Boosting Interfacial Charge Transfer with a Giant Internal Electric Field in a TiO₂ Hollow-Sphere-Based S-Scheme Heterojunction for Efficient CO₂ Photoreduction

Abstract

The construction of an S-scheme charge transfer pathway is considered to be a powerful way to inhibit charge recombination and maintain photogenerated carriers with high redox capacity to meet the kinetic requirements of the carbon dioxide (CO 2 ) photoreduction reaction. For an S-scheme heterojunction, an internal electric field (IEF) is regarded as the main driving force for accelerating the interfacial spatial transfer of photogenerated charges. Herein, we designed a TiO 2 hollow-sphere (TH)based S-scheme heterojunction for efficient CO 2 photoreduction, in which WO 3 nanoparticles (WP) were applied as an oxidation semiconductor to form an intimate interfacial contact with the TH. The S-scheme charge transfer mode driven by a strong IEF for the TH/WP composite was confirmed by in situ X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. As a result, abundant photogenerated electrons with strong reducing ability would take part in the CO 2 reduction reaction. The combination of surface photovoltage spectra and transient photocurrent experiments disclosed that the IEF intensity and charge separation efficiency of the fabricated TH/WP composite were nearly 16.80-and 1.42-fold higher, respectively, than those of the pure TH. Furthermore, sufficient active sites provided by the hollow-sphere structure also enhanced the kinetics of the catalytic reaction. Consequently, the optimized TH/WP composite showed a peak level of CO production of 14.20 μmol g −1 in 3 h without the addition of any sacrificial agent. This work provides insights into the kinetic studies of the S-scheme charge transfer pathway for realizing high-performance CO 2 photoreduction.

Bi2WO6/C3N4 S-Scheme Heterojunction with a Built-In Electric Field for Photocatalytic CO2 Reduction

“…As shown in Figure a,b, the secondary electron cutoff edges ( E cutoff ) of CN and BWO are determined to be 16.74 and 15.81 eV, respectively. The corresponding work function (Φ) could be calculated using the formula Φ = h ν – E cutoff , where h ν is the He I photoelectron energy with a value of 21.22 eV. , The matching electron work function was estimated to be 4.48 eV for CN and 5.41 eV for BWO, respectively, suggesting that the Fermi energy level ( E F ) of BWO is lower than that of CN. As illustrated in Figure c, the electrons would spontaneously flow from CN to BWO through the contact interface when the BWO nanosheets are decorated on the surface of the CN nanosheets.…”

S-Scheme Heterojunction Photocatalysts for CO2 Reduction

“…The hollow sphere structure can not only provide enough active sites, but also improves the light-harvesting efficiency. Su et al [107] prepared S-scheme heterojunctions based on TiO 2 hollow spheres (TH), in which WO 3 nanoparticles (WP) acted as OPs to form close interfacial contacts with TH. Without adding any sacrificial agent, the yield of CO over the WP/TH was 4.73 µmol g −1 h −1 .…”

Hollow dodecahedron K3PW12O40/CdS core-shell S-scheme heterojunction for photocatalytic synergistic H2 evolution and benzyl alcohol oxidation

“…Hydrogen (H2), a clean energy source, has been extensively utilized across a broad spectrum of industries, including power generation, metal smelting, and rocket fuel propulsion [1][2][3][4][5]. Industrial production of H2 primarily relies on methods such as natural gas decomposition and water gas conversion, both of which inadvertently release pollutants, notably CO [6][7][8]. Photocatalytic water splitting has emerged as a sustainable, green method for H2 generation [9][10][11][12].…”