Multivariate Synthesis of Tin Phosphide Nanoparticles: Temperature, Time, and Ligand Control of Size, Shape, and Crystal Structure

Abstract

Tin phosphides make up a class of materials that have received a noteworthy amount of interest in photocatalysis, charge storage, and thermoelectric devices. Dual stable oxidation states of tin (Sn2+ and Sn4+) allow tin phosphides to exhibit different stoichiometries and crystal phases. However, the synthesis of such nanostructures with control over morphology and crystal structure has proven to be a challenging task. Herein, we report the first colloidal synthesis of size-, shape-, and phase-controlled, narrowly disperse rhombohedral Sn4P3, hexagonal SnP, and trigonal Sn3P4 nanoparticles (NPs) displaying tunable morphologies and size-dependent physical properties. The control over NP morphology and crystal phase was achieved by tuning the nucleation/growth temperature, Sn/P molar ratio, and incorporation of additional coordinating solvents (alkylphosphines). The absorption spectra of Sn3P4 NPs (3.0 ± 0.4 to 8.6 ± 1.8 nm) exhibit size-dependent blue shifts in energy gaps (1.38–0.88 eV) compared to the theoretical value of bulk Sn3P4 (0.83 eV), consistent with quantum confinement effects. The trigonal Sn3P4 NPs adopt rhombohedral Sn4P3 and hexagonal SnP crystal structures at 180 and 250 °C, respectively. Structural and surface analysis indicates consistent bond energies for phosphorus across different crystal phases, whereas the rhombohedral Sn4P3 NPs demonstrate Sn oxidation states distinctive from those of the hexagonal and trigonal phases because of the complex chemical structure. All phases exhibit N­(1s) and ν(N–H) energies suggestive of alkylamine surface functionalization and are devoid of tetragonal Sn impurities.

A High‐Rate and Ultrastable Sodium Ion Anode Based on a Novel Sn4P3‐P@Graphene Nanocomposite

“…In the analysis of Sn 3d XPS spectra of SnP compounds, multiple valence contributions (Sn 2+ , Sn 4+ , etc.) [31,34,42] However, since the P terminated surface already leads to the oxidation of Sn to +4, the oxidizing effect of oxygen on Sn may be limited. [34,39,40,42] SnP 3 has a single Sn site surrounded by six P atoms in the crystal structure and a 119 Sn Mössbauer Isomer shift indicates an oxidation state of +3 in bulk crystals, [43] the main Sn 3d 5/2 XPS peak of SnP 3 at 485.5 eV may therefore be assigned to Sn 3+ .…”

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

“…Catalysts 2020, 10, x FOR PEER REVIEW 10 of 22 The Eg values of the pure catalysts samples could be thus estimated from the intercept of the tangent with the baseline absorption data from a plot of F(R)hν 1/2 and F(R)hν 2 versus the photon energy (hν) for indirect and direct transitions, as shown in Figure 10c,d respectively [2] and [49]. TiO2 and BiOCl have large bang gap, while BiOI has a band gap of 1.93 eV (2.35 Ev, direct transitions), which is suitable for visible-light excitation.…”

Synthesis and application of transition metal phosphides as electrocatalyst for water splitting

“…1-octadecene and oleylamine, as reaction medium. TMPs nanostructures can be synthesized by solvothermal method with its morphology and crystal structure controlled by tuning the nucleation/growth process with different temperatures, Sn/P molar ratios, or incorporation of additional coordinating solvents [42]. As shown in Fig.…”

“…In addition, different crystal structures also resulted in different performances. Tallapally [42] used the colloid method to synthesize tin phosphide nanoparticles. By adjusting the synthesis conditions, hexagonal Sn 4 P 3 , hexagonal SnP, and triangular Sn 3 P 4 nanoparticles were respectively prepared.…”