Photoelectrochemical Study of SnS2 in Aqueous Solution

Abstract

n‐Type SnS2 with a layered structure has been grown by chemical vapor transport using phosphorus as doping agent. It has a resistivity of 1 Ω cm and an energy gap of 2.2 eV. It is characterized by very low dark current under anodic polarization. The material is not stable under prolonged illumination in aqueous acidic and basic solutions. However, the stability can be improved considerably in acidic solutions containing potassium iodide. The voltammograms under illumination indicate that the photocurrent onset potential, particularly in alkaline solutions, depends on redox reagents used. Photopotentials do not vary as expected with different redox couples.

Balancing Light Absorption and Charge Transport in Vertical SnS2 Nanoflake Photoanodes with Stepped Layers and Large Intrinsic Mobility

“…[12,17] This is also evident in the chronoamperometric (CA) tests of our optimized SnS 2 nano flake photoanodes ( Figure S12a,b, Supporting Information). However, it has relatively poor sta bility in aqueous solutions.…”

“…However, it has relatively poor sta bility in aqueous solutions. [12,17] This is also evident in the chronoamperometric (CA) tests of our optimized SnS 2 nano flake photoanodes ( Figure S12a,b, Supporting Information). Photocurrents from these photoanodes decrease significantly during the 10 min test in 1 m phosphate buffer, 1 m phosphate buffer + 1 m Na 2 SO 3, and 1 m H 2 SO 4 at a constant applied potential of 0.6 V RHE.…”

“…[17] This observation is further corroborated by inductively coupled plasma optical emission spectrom etry (ICPOES) analysis (Table S1, Supporting Information) that shows high concentration of Sn dissolved in the elec trolyte. [12,17] In contrast, the SnS 2 nanoflakes showed substantially improved stability in the presence of iodide ions in the acidic electrolyte, which is consistent with a previous report. All of these findings corroborate oxida tion and dissolution of SnS 2 photoanodes observed by other researchers.…”

“…Com pared to the asgrown SnS 2 nanoflakes (Figure 7a), those tested in sulfuric acid show significant anodic dissolution (Figure 7b), evident from SEM images and XPS peak for elemental sulfur, which is one of the products of the disso lution reaction. [17] This observation is further corroborated by inductively coupled plasma optical emission spectrom etry (ICPOES) analysis (Table S1, Supporting Information) that shows high concentration of Sn dissolved in the elec trolyte. Similarly, the nanoflakes tested in phosphate buffer undergo surface oxidation (Figure 7c), which seems to slow anodic dissolution, as the nanoflakes appear more intact in the SEM images.…”

“…Similarly, the nanoflakes tested in phosphate buffer undergo surface oxidation (Figure 7c), which seems to slow anodic dissolution, as the nanoflakes appear more intact in the SEM images. [17] During both CA and LSV tests in 1 m H 2 SO 4 + 0.1 m KI ( Figure S14, Supporting Information), our optimized SnS 2 nanoflakes showed no signs of degradation. [12,17] In contrast, the SnS 2 nanoflakes showed substantially improved stability in the presence of iodide ions in the acidic electrolyte, which is consistent with a previous report.…”