In situ Irradiated XPS Investigation on S‐Scheme TiO₂@ZnIn₂S₄ Photocatalyst for Efficient Photocatalytic CO₂ Reduction

Abstract

Recently, a novel step-scheme (S-scheme) heterojunction was proposed and has attracted researchers' attention. [23][24][25][26][27][28][29][30][31][32][33][34][35][36] Usually, S-scheme heterojunction consists of reduction photocatalyst (RP) and oxidation photocatalyst (OP). Besides, the directional migration of free electrons will lead to band bending and internal electric field (IEF) at their interface owing to the work function difference. Notably, under the influence of IEF, the photogenerated electrons of OP with weak reduction ability can recombine with the photogenerated holes of RP with weak oxidation ability; while those with strong redox abilities are preserved. Therefore, reasonable construction of TiO 2 -based S-scheme heterojunction is of great significance to improve photocatalytic reaction performance. Apart from the charge carrier separation, the morphology of photocatalysts is another important factor to influence the photocatalytic performance. [15,17,19,37,38] Photocatalysts with hollow structures have attracted great attention owing to manifold advantages including larger specific surface area, abundant active sites, shortened diffusion distance as well as improved light reflection and scattering. [37,[39][40][41][42][43][44] Therefore, the design of hollow S-scheme heterojunction photocatalyst is of vital importance to enhance photocatalytic performance.ZnIn 2 S 4 , as a typical reduction photocatalyst, stands out for its layered structure, narrow bandgap, suitable redox potentials, and good chemical stability. And it has been used for various photocatalytic applications including hydrogen production, CO 2 reduction, and organic degradation. [45][46][47][48][49][50][51] Unfortunately, pristine ZnIn 2 S 4 photocatalyst shows low photocatalytic efficiency owing to the fast recombination of photogenerated charge carriers. [45][46][47][48][49] Considering the suitable match of band gap of ZnIn 2 S 4 and TiO 2 for S-scheme heterojunction, [27,52] we construct the hollow TiO 2 @ZnIn 2 S 4 core-shell structure. Up to now, to the best of our knowledge, it has never been reported.Herein, we grow ZnIn 2 S 4 nanosheets on the outer surface of TiO 2 hollow spheres by in situ chemical bath deposition reaction. This rational design is not only able to provide large specific surface areas and abundant reaction sites for PCR reaction, but also can effectively suppress the recombination of useful photogenerated electrons and holes. As a result, the optimized TiO 2 @ZnIn 2 S 4 heterojunction exhibits high PCR performance, and the total CO 2 photoreduction conversion rates (the sum yield of CO, CH 3 OH and CH 4 ) are obviously higher than those of blank ZnIn 2 S 4 , TiO 2 , and ex situ prepared TiO 2 -ZnIn 2 S 4 composite. Finally, S-scheme mechanism is also thoroughly analyzed and discussed in this work.Reasonable design of efficient hierarchical photocatalysts has gained significant attention. Herein, a step-scheme (S-scheme) core-shell TiO 2 @ZnIn 2 S 4 heterojunction is designed for photocatalytic CO 2 redu...

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

“…Additionally, an efficient step-scheme (S-scheme) heterojunction can be constructed by PDA-modified ZnO 43 . In S-scheme photocatalyst, when an oxidation photocatalyst (OP) is coupled with a reduction photocatalyst (RP), an internal electric field (IEF) that directing from RP to OP is formed 42,44,45 . Then, when illuminated, the photoinduced holes in the RP recombine with the photoinduced electrons in the OP under the IEF [46][47][48][49] .…”

Emerging Stacked Photocatalyst Design Enables Spatially Separated Ni(OH)2 Redox Cocatalysts for Overall CO2 Reduction and H2O Oxidation

“…It can be seen that the couple of rGO and/or Ni(OH) 2 substantially increases the photocurrent density of CdS, confirming their positive contribution to the separation of electron-hole pairs. [61] Compared with CdS, rGO/ CdS, CdS@Ni(OH) 2 , rGO@Ni(OH) 2 /CdS, and rGO/CdS@ Ni(OH) 2 show 11.7, 5.5, 9.1, and 19.4-fold improvement in the photocurrent, respectively, which is inconsistent with the trend in either CO or O 2 evolution, but in agreement with the sum of CO and H 2 generation. Such a phenomenon is further validated by the PL results, in which obvious PL quenching of CdS can be seen after the introduction of rGO and/or Ni(OH) 2 , and the quenching degree among different samples is in the same order as the photocurrent enhancement (Figure 4b).…”

Boosting Pseudo‐capacitive Sodium Storage in Ultrafine Titanium Dioxide by an In‐situ Porous Forming Strategy

“…Figure 1a [10] Finally, the high-resolution Ti 2p in Figure 1d shows three pinnacles situated at 465.1, 459.6 and 473.2 eV, ordinarily comparing to the Ti 2p 1/2 , Ti 2p 3/2 and the satellite pinnacle of TiO 2 , respectively. [11] Figure 2 was the morphology characterization of the U-TiO 2 / C composite. Figure 2a and Figure S2b-d further testified that the TiO 2 nanoparticles adhere to the surface of the carbon internally with the average size of 11 nm.…”