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• The Tb 2 O 3 /g-C 3 N 4 heterojunction composites were constructed. • The composites reveal excellent photo-degradation efficiency. • The Tb4+/Tb3+ redox center promote the charge carriers separation. • The yield of hydroxyl radical was increasing sharply. • The possible mechanism of material was systematically discussed. Recently, the issue of environmental pollution by wastewater containing dye molecules attracted researcher's attention. It is urgent that seeking high efficiency visible-light driven photocatalyst leads to mitigating environmental contamination. In this work, the novel Tb 2 O 3 /g-C 3 N 4 composite photocatalysts have been successfully synthesized, and the enhanced photocatalytic performance has been thoroughly discussed based on the fully characterization. The X-ray diffraction and scanning electron microscopy exhibited crystalline phases and morphologies of obtained samples. The chemical states and composition of composite photocatalysts were characterized by the X-ray photoelectron spectrometer. The photoluminescence and photocurrent results proved that Tb 2 O 3 /g-C 3 N 4 composite samples possessed higher separation efficiency than that of pure C 3 N 4. The decomposition of organic contaminant and cycle experiment demonstrated that 0.8%Tb 2 O 3 /g-C 3 N 4 composite photocatalyst possessed the best photo-degradation performance and had a good chemical stability. The trapping experiment illustrated that the significantly elevated photocatalytic performance could attribute to the loading of Tb 2 O 3. The in-built redox centers of Tb4+/Tb3+ efficiently promoted the utilization of photo-generated electrons and proliferated the hydroxyl radical. Simultaneously, the mechanism of enhanced photocatalytic performance of obtained composite samples was proposed. This work provides a promising strategy to design novel visible-light-driven photocatalysts and further improve the photocatalysis mechanism survey. The as-prepared Tb 2 O 3 /g-C 3 N 4 composite heterojunction semiconductor exhibited higher photocatalytic activity by degrading organic pollutant under visible light illumination and 0.8%Tb 2 O 3 /g-C 3 N 4 presented the best photo-degradation properties compare with other samples. The degradation efficiency of 0.8%Tb 2 O 3 /g-C 3 N 4 was 1.5 times higher than that of pure C 3 N 4. According to a series of experimental characteristic analysis, it proved that the heterojunction was successfully formed and the existence of Tb 2 O 3 dramatically improved photo-activity of C 3 N 4. The enhanced photocatalytic performance for Tb 2 O 3 /g-C 3 N 4 could be attributed to two aspects: (i) inhibit charge carriers recombination, (ii) the formation of redox center (Tb4+/Tb3+), raise yield of .OH. This work not only provides a thought of high efficiency visible-light-driven photocatalyst, but also further expounds mechanism of action. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel dye-sensitized SrTiO 3 -based photocatalysts for H 2 evolution were successfully constructed. • The deposition of Pt and the introduction of dyes facilitated visible light absorption. • TEOA and EY were the proper choice for enhancing the photocatalytic H 2 evolution activity. • The system of dye-sensitized Pt/STO improved the separation of photoexcited carriers. In this work, strontium titanate (SrTiO 3)-based photocatalysts exhibited superior visible-light-driven photocatalytic hydrogen (H 2) production activity by sensitization with xanthene dyes. A series of Pt-loaded SrTiO 3 (Pt/STO) photocatalysts were successfully prepared to systematically investigate the dependence of photocatalytic performance on the types of sacrificial agents and dyes. Photocatalytic experiments demonstrated that triethanolamine (TEOA) sacrificial agent and Eosin Y (EY) photosensitizer were the proper choice for remarkable enhancement of photocatalytic activity, and the H 2 yield of the optimal system containing 1.0 wt% Pt/STO reached 491.5 μmol in 2.5 h under visible light irradiation. The reasons causing the results were that TEOA could enhance the adsorption of xanthene dyes on SrTiO 3 -based photocatalysts, and bromine groups-containing EY has a high intersystem crossing yield. Electrochemical tests, PL results and fluorescence lifetime further demonstrated the efficient electron transfer behavior occurred from photoexcited EY to the conduction band of SrTiO 3. This study emphasized the potential application of SrTiO 3 -based materials in the field of solar hydrogen production. [ABSTRACT FROM AUTHOR]

Highlights • A novel Bi 2 S 3 @Bi 2 WO 6 /WO 3 ternary composite displayed boosted photocatalytic activity. • A novel Z-scheme/traditional ternary heterojunction system was presented. • The synergistic effect of heterojunction and oxygen vacancy was proposed. Abstract Both the fabricating of heterojunction and oxygen vacancy are the effective methods for boosting the performance of semiconductor photocatalyst. However, the fast recombination of charge carriers and limited light absorption in ubiquitous binary heterojunction are still inherent problems that hinder the practical application of photocatalysts. Herein, a ternary heterojunction of Bi 2 S 3 @Bi 2 WO 6 /WO 3 was fabricated by the facile hydrothermal route combining with an in-situ growth method, and was confirmed by employing elemental mapping and high-resolution transmission electron microscopy. The oxygen vacancy was introduced into Bi 2 S 3 @Bi 2 WO 6 /WO 3 ternary heterojunction as demonstrated by X-ray photoelectron spectroscopy. Compared with Bi 2 S 3 and Bi 2 WO 6 /WO 3 samples, the obtained Bi 2 S 3 @Bi 2 WO 6 /WO 3 composites exhibited higher photocatalytic activity in photodegrading rhodamine B and Tetracycline. The high photocatalytic activity was attributed to the synergistic effect of Z-scheme/traditional heterojunction and oxygen vacancy that extended the visible-light absorption range and promoted the effective separation of photo-generated electron–hole pairs. Based on the trapping experiments and calculated positions of energy band, the photocatalytic mechanisms of the Z-scheme/traditional heterojunction with oxygen vacancy were also proposed. Graphical abstract Brief synopsis: A novel synergistic effect between Z-scheme/traditional heterojunction and oxygen vacancy to design a high-efficiency Bi 2 S 3 @Bi 2 WO 6 /WO 3 ternary photocatalyst. Image, graphical abstract [ABSTRACT FROM AUTHOR]

A novel Ag@AgBr-Ag 2 Mo 3 O 10 ternary core-shell system and a series of AgBr-Ag 2 Mo 3 O 10 hybrids were prepared using a facile in-situ anion-exchange method. Structure and morphology characterization revealed the formation of the Ag@AgBr-Ag 2 Mo 3 O 10 ternary system. Photoluminescence (PL) results indicated the heterojunction structure and the Ag 0 synergistically facilitated the separation of the photogenerated charge carriers. UV–Vis diffuse reflectance spectra (DRS) demonstrated that photosensitive AgBr and Ag strongly broadened the visible light absorption range, with the onset of absorption extending from 460 nm to 500 nm. Degradation experiments suggested that the photocatalytic performance of the Ag@30%AgBr-Ag 2 Mo 3 O 10 sample was remarkably improved compared to those of the Ag 2 Mo 3 O 10 and the AgBr-Ag 2 Mo 3 O 10 hybrids. Significantly, radical trapping experiments revealed that although the conduction band (CB) potentials of Ag 2 Mo 3 O 10 and AgBr were not suitable for the formation of the superoxide radical ( O 2 − ), the ternary system produced O 2 − efficiently. The enhanced production of the O 2 − radical may be due to the band bending of CB that was caused by the equilibration of the Fermi energies of Ag and AgBr-Ag 2 Mo 3 O 10 . This study strongly suggests that design and synthesis of novel photocatalysts that increase the amount of radical species is a potential strategy for boosting photocatalytic performance. [ABSTRACT FROM AUTHOR]

Substitutive doping is a fundamental approach to introduce dopants into a crystalline structure, which resulted in generating the abundant redox centers or oxygen vacancies to promote the separation of photogenerated charge carriers. However, the recombination rate of electron–hole pairs in the single-substituted photocatalysts remained high, thus co-substituting of two sites could be further synergistically restraining the recombination of electron–hole pairs. Herein, the bismuth molybdate (Bi 2 MoO 6 ) photocatalyst, co-substituted by Gd 3+ and W 6+ ions for Bi 3+ and Mo 6+ ions, was synthesized using a hydrothermal method. X-ray photoelectron spectra indicated that the abundant oxygen vacancies were generated in the crystalline Bi 2 MoO 6 after introducing W 6+ ions, and these vacancies adsorbed the extensive O 2 molecules. Additionally, the results of photoluminescence spectra, photocurrent response and trapping experiments demonstrated that the new hydroxyl radicals can be generated by introducing Gd 3+ ions, while the introducing of W 6+ ions contributed to enhancing the productivity of • O 2 − radicals; these two species together promoted the separation and transfer of electron–hole pairs. The results of photocatalytic experiments displayed that Gd/W co-substituted Bi 2 MoO 6 shows much better visible-light photocatalytic activity. These findings developed a novel synergistic effect between redox centers (Gd substitution) and oxygen vacancies (W substitution) to design the high-efficiency photocatalysts. [ABSTRACT FROM AUTHOR]

Samarium and nitrogen co-doped Bi2WO6 nanosheets were successfully synthesized by using a hydrothermal method. The crystal structures, morphology, elemental compositions, and optical properties of the prepared samples were investigated. The incorporation of samarium and nitrogen ions into Bi2WO6 was proved by X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. UV/Vis diffuse reflectance spectroscopy indicated that the samarium and nitrogen co-doped Bi2WO6 possessed strong visible-light absorption. Remarkably, the samarium and nitrogen co-doped Bi2WO6 exhibited higher photocatalytic activity than single-doped and pure Bi2WO6 under visible-light irradiation. Radical trapping experiments indicated that holes (h+) and superoxide radicals ( .O2−) were the main active species. The results of photoluminescence spectroscopy and photocurrent measurements demonstrated that the recombination rate of the photogenerated electrons and holes pairs was greatly depressed. The enhanced activity was attributed to the synergistic effect of the in-built Sm3+/Sm2+ redox pair centers and the N-doped level. The mechanism of the excellent photocatalytic activity of Sm-N-Bi2WO6 is also discussed. [ABSTRACT FROM AUTHOR]

This work constructed the relation between light absorption and separation of electron-hole pairs, and creatively proposed a reliable band gap calculation method to forecast and design of efficient photocatalysts. [Display omitted] • The visible light harvesting was enhanced with the increase of V/Bi ratio. • The separation of charge carriers was restrained with the increase of V/Bi ratio. • DFT calculation has been utilized to explain the inconsistency. • A promising formula has been put forward to calculate the regularity. • Constructed the relation between light absorption and separation of charge carriers. The light harvesting and separation of charge carriers are two decisive factors in the photocatalytic process. In order to reveal the synergic effects of light absorption and separation of charge carriers, and put forward the optimal band gaps of specific photocatalytic systems, Bi 8 V 2 O 17 , Bi 4 V 2 O 11 , BiVO 4 and Bi 4 V 6 O 21 series samples with the V/Bi = 0.25, 0.5, 1 and 1.5 were successfully designed and synthesized. UV–Vis diffuse reflectance spectra (DRS) indicated that the visible light harvesting was tremendously enhanced with the increase of V/Bi ratio. Due to the narrow down of band gaps, photoluminescence (PL) illustrated that the separation of electron-hole pairs was gradually restrained. Although Bi 8 V 2 O 17 showed the best separation of electron-hole pairs, and Bi 4 V 6 O 21 had the best light harvesting range, but the photocatalytic experiments showed that the optimal sample is Bismuth vanadate (BiVO 4). Density functional theory (DFT) calculation has been utilized to explain the above inconsistency, and a promising formula has been put forward to calculate the regularity of light harvesting and separation of electron-hole pairs in the photocatalytic systems. This work constructed the relation between light absorption and separation of electron-hole pairs, and creatively proposed a reliable band gap calculation method to forecast and design of efficient photocatalysts. [ABSTRACT FROM AUTHOR]

Novel Bi2W2O9 and Bi2Mo2O9 with irregular polyhedron structure were successfully synthesized by a hydrothermal method. Compared to ordinary Bi2WO6 and Bi2MoO6, the modified structure of Bi2W2O9 and Bi2Mo2O9 were observed, which led to an enhancement of photocatalytic performance. To investigate the possible mechanism of enhancing photocatalytic efficiency, the crystal structure, morphology, elemental composition, and optical properties of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9 were examined. UV-Vis diffuse reflectance spectroscopy revealed the visible-light absorption ability of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9. Photoluminescence (PL) and photocurrent indicated that Bi2W2O9 and Bi2Mo2O9 pose an enhanced ability of photogenerated electron–hole pairs separation. Radical trapping experiments revealed that photogenerated holes and superoxide radicals were the main active species. It can be conjectured that the promoted photocatalytic performance related to the modified structure, and a possible mechanism was discussed in detail. [ABSTRACT FROM AUTHOR]

• All the Ln 2 O 3 -Bi 2 MoO 6 samples efficiently enhanced the photocatalytic performance. • Specific multivalence Ln 2 O 3 loaded samples additionally produced OH. • The productivity of ·OH was dominated by 4f electronic structure of Ln(n+1)+/Lnn+. • The discipline and possible mechanism of radical production have been put forward. • Provided a foundation for fabricating Ln 2 O 3 -heterojunction photocatalysts. In order to reveal the radicals production mechanism and discipline of heterojunction photocatalysts, a series of novel Ln 2 O 3 -Bi 2 MoO 6 (Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb and Lu) were designed and successfully synthesized. The photocatalytic experiments and radical trapping experiments illustrated that all the Ln 2 O 3 -Bi 2 MoO 6 samples efficiently enhanced the photocatalytic performance, and the samples loaded by single valence Ln 2 O 3 (Nd 2 O 3 , Gd 2 O 3 , Dy 2 O 3 , Er 2 O 3 and Lu 2 O 3) could only produce superoxide radicals (·O 2 -), and holes (h+) in the photocatalytic process, and the samples loaded by multivalence Ln 2 O 3 (Ce 2 O 3 , Yb 2 O 3 , Pr 2 O 3 , Sm 2 O 3 , Eu 2 O 3 and Tb 2 O 3) additionally produced the powerful hydroxyl radical (·OH), and further enhanced the photocatalytic performance. Significantly, the Ln 2 O 3 -Bi 2 MoO 6 could produce abundant ·OH and show superior photocatalytic performance when both valence states of multivalence lanthanide ions are unstable 4f electronic structure (4f2, 4f1 in Pr3+, Pr4+ and 4f5, 4f6 in Sm3+, Sm2+), and the possible mechanism of radicals production in different Ln 2 O 3 -Bi 2 MoO 6 heterojunctions system was creatively put forward. This study deeply investigated the production discipline and mechanism of hydroxyl radical in Ln 2 O 3 -Bi 2 MoO 6 heterojunction photocatalysts, and provided a theory foundation for fabricating novel lanthanide oxide loaded photocatalysts. [ABSTRACT FROM AUTHOR]

The triple-doped Yb/Er/Pr-Bi 2 WO 6 photocatalyst presented the optimal degradation performance under visible light irradiation. The enhanced catalytic property mechanism was ascribed to the abundant superoxide anions and hydroxyl radicals production and the inhibition of charge carriers recombination. Yb/Er/Pr-BWO + hv → e- + h±. O 2 + e- → O 2 − 2e- + h± + O 2 − → HO 2. HO 2 + e- → HO 2 − HO 2 − + h± → H 2 O 2. Pr3+ + H 2 O 2 → Pr4+ + OH− + OH. H 2 O 2 + OH → HO 2 + H 2 O. Pr4+ + HO 2 → Pr3+ + O 2 + H±. H 2 O + h± → OH + H±. [Display omitted] • A novel Yb/Er/Pr-Bi 2 WO 6 catalyst was synthesized using one-step hydrothermal method. • TUnder visible light illumination, the Yb/Er/Pr triple-doped Bi 2 WO 6 exhibited outstanding photocatalytic activity. • The photo-degradation efficiency of 2.0%Yb/2.0%Er/2.0%Pr-Bi 2 WO 6 was 8.1 times for Congo Red than that of individual Bi 2 WO 6. • The mechanism of enhanced photocatalytic performance was due to thepromoted reactive oxide species production and photocarrier separation. • Provides a feasible strategy for improving photocatalytic activity of catalysts and deducing the possible mechanism. Superoxide anions (O 2 −) and hydroxyl radicals (OH) are vital reactive oxide species (ROS) in the photocatalytic process. In this study, a novel triple-doped bismuth tungstate (Yb/Er/Pr-Bi 2 WO 6) superior photocatalyst was constructed using hydrothermal method. The yield of O 2 − and OH are concurrently boosted by the synergistic effect for Yb/Er/Pr triple-doping. The X-ray photo-electron spectra confirmed the existence of oxygen vacancy and Pr4+/Pr3+ redox center, which can act as trap electron center to produce more O 2 − and promote electron-holes pairs separation. Meanwhile, Yb and Er doping observably regulated the valence band position of Bi 2 WO 6 from 2.39 V to 2.63 V, which is beneficial to produce more OH. Comprehensive characterization illustrate that Yb/Er/Pr-Bi 2 WO 6 shows superior performance in photocatalytic activity, photocarrier separation and light absorption efficiency compared with the pristine Bi 2 WO 6 , single-doped Bi 2 WO 6 and co-doped Bi 2 WO 6. The research provides a simple and valid method for enhancing the visible-light-responding photocatalytic property and exploring the possible enhanced photocatalytic performance mechanism. [ABSTRACT FROM AUTHOR]

• The Yb3+/Nd3+ - Bi 2 WO 6 was synthesized using hydrothermal method. • The degradation efficiency of 1.5%Yb3+/0.5%Nd3+-Bi 2 WO 6 was 3.7 times than that of Bi 2 WO 6. • The mechanism of improved photocatalytic proporty was ascribed to the extension range of visible light and the synergistic effect of oxygen vacancies and Yb3+/Yb2+ redox center. • Provide a new concept rational design and acquirement of visible-light-driven photocatalyst. A novel Yb3+/Nd3+-Bi 2 WO 6 photocatalyst with oxygen vacancies was synthesized through one-step hydrothermal method. The 1.5%Yb3+/0.5%Nd3+-Bi 2 WO 6 exhibited an outstanding performance, whose decomposition efficiency of Rhodamine B was 3.7 times higher than that of bare Bi 2 WO 6. The crystal structure, morphology, chemical state and optical properties were systematically investigated to reveal the mechanism of its enhanced photocatalytic performance. Its excellent visible light absorption and an absorption peak at 584 nm due to the excitation of Nd3+ were confirmed by the UV-Vis diffuse reflectance spectra of composite samples. Meanwhile, not only the existence of dopants was confirmed by the X-ray spectroscopy, but the in-built Yb3+/Yb2+ redox center was also revealed. Moreover, the formation of oxygen vacancies and Yb3+/Yb2+ redox center could effectually restrict the recombination of photo-generated electron-hole pairs, which could be demonstrated by photoluminescence characterization. Consequently, the mechanism of an enhanced photocatalytic performance was speculated about the extension range of visible light and the synergistic effect of oxygen vacancies as well as the redox center. This study provides a new concept, a rational design and the acquirement of a high-efficiency visible-light-driven photocatalyst. [ABSTRACT FROM AUTHOR]

• A novel noble-metal-free Mo 2 C-In 2 S 3 photocatalyst was synthesized by hydrothermal method. • Mo 2 C facilitates the separation of charge carriers and extends the visible light absorption of In 2 S 3. • The H 2 generation rate of the optimal Mo 2 C-In 2 S 3 composite was 25.8 times higher than In 2 S 3 -1% Pt. • The possible photocatalytic hydrogen production mechanism was discussed. Currently, designing novel noble-metal-free photocatalysts with efficient carriers migration and catalytically active sites have been a researching hotspot in photocatalytic hydrogen evolution. In this paper, a novel noble-metal-free Mo 2 C-In 2 S 3 heterojunction was synthesized by a simple hydrothermal method. Morphology characterization revealed In 2 S 3 was attached to Mo 2 C. Electrochemical results showed Mo 2 C improved the interface conductivity, and promoted the transportation of photogenerated carriers. Under visible light, the optimal Mo 2 C-In 2 S 3 composite achieved a H 2 generation rate of 535.58 μmol h−1 g−1, which was 175.6 and 25.8 times higher than pristine In 2 S 3 (3.05 μmol h−1 g−1) and In 2 S 3 -1% Pt (20.73 μmol h−1 g−1). In addition, a reasonable mechanism of the elevated photocatalytic activity was also discussed. This study demonstrates commercial Mo 2 C has an important effect of separating carriers and replacing Pt as co-catalyst in heterojunctions. This research also provides a method to design and synthesize new noble-metal-free photocatalysts for excellent hydrogen production activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel CdS-NRs@PW 12 O 40 photocatalyst was synthesized by a simple deposition method. • H 3 PW 12 O 40 facilitates the separation of charge carriers and extends the visible light absorption of CdS-NRs. • All CdS-NRs@PW 12 O 40 composite achieved higher photocatalytic activity. • The photocatalytic mechanism of superior photocatalyst was discussed. In this work, different types of Polyoxometalates (POMs), such as H 3 PW 12 O 40 , H 3 PMo 12 O 40 and TBA [MnMo 6 ] were successfully deposited on CdS nanorods (CdS-NRs) through electrostatic interaction between CdS-NRs and Polyoxometalate. The diffuse reflectance spectra after UV–visible results showed that the POMs enhanced the visible light absorption range of CdS-NRs, which ensured effective light absorption for composites. Photocurrent response results indicated that the carriers separation efficiency of composites had much higher than bare CdS-NRs. The prepared photocatalysts were further subjected for photocatalytic degradation of organic pollutants and around 98% of dye has been removed from the system. The Radical trapping experiments further clarify that that h+ and O 2 − are the major factors in photocatalytic pollutant degradation. To investigate the stability, POM loaded CdS-NRs composite was repeated four times for photocatalysis, which shows high efficiency till fourth cycle. The aforesaid results indicate that, POMs on the surface of CdS-NRs materials effectively enhance the photocatalytic performance and CdS-NRs provide a suitable support for POMs to modify them for heterogeneous catalysis. This work opens a new and feasible pathway to design the heterostructure photocatalysts using POMs and sulfides for high-efficiency environmental purification. [ABSTRACT FROM AUTHOR]

Various Ln a /Ln b co-doped bismuth molybdate (Bi 2 MoO 6 ) photocatalysts were synthesized by a hydrothermal process. The result of photocatalytic experiment demonstrated that the relevant Ln 1 3+ 4 f 7+x /Ln 2 3+ 4 f 7−x (Ln 1 /Ln 2 = Tb/Eu, Dy/Sm, Er/Nd; x = 1, 2, 4) co-doped Bi 2 MoO 6 samples shows higher photocatalytic activities. Moreover, all the photocatalytic activities of Ln 1 /Ln 2 co-doped Bi 2 MoO 6 were higher than that of the corresponding single-doped Bi 2 MoO 6 . The crystalline structures, morphology, constituent contents, chemical state and optical properties of the samples were analyzed in detail. Meanwhile, a new conjecture about the complementary distribution of 4 f orbital electrons in the Ln 1 /Ln 2 redox couple was proposed through co-doping with Ln 1 and Ln 2 ions to improve the photocatalytic activity of Bi 2 MoO 6 . For the Bi 2 MoO 6 photcatalyst, Dy/Sm co-doping displayed the strongest photocurrent response as well as the best photocatalytic activity, while Tb/Eu co-doping displayed the apparently extended visible-light absorption region. These findings provides a novel strategy to fabricate and engineer high-efficiency photocatalysts by selecting appropriate Ln 1 /Ln 2 redox couple. [ABSTRACT FROM AUTHOR]

Lanthanide titanate (La 2 Ti 2 O 7 ) with strong reduction-oxidation ability has been regarded as a new promising photocatalyst. To boost its photocatalytic activity, g-C 3 N 4 /La 2 Ti 2 O 7 composites were designed and constructed. The results reveal that La 2 Ti 2 O 7 nanosheets were well attached to the surface of g-C 3 N 4 and the composites had good visible-light absorption properties. Significantly, compared to pure La 2 Ti 2 O 7 and g-C 3 N 4 , the composites exhibited outstanding photocatalytic performance under visible-light irradiation. The enhanced photocatalytic activity could be derived from the effective transportation of photogenerated electrons from g-C 3 N 4 to La 2 Ti 2 O 7 . The electrons with high reduction ability can generate more active species to participate in the photodegradation reaction. [ABSTRACT FROM AUTHOR]

In this study, a novel SnS 2 /BiOBr heterojunction photocatalyst was synthesized via a facile in-situ growth strategy. The heterojunction interface was formed by loading BiOBr nanosheets on the surface of ultrathin hexagonal SnS 2 nanoplates. UV/Vis diffuse reflectance spectroscopy (DRS) indicated that SnS 2 /BiOBr composites possessed stronger visible-light absorption. The as-fabricated SnS 2 /BiOBr heterojunction nanoplates exhibited considerable improvement in terms of photocatalytic activity for the degradation of rhodamine B (RhB) under visible light irradiation as compared with BiOBr and SnS 2 . The enhanced photocatalytic activity was attributed to the closely contacted interface between BiOBr and SnS 2 , thereby resulting in faster transfer of the photoinduced electron–hole pairs through their interface, as shown by the results of photoluminescence spectroscopy (PL) and photocurrent measurements. Radical trapping experiments demonstrated that holes (h + ) and superoxide anion radicals ( O 2 − ) were the main active species in the photocatalytic oxidation process. The mechanism of the excellent photocatalytic activity of SnS 2 /BiOBr heterojunction composite was also discussed. [ABSTRACT FROM AUTHOR]

A new acting mechanism of oxygen vacancy that effected on the charge separation and light absorption in Lu-doped Bi 2 MoO 6 was proposed, and the formed oxygen vacancies resulted in improving photocatalytic activity. [Display omitted] • Doping of Lu3+ could obviously improve the photocatalytic activity of Bi 2 MoO 6. • The shape transformed from nanosheet to nanorod due to the exposed {0 1 0} facets. • The oxygen vacancies were formed in the lattice of Lu-doped Bi 2 MoO 6. • The formed oxygen vacancy make for enhanced charge separation and light absorption. Lu-doped Bi 2 MoO 6 nanosheets were successfully synthesized by a hydrothermal process. The morphology of Bi 2 MoO 6 can be controlled from nanosheets to nanorods by doping different content of Lu3+, which ascribed to the selectively exposed {0 1 0} facets as the main external surfaces. The results of the first principles calculation and the characterization revealed that the oxygen vacancies were formed in the lattice of Lu-doped Bi 2 MoO 6. What's more, the formed oxygen vacancies played a role in improving charge separation and enhancing light absorption, which confirmed with Photoluminescence spectra (PL) and Diffuse Reflectance Spectra (DRS), respectively. And these results lead to the enhanced photocatalytic activity of Bi 2 MoO 6 for the degradation of RhB and phenol. The introduction of the oxygen vacancies by doping of Lu3+ ions will provide the new strategies to improve the efficiency of photocatalysts. [ABSTRACT FROM AUTHOR]

In this study, a novel Bi 2 O 2 CO 3 /BiOBr p-n heterojunction was synthesized via a two-step solvothermal method. The p-n interface was formed by loading Bi 2 O 2 CO 3 nanoparticles on the surface of BiOBr nanosheets. The crystal structure, morphology, and optical property of the as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectroscopy, respectively. The obtained Bi 2 O 2 CO 3 /BiOBr p-n heterojunction composites exhibited the superior photocatalytic activity for the degrading rhodamine B (RhB) under visible light irradiation as compared with Bi 2 O 2 CO 3 and BiOBr. Four times cycling experiments demonstrated that the composites had good photostability and recyclability. The enhanced photocatalytic activity of Bi 2 O 2 CO 3 /BiOBr composites was mainly attributed to the formation of p-n heterojunction between Bi 2 O 2 CO 3 and BiOBr, thereby resulting in faster transfer of the photoinduced electron–hole pairs through their interface. Radical trapping experiments confirmed that h + and O 2 − were two main active species in the photocatalytic process. The possible mechanism of the enhanced photocatalytic activity was proposed, which revealed the transfer of the charge carriers and the formation of the active species in photocatalytic process. [ABSTRACT FROM AUTHOR]

Direct Z-scheme photocatalyst systems with efficient charge separation as well as outstanding oxidation and reduction ability have been under immense investigation. In our work, direct Z-scheme MoS 2 /Bi 2 WO 6 heterojunctions were prepared by a facile method. The heterostructure was formed by loading MoS 2 nanoparticles on the surface of Bi 2 WO 6 nanosheets. It was found that the as-prepared MoS 2 /Bi 2 WO 6 composites showed superior photocatalytic activity than that of individual MoS 2 and Bi 2 WO 6 . The optimal composite with 4 at% MoS 2 content exhibited the highest photocatalytic activity. Based on the active species trapping experiments, photoluminescence spectroscopy analysis, and photocurrent responses, the possible enhanced photocatalytic mechanism could be ascribed to a direct Z-scheme heterojunction system which can not only increase the separation efficiency of photogenerated electron-hole pairs but also possess a splendid oxidation and reduction ability for high photocatalytic performances. This work provides an effective approach to develop other Bi 2 WO 6 -based direct Z-scheme photocatalytic systems for environmental purification and energy conversion. [ABSTRACT FROM AUTHOR]

• A novel noble-metal-free ternary In 2 S 3 photocatalyst with W-Mo auxiliary pairs was synthesized by a solvothermal method. • WC and MoS 2 can form W-Mo auxiliary pairs that will be utilized to synergistically maximize the photocatalytic activity. • The photocatalytic activity of optimal In 2 S 3 -WC and In 2 S 3 -WC-MoS 2 is much higher than pure In 2 S 3 and In 2 S 3 -1% Pt. • The very possible photocatalytic hydrogen production mechanism of superior photocatalyst was discussed. [Display omitted] Herein, noble-metal-free In 2 S 3 -WC and In 2 S 3 -based photocatalysts with dual cocatalysts of flower-like MoS 2 and bulk WC were synthesized through a facile solvothermal reaction. Electrochemical results indicated WC increased the interface conductance of photocatalyst and boosted the transference of photogenerated carriers. The optimal In 2 S 3 -WC show a hydrogen production rate of 128.11 μmol·h−1·g−1, which is around 6 times higher than In 2 S 3 -1%Pt (20.73 μmol·h−1·g−1). The above results demonstrate commercial WC has a crucial impact of replacing precious metal and separating carriers. Morphology characterization exhibited hydrangea In 2 S 3 and flower-like MoS 2 were attached to bulk WC. Gratifyingly, photocurrent, impedance and photoluminescence results demonstrated MoS 2 further effectively separated the photogenerated carriers. Remarkably, the higher hydrogen generation rate of 390.52 μmol·h−1·g−1 obtained by the optimal ternary In 2 S 3 -WC-MoS 2 composite was around 3 and 18 times higher than the optimal In 2 S 3 -WC and In 2 S 3 -1% Pt. The photocatalytic results demonstrated that "W-Mo auxiliary pairs" was a great efficient synergistic cocatalyst for In 2 S 3 to increase active sites and improve e--h+ pairs separation for H 2 generation. Furthermore, a probable reaction mechanism of the enhanced photocatalytic H 2 generation was also proposed. This presented research provides an effective concept to design novel and efficient noble-metal-free photocatalyst with "W-Mo auxiliary pairs" for prominent H 2 generation activity. [ABSTRACT FROM AUTHOR]

Yb-doped Bi 2 WO 6 nanomaterials were successfully synthesized using a mild hydrothermal method. Remarkably, Yb-doped Bi 2 WO 6 photocatalysts exhibited a higher photocatalytic activity than pristine Bi 2 WO 6 by degrading RhB under visible light irradiation. The optimum mass ratio of Yb to Bi 2 WO 6 was 2.0%, and it presented the highest photo-degradation efficiency. The crystal structures, morphologies, surface chemical states, and optical properties of the as-synthesized photocatalysts were carried out by XRD, SEM, XPS and DRS, respectively. The results of electron paramagnetic resonance spectroscopy, radical trapping experiments, photoluminescence spectroscopy and photocurrent measurements indicated that the Yb-doped Bi 2 WO 6 samples produced more oxygen vacancies and superoxide anion active groups (.O 2 −), inhibited the recombination of the photo-generated electron-hole pairs, and enhanced the photo-degradation performance. As a result, the dopant Yb3+ could enhance photocatalytic performance of Bi 2 WO 6 by introducing oxygen vacancies into its lattice. This study provides a useful strategy for developing effective visible light photocatalysts. Under visible light irradiation, the mechanism of the enhancement photocatalytic performance of Yb–Bi 2 WO 6 samples was proposed, which effected on forming the oxygen vacancies, enhancing the production of superoxide anion active radicals, inhibiting the recombination of photo-generated charge carriers. Image 1 • Doping of ytterbium could obviously improve the photocatalytic performance of Bi 2 WO 6. • The optimum mass ratio of Yb to Bi 2 WO 6 was 2.0%, and it presented the highest photo-degradation efficiency. • Doping of Yb3+ could form the oxygen vacancies and the formed oxygen vacancies make for produced more .O 2 −. • The possible degradation mechanism of Yb–Bi 2 WO 6 photocatalysts was systematically discussed. • Provide a strategy to develop effective visible light catalysts. [ABSTRACT FROM AUTHOR]