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[Display omitted] Designing novel rare-earth-transition metal composites is at the forefront of electrocatalyst research. However, the modulation of transition metal electronic structures by rare earths to induce vacancy defects and enhance electrochemical performance has rarely been reported. In this study, we systematically investigate the mechanism by which Ce-4f electron modulation weakens the Fe-O bond, thereby altering the electronic structure in CeFevNi hydroxide to improve oxygen evolution reaction (OER) performance. Theoretical calculations and experimental characterizations reveal that Ce-4f orbitals function as electron-modulation reservoirs, capable not only of retaining or donating electrons but also of influencing the material's electronic structure. Moreover, Ce-4f bands optimize the Fe lower Hubbard bands (LHB) and O-2p bands, leading to weakened Fe-O bonds and the formation of cationic vacancies. This change results in the upshift of the d-band center at the active sites, favoring the reaction energy barrier for oxygen intermediates in the OER process. The synthesized catalyst demonstrated an overpotential of 201 mV at 10 mA cm−2 and a lifetime exceeding 200 h at 100 mA cm−2 under alkaline conditions. This work offers a proof-of-concept for the application of the mechanism of rare earth-induced transition metal vacancy defects, providing a general guideline for the design and development of novel highly efficient catalysts. [ABSTRACT FROM AUTHOR]

5-Hydroxymethylfurfural (HMF), serving as a versatile platform compound bridging biomass resource and the fine chemicals industry, holds significant importance in biomass conversion processes. The electrooxidation of HMF plays a crucial role in yielding the valuable product (2,5-furandicarboxylic acid), which finds important applications in antimicrobial agents, pharmaceutical intermediates, polyester synthesis, and so on. Defect engineering stands as one of the most effective strategies for precisely synthesizing electrocatalytic materials, which could tune the electronic structure and coordination environment, and further altering the adsorption energy of HMF intermediate species, consequently increasing the kinetics of HMF electrooxidation. Thereinto, the most routine and effective defect are the anionic vacancies and cationic vacancies. In this concise review, the catalytic reaction mechanism for selective HMF oxidation is first elucidated, with a focus on the synthesis strategies involving both anionic and cationic vacancies. Recent advancements in various catalytic oxidation systems for HMF are summarized and synthesized from this perspective. Finally, the future research prospects for selective HMF oxidation are discussed. [ABSTRACT FROM AUTHOR]

The development of dimensionally stable anodes (DSAs) has made the chlorine evolution reaction (CER) the most important industrial anode reaction since the 1960s. However, the preparation of DSA depends on the extensive use of precious metals, Ru and Ir, which are expensive and scarce. Herein, a cationic defect adsorption–oxidation anchoring strategy to immobilize oxidized sub‐nano ruthenium clusters on 2D low‐crystallinity titanium oxide (2D TiOx) substrate is reported. Through the metal oxide−support interaction, the 2D TiOx alters the electronic structure of ruthenium oxide (RuOx), improving its activity, selectivity, and stability for CER. Specifically, the mass activity of the RuOx/2D TiOx electrode is 26.5 and 143.5 times higher than that of the state‐of‐the‐art commercial RuO2 and DSA, respectively, at an overpotential of 100 mV. Moreover, the selectivity of the RuOx/2D TiOx electrode to CER is approximately 96.5%, and it exhibits remarkable durability lasting for over 210 h. Therefore, the 2D TiOx substrate holds significant potential for improving the dispersion, active site density, and atomic utilization of oxidized sub‐nano noble metal clusters. [ABSTRACT FROM AUTHOR]

5-Hydroxymethylfurfural (HMF), serving as a versatile platform compound bridging biomass resource and the fine chemicals industry, holds significant importance in biomass conversion processes. The electrooxidation of HMF plays a crucial role in yielding the valuable product (2,5-furandicarboxylic acid), which finds important applications in antimicrobial agents, pharmaceutical intermediates, polyester synthesis, and so on. Defect engineering stands as one of the most effective strategies for precisely synthesizing electrocatalytic materials, which could tune the electronic structure and coordination environment, and further altering the adsorption energy of HMF intermediate species, consequently increasing the kinetics of HMF electrooxidation. Thereinto, the most routine and effective defect are the anionic vacancies and cationic vacancies. In this concise review, the catalytic reaction mechanism for selective HMF oxidation is first elucidated, with a focus on the synthesis strategies involving both anionic and cationic vacancies. Recent advancements in various catalytic oxidation systems for HMF are summarized and synthesized from this perspective. Finally, the future research prospects for selective HMF oxidation are discussed.

[Display omitted] Transition metal phosphides are highly efficient catalysts that do not rely on noble metals, which have shown great potential in replacing noble metal catalysts and contributing to the advancement of the electrocatalytic hydrogen production industry. To further enhance the catalytic performance of transition metal phosphides, researchers have discovered that cationic vacancy defects can be utilized to regulate their electronic structure, thereby improving their catalytic properties. In this research, we present the successful synthesis of a bifunctional Ni 2 P electrocatalyst (V Fe -Ni 2 P) with cationic vacancy defects through electrodeposition and acid etching techniques. The introduction of cationic vacancies after acid etching is confirmed by electron paramagnetic resonance (EPR) spectroscopy. The V Fe -Ni 2 P electrocatalyst demonstrates excellent catalytic performance in alkaline environments, achieving a current density of 10 mA∙cm−2 at an overpotential of 52 mV for the hydrogen evolution reaction (HER), and the same current density with an overpotential of 154 mV for the oxygen evolution reaction (OER). Additionally, the V Fe -Ni 2 P/NF electrode exhibits remarkable stability over 1000 cyclic voltammetric cycles for both HER and OER. This study presents a novel approach for the synthesis and performance control of highly-efficient transition metal phosphide electrocatalysts, which holds significant importance in the development and design of new energy materials. [ABSTRACT FROM AUTHOR]

The development of dimensionally stable anodes (DSAs) has made the chlorine evolution reaction (CER) the most important industrial anode reaction since the 1960s. However, the preparation of DSA depends on the extensive use of precious metals, Ru and Ir, which are expensive and scarce. Herein, a cationic defect adsorption–oxidation anchoring strategy to immobilize oxidized sub‐nano ruthenium clusters on 2D low‐crystallinity titanium oxide (2D TiOx) substrate is reported. Through the metal oxide−support interaction, the 2D TiOx alters the electronic structure of ruthenium oxide (RuOx), improving its activity, selectivity, and stability for CER. Specifically, the mass activity of the RuOx/2D TiOx electrode is 26.5 and 143.5 times higher than that of the state‐of‐the‐art commercial RuO2 and DSA, respectively, at an overpotential of 100 mV. Moreover, the selectivity of the RuOx/2D TiOx electrode to CER is approximately 96.5%, and it exhibits remarkable durability lasting for over 210 h. Therefore, the 2D TiOx substrate holds significant potential for improving the dispersion, active site density, and atomic utilization of oxidized sub‐nano noble metal clusters.

The inclusion of La-Mn vacancies in LaMnO3 nanoparticles leads to a noticeable change in conductivity behavior. The sample retains its overall insulator characteristic, with a typical thermal activation mechanism at high temperatures, but it presents high magnetoconductivity below 200 K. The activation energy decreases linearly with the square of the reduced magnetization and vanishes when the sample is magnetized at saturation. Therefore, it turns out that electron hopping between Mn3+ and Mn4+ largely contributes to the conductivity below the Curie temperature. The influence of the applied magnetic field on conductivity also supports the hypothesis of hopping contribution, and the electric behavior can be explained as being due to an increase in the hopping probability via spin alignment. [ABSTRACT FROM AUTHOR]

Nickel Oxide (NiO) thin films were deposited over glass and FTO substrates using nebulizer spray pyrolysis technique. The influence of various annealing temperatures (400, 450, 500 and 550 °C) on film stoichiometry and its subsequent effect on physical and electrochromic properties were studied. Structural information, chemical state and change in morphological properties of the deposited films concerning the film stoichiometry and concentration of cationic vacancy (VNi) induced Ni3+ ions are discussed with the help of XRD, XPS, HR-SEM, EDS and AFM. The variation of optical parameters associated with the presence of defects in NiO is reported from UV-Vis spectroscopic analysis. Electrochromic performance of the prepared films was evaluated using cyclic-voltammetry, chronoamperometry, chronocoulometry and iono-optical electrochemical measurements. Enhanced electrochromic behavior with a rapid switching response time of 0.3/0.5 s of bleached/colored states respectively was realized for NiO film with relatively higher concentration of Ni3+. [ABSTRACT FROM AUTHOR]

Rational design and preparation of single‐atom catalysts provide a promising strategy to significantly improve the electrocatalytic activity for water splitting. In particular, single atoms anchored at cationic vacancies can enhance the stability of the catalysts and improve reaction kinetics. In this work, Pt single atoms are loaded at layered α‐Ni2/3Fe1/3(OH)2 by oxidizing Fe2+ with H2PtCl6, and specifically, Pt atoms are anchored at in situ generated iron cationic vacancies during the process, resulting in stabilized Pt single atoms in the surface of α‐Ni2/3Fe1/3(OH)2 with the maximum loading of ≈6.15 wt%. The Pt single atoms not only act as active sites for hydrogen evolution reaction but also regulate the electronic structure of NiFe hydroxides and activate Ni atoms adjacent to Pt for oxygen evolution reaction. Therefore, the water‐splitting electrolyzer assembled with such a bifunctional catalyst shows a smaller overpotential than that with RuO2 and 20 wt% Pt/C catalysts as the anode and cathode, respectively, and efficient solar‐to‐hydrogen conversion. The results demonstrate the practical application of single‐atom Pt catalysts with low cost, large loading, and facile preparation route. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel self-supported Ni 3 S 2 -V Ni /NF catalyst with Ni vacancies was reported. • The XAFS and EPR analysis demonstrate the formation of Ni vacancies. • Ni 3 S 2 -V Ni /NF exhibits an excellent alkaline HER activity that outperforms Pt/C. • DFT uncovers that Ni vacancies could promote the water dissociation kinetics. Developing cost-effective non-precious electrocatalysts with excellent HER performance in alkaline media is of significance for industrial hydrogen production. Herein, we successfully endow Ni 3 S 2 with unprecedentedly enhanced alkaline HER activities by introducing nickel vacancies. The Ni 3 S 2 catalyst with nickel vacancies exhibits an ultralow overpotential of 35 mV at 10 mA cm−2 in 1 M KOH electrolyte, outperforming commercial Pt/C (56 mV) and most reported non-precious electrocatalysts. The electron paramagnetic resonance and X-ray absorption fine structure etc. validates the formation of Ni vacancies and the change of the geometric/electronic structure of Ni 3 S 2. Additionally, the theoretical calculations reveal that the Ni sites with higher valence state neighbouring the Ni vacancies can promote the water dissociation, playing a vital role in accelerating HER kinetics in alkaline media. This work may provide a universal strategy to enhance the HER activity of transition-metal compound catalysts in alkaline media by means of cationic defect engineering. [ABSTRACT FROM AUTHOR]

The inclusion of La-Mn vacancies in LaMnO3 nanoparticles leads to a noticeable change in conductivity behavior. The sample retains its overall insulator characteristic, with a typical thermal activation mechanism at high temperatures, but it presents high magnetoconductivity below 200 K. The activation energy decreases linearly with the square of the reduced magnetization and vanishes when the sample is magnetized at saturation. Therefore, it turns out that electron hopping between Mn3+ and Mn4+ largely contributes to the conductivity below the Curie temperature. The influence of the applied magnetic field on conductivity also supports the hypothesis of hopping contribution, and the electric behavior can be explained as being due to an increase in the hopping probability via spin alignment.

Defect engineering offers a powerful approach to tune the local surface microstructure, electron band structure and chemistry of photo- and electro-catalysts, to thereby enhancing their performance in nitrogen reduction reaction (NRR) and electrocatalytic nitrate reduction to ammonia (NO 3 -RR). The present study has successfully synthesized cobalt-rich vacancy (V Co) Co 3 O 4 through a two-step method, allowing for controlled manipulation of the concentration of cobalt vacancies through heat treatment. The impact of varying concentrations of cobalt vacancies on the performance of photocatalytic nitrogen reduction reaction and electrocatalytic nitrate ammonia production was investigated. Remarkably, the catalysts heat-treated at 500 °C, exhibited a significantly enhanced photocatalytic nitrogen fixation performance with a rate of 67.5 μmol·g-1·h-1. The catalysts heat-treated at 300 °C, exhibited an ammonia yield of 339.05 mmol·g-1·h-1 at -1.1 V (vs. RHE), while achieving a maximum Faraday efficiency of 84.3 % at -0.9 V (vs. RHE). The enhanced activity can be attributed to the presence of cobalt vacancies, which synergistically modulate both the structural and electronic properties. This dual functionality of cobalt-rich vacancy Co 3 O 4 not only underscores its potential as a highly efficient photocatalyst for NRR and an electrocatalyst for NO 3 -RR but also highlights the intricate interplay between defect engineering, microstructural tuning, and electronic structure in promoting diverse catalytic activities. Our findings not only advance the fundamental understanding of defect-induced enhancements but also pave the way for the rational design of multifunctional catalysts capable of excelling in both photo- and electro-catalytic applications. [Display omitted] • The photocatalytic nitrogen fixation performance is influenced by the modulation of cationic vacancies. • Nitrogen was adsorbed on sites in Co vacancies of Co 3 O 4. • Cationic vacancies within Co 3 O 4 act as electron traps, facilitating nitrogen reduction. [ABSTRACT FROM AUTHOR]

Vacancy engineering is one of the most effective strategies to introduce defects for improving electrocatalytic activities of cobalt oxides. Recent intensive research has been conducted to introduce oxygen vacancies for boosting Li–O2 battery performance. However, it is difficult to examine the efficiency of cationic vacancies due to their complicated preparation. Herein, a feasible method is demonstrated to introduce cationic vacancies into cobalt oxides via the thermal treatment of glycerolatocobalt (GlyCo) nanostructure. The formation of GlyCo composed of the repeating CoOCoO units provides the possibility to regulate the ratio between cobalt and oxygen, thus cobalt vacancies in cobalt oxides can be easily created by the thermal treatment. The presence of cobalt vacancies enables the regulation of electronic structure and charge‐transport properties of cobalt oxides with abundant defects on the basis of the experimental results and theoretical calculations, thus improving electrocatalytic activities. Therefore, the Li–O2 battery delivers superior electrochemical performance with large specific capacities of 13 331/12 040 mAh g−1, low overpotentials for the oxygen evolution reaction/oxygen reduction reaction of 1.15/0.23 V and good cycling stability. This work provides a favorable method to create metal vacancies for improving catalytic efficiency of advanced energy materials. [ABSTRACT FROM AUTHOR]

• Design defective NiCoP@NiCo-LDH heterostructured electrode material with cationic vacancies. • Ni and Co vacancies and heterostructure cooperate to facilitates charge redistribution. • 3D microspheres structure can facilitate rapid electron transfer and electrolyte transport. • A high energy density of 94.44 Wh kg−1 was attained at a power density of 850 W kg−1. • DFT elucidates the mechanism of charge transport and storage at the heterointerface as well as the bimetallic vacancy. For hybrid supercapacitors, electrode materials possessing rational cation vacancy heterostructures are crucial in enhancing energy density and conductivity. Herein, we propose a facile strategy to synthesize defective NiCoP@NiCo-LDH (v-NPC-LDH) heterostructures with nanosheets-covered microspheres by two-step electrodeposition, and N-methylpyrrolidone solvent heat treatment. In combination with electrochemical tests and density functional theory (DFT), which clarifies that the charge redistribution generated at the heterogeneous interface facilitates charge transport. In particular, the presence of nickel and cobalt vacancies greatly increases the intrinsic electronic conductivity of NiCo-LDH and promotes the charge storage process. In a three-electrode system, the v-NPC-LDH electrode displays a conspicuously great specific charge of 1110 C g−1, and the specific capacity of v-NPC-LDH electrode material is 85.4 % after 10,000 cycles at 20 A g−1. In addition, the hybrid supercapacitor v-NPC-LDH//AC achieves a high energy density (94.44 Wh kg−1) at a power density of 850 W kg−1. Specifically, two series-connected v-NPC-LDH//AC HSCs can light up LED lamps for 10 min, which indicates their potential application. [Display omitted] [ABSTRACT FROM AUTHOR]

To enhance photoelectrochemical (PEC) water splitting for renewable energy conversion, the conventional strategy is doping nonmetals into anionic vacancies. Compared to anionic vacancies, cationic vacancies are theoretically more effective and reliable for anchoring nonmetals owing to their larger radii and unique advantages. The current research mainly focuses on anionic vacancies, while there are few studies on cationic vacancies due to high formation energy and challenging characterizations by convenient techniques. To overcome the current limitations, nonmetallic S and P atoms are successfully doped into cationic vacancies on the TiO 2 surface for tuning local electronic structures. In contrast to the traditional strategy of reducing the bandgaps, nonmetallic atom doping into cationic vacancies facilitates efficient electronic regulation for PEC enhancement without changing the bandgap. The enhanced performance is attributed to the formation of an oxygen bridge, which can accumulate electrons from surrounding S/P atoms. Significantly, the electron-enriched oxygen bridge efficiently transfers electrons to activate reaction site Ti, which can promote the oxygen evolution reaction performance. Density functional theory calculations reveal that the decrease of reaction energy barriers and the optimization of local electron distribution are conducive to electronic transmission. This would provide a high-efficiency electronic tuning strategy for improving PEC performance.

Mesocrystal MnO cubes consisted of nanocrystals (~16 nm) with percolated nanopores (~10.5 nm) and a porosity of 45% were synthesized through polyvinyl alcohol (PVA) assisted hydrothermal growth and homoepitaxial aggregation. The resulting MnO crystal makes up of appreciable amount of Mn 3+ , ~11.8%, ascribed to incomplete reduction during the hydrothermal growth, and the presence of such an appreciable amount of Mn 3+ is thought to lead to the enhancement of Li ion diffusion coefficient from 6.96×10 −14 cm 2 /s to 3.33×10 −13 cm 2 /s. Carbon coating derived from polyvinyl alcohol and homoepitaxial connection of nanocrystals provides excellent charge and mass transfer pathways. Such mesocrystal MnO cubes enhanced the contact of electrolyte and electrode materials, at the same time the active nanocrystals with trivalent manganese ions and cationic vacancies would promote the conversion reaction for lithium-ion insertion and extraction, leading to a high capacity of 637 mA h/g at 100 mA/g in a relatively smaller voltage range of 0.05–2.50 V, as compared with a voltage window of 0.01–3 V used by other research groups. The high voltage (4 V) Li-ion capacitor, a full cell with mesocrystal MnO cubes as anode and activated carbon as cathode, demonstrated excellent cycling performance with the degradation rate of 0.002% per cycle, and the achieved maximum energy in full capacitor reached 227 W h kg −1 that calculated on the total weight of the active materials in both electrodes. [ABSTRACT FROM AUTHOR]

La 2 Ti 2 O 7 ceramic samples were prepared via conventional solid-state reaction route. The dielectric properties of La 2 Ti 2 O 7 were investigated as functions of temperature (113–1073 K) and frequency (100 Hz–1 MHz). Our results revealed that La 2 Ti 2 O 7 ceramics exhibit intrinsic dielectric response with a dielectric constant of ∼57 in the temperature range below 250 K. Three thermally activated dielectric relaxations were observed when the temperature higher than 250 K. The low-temperature relaxations R1 with the activation energy of 0.38 eV is found to be a polaron relaxation results from hopping holes. The high-temperature relaxations R2 and R3 are related to the conduction progress associated with the singly and doubly ionized oxygen vacancies, respectively. [ABSTRACT FROM AUTHOR]

This work is presented to evaluate the influence of titanium dopant on the various properties of barium ferrite nanoparticles (BaFe 2 O 4). Ba 1−x Ti x Fe 2 O 4+δ with x varying from 0.0 to 1.0 were prepared by chemical technique. The titanium doping results in creation of cationic vacancies with the increased surface area. The crystalline size was decreased with the enhanced Ti4+ doping process. The saturation magnetization was decreased with the increased Ti4+ content. Photocatalytic properties of un-doped and doped BaFe 2 O 4 was investigated for alizarin yellow (AY) dye. The Ba 0.3 Ti 0.7 Fe 2 O 4.7 nanoparticles act as the best photocatalyst with the degradation potential (100.0 %). The enhanced photocatalytic amount was obtained due to the narrowing of band gap of Ba 0.3 Ti 0.7 Fe 2 O 4.7 (2.07 eV). The stability and reusability test shows that the amount of degradation was negligibly decreased after 5th cycles. Thus, the Ti4+ doped barium ferrite proved to be great method in modifying the photocatalytic response in the degradation process. Antibacterial analysis depicts that the high content of Ti4+ doped barium ferrite showed higher antibacterial properties against Staphylococcus aureus and Helicobacter pylori. [Display omitted] [ABSTRACT FROM AUTHOR]

Using Faraday Method of magnetic scale, it was found that magnetic pyrrhotites are formed during roasting of pyrite. When temperature increases up to 220°, magnetic permeability of pyrrhotites, Fe0.855S, Fe0.888S and Fe0.909S, dramatically increase, then falls to zero when temperature is increased further to 310–320°. At temperatures above 570°, an abrupt drop of magnetic permeability is observed, followed by consistent increases in magnetic permeability until reaching its peak at Fe0.855S = 3.75; Fe0.888S = 5.43; Fe0.909S = 2.18 SI unit at 700–800°. Electro-kinetic potentials of pyrrhotites increase with pH rising from pH 5 to 13, and decrease with reduction of the sulfur content from 52.1 mV for Fe0.85S to 40.8 mV for Fe0.89S. [ABSTRACT FROM PUBLISHER]

The conductivity of rubidium nitrate doped with barium nitrate in studied aimed at inserting cationic vacancies into the rubidium nitrate lattice. The conductivity of the RbNO-II phase is shown to increase in proportion with the dopant concentration, which points to the formation of solid solutions and the increase in the concentration of cationic vacancies. The solubility of barium nitrate in phases RbNO-III and IV is low; hence, the conductivity of these phases is virtually independent of the dopant content. The insignificant increase in conductivity of phase IV in the sample containing the high concentration of barium nitrate (1 mol %) is probably associated with the effect of the heterogeneous Ba(NO). [ABSTRACT FROM AUTHOR]

Abstract: The bimolecular ketonization of 1-butanol by lanthanum manganite perovskite of different La/Mn stoichiometry is reported. A quite high catalytic activity at relatively low temperature (∼320°C) is found for La-deficient composition (La/Mn=0.91). The property found is likely attributed to high concentration of the active centers (deep La-site deficiency of the catalyst''s rhombohedral structure form) and to high concentration of the oxidant, i.e., Mn ions of comparatively high valence (V Mn), present in fully occupied Mn-sublattice. All these factors, additionally reinforced by the highest temperature and V Mn variation stability of the catalyst (∼1100°C, 3.4≤×ΔV Mn ≤3.17), ensure its the highest catalytic activity among the other compositions available. [Copyright &y& Elsevier]

Cationic defect engineering is an effective strategy to optimize the electronic structure of active sites and boost the oxygen electrode reactions in lithium-oxygen batteries (LOBs). Herein, Ni-Fe layered double oxides enriched with cationic nickel vacancies (Ni-Fe LDO-V Ni ) are first designed and studied as the electrocatalysts for LOBs. Based on the density functional theory calculation, the existence of nickel vacancy in Ni-Fe LDO-V Ni significantly improves its intrinsic affinity toward intermediates, thereby fundamentally optimizing the formation and decomposition pathway of Li 2 O 2 . In addition, the number of e g electrons on each nickel site is 1.19 for Ni-Fe LDO-V Ni , which is much closer to 1 than 1.49 for Ni-Fe LDO. The near-unity occupation of e g orbital enhances the covalency of transition metal-oxygen bonds and thus improves the electrocatalytic activity of Ni-Fe LDO-V Ni toward oxygen electrode reactions. The experimental results show that the LOBs with Ni-Fe LDO-V Ni electrode deliver low overpotentials of 0.11/0.29 V during the oxygen reduction reaction/oxygen evolution reaction, respectively, large specific capacities of 13 933 mA h g -1 and superior cycling stability of over 826 h. This study provides a novel approach to optimize the electrocatalytic activity of LDO through reasonable defect engineering., (© 2021 Wiley-VCH GmbH.)

The high carrier mobility and narrow band gap underpin the thermoelectric promise of InSb. However, the simple crystal structure, susceptibility of carrier mobility to crystallographic defects, and intrinsically high lattice thermal conductivity are hindrances. Here, we reported an approach that combines isoelectronic substitution and vacancies. First, we iso-electronically substituted In with Ga. We found that more Ga than previously thought could be doped in InSb at the expense of forming secondary phase. The analysis by the Abeles model indicated that strain field fluctuations are the dominant mechanism in phonon scattering. A ZT max of 0.57 at 780 K was obtained in the sample of In 0.6 Ga 0.4 Sb. Next, we implemented cationic vacancies via Te doping to regulate the carrier concentration and carrier mobility. We found the Te doping suppresses the phase separation. The analysis of Callaway model helped identify the specific contribution of various phonon scattering mechanisms. A ZT max of 0.4 at 780 K was obtained in the sample of In 0.85 Ga 0.15 Sb. Finally, we introduced anionic vacancies via excess In. We found that the anion vacancies increased the carrier concentration and suppressed the bipolar effect. A ZT max of 0.59 at 780 K was obtained in In 0.87 Ga 0.15 Sb. The Ga substitution combined with vacancies led to a significant reduction of lattice thermal conductivity of InSb over a wide temperature range. The analysis by the Callaway model showed strain field fluctuations play a crucial role in scattering phonons. Image 1 • (In,Ga)Sb solid solutions were prepared by B 2 O 3 flux method. • Cationic vacancies significantly reduce the lattice thermal conductivity. • Strain field fluctuation was markedly enhanced by cationic vacancies. • Anionic vacancies effectively depress the bipolar effect. • A ZT max of 0.59 at 780 K was obtained in In 0.87 Ga 0.15 Sb. [ABSTRACT FROM AUTHOR]