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A novel AgI/BiOBr/reduced graphene oxide (RGO) composite was prepared through a facile solvothermal method followed by an in-situ precipitation process. The as-prepared AgI/BiOBr/RGO ternary composite exhibited significantly enhanced photocatalytic activity towards the degradation of tetracycline (TC) under simulated sunlight irradiation. The degradation rate of AgI/BiOBr/RGO was approximately 5.9 and 2.9 times higher than that of pristine BiOBr and AgI, respectively. The improved photocatalytic activity of AgI/BiOBr/RGO composite could be ascribed to the synergistic effect of AgI, BiOBr and RGO. The RGO/BiOBr nanosheets could provide aboundant reactive active sites and serve as appropriate substrates for in-situ growth of AgI NPs. Furthermore, RGO with superior electronic conductivity accelerated the separation of photogenerated electron-hole pairs in AgI/BiOBr/RGO composite, as well as extended visible-light absorption capability. The possible degradation pathway of TC was proposed through the identification of intermediate products using LC-MS analysis. Additionally, combined with the results of active species trapping experiments and ESR measurements, a possible mechanism of RGO-promoted Z-scheme charge transfer for AgI/BiOBr/RGO composite was proposed. Image 1 • A novel AgI/BiOBr/RGO ternary composite was successfully synthesized. • AgI/BiOBr/RGO composite showed superior photodegredation of tetracycline. • Possible degradation pathway of tetracycline was analyzed. • A RGO-promoted Z-scheme photocatalytic mechanism was proposed. [ABSTRACT FROM AUTHOR]

Abstract Novel hierarchical sheet-on-sheet WO 3 /g-C 3 N 4 (WOCN) composites were successfully fabricated by simple calcination method using acid-treated SrWO 4 /g-C 3 N 4 as precursors. The morphological observation showed that WO 3 nanosheets were closely anchored on the surface of g-C 3 N 4 nanosheets to construct a hierarchical nanostructure. The as-synthesized WOCN composites exhibited a significantly higher photocatalytic activity towards the photocatalytic degradation of rhodamine B (RhB) compared to pristine g-C 3 N 4 and WO 3 under simulated sunlight irradiation. The optimum photocatalytic activity of the WOCN at a WO 3 mass content of 34.6% was 6.5 and 3.0 times higher than that of pristine WO 3 and g-C 3 N 4 , respectively. The enhanced photocatalytic activities of WOCN composites were attributed to the formation of hierarchical heterostructure, which provided larger specific surface area, better visible-light absorption capability, reduced the recombination of photogenerated electron-hole pairs and enhanced separation efficiency of charge carriers. A Z-scheme photocatalytic mechanism was proposed according to active species trapping experiments. Graphical abstract Image 1 Highlights • Hierarchical sheet-on-sheet WO 3 /g-C 3 N 4 composites were successfully synthesized. • The composites provided larger surface area than pristine g-C 3 N 4 and WO 3. • The hierarchical heterostructure facilitated charge separation and transfer. • The composites exhibited enhanced photocatalytic activity and high stability. • A Z-scheme photocatalytic mechanism was proposed. [ABSTRACT FROM AUTHOR]

Graphene-semiconductor nanocomposites, considered as one of the most promising noblemetal-free photocatalysts, have shown remarkable performance and drawn significant attention in the field of photocatalytic reaction using solar energy, due to the excellent physicochemical properties of graphene. Here, a facile and novel method called liquid-exfoliation and solvethermal method was used for preparing TiO 2 /SnS 2 /RGO nanocomposite with intimate hetero-interface. Under visible-light irradiation, the TiO 2 /SnS 2 /RGO nanocomposite showed high photoactivity for the degradation of Rhodamine B (RhB). The positive synergistic effect is emerged between these layered SnS 2 and RGO components, which contributes to the enhanced photoactivity of TiO 2 nano-particles through reducing the recombination of photogenerated electron/hole pairs, enhancing the rate of electron-transfer and providing more reaction active sites for the degradation of dye molecules. The coupling formation of TiO 2 , SnS 2 and RGO at the interface of composite photocatalyst was investigated by density functional theory (DFT) method in a molecular cluster level and the calculations results showed that the firm structures could be formed at the interfaces of TiO 2 nanoparticles and SnS 2 /RGO. and Active component analysis showed that the synergy of various components containing ·O 2 − , e − , OH was predicted to determine the degradation process. The photocatalytic mechanism was also discussed and Z-scheme electron-transfer was predicted as the charge-transfer type of TiO 2 /SnS 2 on RGO. [ABSTRACT FROM AUTHOR]

A novel 3D hierarchical flower-like BiOBr/Bi 3 O 4 Br heterostructure photocatalyst was synthesized by in-situ growth of ultrathin BiOBr on the surface of Bi 3 O 4 Br nanosheets through a solvothermal process. The 3D hierarchical heterostructure endows BiOBr/Bi 3 O 4 Br heterojunction with a large specific surface area and tight interfacial contact, which can provide sufficient channels for carrier migration. The introduction of Bi 3 O 4 Br can enhance the light absorption ability of BiOBr/Bi 3 O 4 Br photocatalysts. Furthermore, the staggered type II heterostructure energy band alignment formed between BiOBr and Bi 3 O 4 Br can promote the separation of photo-excited carriers. The improved performance of carrier migration and light absorption ability was evaluated by SEM, TEM, BET, EIS, and DRS tests. The results of transient photocurrent response and photoluminescence tests confirmed the improvement for separating photoexcited carriers. The optimal 20% BiOBr/Bi 3 O 4 Br sample exhibited the greatest photocatalytic degradation rate of 97.1% for RhB and 89.4% for TC, under 90 min of simulated solar light irradiation. Its apparent rate constant k values are 0.03378 and 0.02013 min−1, being 9.44 and 2.18 folds than that of Bi 3 O 4 Br, 2.76 and 1.47 folds than that of BiOBr. The free radical scavenging experiment results showed that h+ and •O 2 - are the prime active species during the photodegradation process. Hence, a possible photocatalytic mechanism of type II BiOBr/Bi 3 O 4 Br heterojunction was proposed. [Display omitted] • A novel 3D hierarchical flower-like BiOBr/Bi 3 O 4 Br heterostructure was fabricated by a solvothermal method. • Hierarchical heterostructure can offer wider pore size distribution and tight interfacial contact. • BiOBr/Bi 3 O 4 Br composite exhibited superior photodegradation of RhB and TC. • The BiOBr/Bi 3 O 4 Br composite has a type-II carrier transfer and migrate mechanism. [ABSTRACT FROM AUTHOR]

A novel Z-scheme BiOCl/Bi 24 O 31 Br 10 heterojunction with hierarchical structure was firstly fabricated, in which BiOCl nanosheets grew in-situ and vertically on the surface of Bi 24 O 31 Br 10 nanosheets. The obtained BiOCl/Bi 24 O 31 Br 10 composites exhibited favorable photocatalytic activity for RhB degradation under simulated sunlight irradiation. Especially, BB-0.3 (mass fraction of Bi 24 O 31 Br 10 , 30%) composite performed the best photocatalytic activity, and its degradation rate constant (k) for RhB was nearly 4.1 and 7.7 times higher than that of pure BiOCl and Bi 24 O 31 Br 10 , respectively. Larger specific surface area, wider photo-response range and efficient separation of photogenerated carriers were the main reasons for improving photocatalytic activity, which could be proved by Brunner-Emmett-Teller (BET) analysis, UV–vis diffuse reflectance spectra (UV–vis DRS), photoluminescence spectra (PL), transient photocurrent response and electrochemical impedance (EIS). Meanwhile, the effects of the catalyst dosage, pollutant concentration, initial solution pH and inorganic ions were discussed. Free radical scavenging experiments and electron spin resonance (ESR) measurement indicated that •O 2 - and h+ made significant contributions to the photocatalytic degradation of RhB. And recycling tests showed that the BB-0.3 heterojunction had a good stability. The possible photocatalytic mechanism of the Z-scheme heterojunction between BiOCl and Bi 24 O 31 Br 10 was proposed. [Display omitted] • BiOCl/Bi 24 O 31 Br 10 heterojunction is firstly fabricated by solvothermal method. • BiOCl nanosheets grow in-suit and vertically on the surface of Bi 24 O 31 Br 10. • BiOCl nanosheets and Bi 24 O 31 Br 10 nanosheets form a 3D hierarchical structure. • BiOCl/Bi 24 O 31 Br 10 heterojunction exhibits good photocatalytic activity. [ABSTRACT FROM AUTHOR]

• Several rGO-MoSe 2 with different morphologies and structures were synthesized by a rGO-assisted solvothermal method. • A novel rGO-MoSe 2 /g-C 3 N 4 composite with 3D/2D hierarchical structure was constructed. • rGO-MoSe 2 /g-C 3 N 4 composite showed superior photodegradation of RhB and TC. • rGO between MoSe 2 and g-C 3 N 4 serve as a high-speed channel across Z-scheme junction. • rGO promoted Z-scheme MoSe 2 -based heterojunction mechanism was proposed. [Display omitted] The transition-metal dichalcogenides (TMDs) is a promising photocatalyst for degrading contaminant, while limited active sites and poor carrier mobility are the primary challenges for improving photocatalytic degrading efficiencies in both bare TMDs and TMDs-based photocatalysts. A rGO-MoSe 2 composite with 3D network hierarchical structure was fabricated by the GO-assisted solvothermal method. And then rGO-MoSe 2 /g-C 3 N 4 3D/2D hierarchical structures were constructed by combining rGO-MoSe 2 with g-C 3 N 4 nanosheets. The optimal rGO-MoSe 2 /g-C 3 N 4 composite exhibited the highest photocatalytic degrading rate of 97.4% towards RhB under simulated solar light, and its pseudo-first-order apparent rate constant (k) was 0.0715 min−1, being 5.9 and 12.5-folds higher than that of MoSe 2 /g-C 3 N 4 (0.0121 min−1) and bare g-C 3 N 4 (0.00573 min−1), respectively. The 3D/2D hierarchical structure endow rGO-MoSe 2 /g-C 3 N 4 composite with the improved light-harvesting and abundant active sites, supported by the DRS and BET analyses. And rGO nanosheets could act as efficient transfer and separation channels for electron-hole pairs between MoSe 2 and g-C 3 N 4 , confirmed through the photocurrent response and EIS tests. According to the results of DRS spectra and Mott-Schottky plots, the spatial behavior of photo-induced carriers at interface of rGO-MoSe 2 /g-C 3 N 4 would comply to a Z-scheme transfer pathway under the synergy effects of the internal electric field and band bending. [ABSTRACT FROM AUTHOR]

• A novel BiOCl/Bi 5 O 7 I 2D/3D heterostructure was constructed by in-situ growth method. • The composite exhibited enhanced photocatalytic efficiency for degradation of RhB. • The 2D/3D heterostructure can offer a larger specific surface area and enhanced light absorption capacity. • Type Ⅱ heterojunction of composite can reduce the recombination of photogenerated carriers. [Display omitted] A novel BiOCl/Bi 5 O 7 I (BOC-BOI) heterojunction was prepared by growing ultrathin 2D BiOCl nanosheets in situ on the surface of 3D Bi 5 O 7 I microspheres. The 2D/3D heterostructure of BOC-BOI composites inhibited the agglomeration of BiOCl nanosheets, and benefited the multiple reflection and refraction of light, which greatly enhanced the absorption and utilization of light. The 50-BOC-BOI composite showed 97.7% degradation efficiency of rhodamine B (RhB) after 70 min Xe light irradiation. And its apparent degradation rate constant (k) was 0.0377 min−1, being 4.9 and 15.1 times than that of pristine BiOCl (0.0077 min−1) and Bi 5 O 7 I (0.0025 min−1), respectively. The enhanced photocatalytic activity of BOC-BOI composites was attributed to stronger light capture ability, more abundant active sites and higher charge carrier separation efficiency, confirmed by UV-Vis DRS, SEM, TEM, BET, Zeta potential and electrochemical characterizations. The free radical capture experiments showed that the main active species in this system were holes (h+) and superoxide free radicals (·O 2 −). Combining the results of UV-Vis DRS and Mott-Schottky test, a reasonable type II heterojunction mechanism was proposed. [ABSTRACT FROM AUTHOR]

• BiOIO 3 /BiOI/Bi 2 S 3 (BBS-x) was first synthesized via in situ reduction and chemical deposition. • BBS-x composite has enhanced photocatalytic activity. • BBS-x widens light harvesting ability of BiOIO 3 , improving utilization of solar energy. • The BBS-x composite has a type-Ⅱ carrier migrate and transfer mechanism. [Display omitted] BiOIO 3 /BiOI/Bi 2 S 3 (BBS-x) heterostructure composites are first synthesized via in situ reduction and chemical deposition. The BiOIO 3 /BiOI/Bi 2 S 3 composites integrate the merits of BiOI and Bi 2 S 3 , with a widened light response range and improved light absorbance ability, as confirmed by the DRS test. The close type-Ⅱ interface along with carrier migrate and transfer mechanism can spatially isolate photoinduced e- and h+, hinder the recombination of photogenerated carriers and boost their efficiency transfer and separation, as proven by scanning electron microscopy, transmission electron microscopy, electrochemical impedance spectroscopy, transient photocurrent response, and photoluminescence. These properties enhance the photocatalytic activity of BiOIO 3 /BiOI/Bi 2 S 3 composites when applied to the photodegradation of rhodamine B, regardless of their irradiation with simulated solar light or LED light. The BBS-0.75 composite has the highest apparent rate constant k (0.034 min−1) under simulated solar light irradiation, which is approximately 4.5 times greater than that of pure BiOIO 3 (0.0076 min−1). The BBS-0.75 composite almost completely photodegrades RhB within 30 min under LED light irradiation. Free radical scavenging experiments reveal that •O 2 - and h+ are the main reactive species. Thus, a logical type-II carrier transfer mechanism with dye sensitization is proposed. [ABSTRACT FROM AUTHOR]

• A dual Z-scheme AgI/1T-2H MoSe 2 /Bi 4 O 5 Br 2 heterojunction was designed. • AgI/1T-2H MoSe 2 /Bi 4 O 5 Br 2 composite showed superior photodegradation of RhB and TC. • 1T-2H MoSe 2 between AgI and Bi 4 O 5 Br 2 serves as an interfacial charge transfer bridge across dual Z-scheme junction. • Band offsets were introduced in photocatalytic mechanism of AgI/1T-2H MoSe 2 /Bi 4 O 5 Br 2. • 1T-2H MoSe 2 bridged dual Z-scheme MoSe 2 -based heterojunction mechanism was proposed. [Display omitted] The transition-metal dichalcogenides (TMDs) with 1T phase structure holds great promise for providing abundant active sites and superior conductivity, while the achievement of highly efficient degradation activity over bare TMDs and TMDs-based photocatalysts is still challenges. In this work, a flower-like mixed 1T-2H phase MoSe 2 was synthesized via a sodium borohydride (NaBH 4)-assisted solvothermal method, and then was selected as a "charge-transfer-bridge" to fabricate a dual Z-scheme AgI/1T-2H MoSe 2 /Bi 4 O 5 Br 2 composite with a 0D/3D hierarchical structure. The optimal AgI/1T-2H MoSe 2 /Bi 4 O 5 Br 2 composite exhibited the superior photocatalytic activity towards degrading RhB and TC relative to AgI/2H MoSe 2 /Bi 4 O 5 Br 2 and AgI/Bi 4 O 5 Br 2. The enhancement is attributed to its better light absorption, abundant active sites, and superior charge carrier mobility and separation efficiency, resulted from synergetic effect of 0D/3D structural coupling and energy band matching. Moreover, the important energy band alignments and mixed 1T-2H phase MoSe 2 boosting photocatalytic mechanism of as-prepared AgI/1T-2H MoSe 2 /Bi 4 O 5 Br 2 heterojunction were investigated. This work describes a competitive design and fabrication technique for constructing novel mixed phase TMDs-based Z-scheme heterojunctions to address environmental issues. [ABSTRACT FROM AUTHOR]

A novel BiOIO 3 /MoS 2 (BM-x) 2D/2D heterostructure was firstly constructed by hybridizing BiOIO 3 with MoS 2 through solvothermal process. The formation of BM-x 2D/2D heterostructure with higher specific surface area and larger interfaces can offer ample channel for the transmission of charge, confirmed by SEM, TEM, BET and EIS. Introduction of MoS 2 could improve light harvesting abilities of BM-x composites, which was demonstrated by DRS. Moreover, a staggered type-Ⅱ heterojunction and built-in electric field between BiOIO 3 and MoS 2 were formed, facilitating the separation of photogenerated carriers, proven via transient photocurrent response and PL. The BM-x composites could be applied to the photocatalytic degradation of rhodamine B (RhB). Above properties endow BM-x composites enhanced photocatalytic efficiencies for degradation of RhB than pure BiOIO 3 under simulated solar-light irradiation, and the BM-1.0 composite showed the optimized degradation rate constant (0.04189 min−1), which is 5.2 times higher than that of pristine BiOIO 3 (0.00811 min−1). Free radical scavenging experiments reveal that h+ and •O 2 − are primarily responsible for the photocatalytic degradation of RhB in this system, and a possible type-Ⅱ heterojunction mechanism with dye sensitization was proposed. • BiOIO 3 /MoS 2 2D/2D heterostructure was constructed by solvothermal process. • Introduction of MoS 2 boosted light harvesting ability of BiOIO 3. • Type-Ⅱ heterojunction of composite can reduce photoinduced carriers' recombination. • The 2D/2D heterostructure can offer ample channel for the transmission of charge. • The composite exhibited enhanced photocatalytic efficiency for degradation of RhB. [ABSTRACT FROM AUTHOR]