Sb Bonds Research Articles

Carbodiphosphorane-Activated Distibene and Dibismuthene Dications.

Low-valent antimony and bismuth have emerged as novel platforms for achieving reversible small-molecule activation at main-group metals. Although various examples of oxidative addition reactions at monomeric Sb(I) and Bi(I) have been reported, the chemistry of the heavy group 15 Sb(I)═Sb(I)/Bi(I)═Bi(I) double bonds toward small molecules remains largely unexplored. In this study, we present a straightforward synthesis of distibene and dibismuthene dications coordinated with a neutral carbodiphosphorane (CDP) ligand. The nonbonding interactions between the occupied p-orbital at the CDP ligand and the π-bonding orbital of the Sb═Sb/Bi═Bi bonds yield compounds with exceptionally small HOMO-LUMO gaps. In addition, the reduction of steric hindrance compared to known neutral derivatives stabilized with bulky aryl groups allows for better accessibility of the double bonds. This high reactivity is demonstrated in the oxidative addition of distibene to diphenyldisulfide as well as in [2+2] cycloadditions to alkynes. Additionally, the Sb═Sb bond reversibly adds to 2,3-dimethylbutadiene in a [4+2] cycloaddition reaction.

Catalyst-Free, Zn-Mediated Decarboxylative Coupling of Chlorostibines to Access Alkylstibines with Stable C(sp3)-Sb Bonds.

Herein, decarboxylative C(sp3)-Sb coupling of aliphatic carboxylic acid derivatives with chlorostibines to access alkylstibines has been achieved. This catalyst-, ligand-, and base-free approach using zinc as a reductant affords various kinds of benzyldiarylstibines and other monoalkyldiarylstibines and tolerates various functional groups, including chlorine, bromine, hydroxyl, amide, sulfone, and cyano groups. The late-stage modification and the gram-scale experiments illustrate its potential application.

Without Dissolvent: Fast Inducing Cable‐Like Sb2S3@C from Natural Minerals with Enhanced Preferential Planes and Sulfur‐Defects Toward High‐Rate Properties

AbstractDeveloping novel anodes with outstanding fast‐charging properties is crucial for next‐generation energy storage research. Sb2S3 materials are deemed promising electrodes due to their high theoretical specific capacity. However, they are restricted by sluggish bulk‐phase kinetics, bringing about inferior electronic conductivity at high current density. In this work, the cable‐like SS@C‐x anodes are successfully prepared via the thermal‐chemical treatment method. Through the tailoring of habit modifiers, their unique core–shell architectures are induced with (hk1) preferential planes and the construction of S‐defects, accompanied by lowered energy barriers. Meanwhile, assisted by C─S and C─O─Sb bonds, the charge accumulation on the surface can be rapidly released toward the bulk phase. As expected, for the as‐optimized samples, the capacity of 603.7 mAh g−1 can remain after 100 cycles at 1.0 A g−1. Even at 10.0 A g−1, their superior capacity of 436.1 mAh g−1 can be noted, and it still displayed the reversible capacity of 479 mAh g−1 at −5 °C. Assisted by kinetic analysis, the great electrochemical properties mainly come from the reduced migration energy barriers and accelerated Li+ diffusion rates. Given this, the work is expected to shed light on crystal orientation tuning and defect engineering for advanced metal‐based energy storage materials.

Enhancing the stability of Sb2Se3 alloy through structural alterations on Bi addition

Sb2Se3 has attracted a lot of research interest as an environmentally friendly material with diverse applications. (Sb2Se3)100−xBix(x = 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2) alloys are synthesized via melt quenching. Energy Dispersive X-ray (EDX) spectra confirm the Sb, Se, and Bi presence in bulk samples. X-ray diffraction (XRD) spectra confirm orthorhombic crystal structure in Bi-doped Sb2Se3 alloys. FTIR and Raman spectroscopy observations indicate an alteration in local structure on Bi addition. Far-IR spectroscopy points to Bi bonding with Se forming Bi2Se3 units. There is shifting of Raman peaks, corroborating the structural alteration in alloys on Bi incorporation. The peak intensity of Raman modes for Sb–Sb bond (B1g mode) decreases and for Sb–Se bond (A1g mode) increases, due to formation of Bi2Se3 structural units on Bi incorporation. The formation of stable Bi2Se3 units on Bi addition to Sb2Se3 alloys may be explored for potential application in topological insulators.

Constructing Robust Interfacial Chemical Bond Enhanced Charge Transfer in S‐Scheme 3D/2D Heterojunction for CO2 Photoreduction

AbstractA stable ZnTe@Cs3Sb2I9 catalyst with 3D/2D‐hollow‐composite structure is constructed for CO2 photocatalytic reduction via the in situ growth of Cs3Sb2I9 nanosheets on hollow ZnTe microspheres using lattice matching. The formed Tellurium‐Antimony (Te─Sb) bonds improved the poor contact at the heterojunction interface, effectively promoted charge separation, and successfully suppressed photocorrosion. The unique core‐shell structure not only strengthens light absorption but also improves CO2 adsorption capacity. Consequently, the S‐scheme heterojunction with the synergistic effect of chemical bonds and 3D/2D‐hollow‐composite structure significantly enhances photocatalytic performance. The ZnTe@Cs3Sb2I9 photocatalyst offers a CO selectivity of 90.5%, which is higher than that of pure ZnTe (22.9%) and Cs3Sb2I9 (56.9%). This structure holds great promise for practical applications in CO2 photocatalytic reduction.

DFT simulation to study the physical properties of ternary intermetallic materials ACuSb (A=Ca, Sr, Ba) for solar cell and TBC materials

This study carried out the configurational, bulk, electronic, optical as well as thermodynamic features of ternary materials ACuSb (A = Ca,Sr, Ba) using first-principles DFT-based calculations. The explored lattice constants as well as unit cell volume are very close to hypothetical results which make sure the correctness of the present study. According to the investigated elastic stiffness constants, the studied compounds are mechanically stable as they hold the Born's stability criteria. Utilizing the calculated values of elastic constants the several polycrystalline parameters such as elastic moduli (B, Y, E), machinability index (μm), hardness (HV), Poisson's ratio, Pugh's and isotropic/anisotropic factor of ACuSb (A = Ca,Sr, Ba) have been calculated and discussed in details. Very high machinability indices of these phases ensure their industrial applications. Since the values of Poisson's and Pugh's are ν < 0.26 and B/G < 0.75, therefore the phases ACuSb (A = Ca,Sr, Ba) show brittle manner. The direction-dependent features of these materials are confirmed from the Universal anisotropy factor analysis. Band structure analysis reveals that every compounds exhibit metallic character. Bond population analysis revealed the different covalent and ionic bonding tendencies in these compounds, with apparent differences in the nature of Cu–Sb bonds. Furthermore, the absorption coefficients of BaCuSb ensures its excellent suitability for solar cell applications, as it demonstrated remarkable UV-range absorption capabilities, distinguishing it from the other compounds in this regard. The thermal analysis demonstrated that these compounds exhibit remarkably low thermal conductivity, indicating their appropriate applications in thermal barrier coating (TBC) materials.

Sb induced effect on glass transition, crystallization kinetics and optical properties of Se96Sn4 alloy

Se96-xSn4Sbx (x = 0, 2, 4, 6, and 8) glassy alloys were prepared using the melt quench technique. Thermal measurements were carried out using differential scanning calorimetry (DSC) in non-isothermal mode. Kissinger and Moynihan methods are used for glass transition kinetics, while Kissinger, Takhor, and Augis-Bennet methods are used to study crystallization kinetics. The inclusion of Sb in the alloy increased the glass transition temperature (Tg), activation energy of the glass transition (Et), and activation energy of crystallisation (Ec). The chemical bond approach has been used to explain the results. The rising trend of Ec is explained by the production of SnSe4/2 structural units with energies greater than those of Se–Se and Se–Sb bonds, increasing the degree of cross-linking. The dimensionality of crystal growth changes from one to two with the addition of Sb to the Se-Sn alloy. The criterion for thermal stability was addressed by using the enthalpy emitted during the crystallization process. In addition, Kubelka-Munk transformation and Tauc plots were used to calculate the band gaps. The energy gap (Eg) decreases from 3.72 to 1.60 eV as the Sb concentration increases from 0 to 8 atm%.

A Distibene with Extremely Long Sb=Sb Distance and Related Heavier Dipnictenes from Salt‐Free Metathesis Reactions

AbstractConversions of organoelement diamides, ArDippE(NMe2)2 (E=Sb, Bi; ArDipp=C6H3‐2,6‐Dipp2), with Ph2SnH2 as reducing agent gave access to low‐valent, heavier group 15 dimers ArDippSb=SbArDipp and ArDippBi=BiArDipp, while only readily removable byproducts (i. e. dihydrogen, amines) and cyclo‐(Ph12Sn6) are generated during the reaction. Moreover, experiments involving the reaction of organoantimony hydride species Ar*2SbH (Ar*=C6H2‐2,6‐(Ph2CH)2‐4‐iPr) with Bi(NEt2)3 yielded a second novel distibene, Ar*Sb=SbAr*, with the currently longest Sb−Sb bond distance of 2.8605(5) Å in a distibene. In conversions of TbbSnH3 (Tbb=C6H2‐2,6‐(CH(SiMe3)2)2‐4‐tBu) with Bi(NEt2)3, ligand migration resulted in the isolation of TbbBi=BiTbb. Remarkably, the herein reported novel inorganic coupling route enables preparation and isolation of heavier dipnictenes without the formation of inorganic salts. All four low‐oxidation state compounds were isolated and subsequently characterized using state of the art techniques, i. e. X‐ray crystallography, NMR and UV/Vis spectroscopy.

Adsorption of Sb(III) and Pb(II) in wastewater by magnetic γ-Fe2O3-loaded sludge biochar: Performance and mechanisms

Magnetically modified carbon-based adsorbent (BC@γ-Fe2O3) was prepared through facile route using activated sludge biomass and evaluated for the simultaneous removal of Sb(III) and Pb(II). BC@γ-Fe2O3 exhibited outstanding Sb(III) and Pb(II) adsorption capacity when 200 mg of adsorbent was employed at pH 5.0 for 240 min, with the removal efficiency higher than 90%. The experiments demonstrated the excellent reusability and the potent anti-interference properties of the prepared absorbent. Freundlich and pseudo-second-order kinetic were prior to describe the adsorption process. The adsorption of Sb(III) and Pb(II) onto BC@γ-Fe2O3 was spontaneous and endothermic. BC@γ-Fe2O3 with high specific surface area revealed the exceptional competence to absorb Sb(III) and Pb(II) through pore filling, electrostatic adsorption and complexation. The adsorption mechanisms of Sb(III) and Pb(II) showed similarities with slight disparities. The removal of Sb(III) involved the Fe–O–Sb bond and π-π bond, while the adsorption of Pb(II) was closely related to ion exchange. Moreover, Sb(III) was oxidized to Sb(V) in a minor part during adsorption. The Fe–O–Cl active sites on BC allowed for the binding of γ-Fe2O3, guaranteeing the abundant adsorption sites and stability. BC@γ-Fe2O3 provides an efficient and green insight into the simultaneous removal of complex heavy metals with promising application in wastewater treatment.

Controllable single phase enables superior thermal stability in Sb-Sn-S films

Sb-Sn-S thin films were prepared by magnetron sputtering, and the effects of the SnS content on the macroscopic performance and microstructure of Sb were investigated. Results show that Sb55(SnS)45 exhibited the best performance, with a crystallization temperature of 210 °C, solving the issue of spontaneous Sb crystallization. However, the thermal stability of Sb37(SnS)63 film could no longer be significantly improved. The investigated crystallization mode revealed that Sb55(SnS)45 exhibited a growth-dominated crystallization behavior, maintaining a high crystallization rate while substantially improving the thermal stability. In terms of the microstructure, high-energy Sb–S and Sb–Sn bonds were formed, breaking the originally unstable Sb–Sb bonds. In the case of Sb37(SnS)63, the internal Sb–S and Sb–Sn bonding environment reached a saturation state, and the excessive introduction of SnS resulted in the stacking arrangement of the Sb–Sn–S amorphous alloy, leading to lattice distortion. However, an appropriate amount of Sb–Sn–S amorphous alloy polymerized around the SbSn grains, limiting the grain growth and the element segregation, thereby enhancing the long-term stability of the phase-change thin film.

Actinide‐Pnictide Chemistry: A Uranium Primary Alkyl Stibinide and a Diuranium Hexaantimonide‐Tetralithium Zintl Cluster

AbstractStructurally characterised U−Sb bonds are rare. Here, the synthesis and characterisation of [U(TrenDMBS){Sb(H)C(H)(SiMe3)2}] (5, TrenDMBS=N(CH2CH2NSiMe2But)3) and [{U(TrenTIPS)}2{Sb3(μ6‐Li)(μ‐Li[THF]2)3Sb3}] (6, TrenTIPS=N(CH2CH2NSiPri3)3) are reported. Complex 5 is an unprecedented primary stibinide actinide complex and 6 can be formulated as containing a unique triple decker 20 skeletal‐electron distorted closo tricapped Zintl cluster (Sb3Li4Sb3)2− that is analogous to the D3h closo tricapped trigonal prism form of [Ge9]2−. Quantum chemical calculations emphasise polar U−Sb bonding in 5 and 6, and that viewing (Sb3Li4Sb3)2− as a single unit rather than two distinct but contiguous (Sb3)3− units, themselves unprecedented in molecular actinide chemistry, is valid due to the presence of three weak (Sb3)⋯(Sb3) (3, −1)‐bond critical points. Complexes 5 and 6 highlight the challenges of preparing polar U−Sb bonds and the underlying tendency for unpredictable cluster formation with Sb.

Abnormally soft acoustic phonons in the Mg3Sb2 allomerisms

Softening modes in phonon dispersion are often indications of intriguing physical phenomena such as phase transition and exotic thermal conductance. The promising thermoelectric material Mg3Sb2 and its allomerisms including CaZn2Sb2, SrZn2Sb2, etc. are investigated for phonon dispersion variation in this study using density functional theory (DFT) calculations. Two different soft transverse acoustic (TA) modes are present in Mg3Sb2, one at the A point along the out-of-plane direction and the other at the in-plane M point with a lower frequency. In contrast, the in-plane TA modes of CaZn2Sb2 and SrZn2Sb2 exhibit much higher in energy, but they both have extremely soft TA modes at the A point instead. Here, we construct an oscillator model based on the projected interatomic force constant tensor along vibrational directions. Our results suggest that the disappearing shear interaction of the near-neighbor bond, tilted Mg–Sb plays a large role in the abnormally soft in-plane TA mode in Mg3Sb2. In contrast, the covalent vertical Zn–Sb bonds in CaZn2Sb2 and SrZn2Sb2 have also negligible shear interactions. In all cases, the “missing” nearest-neighbor interaction, combined with the weak next-neighbor interaction and repulsive long-range interaction result in the observed low-energy TA modes. Soft acoustic phonon is associated with lower thermal conductivity frequently. In general, we expect such in-depth analyses on the origin of these abnormally soft phonon modes in the Mg3Sb2 allomerisms would provide insights into seeking high-performance thermoelectric materials in the rich family of the Zintl phase compounds.

Tuning the Radius Ratio to Enhance Thermoelectric Properties in the Zintl Compounds AM2Sb2 (A = Ba, Sr; M = Zn, Cd)

Five novel Zintl phase solid solutions in the Ba1–xSrxZn2–yCdySb2 (0 ≤ x ≤ 0.13(1); 0 ≤ y ≤ 0.32(2)) system were successfully synthesized by the molten Pb metal-flux method, and the powder X-ray diffraction and single-crystal X-ray diffraction analyses proved that all five title compounds adopted the BaCu2S2-type phase having the orthorhombic Pnma space group (Z = 4, Pearson code oP20) with five crystallographically independent atomic sites. The previously studied BaCu2S2-type antimonides demonstrated a limited tolerance for doping in contrast to the CaAl2Si2-type antimonides. To understand the relatively narrower phase width and limited dopability of the title BaCu2S2-type phase than the CaAl2Si2-type phase in the overall Ba1–xSrxZn2–yCdySb2 system, the radius ratio of cations and anionic elements r+/r– for two structure types were thoroughly investigated. For the first time, the r+/r– ratio was identified as a critical factor for the phase selectivity: (1) r+/r– > 1 favored the BaCu2S2-type phase, and (2) r+/r– < 1 favored the CaAl2Si2-type phase. We also revealed the structural transformation mechanism from the more widely observed CaAl2Si2-type phase to the title BaCu2S2-type phase as the relatively larger cationic elements were introduced to the system. A series of DFT calculations using the three hypothetical models indicated that a resonance peak near EF in the density of states curves was descended from the relatively flat band structure at several special symmetry points rationalizing the enhanced Seebeck coefficients of Ba0.94(1)Sr0.06Zn1.86(3)Cd0.14Sb2 and Ba0.96(1)Sr0.04Zn1.68(2)Cd0.32Sb2. Electron localization function analysis rationalized the correlation between the polarity change of anionic Zn/Cd–Sb bonds and the charge carrier mobility on the anionic frameworks. Temperature-dependent thermoelectric properties were studied for the four title compounds, and the results proved that the Sr and Cd doping in the title Ba1–xSrxZn2–yCdySb2 system successfully enhanced the ZT values through the increased Seebeck coefficients and the reduced total thermal conductivities.

Graphite Carbon-Doped Sb2Te Nanostructures for Phase-Change Memory Applications

High thermal stability, fast operation speed, low thickness variation, and low resistance drift of phase-change nanomaterials are the essential characteristics in phase-change memory (PCM) applications. In this work, we put forward a graphite carbon-doped Sb2Te (C-Sb2Te) chalcogenide with semiconductor process compatibility. Our results prove that the proposed C-Sb2Te has excellent thermal stability and high operation speed. More importantly, the thickness change and resistance drift are only 0.89% and 0.0149, respectively. The C-Sb2Te-based memory device exhibits a high switching speed to the instrument test limit (5 ns) with a large resistance ratio, low operation voltage (2 V), and low power consumption (6.9 pJ). The proposed C-Sb2Te nanostructure material exceeds both conventional Ge2Sb2Te5 and transition-metal-doped Sb2Te materials in terms of its performance. Ab initio molecular dynamics simulations reveal that C–C and C–Sb bonds as well as C–C chains are formed in C-Sb2Te, and C doping constrains phase transition in a small region and refines grains of C-Sb2Te, thus resulting in the high performance. Our study suggests that C-Sb2Te is a potential candidate for high-speed, high-thermal-stability, and high-reliability PCM applications.

Anchoring atomic antimony in an intercalative Mo–S frameworkviasoft covalent bonding for fast-charging and long-lived sodium ion batteries

This work addresses the critical issue of volume expansion of alloy-type Sb anode by dispersing atomic Sb into a robust Mo–S framework via soft Mo–Sb bonds. 60C fast-charging over 10 000 cycles is achieved by utilizing this new Mo2SbS2 anode.

NaCdSb: An Orthorhombic Zintl Phase with Exceptional Intrinsic Thermoelectric Performance

AbstractMany Zintl phases are promising thermoelectric materials owning to their features like narrow band gaps, multiband behaviors, ideal charge transport tunnels, and loosely bound cations. Herein we show a new Zintl phase NaCdSb with exceptional intrinsic thermoelectric performance. Pristine NaCdSb exhibits semiconductor behaviors with an experimental hole concentration of 2.9×1018 cm−3 and a calculated band gap of 0.5 eV. As the temperature increases, the hole concentration rises gradually and approaches its optimal one, leading to a high power factor of 11.56 μW cm−1 K−2 at 673 K. The ultralow thermal conductivity is derived from the small phonon group velocity and short phonon lifetime, ascribed to the structural anharmonicity of Cd−Sb bonds. As a consequence, a maximum zT of 1.3 at 673 K has been achieved without any doping optimization or structural modification, demonstrating that NaCdSb is a remarkable thermoelectric compound with great potential for performance improvement.

NaCdSb: An Orthorhombic Zintl Phase with Exceptional Intrinsic Thermoelectric Performance.

Many Zintl phases are promising thermoelectric materials owning to their features like narrow band gaps, multiband behaviors, ideal charge transport tunnels, and loosely bound cations. Herein we show a new Zintl phase NaCdSb with exceptional intrinsic thermoelectric performance. Pristine NaCdSb exhibits semiconductor behaviors with an experimental hole concentration of 2.9×1018 cm-3 and a calculated band gap of 0.5 eV. As the temperature increases, the hole concentration rises gradually and approaches its optimal one, leading to a high power factor of 11.56 μW cm-1 K-2 at 673 K. The ultralow thermal conductivity is derived from the small phonon group velocity and short phonon lifetime, ascribed to the structural anharmonicity of Cd-Sb bonds. As a consequence, a maximum zT of 1.3 at 673 K has been achieved without any doping optimization or structural modification, demonstrating that NaCdSb is a remarkable thermoelectric compound with great potential for performance improvement.

Highly Efficient and Robust Monolith of a Metal–Organic Framework Hybrid Aerogel for the Removal of Antimony from Water

Antimony contamination is of increasing concern across various environmental media. Removal of antimony from water is a pressing issue, and an associated challenge in the operational treatment of wastewater is developing material of high Sb absorbance efficiency together with facile applicability. This work details, for the first time, a 3D porous hybrid aerogel comprising metal–organic frameworks (MOFs) embedded in the cellulose nanocrystal matrix using a bottom-up approach based on hydrazone cross-linking of hydrazide and aldehyde, specifically designed for removal of Sb(V) from contaminated water. The hybrid aerogel was fabricated, and the resulting product presents a monolithic architecture with a diameter of 2 cm and a super low density of 7.96 mg cm–3. The hybrid aerogel has fast adsorption kinetics, a broad working pH range, strong anti-interference capability, and high selectivity. In particular, the material has an ultrahigh adsorption capacity (575 mg g–1) for Sb(V) that is far superior to other adsorbents. Site energy thermodynamic and mass transfer modeling results demonstrated that the cross-linked celluloses greatly disperse and protect the embedded MOFs so that abundant active Bi–O sites strongly adsorb Sb(V) by forming Bi–O–Sb bonds. Almost complete (97%) removal of Sb(V) from 5 mL of spiked tap water (50 μg L–1) was achieved in 2 min by simple extrusion through a syringe device assembled with blocks of the hybrid aerogel and is well below the maximum contaminant level for Sb(V) of 6 μg L–1 in drinking water. This work paves the way for shaping powder adsorbents into convenient and tailorable free-standing monoliths, and with these features the hybrid aerogel is a promising candidate for practical treatment of Sb(V)-contaminated water.

Biochar microtube interconnected hydrotalcite nanosheets for the adsorption of aqueous Sb(III)

Actuated by the non-ionic heavy metal of antimony (Sb) contaminants with undesired toxicity to the environment and human health, capturing Sb is urgent to remedy contaminated water. Herein, the lamellar MnCo hydrotalcite was grown on catkin-derived biochar through the in situ etching of ZIF-L to construct a hierarchical microtube@nanosheet hybrid (CLMH) for Sb immobilization. The adsorption behaviour and mechanism of trivalent antimony (Sb (III)) on the CLMH were investigated. The CLMH shows good pH applicability for capturing Sb(III) at pH from 2 to 9. The excellent adsorption capacity of CLMH for Sb(III) is 247.62 mg g−1 at 303 K, and the endothermic process is proved by the positive value of Δ (10.54 kJ mol−1). The adsorption process is fitted with the intra-particle diffusion model, which can be described with external mass transfer, intraparticle diffusion in pores, and equilibrium stage. The adsorption mechanism is proved, which includes the bind of Metal–O–Sb bonds by inner-sphere complex, the embedding of Sb in the intercalation of hydrotalcite, redox between Mn and Sb, and functional groups dependent anchoring effect. The work benefits the understanding of the antimony removal behaviour over the hierarchical microtube@nanosheet hybrids.

Role of Oxygen and Fluorine in Passivation of the GaSb(111) Surface Depending on Its Termination

The mechanism of the chemical bonding of oxygen and fluorine on the GaSb(111) surface depending on its termination is studied by the projector augmented-waves method within density functional theory. It is shown that on an unreconstructed (111) surface with a cation termination, the adsorption of fluorine leads to the removal of surface states from the band gap. The binding energy of fluorine on the cation-terminated surface in the most preferable Ga-T position is lower by ~0.4 eV than that of oxygen, but it is significantly lower (by ~0.8 eV) on the anion-terminated surface. We demonstrate that the mechanism of chemical bonding of electronegative adsorbates with the surface has an ionic–covalent character. The covalence of the O–Sb bond is higher than the F–Sb one, and it is higher than both O–Ga and F–Ga bonds. Trends in the change in the electronic structure of the GaSb(111) surface upon adsorption of fluorine and oxygen are discussed. It is found that an increase in the oxygen concentration on the Sb-terminated GaSb(111) surface promotes a decrease in the density of surface states in the band gap.