The ternary chalcogenide AgBiS2has attracted widespread attention in the field of photovoltaic and photoelectric devices due to its excellent properties. In this study, AgBiS2powders with an average diameter of 200 nm were prepared via a simple and convenient reflux method from silver acetate, bismuth nitrate pentahydrate, and n-dodecyl mercaptan. The adjustment of the ratios of Ag:Bi:S raw materials and of the reaction temperatures were carried out to investigate the significance of the synthesis conditions toward the composition of the as-synthesized AgBiS2. The results of XRD indicated that the powders synthesized at a ratio of 1.05:1:2.1 and a synthesis temperature of 225 °C have the lowest bismuth content and the highest purity. The synthesized AgBiS2crystallizes in a rock salt type structure with the cubicFm3¯mspace group. Scanning and transmission electron microscopy, thermogravimetric analysis, ultraviolet–visible–near-infrared spectra, and photocatalytic degradation performance were employed to characterize the as-synthesized samples. The results demonstrated that AgBiS2powders display thermal stability; strong absorption in the ultraviolet, visible, and partial infrared regions; and an optical bandgap of 0.98 eV. The obtained AgBiS2powders also have a good degradation effect on the methylene blue solution with a degradation efficiency of 58.61% and a rate constant of 0.0034 min−1, indicating that it is an efficient strategy for sewage degradation to reduce water pollution.Keywords:AgBiS2;reflux method;photocatalytic degradation
Heng Quan Yang,Lei Miao,Cheng Yan Liu,Chao Li,Sawao Honda,Yuji Iwamoto,Rong Huang,Sakae Tanemura
Antimony telluride (Sb2Te3) and its based alloys are of importance to p-type semiconductors for thermoelectric applications near room temperature. Herein, we report a simple, low-energy intensive, and scalable surfactant-assisted reflux method for the synthesis of Sb2Te3 nanoparticles in the solvent ethylene glycol (EG) at low temperatures (120–180 °C). The formation mechanism of platelike Sb2Te3 nanoparticles is proposed. Also, it is found that the size, shape, and chemical composition of the products could be controlled by the introduction of organic surfactants (CTAB, PVP, etc.) or inorganic salts (EDTA-Na2, NaOH, etc.). Additionally, the collected Sb2Te3 nanoparticles were further fabricated into nanostructured pellets using cold-compaction and annealing techniques. Low resistivity [(7.37–19.4) × 10–6 Ω m], moderate Seebeck coefficient (103–141 μV K–1), and high power factor (10–16 × 10–4 W m–1 K–2) have been achieved in our Sb2Te3-nanostructured bulk materials. The relatively low thermal conductivity (1.32–1.55 W m–1 K–1) is attained in the nanobulk made of PVP-modified nanoparticles, and values of ZT in the range of 0.24–0.37 are realized at temperatures ranging from 50 to 200 °C. Our researches set forth a new avenue in promoting practical applications of Sb2Te3-based thermoelectric power generation or cooling devices.
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