TiO2/In2S3 S-scheme photocatalyst with enhanced H2O2-production activity

Abstract

Photocatalytic production of hydrogen peroxide (H 2 O 2 ) is an ideal pathway for obtaining solar fuels. Herein, an S-scheme heterojunction is constructed in hybrid TiO 2 /In 2 S 3 photocatalyst, which greatly promotes the separation of photogenerated carriers to foster efficient H 2 O 2 evolution. These composite photocatalysts show a high H 2 O 2 yield of 376 μmol/(L•h). The mechanism of charge transfer and separation within the S-scheme heterojunction is well studied by computational methods and experiments. Density functional theory and in-situ irradiated X-ray photoelectron spectroscopy results reveal distinct features of the S-scheme heterojunction in the TiO 2 /In 2 S 3 hybrids and demonstrate charge transfer mechanisms. The density functional theory calculation and electron paramagnetic resonance results suggest that O 2 reduction to H 2 O 2 follows stepwise one-electron processes. In 2 S 3 shows a much stronger interaction with O 2 than TiO 2 as well as a higher reduction ability, serving as the active sites for H 2 O 2 generation. The work provides a novel design of S-scheme photocatalyst with high H 2 O 2 evolution efficiency and mechanistically demonstrates the improved separation of charge carriers.

Enhanced Photocatalytic H₂O₂ Production over Inverse Opal ZnO@ Polydopamine S-scheme Heterojunctions

“…However, ZP2 showed a stronger DMPO-•OH signal than pure ZnO. This phenomenon correlated with the holes that survived in ZnO valence band (VB) with stronger oxidation ability owing to S-scheme charge transfer in ZP2 13,42,46 . Fig.…”

“…The apparent quantum yield of ZP2 was 13.96% under the irradiation of a 365 nm light source. Further increasing the PDA amount could deteriorate the photocatalytic H2O2 production performance (e.g., 656.1 μmol•L −1 •h −1 for ZP3) because of the light-shielding effect 13,41 . The recyclability and stability of ZnO@PDA were also investigated.…”

“…The global energy market demands three million tons of H2O2 per year 7 . Currently, H2O2 is produced via anthraquinone (AQ) process [8][9][10] , direct hydrogen-oxygen reaction 11,12 and oxidation of alcohols 13,14 . These methods either demand high energy input or cause environmental pollution, which significantly hinder their largescale application [15][16][17] .…”

“…Moreover, it also reduces our energy reliance on unsustainable fossil fuels and alleviates environmental pollution 15,19,20 . To date, various semiconductors have been developed for photocatalytic H2O2 production, including TiO2 13,16,21 , ZnO [22][23][24] , g-C3N4 [25][26][27] , CdS 28,29 , graphene 30,31 and BiVO4 32 . Among them, ZnO, featured with non-toxicity, stability and earth-abundance, has attracted much interest 33 , but it still suffers from poor absorption of sunlight and fast recombination of photoinduced charge carriers 34 .…”

Inorganic Metal‐Oxide Photocatalyst for H2O2 Production

“…), graphic carbon nitride (g-C 3 N 4 ), [25] metal sulfides (In 2 S 3 , CdS, etc. ), [26,27] bismuth vanadate (BiVO 4 ), [28,29] metal-organic frameworks (MOFs), [30,31] and semiconducting polymers (polypyrrole, polydopamine, etc.). [32] Among these classes of photocatalysts, metal oxides have low cost, relatively good stability, and biocompatibility.…”