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A porphyrin-based conjugated organic polymer (COP) was constructed from 5,10,15,20-tetrakis(4-bromophenyl)porphyrin copper (CuTBPP) and 5,5′-bis-ethynyl-2,2′-bipyridine (BPY) via Sonogashira coupling. Its complex Co/CuTBPP–BPY–COP (with dual metal sites composed of copper porphyrin and a cobalt BPY unit) was prepared by coordination with Co2+. All of the prepared CuTBPP–BPY–COP and Co/CuTBPP–BPY–COP compounds exhibited excellent photocatalytic performance toward CO2 reduction under visible-light irradiation without another sacrificial reagent but only H2O. Co/CuTBPP–BPY–COP (dual metal sites) exhibited better photocatalytic activity than CuTBPP–BPY–COP (a single metal site). Co/CuTBPP–BPY–COP retained a higher photocatalysis capacity for CO2 reduction after 10 consecutive cycles. The total quantity of CO product was 263.2 μmol g−1 after 10 h of irradiation. Theoretical studies indicate that introducing Co metal centers and nitro groups are more favorable for the photoreduction catalysis of CO2 compared with that using CuTBPP–BPY–COP. [ABSTRACT FROM AUTHOR]

In this study, Cu and Cu2O hybrid nanoparticles were synthesized onto the WO3 nanoflake film using a one-step electrodeposition method. The critical advance is the use of a heterojunction consisting of WO3 flakes and Cu2O as an innovative stack design, thereby achieving excellent performance for CO2 photoreduction with water vapor under visible light irradiation. Notably, with the modified Cu nanoparticles, the selectivity of CH4 increased from nearly 0% to 96.7%, while that of CO fell down from 94.5% to 0%. The yields of CH4, H2 and O2 reached 2.43, 0.32 and 3.45 mmol/gcat after 24 h of visible light irradiation, respectively. The boosted photocatalytic performance primarily originated from effective charge-transfer in the heterojunction and acceleration of electron-proton transfer in the presence of Cu nanoparticles. The S-scheme charge transfer mode was further proposed by the in situ-XPS measurement. In this regard, the heterojunction construction showed great significance in the design of efficient catalysts for CO2 photoreduction application. [ABSTRACT FROM AUTHOR]

The CaBi 6 O 10 /Bi 2 WO 6 S-scheme heterojunction films achieved an approximately 89.5% degradation of 4-CP after only 60 min of visible-light exposure within the fixed-bed photoreactor setup. [Display omitted] Efficient photocatalysts played a crucial role for degrading phenol pollutants in wastewater and vital for environmental remediation. In this study, a series of novel CaBi 6 O 10 /Bi 2 WO 6 (CBO/BWO) step-scheme (S-scheme) heterojunction films were synthesized on the glass substrates through a facile and rapid spraying-calcination method. The CBO/BWO film demonstrated superior visible-light-driven catalytic activity for p-chlorophenol (4-CP) degradation within the fixed-bed photoreactor setup, compared with those of the single-component samples. Typically, the optimal 40CBO/BWO catalyst achieved 4-CP degradation efficiency of approximately 89.5 % after only 60 min under light exposure, attributed to the enhanced visible-light-absorption property and effective charge separation within the S-scheme heterojunction while maintaining high redox abilities among photoinduced carriers. Furthermore, the CBO/BWO catalyst displayed robust resistance to various metal cationic additives. Multiple key intermediates, such as phenol, dihydroxybenzene, benzoquinone and maleic acid, were identified in catalyzing process of 4-CP decomposition via oxidation processes involving hydroxyl radicals and superoxide radical as the primary active species. The above feasible photodegradation mechanism was elucidated and proven. Hence, this work offers valuable insights into developing efficient heterostructure photocatalysts for practical application of environmental remediation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The interstitial carbon and substitutional iodine codoped TiO 2 was synthesized. • The RhB and MO degradation performance was promoted by the C and I co-doping. • The photocatalysis for mixed degradation was accomplished under natural light. • The C and I co-doping facilitated the OH formation from H 2 O 2. Abstract Increasing the efficiency of dye degradation is a critical issue for the application for photocatalysis. It is one of the greatest challenges to enhance the utilization of photo generated carriers in semiconductor, especially for sunlight irradiation. In this study, I/C-codoped TiO 2 was synthesized by a simple solvothermal-calcination method. The codoping interstitial carbon and substitutional iodine not only widened the light absorption range of the TiO 2 photocatalysts, but also enhanced the separation of photo-induced carriers. The photocatalytic activities of RhB and MO degradation over the 4-I/C-TiO 2 photocatalyst could reach 98.2% and 94.2% after 25 min visible light irradiation (λ ≥ 400 nm), respectively. Notably, 4-I/C-TiO 2 showed good activity for MO and RhB mixed degradation and could also accomplish the photocatalytic degradation in the above mixed system under natural sunlight irradiation. According to the dark catalytic experiment, I/C-codoping could effectively accelerate the formation of hydroxyl radicals from the generated H 2 O 2 , which was formed for the enhanced photocatalytic activity of dye degradation. The gained knowledge may provide some insights into the photocatalytic degradation over the codoped TiO 2 catalyst. [ABSTRACT FROM AUTHOR]

The construction of p–n heterojunction is an efficient strategy to restrain photogenerated charge carriers recombination and enhance the photocatalytic efficiency toward H 2 evolution from water splitting. Herein a novel p–n heterojunction Mn 0.25 Cd 0.75 S/Co 3 O 4 was synthesized via facile hydrothermal method. Photocatalytic H 2 evolution of as-synthesized Mn 0.25 Cd 0.75 S/Co 3 O 4 composites in the absence of noble metal co-catalysts under visible light irradiation ( λ ≥ 400 nm) was investigated. The results demonstrated that photocatalytic H 2 evolution of Mn 0.25 Cd 0.75 S was significantly enhanced by loading Co 3 O 4 nanoparticles. It was confirmed that 0.48 wt% of Co 3 O 4 loading content achieved the highest H 2 evolution rate of 25.71 mmol/g/h, which was about 5.35 times higher than that of pure Mn 0.25 Cd 0.75 S. The remarkably improved photocatalytic activity could be attributed to the formation of the p–n junction at the interface between Mn 0.25 Cd 0.75 S and Co 3 O 4 , effectively promoting interfacial charge transfer and separation. This work revealed that the p–n heterojunction Mn 0.25 Cd 0.75 S/Co 3 O 4 may be a promising candidate for efficient energy conversion. [ABSTRACT FROM AUTHOR]

A series of Fe 2 O 3 materials with hydroxyl are synthesized in different monohydric alcohol (C 2 – C 5 ) solvents by solvothermal method and characterized by XRD, BET, XPS, TG and EA. The amount of hydroxyl is demonstrated to be emerged on the surface of the as-synthesized Fe 2 O 3 particles and their contents are determined to be from 7.99 to 3.74 wt%. The Cr(VI) reduction experiments show that the hydroxyl content of Fe 2 O 3 samples exacts great influence on the photocatalytic activity under visible light irradiation (λ > 400 nm) and that the Fe 2 O 3 sample synthesized in n-butyl alcohol exhibits the optimal photocatalytic activity. The synergistic photocatalysis for 4-Chlorophenol (4-CP) degradation and Cr(VI) reduction over above Fe 2 O 3 sample is further investigated. The photocatalytic ratio of Cr(VI) reduction are enhanced from 24.8% to 70.2% while that of 4-CP oxidation are increased from 13.5% to 47.8% after 1 h visible light irradiation. The Fe 2 O 3 sample keeps good degradation rates of mixed pollutants after 9 runs. The active oxygen intermediates O 2 − , OH and H 2 O 2 formed in the photoreaction process are discovered by ESR measurement and UV–vis test. The photocatalytic degradation mechanism is proposed accordingly. [ABSTRACT FROM AUTHOR]

Enhancing photocatalytic efficiency of mixed-pollutant degradation is a critical issue for the application in wastewater purification, especially under natural-sunlight illumination. CuBi 2 O 4 rods decorated with Fe 2 O 3 nanoparticles were synthesized by the hydrothermal method. The Fe 2 O 3 /CuBi 2 O 4 composites exhibited significantly enhanced photocatalytic activity for Fenton oxidation of Rhodamine B (RhB) and 4-nitrophenol (4-NP) in the near-neutral catalytic system, and the degradation efficiency of the above two pollutants reached above 90% after 50 min of visible-light irradiation. Meanwhile, the good catalytic performance and stability were maintained in the seventh cycling test. Notably, the efficient synchronous degradation of the above mixed pollutants was accomplished under natural-sunlight over the optimal 7%Fe 2 O 3 /CuBi 2 O 4 catalyst. The staggered band structure in the heterojunction was determined by DRS and UPS results, and the S-scheme electron transfer mode was verified by the in situ-XPS measurement under dark and light conditions. The study is expected to be beneficial to explore step-scheme (S-scheme) semiconductor photocatalysts for natural-sunlight-driven Fenton oxidation of mixed pollutants. [Display omitted] • Fe 2 O 3 nanoparticles decorated CuBi 2 O 4 rods was synthesized. • The photocatalysis for mixed degradation was accomplished under natural light. • The 4-NP and RhB degradation performance was promoted by the heterojunction. • S-scheme charge transfer was proven by the in situ-XPS measurement. [ABSTRACT FROM AUTHOR]

• CuBi 2 O 4 decorated Bi 2 O 3 with dominant (020) facets was synthesized. • Bi 2 O 3 /CuBi 2 O 4 thin film on glass with a large area was easily obtained. • Bi 2 O 3 /CuBi 2 O 4 exhibited the high photocatalytic activity for CO 2 reduction in 12 h. • The dominant (020) facets of Bi 2 O 3 enhanced the absorbed ability for H 2 O. • Composite film showed resisted physical damage and catalytic stability for 5 cycles. [Display omitted] CuBi 2 O 4 /Bi 2 O 3 thin film was synthesized on the commercial glass by a spray pyrolysis-calcination method. The monoclinic phase Bi 2 O 3 with dominant (0 2 0) facets was grown on the surface of tetragonal phase CuBi 2 O 4 by the temperature control of spraying process. Photocatalytic activities of the synthesized materials for CO 2 reduction were measured in the presence of water vapor under visible light irradiation (λ > 400 nm). The CO, CH 4 and O 2 yields of the optimal composite film reached 247.62, 119.27 and 418.00 μmol/m2 after 12 h of irradiation. The composite film resisted physical damage and showed good photocatalytic activity in the cycling tests. Moreover, it was found that the types of main products changed with the light intensity and their yields varied with the light wavelength. The exposed (0 2 0) facets efficiently improved the adsorbed ability for H 2 O molecules. Meanwhile, the hydrophobicity of the film surface ensured that the adsorbed sites of CO 2 were unoccupied by abundant H 2 O molecules. The S-scheme charge transfer mechanism was further confirmed by the interlaced band alignment of the CuBi 2 O 4 /Bi 2 O 3 heterostructure and the controlled experiment with different light conditions. The results gained in this report may open up an avenue to design advanced S-scheme heterostructures with suitable transitional-metal oxides for photoreduction CO 2 to solar fuels. [ABSTRACT FROM AUTHOR]

B and K co-doped g-C 3 N 4 , synthesized by molten salt method, exhibits the good photocatalytic performance for water vapor splitting and recycled molten salt was used for preparation of codoped g-C 3 N 4. • B and K co-doped g-C 3 N 4 was synthesized by molten salt method. • The good photocatalytic performance for water vapor splitting was found. • Recycled molten salt was used for preparation of codoped g-C 3 N 4. • Photocatalyst exhibited good cycling and stability. • Doped B and K accelerated the photoinduced electron-hole separation. Photocatalytic overall water splitting is one of the green and efficient energy technologies. Due to difficult release of O 2 from photocatalysts, the simultaneous generation of H 2 and O 2 is a critical challenge for water splitting. B and K co-doped g-C 3 N 4 (B/K-g-C 3 N 4) catalyst was synthesized by the recyclable molten-salt method in this study. Compared with the K doped and pristine g-C 3 N 4 samples, B/K-g-C 3 N 4 exhibited the highest photocatalytic activity for water vapor splitting under visible light illumination. The yield ratio of H 2 and O 2 reached approximately 2:1, and the corresponding rates were 1.18 and 0.58 μmol/h after 24 h of illumination. The B/K-g-C 3 N 4 sample demonstrated good photocatalytic stability after 9 cycles. Additionally, the co-doped g-C 3 N 4 catalyst, obtained from the repeatedly recyclable salts, still exhibited equivalent photocatalytic activity. Based on the built structure model with g-C 3 N 4 , the HOMO and LUMO distributions were changed by B and K co-doping, leading to improved separation of photoinduced carriers. The photocatalytic mechanism for water splitting over g-C 3 N 4 semiconductor was speculated. [ABSTRACT FROM AUTHOR]

• α-Fe 2 O 3 deposited porous polystyrene fiber was synthesized. • The stable micro-nano structure was formed by γ-ray method. • The photocatalytic degradation for 4-CP and 4-NP was accomplished. • Fe 2 O 3 /PS fiber showed the good stability for 6 cycling. Photocatalytic degradation by efficient and easy recyclable semiconductor-catalysts is an ideal way to solve the environmental problem. A series of Fe 2 O 3 /Polystyrene (Fe 2 O 3 /PS) composite fibers with hydrophobic property were obtained by the electrospinning and γ-Ray irradiation methods. The γ-Ray irradiation treatment not only formed steady micro-nano construction of nanoparticles and fiber, but also reduced the hydroxyl group on Fe 2 O 3 surface. The high photocatalytic efficiencies of Fe 2 O 3 /PS fiber were discovered with the high content of 4-chlorophenol (4-CP) and 4-nitrophenol (4-NP), due to the synergetic effect of adsorption and degradation. The suitable adsorption capacity of Fe 2 O 3 /PS could promote the utilization of the generated hydroxyl radical(OH) to directly oxidize the adsorbed pollutant molecules. Additionally, the photocatalytic activities for 4-CP and 4-NP still reached 80% and 75% in the 6th cycling and the composite fiber exhibited the good recyclability, which has the application development prospect for wastewater treatment. The mechanism of 4-CP and 4-NP decomposition was verified. Hence, the gained results could provide some insights into phenol degradation over the multifunctional and efficient catalyst. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Cu 2 O decorated WO 3 nanosheets with dominant (0 0 1) facets was synthesized. • Cu 2 O/WO 3 exhibited the high photocatalytic activity for CO 2 reduction in 24 h. • The dominant (0 0 1) facets of WO 3 enhanced the photocatalytic activity. • Cu 2 O/WO 3 showed good stability for 4 cycles. Abstract Systematical design and controllable assembly of nanostructured photocatalysts have received much attention in the field of CO 2 reduction. The Cu 2 O decroted hexagonal WO 3 nanosheets with and without dominant (0 0 1) facets (Cu 2 O/WO 3 -001 and Cu 2 O/WO 3) were synthesized vertically on the surface of fluorine-doped stannic oxide (FTO) substrate and their photocatalytic performance for CO 2 reduction were evaluated in the presence of H 2 O vapour under visible light irradiation (λ > 400 nm). The Cu 2 O/WO 3 -001 catalyst exhibited higher photocatalytic activity than those of Cu 2 O, WO 3 -001 and Cu 2 O/WO 3. The maximal product yields of CO, O 2 and H 2 for Cu 2 O/WO 3 -001 after 24 h illumination reached 11.7, 5.7 and 0.7 μmol, respectively, and good cycling ability was discovered after 4 cycles. The (0 0 1) facet of hexagonal phase WO 3 nanosheet was in favor of the H 2 O oxidation in the CO 2 reduction process. Additionally, the Z-scheme charge transfer mode of Cu 2 O/WO 3 heterojunction could promote photoinduced charge separation and enhance redox ability of the separated electrons and holes, leading to excellent photocatalytic CO 2 reduction performance. The study may provide some insights into the coherent design of specific nanosheet photocatalysts with Z-scheme charge transfer for CO 2 reduction. [ABSTRACT FROM AUTHOR]