Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H₂ Evolution

Abstract

Vacancy defects engineering is a valid strategy to enhance the separation efficiency of photo-generated charges. Herein, a zinc vacancy mediated S-scheme ZnCdS/ZnS composite derived from ZnCdS/MOF-5 was constructed in-situ through the sacrificial reagent of Na 2 S/Na 2 SO 3 aqueous solution in visiblelight irradiation. The MOF-5 converted to ZnS (ZnSÀ V Zn ) with abundant zinc vacancies which were proved by the XPS and PL results. ZnSÀ V Zn has two-photon absorption performance, which immensely enhanced the visible light absorption capacity for the photocatalysts. The photo-generated electrons of ZnSÀ V Zn on the Zn-vacancy defect would regroup with the holes in the valence band (VB) of ZnCdS via ohmic contact which is induced by Zn-vacancy defects. Therefore, the photoexciton of ZnCdS can be able to separate effectively and eliminate the useless electrons and holes. The ZnCdS/ZnS(20) sample revealed an outstanding photocatalytic hydrogen generation rate of 12.31 mmol h À 1 g À 1 with a turnover number (TON) of 64.61, which is about 82.06 and 21.98 times greater than that of neat ZnSÀ V Zn and ZnCdS. This work gives an insight into the design of the zinc vacancy-engineered S-scheme photocatalyst of ZnCdS/ZnS for highly efficient photocatalysis.

Amorphous WP‐Modified Hierarchical ZnIn2S4 Nanoflowers with Boosting Interfacial Charge Separation for Photocatalytic H2 Evolution

“…As shown in Figure 4d, the areas where lattice fringe breaks become less ordered are sulfur vacancies on the surface of 10% WP/ZnIn 2 S 4 (pink dotted box). [ 8,51,52 ]…”

“…It can be seen from Figure 6 that the three samples all belong to type IV isotherms with a typical H3 hysteresis loop, indicating that all of the samples have a mesoporous structure. [ 8 ] The BET specific surface area ( S BET ), pore size ( D P ), and pore volume ( V P ) parameters of ZnIn 2 S 4 , amorphous WP, and 10% WP/ZnIn 2 S 4 samples are listed in Table 1 . It can be concluded from Table 1 that the specific surface areas of pure ZnIn 2 S 4 , amorphous WP, and 10% WP/ZnIn 2 S 4 composite are 88.23, 16.61, and 57.52 m 2 g –1 , respectively.…”

“…[ 47 ] Furthermore, the corresponding band gaps of ZnIn 2 S 4 and 10% WP/ZnIn 2 S 4 were estimated from the Tauc equation αhν = A ( hν − Eg ) 1/2 for the direct bandgap material (where α is absorption coefficient, A is a constant, hν is the photon energy, and E g is the bandgap energy). [ 8 ] As shown in Figure 7b, the bandgap values of ZnIn 2 S 4 and WP/ZnIn 2 S 4 are 2.09 and 2.3 eV, respectively. Figure 7c is Mott–Schottky plots of ZnIn 2 S 4 and amorphous WP, which can further study the types and band structures of catalysts.…”

“…[ 4–7 ] Photocatalytic water splitting via semiconductors to generate hydrogen is considered to be one of the most promising, eco‐friendly, and renewable manners. [ 8–10 ] However, many semiconductor‐based photocatalysts have lower hydrogen production efficiency due to their limited light absorption capacity and high‐speed recombination of photogenerated electron holes, which hinders their further potential practical usage. [ 11–13 ]…”

Engineering of Band Structure of Bismuth Selenide Ultrathin Nanosheets as Multifunctional Material for Photocatalytic Application

“…The saturated adsorption platform cannot be found in the N 2 adsorption isotherm curves (Figure S2a, Supporting Information), indicating that the two materials have IV type isotherms with H3 type hysteresis loops, and their pore structures are irregular and exhibit mesoporous characteristics. [ 32 ] The BET surface areas are 7.12 and 27.2 m 2 g −1 , the pore volume is 0.036 and 0.125 cm 3 g −1 and the average pore diameters are 20.5 and 18.3 nm (Figure S2b, Supporting Information) for BS and BSN‐2, respectively. The results show that the BET area and pore size of BSN‐2 may be conducive to the absorption of light and produce more valid active sites for the adsorption of pollutant molecules, resulting in improvement of the catalytic activity.…”