Sb Vacancies Research Articles

2D Self-Assembly of Large-Sized Inorganic Nanosheets Leading to Enhanced Power Factors in Earth-Abundant Cu3SbSe4-Based Flexible Hybrid Films.

Fabrication of large-sized inorganic nanosheets is an efficient strategy to promote carrier transportation in flexible thermoelectric (TE) films. Herein, we report the self-assembly of large-sized Cu3SbSe4 nanosheets by using a Se nanowire template via wet chemical synthesis and then vacuum-assisted filter these plate-like microcrystals on nylon to prepare Cu3SbSe4 flexible thermoelectric (TE) hybrid films. SEM reveals that the as-synthesized Cu3SbSe4 powders by using Se nanowires as selenium sources presented 2D plate-like micron structures uniformly and tightly self-assembled by acute triangle-like nanoparticles. Furthermore, XPS evidences that extra Sb vacancies are generated in the unit cell of Cu3SbSe4 crystals synthesized by using the Se NW template, resulting in the shrinkage of the unit cell and the narrowing interplanar spacing, which are characterized by XRD and TEM. As a result, both carrier concentration and carrier mobility have been significantly improved. The high carrier concentration is proved to originate from the extra carriers induced by Sb vacancies, and the high carrier mobility of the film is mainly ascribed to its continuous grain boundaries in the plate-like microcrystal morphology. The large-sized nanosheet Cu3SbSe4/nylon hybrid film (CSS MPs) exhibits a high power factor (PF) of 235.45 μW m-1 K-2 at 400 K, which is 4.23 times higher than that of the Cu3SbSe4/nylon hybrid film (CSS NPs) where Cu3SbSe4 crystals are synthesized by using raw Se particles. This work reveals a novel approach to prepare plate-like Se-based semiconductors, which requires both high carrier concentration and high carrier mobility.

Theoretical insights into the interplay between Sb vacancy and Fe on magnetic and optoelectronic properties of Fe-doped antimonene

Fe substitution and its complex with Sb vacancy (VSb) in antimonene have been investigated using the hybrid functional method, dedicated to self-consistently predicting and interpreting their effects on the magnetic properties and optoelectronic functionalities of antimonene. First, we find that a single Fe substitution induces magnetism via the Sb(5p)-Fe(3d) hybridization, and promotes the optical absorption through inducing redshift and absorption peak. Further incorporation of VSb stabilizes Fe dopant via the strong attraction, forming a Fe-VSb cluster. The clustering of VSb with Fe causes the electron localizations at both Fe and VSb sites, leading to (i) the ferromagnetic Sb(5p)-Fe(3d) hybridization and (ii) the polarization of electrons at VSb, remarkably enhancing the magnetism. Simultaneously, the Fe-VSb cluster induces more evident redshift and absorption peak than a single Fe dopant, effectively boosting the photoabsorption. This work has implications in modulating electronic and magnetic properties of antimonene to developing the spintronic and optoelectronic applications.

Enhancement on thermoelectric performance by Ti doping and vacancies

Due to the exceptionally low lattice thermal conductivity, AgSbTe2 has emerged as a promising thermoelectric material. However, unlike other IV-VI compounds, most reported AgSbTe2 samples exhibit relatively poor electrical performance due to low carrier concentration. Herein, an unusually strategy of introducing dopants and vacancies on the same site of Sb is adopted, which significantly improves the electrical performance of AgSbTe2. It is found that Ti doping on Sb site can increase the carrier concentration and promote band convergence, based on which the introduction of Sb vacancy further enlarges the carrier concentration to approach the optimal value without affecting the carrier mobility. Consequently, an excellent average power factor of 1.4 mW m−1K−2 is achieved in AgSb0.94 Ti0.05Te2 from 323 K to 623 K. Combining with reduced thermal conductivity due to strengthened phonon scattering induced by the abundant lattice defects, a peak zT of 1.8 and a high average zT of 1.3 are attained. These results provide some new insights for improving the thermoelectric performance of AgSbTe2 based compounds.

The synergy of Sb doping and vacancy equilibrium charge improves the thermoelectric properties of GeMnTe2

GeMnTe2 is considered to be an excellent thermoelectric material because it is cheaper and easier to obtain than GeTe, has a higher carrier concentration than MnTe, and its cubic structure is not prone to phase transition and is relatively stable. The aim of this paper is to optimize the carrier concentration of GeMnTe2 and reduce the thermal conductivity by Charge Balance Vacancy Engineering, thus giving the material higher thermoelectric properties. In this paper, GeMnTe2 has obtained better thermoelectric properties by Charge Balanced Vacancy Engineering. Sb is introduced into GeMnTe2 as an effective dopant, which leads to an increase in the density of states near the Fermi level. In the heat, when Sb doping concentration was 0.1 and the actual content of Ge was 0.85, the highest power factor was 13.72 μWcm−1K−2, which was 17.70% and was head and shoulders above the pure. The ZT value was 0.67 and the maximum value of Ge0.97MnSb0.02Te2 sample was 0.8 at the pure phase condition of 770 K, which was about 19.94% higher than that of GeMnTe2, which proved that Charge Balance Vacancy Engineering is an effective technique to improve the thermoelectric performance of GeMnTe2 thermoelectric devices.

Anisotropic magnetoresistance and quantum oscillation in Sb2Te3 single crystal synthesized by a Te-flux method

Topological insulators (TIs) have attracted the widespread attentions due to their unique electronic structures and novel physical properties in past decades. Here, we investigate the magnetoresistance (MR) and Shubnikov-de Haas (SdH) oscillation in topological Sb2Te3. It is found that the angle-dependent MR shows the obvious anisotropy, and the maximal MR reaches ∼220% with the magnetic field rotated in ab plane at 2.5 K and 9 T. The Landau-level fan diagram indicates that Sb2Te3 possesses a nontrivial Berry phase. Comparing the SdH oscillations measured by the magnetic fields rotated in bc and ab planes, we find that the oscillation frequencies are similar, and the Berry phase shift is very slight. The first-principles calculations demonstrate that Sb vacancy can introduce an additional band across the Fermi level. The anisotropy of the Fermi surfaces reveals the anisotropic MR.

Modulated Fermi Level and Relaxed Lattice Strain Leading to Enhanced Thermoelectric Properties in AgSbSe2

Cubic-phase AgSbSe2 has been known as a decent p-type thermoelectric material, due to its intrinsically low lattice thermal conductivity; nevertheless, the difficulty in modulating its electrical transport performance impeded its further competition with other state-of-the-art mid-temperature thermoelectrics. In this work, we investigated the effects of Pb doping and Sb vacancies on modulating the thermoelectric properties of AgSbSe2. Pb doping was found to be able to obviously increase the hole concentration, leading to a descending of Fermi level well into the multiple valence bands, thus leading to an enhanced band degeneracy; subsequent Sb vacancies could play the role of relaxing the local lattice strains due to PbSb substitution, resulting in a weakened charge carrier scattering and enhanced weighted mobility. Consequently, a peak power factor PFmax of 7.5 μW cm–1 K–2 at 523 K was achieved in the composition of AgSb0.935Pb0.06Se2, which is 40% higher than that of pristine AgSbSe2. Furthermore, Pb doping and Sb vacancies induce enhanced point defect scattering of high-frequency heat-carrying phonons, yielding a reduced lattice thermal conductivity and a remarkably enhanced maximal ZTmax value of 1.02 at 723 K in the sample AgSb0.935Pb0.06Se2.

Classification of lattice defects and the microscopic origin of p-type conductivity of Sb2Se3 solar cell absorber with varying Al2O3-layer thicknesses

Based on first-principles calculations, herein, we reveal the origin of p-type conductivity and the roles of Al and O in the enhancement of hole concentration in Sb2Se3 thin films. A new class of low-energy defects with shallow acceptor levels is presented by substituting Se with O and inducing Sb vacancy [OSe–VSb] complex. Moreover, the concentration of holes induced by the intrinsic and extrinsic defects is calculated and discussed. Our results can explain the intriguing experimental observation where the hole concentration is enhanced after Al2O3 capping and provide a new insight to the defect chemistry and physics of Sb2Se3 thin films. In addition, Al2O3 layers with varying thicknesses have been deposited on the surface of Sb2Se3 films. The crystallinity, orientation and electrical properties of Sb2Se3 films have been investigated in detail. Lastly, 6.87% efficiency of Sb2Se3 solar cells without other optimization has been obtained based on the structure of FTO/CdS (CBD)/Sb2Se3/Al2O3/Au.

Ab initio расчет зонной структуры и свойств модификаций соединения Ti-=SUB=-3-=/SUB=-Sb, допированного литием

Using the density functional theory (DFT) in the local electron spin density approximation (LSDA), 2×2×2 supercells based on the Ti3Sb compound have been studied. The supercells contained their own vacancies and doped lithium atoms replacing Ti and/or Sb. The DFT-LSDA method was used to calculate the structural, electronic, and magnetic properties, the enthalpy of formation, and the cohesion energy of supercells of two modifications of the Ti3Sb compound. We studied supercells with cubic system (A15 type structure; a = 5.217 Å) and tetragonal system (D8_m type structure; а = 10.457 Å, с = 5.258 Å). It has been established that the distribution of the density of states of the Ti3Sb cubic system has a more metallic character than for the D8_mTi3Sb modification. The enhancement of "metallicity" in the cubic modification A15 Ti3Sb is associated with an increase in the Ti–Sb interatomic distance in the crystal. Due to this, the degree of metallic bonding increases during the electronic interaction between Ti and Sb atoms near the Fermi level in Ti3Sb. In DFT calculations, the spin-polarized density of states was taken into account. It has been established that in both modifications (A15 and D8_m) of Ti3Sb near the Fermi level for s, p, d-states with spin "up" and spin "down" there is a spin imbalance in the population of energy levels. Defect-containing supercells based on Ti3Sb were studied by DFT-LSDA calculations. It is shown that Ti and/or Sb vacancies in the lattices of Ti3Sb crystals of both modifications (A15 and D8_m) increase the magnetic moment (M) as compared to the value of M (M_tot = 0.08 μ_B) of a “pure” Ti3Sb crystal. Considering that Al5 Ti3Sb is also interesting as a material for Li-ion batteries, we studied Ti3Sb–Li supercells doped with lithium. Li-doping and the creation of own Ti and/or Sb vacancies changes the distance between atoms in Ti3Sb. Correspondingly, the resulting local magnetic moments near the Ti or Sb vacancies also change. The enthalpy of formation and magnetic moment of Ti3Sb and Ti3Sb–Li based supercells are calculated. DFT calculations of the structural stability of binary compounds (phases) have been carried out, and the stability of conodes between phases in the Ti–Sb–Li system has been established. The isothermal section of the Ti–Sb–Li system was plotted at 298 K. It is shown that the introduction of various lithium concentrations (<6.25 at. % Li) into the Ti3Sb (Space group Pm3 ̅n; № 223; a = 5.217 Å) crystal lattice reduces the partial magnetic moment of Ti in the Ti3Sb–Li supercell.

Ab initio calculation of the band structure and properties of modifications of the Ti-=SUB=-3-=/SUB=-Sb compound doped with lithium

Using the density functional theory (DFT) in the local electron spin density approximation (LSDA), 2x2x2 supercells based on the Ti3Sb compound have been studied. The supercells contained their own vacancies and doped lithium atoms replacing Ti and/or Sb. The DFT-LSDA method was used to calculate the structural, electronic, and magnetic properties, the enthalpy of formation, and the cohesion energy of supercells of two modifications of the Ti3Sb compound. We studied supercells with cubic system (A15 type structure; a=5.217 Angstrem) and tetragonal system (D8m type structure; a=10.457 Angstrem, c=5.258 Angstrem). It has been established that the distribution of the density of states of the Ti3Sb cubic system has a more metallic character than for the D8m Ti3Sb modification. The enhancement of "metallicity" in the cubic modification A15 Ti3Sb is associated with an increase in the Ti-Sb interatomic distance in the crystal. Due to this, the degree of metallic bonding increases during the electronic interaction between Ti and Sb atoms near the Fermi level in Ti3Sb. In DFT calculations, the spin-polarized density of states was taken into account. It has been established that in both modifications (A15 and D8m) of Ti3Sb near the Fermi level for s-, p-, d-states with spin "up" and spin "down" there is a spin imbalance in the population of energy levels. Defect-containing supercells based on Ti3Sb were studied by DFT-LSDA calculations. It is shown that Ti and/or Sb vacancies in the lattices of Ti3Sb crystals of both modifications (A15 and D8m) increase the magnetic moment (M) as compared to the value of M (M=0.08 μB) of a "pure" Ti3Sb crystal. Considering that Al5 Ti3Sb is also interesting as a material for Li-ion batteries, we studied Ti3Sb-Li supercells doped with lithium. Li-doping and the creation of own Ti and/or Sb vacancies changes the distance between atoms in Ti3Sb. Correspondingly, the resulting local magnetic moments near the Ti or Sb vacancies also change. The enthalpy of formation and magnetic moment of Ti3Sb and Ti3Sb-Li based supercells are calculated. DFT calculations of the structural stability of binary compounds (phases) have been carried out, and the stability of conodes between phases in the Ti-Sb-Li system has been established. The isothermal section of the Ti-Sb-Li system was plotted at 298 K. It is shown that the introduction of various lithium concentrations (≤6.25 at.% Li) into the Ti3Sb (Space group Pm3 n; N 223; a=5.217 Angstrem) crystal lattice reduces the partial magnetic moment of Ti in the Ti3Sb-Li supercell. Keywords: Ti3Sb intermetallic compounds, A15 cubic modification, D8m tetragonal modification, doping with lithium, Ti3Sb-Li, DFT-LSDA calculations, supercell, electronic and magnetic properties, Ti-Sb-Li phase stability.

Enhanced thermoelectric properties in Sb/Ge core/shell nanowires through vacancy modulation

In the present work, we have modified the physical and electronic structure of Sb/Ge core/shell nanowires via vacancy creation and doping with foreign atoms with the aim to improve their thermoelectric energy conversion efficiency. Sb/Ge-NWs having a diameter of 1.5 Å show metallicity with 2Go quantum conductance. The stability of the nanowires is assessed through the calculation of their formation energy. The formation of one vacancy at either the Sb- and Ge-site modifies substantially the electronic properties. From the comparison of the thermoelectric properties of the nanowires with and without the vacancy, we have found that the figure of merit for the Sb/Ge NW with one Sb vacancy increases of 0.18 compared to the pristine NW. The NW doping with different transition metals: Fe, Co, Ni and Cu have been found to also enhance the conversion efficiency. Thus, our calculations show that the thermoelectric performance of metal–semiconductor core–shell NWs can be in principle improved as much as 80% by vacancy formation and doping.

Advancing thermoelectrics by vacancy engineering and band manipulation in Sb-doped SnTe–CdTe alloys

A decrease in valence band energy offset can considerably improve the thermoelectric performance of SnTe, and alloying CdTe in SnTe has been confirmed to be efficient for inducing band convergence. However, the low solubility of CdTe in SnTe severely limits the further decrease in the energy offset and the reduction of lattice thermal conductivity. Inspired by the high solubility of Sb in SnTe-based thermoelectric materials, the trivalent Sb is introduced into SnTe–CdTe alloys, aiming at manipulating the thermoelectric transport properties. Combined with the valence band model, it is demonstrated that high concentration of Sb in SnTe–CdTe enables a further optimization in valence band structures, resulting in an improvement in density-of-state effective mass, thus significantly reinforces the power factor in the whole temperature range. Meanwhile, we propose the solid solution mode of Sb in SnTe, which always generates vacancies to balance the valence state, and the introduction of vacancies explains the reduced lattice parameters and almost constant carrier concentration. Particularly, the Debye–Callaway model quantitatively compares the contribution of Sb substitutional defects and vacancy defects. As a result, an enhanced zT of ∼1.1 has been achieved for Sn0.83Cd0.05Sb0.12Te at 823 K. This work clearly shows the critical role of Sb for enhancing the thermoelectric performance of SnTe–CdTe materials.

Characterization of flexible dilute nitride InSbN thin films and exploratory study for epidermal optoelectronics

Flexible devices have recently been actively investigated for various purposes. Sb-based materials particularly attractive for medical applications. We grew InSb and dilute nitride InSbN thin films on polyimide (PI) films and on quartz substrates by reactive radio frequency magnetron sputtering. By comparing the properties of thin films grown on PI films with those on quartz substrates, we revealed that InSb/PI contains large amount of native defects which originate from Sb clusters and Sb vacancies (VSb). Although the properties of the thin films grown on quartz substrates did not improve by nitridation, dilute nitride InSbN/PI showed superior properties to InSb/PI. These changes in thin film properties suggest that nitridation generates the substitution of VSb for N and the suppression of native defect formation. Consequently, dilute nitride InSbN/PI is potentially useful in electronic device applications. Furthermore, we evaluated the skin absorption of dilute nitride InSbN/PI. As a result, both In and Sb hardly permeated and were retained inside the skin. We conclude that the flexible dilute nitride InSbN/PI can be applied to epidermal optoelectronics.

Enhanced thermoelectric performance of nominal 19-electron half-Heusler compound NbCoSb with intrinsic Nb and Sb vacancies

Since 2015, when we first reported that the half-Heusler alloy NbCoSb with a nominal 19-valence-electrons composition exhibits the moderate thermoelectric properties of a heavily doped n-type semiconductor, we have been studying the preparation of pure-phase materials. Here we report, for the first time, the effects of Nb and Sb deficiencies on the phase composition and thermoelectric properties of NbCoSb. The experimental results show that phase-pure material can be achieved if the composition is slightly Nb and Sb deficient and that intrinsic vacancy defects have a remarkable effect on the thermoelectric performance. The ZT value is doubled and a maximum ZT of 0.8 is achieved in Nb0·97CoSb0.99 at 973 K, benefiting from the elimination of impurity phases and the optimization of carrier concentration. This work proves that introducing vacancy defects is an effective strategy to improve the thermoelectric properties of some half-Heusler alloys, especially of nominal 19-electron half-Heusler compounds.

In-situ growth of high-performance (Ag, Sn) co-doped CoSb3 thermoelectric thin films

• A high ZT of ~0.52 is achieved in n -type (Ag, Sn) co-doped CoSb 3 at 623 K. • Extensive characterizations and computational results confirm both Sn and In as fillers prefer to occupy the interstitial sites in the CoSb 3 lattice. • The Fermi level moved into the conduction bands and increase of the density of state after doping, resulting in the increase power factor. • Young modulus and hardness of co-doped sample enhanced after Ag and Sn doping, indicating its potential for applying to miniature thermoelectric devices. Owing to the unique features, such as mechanically robust, low-toxic, high stability, and high thermoelectric performance, CoSb 3 -based skutterudite materials are among art-of-the state thermoelectric candidates. In this work, we develop a facile in-situ method for the growth of well-crystallinity (Ag, Sn) co-doped CoSb 3 thin films. This preparation method can efficiently control the dopant concentration and distribution in the thin films. Both the density functional theory calculation and the experimental results suggest that Sn and Ag dopants trend to enter the lattice and preferentially fill interstitial sites. Additionally, band structure calculation results suggest that the Fermi level moves into the conduction bands due to co-doping and eventually induces the increased electrical conductivity, which agrees with the optimization of carrier concentration. Moreover, an increase in the density of state after co-doping is responsible for the increased Seebeck coefficient. As a result, the power factors of (Ag, Sn) co-doped CoSb 3 thin films are greatly enhanced, and the maximum power factor achieves over 0.3 mW m −1 K −2 at 623 K, which is almost two times than that of the un-doped CoSb 3 film. Multiple microstructures, including Sb vacancies and Ag/Sn interstitial atoms as point defects, and a high density of lattice distortions coupled with nano-sized Ag-rich grains, lead to all scale phonon scatterings. As a result, a reduced thermal conductivity of ~0.28 W m −1 K −1 and a maximum ZT of ~0.52 at 623 K are obtained from (Ag, Sn) co-doped CoSb 3 thin films. This study indicates our facile in-situ growth can be used to develop high-performance dual doped CoSb 3 thins . The well-crystallized (Ag, Sn) co-doped thermoelectric thin films have been synthesized by a facial in-situ growth process and a high ZT of ~0.52 is achieved by rational band engineering and structural manipulations.

Antimonene Allotropes α- and β-Phases as Promising Anchoring Materials for Lithium–Sulfur Batteries

In a quest to mitigate the undesirable shuttling effect that hampers the performance of Li-S batteries, we adopted first-principles calculations to study the anchoring mechanism of lithium polysulfides on antimonene phases, i.e., α-Sb and β-Sb. The anchoring mechanisms of LiPSs on α-Sb and β-Sb were studied through calculations of binding energy, charge transfer, and vertical binding distances from the monolayer to LiPSs. The results indicated that pristine α-Sb and β-Sb showed significant physisorption/chemisorption interactions toward LiPSs due to the considerable Eb values (0.71-1.68 and 0.96-2.07 eV, respectively). Meanwhile, with single Sb vacancy, the binding strength was enhanced (0.83-2.91 eV) for the β-Sb monolayer. Furthermore, we substituted the Sb atom with the Sn/Te atom and found stronger Eb (1.32-5.69 and 0.45-4.81 eV). All these bindings of LiPSs were much stronger than their interactions with those of electrolytes (DME/DOL) (Eb values: 0.20-1.16 and 0.17-1.07 eV). Also, we investigated the redistribution of electrons and the influence of electronic states near the Fermi level in DOS for LiPSs on α-Sb and β-Sb. Our findings suggest that pristine and defected β-Sb monolayers could be an excellent anchoring material for Li-S batteries.

Effect of vacancy defects on photoelectric properties of K2CsSb photocathode

A variety of different vacancy defect compounds may be formed during the preparation of the K2CsSb photocathode. To better understand the action mechanism of vacancy defects, the influence of Cs vacancy, K vacancy, Sb vacancy, Cs-K vacancy, Cs-Sb vacancy, K-Sb vacancy on the electronic structures and optical properties of K-Cs-Sb cathodes were investigated by the first-principles method based on density functional theory. The band structures show that, K-Cs-Sb cathode materials with Sb vacancy, Cs-Sb vacancy, K-Sb vacancy, adjacent K double vacancies are indirect bandgap semiconductors, other models are all direct bandgap semiconductors. Besides, the Sb vacancy-contained models exhibit n-type semiconductor property, while other models with only K or Cs vacancy all exhibit p-type semiconductor property. The calculated results about formation energy and formation enthalpy indicate that the Cs vacancy defects are easier to form and more thermodynamically stable than other vacancy defects. In terms of optical properties, in the energy range of 2.4–3.2 eV produced by neutrino scintillator radiation, K2CsSb without vacancy defects possesses the maximum absorption coefficient. The Sb vacancy-contained defects cause the absorption coefficient peak to shift to the lower energy position, while other vacancy defects without Sb vacancies are just the opposite.

Vacancy defect control of colossal thermopower in FeSb2

Iron diantimonide is a material with the highest known thermoelectric power. By combining scanning transmission electron microscopic study with electronic transport neutron, X-ray scattering, and first principle calculation, we identify atomic defects that control colossal thermopower magnitude and nanoprecipitate clusters with Sb vacancy ordering, which induce additional phonon scattering and substantially reduce thermal conductivity. Defects are found to cause rather weak but important monoclinic distortion of the unit cell Pnnm → Pm. The absence of Sb along [010] for high defect concentration forms conducting path due to Fe d orbital overlap. The connection between atomic defect anisotropy and colossal thermopower in FeSb2 paves the way for the understanding and tailoring of giant thermopower in related materials.

Improving the power factor and figure of merit of p-type CuSbSe2via introducing Sb vacancies

A large ZT of 0.50 is achieved for CuSb0.91Se2 due to 44% enhancement of power factor and 22% reduction of lattice thermal conductivity, which is realized through introducing Sb vacancies.

Improving the thermoelectric performance of Ti-doped NbFeSb by substitutional doping of the Sb atoms with the isoelectric and heavy Bi atoms

Solute Bi atoms in Nb0.8Ti0.2FeSb1−xBix samples scatter phonons and increase the effective mass, increasing the ZT within the Bi solubility limit; above this limit, concomitant Sb vacancies disproportionately donate holes, resulting in poor ZT.

Surface-engineered oxidized two-dimensional Sb for efficient visible light-driven N2 fixation

Abstract Solar N2 fixation under visible light offers a promising method toward sustainable NH3 production at benign conditions. However, it still remains a formidable challenge to activate and cleave N N bonds and promote the separation and transport of electrons and holes during photocatalysis. To address these issues, the discovery and design of high-performance and robust photocatalysts is imperative. Here, we report the defect engineering of two-dimensional oxidized Sb nanosheets to activate intrinsically inactive Sb for efficient visible light-driven N2 reduction to NH3. Impressively, the Sb nanosheets rich in Sb and oxygen vacancies afford a remarkable NH3 formation rate of up to 388.5 μgNH3 h−1 gcat.−1 without cocatalyst in visible light, 8 times higher than that for bulk Sb and also significantly outperforming many previously reported photocatalysts. The defective Sb nanosheets exhibit excellent stability after five successive reaction cycles. Further density functional theory calculations reveal a considerably strong interaction between N2 and defects on the surface and edge of Sb nanosheets, which facilitates the formation of *NNH (N2 + (H+ + e-) → *NNH, where * denotes an adsorption site), thus promoting photocatalytic N2 reduction. This finding opens a novel avenue to enhancing N2 photofixation over inherently inactive surfaces by synergistically engineering defect sites.