Enhanced Charge Carrier Lifetime of TiS₃ Photoanode by Introduction of S₂²⁻ Vacancies for Efficient Photoelectrochemical Hydrogen Evolution

Abstract

Recent advances in layered TiS 3 has shown appealing potential for photoelec trochemical hydrogen evolution due to its excellent optical and electronic properties. Here, an excellent photoanode, composed of TiS 3 nanoribbon arrays with moderate S 2 2− vacancies, is proposed to achieve efficient photo electrochemical hydrogen evolution. These unique S 2 2− vacancies are intro duced in the TiS 3 photoanode by a simple vacuum reannealing method, which is inspired by crystal structure analyses of TiS 3 and TiS 2 . The existing S 2 2− vacancies are revealed to significantly promote the electron conductivity, charge separation, and transport of the photoanode simultaneously. The resulting TiS 3−x photoanode with ≈22% S 2 2− vacancies exhibits a twofold increase in the electron diffusion length for efficient electron collection and a remarkably high photocurrent density of 15.35 mA cm −2 at 1.4 V versus reversible hydrogen electrode.

Efficient Photocatalytic Hydrogen Peroxide Generation Coupled with Selective Benzylamine Oxidation over Defective ZrS3 Nanobelts

“…It is demonstrated that the ZrS 3 layer is parallel to the axial direction of NB, which is in favor of charge carrier transport. 34 As shown in the diffuse re ectance UV-vis spectra ( E fb is commonly used to estimate the CBM for a series of n-type semiconductors at the surface in an aqueous environment, which agreed with their theoretically determined values. 1,38,[46][47][48] Previsous stduies on the energy positions of semicondutors have shown that the CBM of zirconium-based sul des is very close to their E fb , 31,47 and therefore the CBM of ZrSS 2-x , and ZrS 1-y S 2-x are higher than the potential for two-electron reduction of O 2 , and their VBMs lie far below the oxidation potential of benzylamine, 12,15,48,49 indicating that these photocatalysts are applicable to the photocatalytic O 2 reduction and benzylamine oxidation.…”

“…29 The Raman spectra show an obvious red-shift of A g s-s mode by ~5 cm -1 from ZrS 3 to ZrSS 2-x and ZrS 1-y S 2-x , originating from the introduction of S 2 2− vacancies. 34 We also observed a 3 cm -1 red-shift of A g rigid mode from ZrS 3 and ZrSS 2-x to ZrS 1-y S 2-x . Since the A g rigid is correlated to the vibration of quasi-one-dimensional chains in the direction of c axis ( Figure S5a), the shift of A g rigid mode in ZrS 1y S 2-x results from the introduction of S 2− vacancies, which alters the length of Zr-S bonds within each chain.…”

“…The ZrSS 2-x NBs were prepared using the previously reported vacuum annealing method. 34 Speci cally, the as-grown ZrS 3 NBs were sealed in the quartz ampule again, which was then heated to 700 ℃ and last for 15 mins to fabricate ZrSS 2-x NBs. In addition, 0.5 g ZrSS 2-x NBs were placed in a 50 mL Te on-lined autoclave lled with 30 mL ethanediamine (≥98 % purity, Sigma-Aldrich) and 100 mg Li, and the autoclave was subsequently kept in an oven at 120 °C for 24 h. After cooling down to the room temperature, the mixture was rst washed in 0.2 M HCl and then rinsed several times in deionized water and ethanol, where the ZrS 1-y S 2-x NBs was nally obtained.…”

“…32 Intriguingly, the conduction band of ZrS 3 is mainly composed of Zr d-orbitals, 27,29 which has a much more negative potential than the can greatly promote the separation of photogenerated charge carriers in TMTs (Schematic S1a and b). 34,35 In addition, the anion vacancies existing on the surface of n-type semiconductors can further improve its photocatalytic and photoelectrochemical performance by accelerating the kinetics of hole transfer on the surface. [36][37][38][39] The crystal structure analysis of ZrS 3 inspires us that the S 2 2and S 2-vacancies can be separately introduced into ZrS 3 by different methods (Schematic 1 and S1).…”

Highly active deficient ternary sulfide photoanode for photoelectrochemical water splitting

“…However, apart from the factor of photochemical photocorrosion, which can be dramatically suppressed by the usage of sacrificial agents or surface decoration of passive layers [12][13][14] , the metal sulfides directly employed as photoanodes usually exhibit low photoinduced electron-hole separation efficiencies and sluggish surface water oxidation kinetics [15][16][17][18] , which limits the application of metal sulfides-based photoanodes. The defects in metal sulfide, especially for introducing sulfur vacancies, are evidenced as an effective strategy to enhance the photocatalytic and PEC properties [19][20][21][22] . The trap states introduced by sulfur vacancies can act as capture centers to enable charge carrier separation.…”