Nanostructured SnS with inherent anisotropic optical properties for high photoactivity

Abstract

In view of the worldwide energy challenge in the 21(st) century, the technology of semiconductor-based photoelectrochemical (PEC) water splitting has received considerable attention as an alternative approach for solar energy harvesting and storage. Two-dimensional (2D) structures such as nanosheets have the potential to tap the solar energy by unlocking the functional properties at the nanoscale. Tin(ii) sulfide is a fascinating solar energy material due to its anisotropic material properties. In this manuscript, we report on exploiting the 2D structure modulated optical properties of nanocrystalline SnS thin film synthesized by chemical spray pyrolysis using ambient transport in the harvesting of solar energy. We obtained the nanostructured SnS with well-preserved dimensions and morphologies with one step processing. The work demonstrates that the intrinsically ordered SnS nanostructure on FTO coated glass can tap the incident radiation in an efficient manner. The structure-property relationship to explain the photo-response in nanocrystalline-SnS is verified experimentally and theoretically. The novel design scheme for antireflection coating along with the anisotropic properties of SnS is conceived for realizing a PEC cell. The developed PEC cell consists of a SnS photoanode which shows considerably high photocurrent density of 7 mA cm(-2) with aqueous media under AM 1.5G, 100 mW cm(-2) exposure with notably stable operation. Electrochemical impedance spectroscopy revealed that a non-ideal capacitive behavior as well as drift assisted transport across the solid-state interface is responsible for such a high photo-current density in the nanocrystalline-SnS photoanode.

Facile Formation of Nanodisk‐Shaped Orthorhombic SnS Layers from SnS2 Particles for Photoelectrocatalytic Hydrogen Production

“…Raman spectra of the highly crystalline SnS films grown on Si wafer are taken with a Helium Neon Laser 532 nm at room temperature (RT) and are shown in Figure d. The Raman spectra demonstrate six Raman peaks at 68, 94, 162, 191, 219, and 288 cm −1 which correspond to the Raman modes of SnS, while Raman peak at 520 cm −1 is due to the Si substrate. The Raman peaks at 68, 162 and 288 cm −1 correspond to B 1g , B 3g , and B 2g Raman modes of SnS, respectively and the other three peaks (94, 191 and 219 cm −1 ) are assigned to the A g modes of SnS . Observation of all the Raman modes of the SnS phase in our SnS sample confirms again the highly crystalline orthorhombic nature of our SnS film.…”

“…As a two‐dimensional (2D) material with an analogous structure as black phosphorus, yet with a finite band gap unlike graphene, tin sulfides have gained considerable attention among the family of two‐dimensional (2D) materials . Among tin sulfides, SnS (tin monosulfide, Herzenbergite) is known as a potential candidate for solar energy utilization due to its fascinating electronic properties such as direct optical band gap (1.4–1.7 eV) and a high absorption coefficient (>10 4 cm −1 ), in addition to the fact that it is earth‐abundant, non‐toxic and air stable . SnS has a structure with an orthorhombic unit cell, in which each tin atom is coordinated to six sulfur atoms in a highly distorted octahedral geometry.…”

“…All of these devices were prepared with the SnS films thicker than 400 nm. Preparation of thinner SnS films with thickness less than 100 nm with a high purity and a crystallinity in an one‐step process would be desired for enhancing photo‐efficiency in a photoelectrochemical cell …”

“…[1][2][3][4][5][6] Amongt in sulfides, SnS (tin monosulfide, Herzenbergite) is known as ap otentialc andidate for solar energy utilizationd ue to its fascinating electronic properties such as direct optical band gap (1.4-1.7 eV) and ah igh absorption coefficient (> 10 4 cm À1 ), in addition to the fact that it is earth-abundant, non-toxic and air stable. [7][8][9][10][11][12][13] SnS has as tructure with an orthorhombic unit cell, in which each tin atom is coordinated to six sulfur atoms in ah ighly distorted octahedral geometry.T wo corrugated tin sulfide double layers constitute as ingle unit cell and each SnS layer consists of ac ovalently bondedn etwork within the 2D lattice with no dangling bonds. This 2D nature of the SnS layer renders only aw eak interaction between neighboring layers via van der Waalsi nteractions, which allows easy separation andfabrication of layered composite structures with highly disparate atomic layerst oc reate aw ide range of van der Waals( vdWs)h eterostructures without any constraints of lattice match and compatibility.T herefore, the processability of SnS combined with its extraordinary physicala nd chemical properties makes it ap erfect model system in exploring new 2D properties.…”

Highly Photoactive and Photo-Stable Spray Pyrolyzed Tenorite CuO Thin Films for Photoelectrochemical Energy Conversion

“…[49][50][51][52][53] The growth of nanocrystalline CuO thin film can be manipulated by the pyrolysis of aqueous CuCl 2 precursor in the temperature range of 300-400 • C in ambient air according to the following reaction:…”