Vertically aligned two-dimensional SnS₂ nanosheets with a strong photon capturing capability for efficient photoelectrochemical water splitting

Abstract

Two-dimensional (2D) metal dichalcogenides have emerged as attractive materials for application in photoelectrochemical (PEC) water splitting due to their unique structure and strong interaction with light.

SnS2 Nanosheets/H‐TiO2 Nanotube Arrays as a Type II Heterojunctioned Photoanode for Photoelectrochemical Water Splitting

“…As et of linear sweepsw ere recorded in the dark and under illumination as shown in Figure 2a.T he photocurrent density of SnS 2 /Tir eached 1.14 mA cm À2 at 1.4 V( vs. RHE), attributed to the strong photon-capturing capability of www.chemsuschem.org 2D SnS 2 nanosheets. [23] The photocurrent increased 3.5-fold to 4mAcm À2 for SnS 2 /H-TiO 2 /Ti. However,t he photocurrentw as only 0.056 mA cm À2 for SnS 2 /TiO 2 /Ti.…”

“…Electronsa re collected in the wall center and transported to the back contact whereas holes are driven to the wall/electrolyte interface. [23] However,S nS 2 exhibits relatively low efficiency in photocatalysis and PEC water splitting owing to poor charget ransporta nd the low separation rate of its photoinduced electrons and holes. [11] Introducing oxygen vacancies (V O ) into TiO 2 NTst hroughh ydrogen treatment [12] or chemical [13] or electrochemical reduction [14] can increaset he conductivity and light-harvesting, hence significantly enhancing the solar-tohydrogen conversion efficiency of PEC cells.…”

“…The binding energies of Sn 3d 5/2 ,Sn3d 3/2 ,S2p 3/2 ,S2p 1/2 ,T i2p 3/2 ,and Ti 2p 1/2 in both samples were centered at 486.8, 495.2, 161.8, 163.0, 459.08, and 464.68 eV,r espectively ( Figure S2 in the Supporting Information). [23] The photocurrent increased 3.5-fold to 4mAcm À2 for SnS 2 /H-TiO 2 /Ti. The two peaks at 530.53 and 531.98 eV in the O1ss pectrum of TiO 2 NTsc orresponded to surfacel attice oxygen (O L )a nd surface OH (O OH )s pecies.…”

“…[16] Therefore, this structure has been widely demonstrated for WO 3 , [17] BiOX (X = Cl, Br,I ), [18] Fe 2 O 3 , [19] and In 2 S 3 [20] in PEC applications.2 Dg raphene-like layered SnS 2 crystals, possessing av isible-light band gap of 2.2-2.35eVa nd ap eculiar CdI 2 -type layered structure consistingo fS -Sn-S triple layers, [21] have been applied in photocatalytic CO 2 reduction [22] and PEC water splitting. [23] However,S nS 2 exhibits relatively low efficiency in photocatalysis and PEC water splitting owing to poor charget ransporta nd the low separation rate of its photoinduced electrons and holes. [24] Hu et al constructed at rap-like SnS 2 /TiO 2 NT arrays photoanode through the solvothermal method, which exhibited ah igh photocurrent density (1.05 mA cm À2 )at0 .5 V(vs. saturated calomel electrode) under simulated light irradiation.…”

“…The calculated band gaps for TiO 2 and SnS 2 were 3.33 and 2.26 eV,r espectively (Figure 3b), consistent with the values of previousw ork. [23] The charge-transfer properties were examined with EIS measurements. The flat-band potentials V fb were calculated according to the Mott-Schottky Equation (2): in which C sc is the capacitance of the space-charge layer, e 0 is the electron charge, e 0 is the vacuum permittivity, e r is the dielectric constant, N d is the donor density, V is the electrodeappliedp otential, V fb is the flat-band potential, ki st he Boltzmann constant, and T is the absolute temperature.…”