Ligands Induced the Growth of Colloidal AgInS2 Nanoparticles with Tuned Structure and Photoluminescence Property

Understanding the growth mechanism of AgInS2 nanoparticles could benefit the designed growth of I-III-VI2 nanomaterials and their applications in photonics, optoelectronics, etc. Herein, using tris(dibutyldithiocarbamate) indium(III) [In((C4H9)2NCS2)3] ([InR3]) and dibutyldithiocarbamate silver(I) [Ag((C4H9)2NCS2)] ([AgR]) precursors, AgInS2-based nanoparticles with different structures have been synthesized in a controlled manner through a one-pot approach via different growth mechanisms in 1-dodecanethiol (DDT) and oleylamine (OLA), respectively. The DDT and OLA could participate in the decomposition of precursors; thus, the [AgR]/DDT, [InR3]/DDT, [AgR]/OLA, and [InR3]/OLA were used herein to describe the decomposition steps. In DDT, the decomposition activity of [AgR]/DDT was much higher than that of [InR3]/DDT; thus, the sequential decomposition of [AgR]/DDT and [InR3]/DDT led to the formation of the Ag2S nanoparticles intermediate first, which then reacted with [InR3]/DDT to form metastable o-AgInS2 nanoparticles via the cation exchange and alloy process, and finally evolved into o-AgInS2@InSx core@shell nanoparticles, while in OLA, the decomposition activity of [AgR]/OLA was slightly higher than that of [InR3]/OLA. Thus, the quasi-co-decomposition of [AgR]/OLA and [InR3]/OLA led to the formation of Ag-rich Ag-In-S amorphous nanoparticles intermediate first and then quickly evolved into stable t-AgInS2/InSx nanoparticles. In addition, the photoluminescence quantum yield (PLQY) of t-AgInS2/InSx nanoparticles was higher than that of o-AgInS2@InSx nanoparticles.

Visible Light Motivated the Photocatalytic Degradation of P-Nitrophenol by Ca2+-Doped AgInS2

4-Nitrophenol (4-NP) is considered a priority organic pollutant with high toxicity. Many authors have been committed to developing efficient, green, and environmentally friendly technological processes to treat wastewater containing 4-NP. Here, we investigated how the addition of Ca2+ affects the catalytic degradation of 4-NP with AgInS2 when exposed to light. We synthesized AgInS2 (AIS) and Ca2+-doped AgInS2 (Ca-AIS) with varying amounts of Ca2+ using a low-temperature liquid phase method. The SEM, XRD, XPS, HRTEM, BET, PL, and UV-Vis DRS characteristics were employed to analyze the structure, morphology, and optical properties of the materials. The effects of different amounts of Ca2+ on the photocatalytic degradation of 4-NP were investigated. Under visible light illumination for a duration of 120 min, a degradation rate of 63.2% for 4-Nitrophenol (4-NP) was achieved. The results showed that doping with an appropriate amount of Ca2+ could improve the visible light catalytic activity of AIS. This work provides an idea for finding suitable cheap alkaline earth metal doping agents to replace precious metals for the improvement of photocatalytic activities.

Self-powered photoelectrochemical aptasensor based on AgInS2@Co/Ni-UiO-66@CDs photoelectrode for estradiosl detection

A self-powered photoelectrochemical (PEC) aptasensor was constructed to sensitively detect 17β-estradiol (E₂). Firstly, a reasonable AgInS₂@Co/Ni-UiO-66@Carbon Nanodots (CDs) photoelectrode with excellent photoelectrochemical performance was built by a simple two-step preparation method. The Co and Ni doping markedly improved the activity of UiO-66; the matched energy level of AgInS₂ and Co/Ni-UiO-66 promoted the separation of electron-hole pairs, and the coupling of CDs further enhanced the conductivity and light utilization. Therefore, a steady anode-photocurrent signal output was obtained in 0.0 V bias voltage, providing a reliable photoelectric translating platform for assembling a self-powered PEC aptasensor. The E₂-aptamer was adopted as a recognition unit to enhance the selectivity and sensitivity of the proposed aptasensor. The specific recognition reaction between E₂ and aptamer administering to a raised photocurrent signal and the concentration of E₂ was quantified by counting the fluctuation of the anode-photocurrent signal. The linear response range of the PEC aptasensor was 1.0 × 10^-5-10 nmol/L, and the detection limit (S/N = 3) was lower than 3.0 fmol/L under optimal conditions. The fabricated aptasensor exhibited admirable selectivity, high sensitivity, rapid response, and wide linear range, demonstrating an extensive application prospect for environmental endocrine disruptor detection.

Indium(II) Chloride as a Precursor in the Synthesis of Ternary (Ag-In-S) and Quaternary (Ag-In-Zn-S) Nanocrystals

A new indium precursor, namely, indium(II) chloride, was tested as a precursor in the synthesis of ternary Ag-In-S and quaternary Ag-In-Zn-S nanocrystals. This new precursor, being in fact a dimer of Cl2In-InCl2 chemical structure, is significantly more reactive than InCl3, typically used in the preparation of these types of nanocrystals. This was evidenced by carrying out comparative syntheses under the same reaction conditions using these two indium precursors in combination with the same silver (AgNO3) and zinc (zinc stearate) precursors. In particular, the use of indium(II) chloride in combination with low concentrations of the zinc precursor yielded spherical-shaped (D = 3.7-6.2 nm) Ag-In-Zn-S nanocrystals, whereas for higher concentrations of this precursor, rodlike nanoparticles (L = 9-10 nm) were obtained. In all cases, the resulting nanocrystals were enriched in indium (In/Ag = 1.5-10.3). Enhanced indium precursor conversion and formation of anisotropic, longitudinal nanoparticles were closely related to the presence of thiocarboxylic acid type of ligands in the reaction mixture. These ligands were generated in situ and subsequently bound to surfacial In(III) cations in the growing nanocrystals. The use of the new precursor of enhanced reactivity facilitated precise tuning of the photoluminescence color of the resulting nanocrystals in the spectral range from ca. 730 to 530 nm with photoluminescence quantum yield (PLQY) varying from 20 to 40%. The fabricated Ag-In-S and Ag-In-Zn-S nanocrystals exhibited the longest, reported to date, photoluminescence lifetimes of ∼9.4 and ∼1.4 μs, respectively. It was also demonstrated for the first time that ternary (Ag-In-S) and quaternary (Ag-In-Zn-S) nanocrystals could be applied as efficient photocatalysts, active under visible light (green) illumination, in the reaction of aldehydes reduction to alcohols.