The most prevalent techniques for synthesizing nanomaterials are the hydrothermal and solvothermal procedures. In contrast to alternative procedures for synthesizing nanostructured materials, the hydrothermal approach offers the benefits of low synthesis temperature and small grain size. This approach may produce a wide range of morphologies, including nanorods (Yu et al., 2020; Jayababu et al., 2021), nanosheets (Lu et al., 2015; Li et al., 2020b), nanowires (Yang et al., 2009; Wan et al., 2011), and nanotubes (Wang et al., 2010). Moreover, in contrast to other synthesis methods, the hydrothermal approach has an excessively high oxygen affinity for positively charged metal and negatively charged Te ions, resulting in the formation of oxides. Reducing agents, such as hydrazine and sodium borohydride, are necessary to avoid oxide impurities in tellurides.

Wang et al. adopted the hydrothermal technique to synthesize Bi₂Te₃ nanotubes with diameters of 100 nm and lengths of 500–1,000 nm by using sodium borohydride as the reducing agent and EDTA as the surfactant (Figure 2A–D) (Wang et al., 2010). Zhang et al. created carbon-encapsulated porous Sb₂Te₃ nanoplates with porous architectures via the hydrothermal and carbonization processes, with carbon shell thicknesses ranging from 50 to 80 nm (Figures 2E–J) (Zhang et al., 2019b). Their approach can successfully produce nanomaterials, such as Ag₂Te (Zhang et al., 2006), Bi₂Te₃ (Wang et al., 2010), CdTe (Gong et al., 2011), Cu₂Te (Zhang et al., 2006), Cu_2-xTe (Jamwal et al., 2016a), HgTe (Salavati-Niasari et al., 2010), NiTe (Zhang et al., 2002), and PbTe (Jamwal et al., 2016b).

Similar advantages can be attained in solvothermal reactions, such as when one or more precursors are dissolved in a non-aqueous solvent. The BiSbTe₃ nanosheets were prepared under solvent-heated conditions by using ethylene glycol as the solvent (Figures 2K–M) (Zhu et al., 2020). The unique nano-plate structure of BiSbTe₃ increases the exposure of the electrolyte, leading to high utilization of the composite electrode material during cycling. In addition, the solvothermal method is also commonly used to prepare other metal tellurides, such as Bi₂Te₃ (Liu et al., 2017a), Cu _x Te (Liu et al., 2017a), PbTe (Liu et al., 2017a), Ag₂Te (Liu et al., 2017a), and Sb₂Te₃ (Yan et al., 2016).

CVD is generally used to create thin film materials. This approach is based on the principle of utilizing gaseous precursor reactants to produce thin films on a substrate by breaking down specific components of the gaseous precursor via atomic and intermolecular chemical interactions (Zhou et al., 2015; Naylor et al., 2016; Zhou et al., 2017b; Yoo et al., 2017). The form and properties of the 2D metal tellurides are influenced by the substrates, precursors, and temperature, among other factors (Zhou et al., 2016; Zhang et al., 2019c; Huang et al., 2019; Kim et al., 2020). CVD method is the most widely used method for the synthesis of tellurides, which has good scalability and can be controlled to prepare large-area films or two-dimensional crystals.

Recently, MoTe₂ has received widespread attention owing to its distinct semiconducting and semi-metallic characteristics. Kong et al. investigated a CVD technique for fabricating uniform high-crystalline 2H and 1T'-MoTe₂ films (Naylor et al., 2016). Various products were created by varying the precursor, carrier gas, and temperature. Under the same conditions, they observed that MoO₃ precursors converted more easily into 2H-MoTe₂, whereas MoO and MoO_x (x < 3) precursors converted more effectively into 1T'-MoTe₂. A year later, Kong et al. improved the preparation process and successfully synthesized large-size homogeneous 1T'-MoTe₂ (Zhou et al., 2016). They further determined the significant effect of the molybdenum precursor on the formation of 1T'-MoTe₂ (Figure 3A–E). 1T'-MoTe₂ was reliably created when MoO₃ was utilized as a precursor. Furthermore, the amount of Te used in the synthesis of 1T'-MoTe₂ had a substantial impact. If the Te supply is sufficient, then 2H-MoTe₂ would be produced; otherwise 1T'-MoTe₂ would be produced (Zhou et al., 2016). The established CVD technique also allowed for the large-scale direct synthesis of WTe₂ and MoTe₂ multilayers and monolayers (Zhou et al., 2017b). The thickness of the WTe₂ and MoTe₂ atomic layers was adjusted using growth time. (Figure 3F–M).

In addition to 2D WTe₂ and MoTe₂, many other 2D transition metal tellurides can be grown via CVD methods. Li et al. reported a method that can precisely control 2H-MoTe defects grown by a large-scale phase-change-assisted CVD process using selective etching of I₃ ⁻ solutions (Zhou et al., 2021). Liu et al. reported a facile CVD method to synthesize Mo_xW_1-xTe₂ with controlled thickness and chemical composition ratios to investigate its design of material devices from a topological quantum state perspective (Chubilleau et al., 2011). Li et al. reported a strategy using mixed molten salts for enhancing the CVD growth of 2D WTe₂ crystals with large grain size and yield, acting as a synergist (Jayababu et al., 2021).

Electrochemical deposition (ECD) is another effective method for obtaining metal tellurides. ECD has the outstanding advantage of easily controlling the morphologies of metal tellurides by using removable templates. Compared with other methods, the ECD method is simple, not limited by grain size and shape, and the prepared crystalline materials have unique properties. Applied electrical potential and deposition rate are two critical parameters of smooth ECD.

Islam et al. suggested an ECD technique for handling bespoke Al₂O₃ (AAO) stencils that neither needed extensive hole branching nor would damage the aluminum substrate(Figure 4) (Wu et al., 2020). CdTe nanotubes have a high aspect ratio of one-dimensional nanostructures compared to other nanostructures and have amplified optical waveguide properties. Therefore, they are designed as visible light responsive photocatalysts. Figure 4A shows that CdTe was electrochemically deposited onto tailored AAO stencils, which has been sheared by utilizing the full AAO to allow for the acquisition of through-hole and self-supporting features on the Al substrate. The CdTe nanotubes developed in the sulfate bath after the barrier layer has been completely removed, as shown in Figure 4B. The image within the red border is a magnified view of the designated section in the red circle, revealing the hollow ends of the vertically aligned nanotubes. This feature implies the significant advantage of the material to provide electrical contact during cathodic deposition because the aluminum base remains intact even after the barrier layer is completely removed. Meanwhile, broaching barrier layer (BBL) was polarized in dilute H₂SO₄, compared to neutral KCl solution and immersion in H₃PO₄ solution, resulting in a totally etched barrier layer that was innocuous to the substrate aluminum.

Choa et al. converted Ag₂Te nanotubes to PbTe nanotubes by changing the silver-to-lead atomic ratio through the combined processes of electrostatic spinning, ECD, and cation exchange (Figures 5A–F) (Deshagani et al., 2020). Silver atoms were diffused into the Te layer and transformed into Ag₂Te nanofibers by ECD using silver nanofibers synthesized by electrostatic spinning as the starting material. Then, the crystalline transition of Ag_xTe_y to PbTe nanocomposites was controlled by the cation exchange from Ag⁺ cations to Pb²⁺ cations.

In addition to the abovementioned three methods, many other chemical routes can be used to extensively investigate the synthesis of metal telluride nanomaterials. Examples are microwave synthesis (Ye et al., 2019), spray pyrolysis (Chen et al., 2019), biosynthesis (Poulose et al., 2016), and laser ablation techniques (Jayababu and Kim, 2021). A good method allows for the accurate control of certain features, including spatial structure and distribution, which significantly impact the performance of electrode materials. Kang et al. investigated anode materials for potassium ion batteries using spray pyrolysis to make cobalt telluride-C (CoTe₂-C) composite microspheres, as shown in Figure 5G, (Yang et al., 2020). As Te needed to be directly embedded into the composite microspheres, a simple one-step post-treatment technique was used to prepare CoTe₂-C composite microspheres. Their approach could be explained by Ostwald maturation induced by the formation of the CoTe₂ crystals.

Telluride has a substantially greater electrical conductivity and is projected to perform better electrochemically compared with other materials, leading to the widespread research and advancement of metal tellurides built into diverse nanostructures for supercapacitor (SC) applications (Liu et al., 2017b; Rathore et al., 2022). Kim et al. created silver-decorated NiFe alloy telluride nanorods (AMMT HNRs) on nickel foam (NF) (Figure 6A) (Jayababu et al., 2021). The robust electroactivity of the NiFe alloy, the high conductivity of Te and Ag, and the porous layered structure of the telluride all contributed to the AMMT HNRs/NF electrode’s outstanding electrochemical performance. The electrode exhibited a stability of 80.4% over 3,000 cycles. After employing AMMT HNRs/NF and carbon-coated NF as positive and negative electrodes, respectively, and cellulose membranes as separators, high areal energy and power densities were reported in hybrid supercapacitors. (Figure 6B).

NiTe, as an SC electrode material, has also attracted the interest of scientists (Park et al., 2018; Song et al., 2021; Yu et al., 2021). The NiTe achieved outstanding electrochemical performance as a coexisting pseudo capacitive material for NiS reported by Wu et al. (Chen et al., 2019). As shown in Figure 6D, four electrochemical reactions occurred on the NiS/NiTe/Ni (NST) electrode. During charging, the volume increased from the inner layer to the outer layer; during discharge, the volume was reduced from the outer layer to the inner layer. The NST was the positive electrode of the asymmetric SC, whereas the active carbon (AC) was the negative electrode. The high capacitance retention and ultra-long cycle life (200000 cycles, Figure 6E) demonstrated the important role of the synergistic structure to structural stability. Additionally, CoTe₂ (Manikandan et al., 2020), CuCoTe (Fu and Lee, 2019), VTe₂ (Ahmad et al., 2021), and MoTe₂ (Jin et al., 2018) have been widely used as electrode materials for high-performance capacitors.

Metal tellurides have emerged as the most feasible alternative for cutting-edge ion battery anode materials because to their layered crystal structure, high intrinsic conductivity, and high trap density (Zhu et al., 2020; Guo et al., 2021; Hassan et al., 2021). Kang et al. used a structurally distinct FeTe₂ and carbon nanocomposite as anode material for potassium ion batteries (Figure 7) (Park and Kang, 2020). The hollow carbon nanospheres that housed the iron telluride nanocrystals (FeTe₂-C) offered enough space to accommodate for the nanocrystals’ enormous volume variations during charging and discharging. During cycling, nanocrystal extrusion within the solid hollow carbon nanospheres was controlled, and no FeTe₂ from the electrode were lost, showing strong structural integrity (Park and Kang, 2020). Kang et al. also investigated the reaction mechanism of the CoTe₂-C composite microsphere as an anode material for potassium ion batteries and the related potassium ion conversion. Where the mechanism of the CoTe₂ phase transition reaction can be expressed as: 2 C o T e 2 + 7 K + 7 e − → 2 C o + K 5 T e 3 + K 2 T e   2 C o + K 5 T e 3 + K 2 T e ↔ 2 C o T e + 2 T e + 7 K + 7 e −  

The surface-driven reactions during rapid potassiumization/depotassiumization significantly promote the charge storage of CoTe₂-C in potassium ion cells, leading to excellent rate performance. And the high contribution of the capacitance-controlled behavior of CoTe₂-C indicates its good multiplicative performance. At a current density of 0.5 A g⁻¹, the CoTe₂-C composite has a 100th cycle discharge capacity of 189.5 mAh g⁻¹ (Chen et al., 2019). In addition, Kim et al. (Fu and Lee, 2019) investigated a CuCo LDHs-coated CuCoTe honeycomb nanosheet as anode for hybrid SCs. They demonstrated the material’s excellent electrochemical performance and high stability (Chen et al., 2019).

Depicted as 2D materials, tellurides have also been recently described as electrocatalytically active materials with low cost and strong catalytic activity (Luxa et al., 2017; Han et al., 2020). Nath et al. used hydrothermal and electrodeposition methods to create 5 and 8 nm-thick Ni₃Te₂ films (De Silva et al., 2018). Voltammetric cycling and linear sweep voltammetry were used to examine the OER catalytic activity of the as-synthesized materials in the alkaline electrolytes. Their results showed that Ni₃Te₂ films have a high catalytic efficiency of 10 mA cm⁻² with a notably low overpotential of 180 mV. The overpotential value was much lower than that needed for nanostructured Ni₃Se₂ (190 mV) (Xu et al., 2019) and Ni₃S₂ (260 mV) (Li et al., 2022). Nanodendritic MoTe₂ was used as an electrocatalyst for hydrogen precipitation reaction (Zhou et al., 2017a). Nanodendrimers were created electrochemically on Mo-doped reduced polyimide/graphene oxide composite substrates. The deposition period increased the size of the nanodendrites. Their findings further showed that nanodendrimers have the potential to be good catalysts for hydrogen precipitation in neutral fluids. Ashiq et al. proposed a highly active Cu₇Te₄ nanowire synthesized through water oxidation as an electrocatalyst for water oxidation reaction (Zhang et al., 2022). Chu et al. demonstrated the ability of FeTe₂ to function as an efficient and durable nitrogen reduction electrocatalyst, with an excellent combination of NH₃ yield and Faraday efficiency (Yao et al., 2022). Metal telluride materials, such as Sb₂Te₃ (He et al., 2022), MoTe₂[99], Ni₃Te₂-CoTe[100], and NiTe-HfTe₂[101], have received extensive attention for their potential application in electrocatalysis.

Because of its low cost, environmental friendliness, and high energy density, Li-S batteries are appealing next-generation energy storage technologies. Meanwhile, owing to the intrinsic 2D structure of telluride, it offers an interesting function in Li-S batteries (Wang et al., 2019; Guo et al., 2021; Hassan et al., 2021).

Xie et al. examined diphenyl ditelluride (DPDTe) as bifunctional electrolyte additive for high-efficiency sulfur cathodes and dendrite-free lithium anodes[102]. As shown in Figures 8A–E, the presence of DPDTe enables catalytic mediation by Te radicals, which is accountable for substantially enhancing LIPS redox dynamics and regulating Li₂S accumulation. DPDTe can also combine with metallic lithium to generate a uniform, dense, and stable organic–inorganic hybrid SEI to minimize the nucleation overpotential of lithium and promote uniform lithium deposition, thereby successfully limiting the formation of lithium dendrites. The addition of DPDTe can improve sulfur usage and lead to highly reversible lithium stripping/plating, further resulting in good rate capability (611.4 mAh g⁻¹ at 5C) of Li-S batteries.

Zhan et al. explored a phosphorus-doped nickel Te electrocatalyst (P⊂NiTe_2-x) grown on carbon-based (MSC) as a functional layer for high-performance Li-S battery separators (MSC/P⊂NiTe_2-x)[103]. The increased electrochemical performance implies that the P doping of Te vacancies can enhance Li-S battery conductivity, boost adsorption, and decrease the redox energy barrier of Li-S batteries. MSC nanosheets enable NiTe₂ nanoparticles to disperse and diffuse Li⁺. Ex-situ X-ray absorption spectroscopy and in-situ Raman spectroscopy both demonstrated the ability of MSC/P⊂NiTe_2-x to inhibit the shuttle effect and accelerate the redox conversion (Figures 8F–J). Compounding telluride materials in the electrode[91, 104], electrolyte, and diaphragm coatings has become one of the important strategies of breaking through the severe shuttle effect of Li-S batteries.