0.91 eV using the Heyd-Scuseria-Ernzerhof(HSE06)functional in consideration of the spin-orbit coupling(SOC)effect.The Bi_(2)Sn_(2)Te_(6)monolayer is high thermodynamically and mechanically stable by the assessments of elastic modulus,phonon dispersion curves,and ab initio molecular dynamics(AIMD)simulations.The hybrid bonding characteristics are discovered in Bi_(2)Sn_(2)Te_(6)monolayer,which is advantageous for phonon scattering.The antibonding interactions near the Fermi level weaken the chemical bonding and reduce the phonon vibrational frequency.Due to the short phonon relaxation time,strong anharmonic scattering,large Grüneisen parameter,and small phonon group velocity,an ultralow lattice thermal conductivity(0.27 W/(m·K)@300 K)is achieved for the Bi_(2)Sn_(2)Te_(6)monolayer.The optimal dimensionless figure of merit(ZT)values for the n-type and p-type Bi_(2)Sn_(2)Te_(6)monolayers are 2.68 and 1.63 at 700 K,respectively,associated with a high TE conversion efficiency of 20.01%at the same temperature.Therefore,the Bi_(2)Sn_(2)Te_(6)monolayer emerges as a promising candidate for TE material with high conversion efficiency.展开更多
Magnetic fields are known as clean,economic,and effective tools to modify band and magnetic structures of materials.When coupled with catalytic processes such as the hydrogen evolution reaction(HER),they have the pote...Magnetic fields are known as clean,economic,and effective tools to modify band and magnetic structures of materials.When coupled with catalytic processes such as the hydrogen evolution reaction(HER),they have the potential to control catalytic efficiency.Herein,we studied the magnetic response of a series of materials as HER catalysts,specifically ferromagnetic Co_(2)VGa,Co_(2)MnGa,and Ni,ferrimagnetic Mn_(2)CoGa,and paramagnetic Pt.展开更多
文摘The intrinsic symmetrical electron distribution in crystalline metal sulfides usually causes an improper electronic configuration between catalytic S atoms and H intermediates(H_(ad))to form strong S-H_(ad) bonds,resulting in a low photocatalytic H_(2) evolution activity.Herein,a cobalt-induced asymmetric electronic distribution is justified as an effective strategy to optimize the electronic configuration of catalytic S sites in NiCoS cocatalysts for highly active photocatalytic H_(2) evolution.To this end,Co atoms are uniformly incorporated in NiS nanoparticles to fabricate homogeneous NiCoS cocatalyst on TiO_(2) surface by a facile photosynthesis strategy.It is revealed that the incorporated Co atoms break the electron distribution symmetry in NiS,thus essentially increasing the electron density of S atoms to form active electron-enriched S^(2+δ)–sites.The electron-enriched S^(2+δ)–sites could interact with Had via an increased antibonding orbital occupancy,which weakens S–Had bonds for efficient H_(ad) adsorption and desorption,endowing the NiCoS cocatalysts with a highly active H_(2) evolution process.Consequently,the optimized NiCoS/TiO_(2)(1:2)photocatalyst displays the highest H_(2) production performance,outperforming the NiS/TiO_(2) and CoS/TiO_(2) samples by factors of 2.1 and 2.5,respectively.This work provides novel insights on breaking electron distribution symmetry to optimize catalytic efficiency of active sites.
基金funding support from the National Natural Science Foundation of China(22075238)the Natural Science Foundation of Fujian Province of China(2023J06009)+1 种基金IKKEM(RD2020020101 and RD2022040601)the New Cornerstone Science Foundation.
文摘CONSPECTUS:Over the past decade,solution-processed organic−inorganic hybrid perovskite solar cells(PSCs)have emerged as a viable alternative to traditional crystalline silicon photovoltaics,with power conversion efficiency(PCE)increasing notably from 3.8%to over 26%.This remarkable advancement is attributed to the unique band structures and exceptional defect tolerance of the hybrid perovskites.The bandgaps in perovskites derive from their antibonding orbitals at both the valence band maximum and conduction band minimum.Consequently,bond breaking creates states away from the bandgap,resulting in either shallow defects or states within the valence band.Despite defect densities up to 106 times higher than single-crystal silicon,polycrystalline perovskite films(<1μm thick)can still achieve comparable device performance due to their high defect tolerance.Superior photovoltaic performance in perovskite films depends on an efficient wetchemical process,offering a notable advantage over silicon-based photovoltaic technology.Evidently,solvent characteristics and their potential interaction with perovskites significantly impact crystal growth from precursor inks,subsequent polycrystalline film quality,and the ultimate performance of devices.Understanding solvent properties in relation to film formation processes is essential for informing solvent selection in the emerging perovskite photovoltaics and its future commercialization.In this Account,we present a thorough analysis of solution-processed perovskite films,encompassing the crystallization process and phase transition of perovskiterelated solvated complexes,and structure passivation of perovskite phase.We systematically categorize the prevalent solvents utilized in film preparation and outline a solvent roadmap for producing high-quality perovskite films from a chemical perspective,considering their interaction with the perovskite structure.We also address often-overlooked factors in solvent selection in current research.First,middle-polarity dispersion solvents fundamentally govern nucleation and growth kinetics of perovskite solvated films in the solution phase,thereby significantly shaping film morphology.However,control over the solvation interaction between dispersion solvent and perovskite structure for morphology regulation remains insufficient.Second,high-polarity binding solvents interact with the perovskite structure via solvent-involved intermediates,optimizing crystallization kinetics in the solution phase(sol−gel state)and controlling phase-transition kinetics of the intermediate phase.This interaction influences the crystal and structural properties of the resultant perovskite phase though managing the intermediate phase remains challenging.Third,lowpolarity modification solvents,combined with functional passivation molecules,are employed to modulate interface energetics of perovskite films by enabling both chemical defect passivation and physical field-effect passivation.However,achieving optimal interface energetics by forming heterojunctions or homogeneous interfaces through solvent selection is still difficult.By integrating fundamental solvent mechanisms and design criteria,comprehensive strategies can be formulated to achieve high PCE and stability in photovoltaics.Finally,we discuss key challenges and future perspectives in commercializing solution-processed perovskite photovoltaics,with the goal of inspiring innovative material designs and solvent engineering approaches.
基金supported by the National Natural Science Foundation of China(Grant No.21503039)Department of Science and Technology of Liaoning Province(Grant No.2019MS164)+1 种基金Department of Education of Liaoning Province(Grant Nos.LJ2020JCL034,JYTQN2023209)Discipline Innovation Team of Liaoning Technical University(Grant No.LNTU20TD-16)。
文摘The crystal structure,mechanical stability,phonon dispersion,electronic transport properties and thermoelectric(TE)performance of the Bi_(2)Sn_(2)Te_(6)monolayer are assessed with the first-principles calculations and the Boltzmann transport theory.The Bi_(2)Sn_(2)Te_(6)monolayer is an indirect semiconductor with a band gap of 0.91 eV using the Heyd-Scuseria-Ernzerhof(HSE06)functional in consideration of the spin-orbit coupling(SOC)effect.The Bi_(2)Sn_(2)Te_(6)monolayer is high thermodynamically and mechanically stable by the assessments of elastic modulus,phonon dispersion curves,and ab initio molecular dynamics(AIMD)simulations.The hybrid bonding characteristics are discovered in Bi_(2)Sn_(2)Te_(6)monolayer,which is advantageous for phonon scattering.The antibonding interactions near the Fermi level weaken the chemical bonding and reduce the phonon vibrational frequency.Due to the short phonon relaxation time,strong anharmonic scattering,large Grüneisen parameter,and small phonon group velocity,an ultralow lattice thermal conductivity(0.27 W/(m·K)@300 K)is achieved for the Bi_(2)Sn_(2)Te_(6)monolayer.The optimal dimensionless figure of merit(ZT)values for the n-type and p-type Bi_(2)Sn_(2)Te_(6)monolayers are 2.68 and 1.63 at 700 K,respectively,associated with a high TE conversion efficiency of 20.01%at the same temperature.Therefore,the Bi_(2)Sn_(2)Te_(6)monolayer emerges as a promising candidate for TE material with high conversion efficiency.
基金supported by the European Research Council(ERC Advanced grant no.742068‘TOPMAT’)the DFG through SFB 1143(project ID.247310070)the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat(EXC2147,project ID 39085490),and DFG project HE 3543/35–1.
文摘Magnetic fields are known as clean,economic,and effective tools to modify band and magnetic structures of materials.When coupled with catalytic processes such as the hydrogen evolution reaction(HER),they have the potential to control catalytic efficiency.Herein,we studied the magnetic response of a series of materials as HER catalysts,specifically ferromagnetic Co_(2)VGa,Co_(2)MnGa,and Ni,ferrimagnetic Mn_(2)CoGa,and paramagnetic Pt.
