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A synergistic strategy of Facet engineering and the construction of Z-scheme heterojunctions is expected to improve internal consumption and insufficient carriers in photocatalysis significantly. In this paper, Fe 2 O 3 nanoparticles were selectively grown on the (110) facet of BiVO 4 , and facet orientation-supported Z-scheme heterojunction of BiVO 4 (110)-Fe 2 O 3 was constructed for the photocatalytic degradation of tetracycline. The effects of catalyst dosage, pH, temperature, and other conditions on the degradation performance were systematically investigated and found to have excellent catalytic activity, structural stability, and reusability. The removal of TC (15 mg·L−1) under 60 min visible light irradiation were 57.7%, 81.7%, and 91.5% for single-phase catalyst, non-directionally loaded BiVO 4 -Fe 2 O 3 and directionally loaded BiVO 4 (110)-Fe 2 O 3 Z-scheme heterojunction (0.3 g·L−1), respectively. Combining photoelectric testing and DFT calculation, it was confirmed that the presence of the built-in electric field from BiVO 4 (110) pointing to Fe 2 O 3 (110) in BiVO 4 (110)-Fe 2 O 3 Z-scheme heterojunction facilitates the separation and transfer of photogenerated carriers and significantly improves the photodegradation performance of the material. In addition, the intermediates and degradation pathways were investigated in detail. [Display omitted] • Facet orientation-supported Z-scheme heterojunction BiVO 4 (110)-Fe 2 O 3 was constructed. • Effects of different conditions on tetracycline (TC) photodegradation were investigated. • The removal of TC was 57.7%, 81.7%, and 91.5% for BiVO 4 , BiVO 4 -Fe 2 O 3 and BiVO 4 (110)-Fe 2 O 3 respectively. • BIEF from BiVO 4 (110) to Fe 2 O 3 facilitates separation and transfer of photogenerated carriers. • The intermediates and degradation pathways were investigated in detail. [ABSTRACT FROM AUTHOR]

Photocatalytic activation of persulfate for the synergistic degradation of pollutants has become a major research hotspot, but the activation effect is poor due to the problems of low catalyst carrier separation efficiency and insufficient active sites. In this study, direct Z-Scheme heterojunctions of MoO 2 @CoFe LDHs were prepared by a simple hydrothermal method and a Co and Fe dual active site system was constructed to activate Na 2 S 2 O 8 (PS) for the synergistic degradation of tetracycline under visible light. The results showed that the synergistic degradation of tetracycline was 3.7 times and 2.7 times more efficient than the original heterojunction and PS, respectively. Combining material characterisation, photovoltaic performance tests and theoretical calculations revealed that the high efficiency is attributed to the formation of an internal electric field under the Z-Scheme heterostructure type generating effective electron-hole separation, with more photo-generated electrons converted into radicals acting together with holes to degrade the TC and activate the PS. More importantly, Co(II) and Fe(II) provide electrons to synergistically activate PS, and a portion of the photogenerated electrons and PS activation intermediates can facilitate cycling between Co(II)/Co(III) and Fe(II)/Fe(III) to accelerate PS activation. This paper's work on activating PS-assisted Z-Scheme heterojunctions for the efficient degradation of TC provides a reference for the study of high-performance photocatalytic catalysts for the degradation of organic pollutants. [Display omitted] • MoO 2 @LDHs Z-scheme heterojunction was prepared and activated with Na 2 S 2 O 8 (PS). • A series of influencing factors on TC photodegradation were investigated. • The removal of TC increased sharply to 92.7 % with the addition of 6 mmol/L PS. • BIEF boosts electrons to be converted into radicals during the degradation of TC. • Combination of Co(II) and Fe(II) provide electrons to synergistically activate PS. [ABSTRACT FROM AUTHOR]

[Display omitted] • BiVO 4 /ZnIn 2 S 4 heterojunction rich in sulfur vacancy (BVO/S v -ZIS) were used for pNRR. • Without sacrificial reagent, the ammonia generation rate reached 80.6 μmol·g−1·h−1. • Sulfur vacancy (S v) is the active site of N 2 chemisorption. • Photogenerated electrons are transferred to N 2 molecules with S v as a bridge. • Efficiency of electron injection into N 2 molecules on heterojunction was enhanced. The low efficiency of photogenerated electron injection into N 2 molecule is the key problem to limit the improvement of activity for photocatalytic ammonia synthesis of heterojunction materials. In this paper, BiVO 4 /ZnIn 2 S 4 direct Z-scheme heterojunction rich in sulfur vacancies (BVO/S v -ZIS) were synthesized by solvothermal method and used for photocatalytic nitrogen reduction reaction (pNRR). Without sacrificial reagent, the ammonia generation rate reached 80.6 μmol·g−1·h−1, which is 3.5 times and 4.5 times higher than that of pristine BVO and ZIS, respectively. The results of N 2 -TPD, XPS and DFT calculation show that sulfur vacancy (S v) is not only the active site of N 2 chemisorption, but also can capture photogenerated electrons and change the local electronic structure on the surface of heterojunction. The photogenerated electrons are continuously transferred to N 2 molecules with S v as a bridge, so as to break the barrier and enhance the efficiency of electron injection into N 2 molecules during pNRR on heterojunction. [ABSTRACT FROM AUTHOR]

[Display omitted] In this paper, the novel 3D hollow Z-scheme heterojunction photocatalysts based on Bi 2 O 3 and CoAl layered double hydroxides (Bi 2 O 3 @CoAl-LDHs) were prepared for efficient visible-light-driven photocatalytic ammonia synthesis. The synthesized nanohybrid exhibits excellent photocatalytic ammonia synthesis performance (48.7 μmol·L−1·h−1) and structural stability, which is primarily attributed to the fact that Z-scheme heterojunction significantly enhanced lifetime of photogenerated carriers (6.22 ns) and transfer efficiency of surface photogenerated electrons (72.5%). Strict control experiments and nitrogen isotope labeling results show that nitrogen and hydrogen in the produced ammonia come from nitrogen and water in the reactant respectively. Electron paramagnetic resonance (EPR) experiments and density functional theory (DFT) calculations further reveal that the built-in electric field due to the difference between Bi 2 O 3 and CoAl-LDHs is the key to constructing the Z-scheme heterojunction. In addition, results of partial density of states (PDOS) show that Co in Bi 2 O 3 @CoAl-LDHs composite is the active site for photocatalytic N 2 fixation. [ABSTRACT FROM AUTHOR]

• Fe-POMs/LDHs Z-scheme heterojunction was constructed for photodegradation of tetracycline (TC). • Heterojunction degraded TC up to 90.7 %, which is much higher than that of only PS and catalyst. • Built-in electric field in Z-scheme heterojunction promotes carrier transport. • High reduction potential of heterojunction is benefit for PS activation to generate sulphate radical. • Cycling between Co(II)/Co(III), Fe(II)/Fe(III) and W(IV)/W(VI) can continuously activate PS. Semiconductor photocatalytic activation of persulfate for synergistic degradation of pollutants is a hotspot, but the activation effect is insufficient due to the slow carrier transport and the limited strength of the reduction potential. In this paper, Fe-POMs/LDHs Z-scheme heterojunction photocatalyst was constructed for the degradation of tetracycline (TC). Under optimal conditions, the heterojunction degraded tetracycline up to 90.7 %, which was 2.9 and 3.0 times higher than that of single-phase PS versus Fe-POMs/LDHs (unactivated PS), and the degradation rate still reached more than 80 % after four recycles. Material characterization and theoretical calculations revealed that the excellent photocatalytic activity was attributed to the composite constructed as a Z-Scheme heterojunction. On the one hand, the high-intensity built-in electric field promotes carrier transport; meanwhile, the material possesses a high reduction potential, which promotes the activation of Na 2 S 2 O 8 (PS) to generate sulfate radicals, which creates a synergistic effect in the photodegradation of tetracycline (TC). In addition, elements such as Co(II), Fe(II), and W(IV) provide additional electrons to accelerate the activation of PS, and a portion of the photogenerated electrons and PS activation intermediates can promote the cycling between Co(II)/Co(III), Fe(II)/Fe(III), and W(IV)/W(VI) to continuously activate PS. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Semi-coherent interface Cu 2 O/Cu 7 S 4 heterojunction was constructed by epitaxial growth method. • Semi-coherent interface Cu 2 O/Cu 7 S 4 heterojunction forms a unique S-Cu-O bonds. • The semi-coherent interface and S-Cu-O bonds jointly promote the degradation of tetracycline. • The removal of tetracycline can reach 95.93% under optimal conditions. • The photodegradation pathway of TC is proposed. The steric effect caused by the lattice mismatch between the two phases hinders the separation and transfer of photogenerated carriers, which is one of the important factors limiting the activity of heterojunction photocatalysts. In this paper, semi - coherent interface Cu2O/Cu7S4 heterojunction was successfully constructed based on the epitaxy growth method of anion exchange. The degradation of tetracycline by semi - coherent interface Cu 2 O/Cu 7 S 4 -30 heterojunction under simulated visible light reached 95.3 % at 60 min, which is a significant improvement compared with single-phase catalysts and ordinary heterojunction catalysts (Cu 2 O/Cu 7 S 4 -mix). The experimental characterization and theoretical calculations confirmed the existence of unique S-Cu-O chemical bonds in the semi - coherent interface Cu 2 O/Cu 7 S 4 heterojunction. On the basis of heterojunction energy band bending and the formation of built-in electric fields, the S-Cu-O bonds can act as a specific bridge to further facilitate the separation, transfer and delivery of photoelectrons and holes, which contributes to the generation of more oxidatively active species (mainly superoxide radicals and holes). In addition, based on experimental characterization and theoretical calculations, the intermediates, degradation pathways and photodegradation mechanisms of the degradation process have also been discussed in detail. [ABSTRACT FROM AUTHOR]

[Display omitted] • In 2 O 3 @ZnCr − LDHs Z − scheme/PS − AOPS was fabricated and used for tetracycline photodegradation. • The removal of tetracycline (TC) reached 83 % within 45 min by Z − scheme/PS − AOPS. • The electrons are transferred from In 2 O 3 to LDHs boosted by build-in electronic field. • In 2 O 3 @ZnCr − LDHs can photo-activate persulfate to generate more oxidative sulfate radicals. • Sulfate radical has synergistic effect with hydroxyl and superoxide radical to degrade TC. Z − scheme heterojunctions can increase the electron transfer rate, inhibit the recombination of electrons and holes, and enable the material to possess a more vital redox ability. In this work, In 2 O 3 @ZnCr − LDHs Z − scheme heterojunction was fabricated by complexing ZnCr layered double hydroxides (LDHs) nanosheets on ho llow In 2 O 3 nanorods and used for photocatalytic degradation of tetracycline (TC), a typical antibiotic. Under the optimal conditions of 0.6 g/L In 2 O 3 @ZnCr − LDHs, pH of 9, and reaction temperature of 40 °C, it takes 150 min for the degradation rate of TC to reach 87 %. With the addition of persulphate (PS) to form advanced oxidation processes (AOPs), the TC removal rate reached 83 % within 45 mins, and improvement was evident. When adding persulfate (PS) to form advanced oxidation processes (AOPs), the removal of TC reached 83 % within 45 min, and the improvement effect was pronounced. XPS, ESR, photoelectric performance test and DFT calculations show that the excellent photocatalytic activity is attributed to the built-in electric field in the direct Z − scheme heterojunction, which can boost the transfer of photogenerated carriers and reduce the recombination of electron-hole pairs. In addition, the heterojunction can photo-activate PS to generate more oxidative sulfate radicals, which has a synergistic effect with hydroxyl radical and superoxide radical to degrade TC. Therefore, the Z − scheme/PS − AOPs system has a potential application in antibiotic contaminant degradation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A 0D/2D Cu 2 O/BiOCl S-scheme heterojunction was fabricated. • Cu 2 O/BiOCl was used for photodegradation of tetracycline, a typical antibiotic. • The removal of tetracycline can reach 90.3% under optimal conditions. • Superoxide and hydroxyl radical acted on degradation of tetracycline. • There are mainly six intermediates for tetracycline photodegradation. Single-phase photocatalysts exhibit low performance of photocatalytic degradation of pollutants, which is mainly due to the fact that most intrinsic photocatalysts can only produce one active species for degradation reactions. In order to solve this problem, the 0D/2D Cu 2 O/BiOCl S-scheme heterojunction was successfully constructed through a facile hydrothermal route. The obtained 0D/2D Cu 2 O/BiOCl displays high catalytic activity for tetracycline (TC) photodegradation, and 90.3% of TC was photodegraded within 80 min, which is much better than that by pure Cu 2 O and BiOCl. The excellent photocatalytic activity can be ascribed to the formation of S-scheme heterostructures, which enables the photocatalyst to generate superoxide radicals and hydroxyl radicals, and at the same time, makes the oxidation potential more positive and the reduction potential more negative. It is further proved by the results of experimental characterization and theoretical calculation show that the built-in electric field between Cu 2 O and BiOCl is a key factor in inducing the path of S-scheme electron transmission. In addition, the effects of various reaction conditions, including catalyst dosage, pH value and reaction temperature, on the photodegradation of tetracycline were discussed in detail. The intermediates and degradation path were also discussed in detail by liquid chromatography-mass spectrometry. [ABSTRACT FROM AUTHOR]

The decahedral morphology of BiVO 4 and ZnCr-layered double hydroxides (LDHs) nanosheets enables the construction of a BiVO 4 @LDHs Z -scheme heterojunction (BiVO 4 as core and LDHs as a shell) for photocatalytic degradation of norfloxacin, typical antibiotic. The effects of initial concentration of norfloxacin, catalyst loading, reaction temperature, and pH value on the performance of photodegradation were studied. It was found that the removal of norfloxacin can reach 90.3% under the optimized conditions. The core-shell structure enhances the specific surface area, improves the energetic alignment of the band structures, and produces enough hydroxyl and superoxide radicals to degrade norfloxacin. Density functional theory (DFT) calculations show that a built-in electric field is formed between ZnCr-LDHs and BiVO 4 , which promotes the transfer of photogenerated electrons from the valence band of ZnCr–LDHs to the conduction band of BiVO 4. This transfer accelerates the flow of photogenerated electrons and reduces the recombination of electron-hole pairs, so that BiVO 4 @LDHs heterojunction shows excellent photocatalytic activity for norfloxacin. [Display omitted] • A coating BiVO 4 @LDHs Z -scheme heterojunction was constructed. • BiVO 4 @LDHs was used for photocatalytic degradation of norfloxacin, a typical antibiotic. • The removal of norfloxacin can reach 90.3% under optimal conditions. • Superoxide and hydroxyl radical can be produced and acted on degradation of antibiotics. • A built-in electric field is formed, which promotes transfer of electrons from ZnCr-LDHs to BiVO 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • A core–shell S–scheme heterojunction (Bi 2 O 3 @LDHs) was synthesized. • The highest removal for Rhodamine B (RhB) is 90.36%, the activity is 37.65 mg g−1h−1. • The effects of amount of catalyst, light intensity, pH and temperature were optimized. • Kinetic of RhB photodegradation catalyzed by LDHs and Bi 2 O 3 @LDHs was obtained. • Intermediates, degradation pathway and photocatalytic mechanism were discussed. In this paper, based on Bi 2 O 3 and CoAl–layered double hydroxides (LDHs), a core–shell structure S–scheme heterojunction catalyst (Bi 2 O 3 @LDHs) was synthesized and used for photodegradation of Rhodamine B (RhB), a typical dye. The effects of the amount of catalyst (A), light intensity (B), pH value (C) and reaction temperature (T) on the degradation performance were discussed. The apparent kinetic equation of RhB photodegradation catalyzed by LDHs and Bi 2 O 3 @LDHs are: ln (C / C 0) = - 5.661 × 10 5 e - 30.01 × 10 3 RT × [ A ] 0 0.9348 × [ B ] o 1.0348 × [ C ] 0 0.9965 × t and ln (C / C 0) = - 8.398 × 10 3 e - 16.39 × 10 3 RT × [ A ] 0 1.2547 × [ B ] o 1.5279 × [ C ] 0 1.0197 × t. Under the best reaction conditions of the amount of catalyst is 40 mg, the light intensity is 400 W, the reaction pH value is 9, and the reaction temperature is 303 K, the highest removal is 90.36%, and the activity is 37.65 mg g−1h−1. In addition, by means of radical characterization and DFT calculation, the formation mechanism of built–in electric field and the promotion of S–scheme electron transport path in heterojunction were systematically analyzed, and the degradation intermediates and degradation paths were also discussed. [ABSTRACT FROM AUTHOR]

Z–scheme heterojunction has the advantages of high carrier separation efficiency and strong oxidation ability, which is a potential material for photodegradation. In this paper, CdS@Zn,Cr-layered double hydroxides (CdS@LDHs) Z–scheme heterojunction was synthesized and used for photocatalytic degradation of tetracycline (TC). The effects of the amount of catalyst, pH value of the solution, initial concentration of TC, light intensity, and reaction temperature were studied. The degradation kinetics and mechanism were also discussed in detail. Under the optimal conditions (initial concentration of TC 50 mg/L, pH 9, light intensity 500 W, the amount of the catalyst 25 mg, and reaction temperature 45 °C), the highest removal percentage and the corresponding activity of CdS@LDHs was 93.04% and 37.09 mg g−1 h−1, respectively. In addition, DFT calculation confirmed the existence of built–in electric field (BIEF) in the heterojunction, which promotes the electron transfer from CdS to LDHs. The amount of electron transfer was accelerated, and the recombination of electron and hole was obviously inhibited, so that they were more involved in oxidation and reduction. Thus, it makes CdS@LDHs heterojunction as a highly efficient catalyst for photodegradation of TC. [Display omitted] • A novel Z–scheme heterojunction was used for photodegradation of tetracycline. • The removal activity of tetracycline by heterojunction was 37.09 mg g−1 h−1. • The existence of built–in electric field was confirm in heterojunction. • Built–in electric field promotes the electron transfer from CdS to LDHs. [ABSTRACT FROM AUTHOR]

• CdS and LDHs were structurally arranged by forming a heterojunction. • Solvated electrons can be generated, transported, and promote the photocatalytic activity of ammonia synthesis. • Heterojunction formed by 003/012 facet of LDHs and 002 facet of CdS is benefit for BIEF and BCS efficiency. • Solvated electrons drive the reduction of N 2 and the formation of -N 2 H in the rate-determining step. • DRIFTS indicates the formation of imine (-NH = NH) that sheds light on mechanism of the photocatalysis. Photocatalytic reduction of N 2 to NH 3 is kinetically hindered because of the formation of high-energy reaction intermediates and intrinsically low efficiency of hot-carrier dynamics at typical reactant/photocatalyst interface. Direct injection of energized solvated electrons into a reactant medium has the potential to effectively overcome these barriers. Here, we demonstrate that when the two semiconducting materials, CdS and LDHs, are structurally arranged by forming a heterojunction, solvated electrons can be effectively generated, transported, and eventually promote the photocatalytic activity of ammonia synthesis in the form of solvated electrons in an aqueous solution. In particular, when 003 or 012 crystal face of LDHs and 002 facet of CdS form a heterojunction, the built-in electric field (BIEF) promotes the bulk-charge separation (BCS) of hot carriers from LDHs and CdS to the reaction media efficiently. As demonstrated in our theoretical calculations, solvated electrons form at the H 2 O/photocatalyst interface and drive the reduction of N 2 and the formation of -N 2 H in the rate-determining step. Using in-situ DRIFTS, we were able to capture the formation of imine (-NH=NH) as one of the reaction intermediates that sheds light on the atomistic mechanism of the photocatalyzed reaction. DFT calculation also indicates that CdS@LDHs-3 (003 crystal face of LDHs and 002 facet of CdS) has the minimum relative energy for the rate-determining step and is therefore the most favorable configuration for the ammonia synthesis reaction, as confirmed by the experimental results. [ABSTRACT FROM AUTHOR]