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In this study, a novel Z-scheme Bi 19 S 27 Br 3 /CoAl-LDH heterojunction was prepared. An interface charge transfer channel was established between Bi 19 S 27 Br 3 and CoAl-LDH, accelerating the transition efficiency of interface electrons from CoAl-LDH to Bi 19 S 27 Br 3. Thereby ensuring more excited electrons to participate in CO 2 photoreduction reactions. The reduction products were tested under artificial light conditions, and triethanolamine was selected as a sacrificial agent. After 5 h of illumination, the CO yield of Bi 19 S 27 Br 3 /CoAl-LDH Z-scheme heterojunction was 86.41 μmol·g−1 is 4 times and 7 times higher than Bi 19 S 27 Br 3 and CoAl-LDH, respectively. The yield of CH 4 in Bi 19 S 27 Br 3 /CoAl-LDH is 3.97 μmol·g−1 is 4 times higher than CoAl-LDH. Also Bi 19 S 27 Br 3 itself does not produce CH 4. The results indicate that the Z-scheme heterojunction effectively enhances the photoreduction ability of CO 2 , providing a new approach for accurately controlling the direction of photo generated charge separation to prepare high-performance photocatalysts. [Display omitted] • Z-scheme heterojunction improves the efficiency of charge utilization and retains a large number of reducing electrons. • Bi 19 S 27 Br 3 /CoAl-LDH has good photocatalytic reduction performance of CO 2. • Bi 19 S 27 Br 3 acts as an electronic collector. • composite photocatalyst has excellent chemical stability. • The electron migration pathways were determined through electrochemistry, ESR, UPS and DFT, demonstrating the high photocatalytic reduction performance of the composite material. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel CD-BVO/rGH photocatalyst was constructed by coupling Carbon dot-coupled BiVO 4 with rGH. • CD-BVO/rGH display enhanced photocatalytic activity for TCH degradation and CO 2 reduction. • The synergetic effects of CD-BVO and rGH can enhanced the separation of carriers. • Possible photocatalytic reaction mechanism of TCH degradation and CO 2 reduction was presented. In this study, we fabricated a novel hybrid photocatalyst (CD-BVO/rGH) by coupling carbon dot (CD)-decorated BiVO 4 (BVO) with a reduced graphene hydrogel (rGH). The CD-BVO/rGH photocatalyst significantly enhanced the photocatalytic efficiency for tetracycline hydrochloride (TCH) degradation compared with pure BVO and BVO/rGH under simulated solar irradiation. CD-BVO/rGH also showed a substantial performance in the photocatalytic reduction of CO 2. The enhanced photocatalytic activity of CD-BVO/rGH is attributed to synergistic effects, such as better light energy utilization via the upconversion effects of the CDs and the enhanced migration and separation of photoexcited carriers by the three-dimensional (3D) network structure of the rGH. The systematic analysis of the band structure, electron spin resonance, and free radical trapping revealed that h+ and O 2 – mediate the final photocatalytic degradation of pollutants. Our results provide insight into the design and construction of highly efficient hybrid photocatalysts combined with functional carbon nanostructures to enhance the photocatalytic activity for the photodegradation of environmental pollutants and CO 2 reduction. [ABSTRACT FROM AUTHOR]

ZnO/g-C3N4 was prepared by carrying out a simple one-step calcination process. The ZnO/g-C3N4 composite was characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), transient photocurrent responses and photo-luminescence (PL) spectroscopy. Compared with pure g-C3N4, the composite showed increased photocurrent under UV irradiation, and overall significantly improved photocatalytic performance. Photocatalytic experiments showed specifically the composite made of a ZnO-to-g-C3N4 mass ratio of 3 : 1 displaying the best catalytic performance. The yields of CO and CH4 under UV irradiation were, respectively, 13.4 times and 49.7 times that of g-C3N4. In addition, a direct Z-scheme electron transfer mechanism was proposed to possibly play a large role in reducing charge recombination and to effectively improve photocatalytic CO2 reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design of a Bi 2 O 3−x /NiAl-LDH S-scheme heterojunction to promote the separation of carriers. • Utilizing the LSPR effect to boost photothermal-assisted photocatalytic CO 2 reduction. • The introduction of Bi 2 O 3−x extends the photoresponse to long wavelength region. In this study, a new type of 2D/2D Bi 2 O 3−x /NiAl-LDH (BO/NA-LDH) S-scheme photocatalyst was prepared by combining NiAl-LDH with Bi 2 O 3−x by wet chemical deposition for obtaining efficient photothermal-assisted photocatalytic reduction of CO 2 under simulated sunlight irradiation. In particular, the as-prepared optimal 50-BO/NA-LDH sample exhibited the CO production yield of 83.55 ± 2.76 μmol/g/h, which was 9 and 27 times that of BO (9.32 ± 0.62 μmol/g/h) and NA-LDH (3.09 ± 0.38 μmol/g/h), respectively. The enhancement of photothermal-assisted activity over the 50-BO/NA-LDH system was mainly attributed to the coupling of the photothermal conversion performance of Bi 2 O 3−x and improving the migration efficiency of interface carriers of S-scheme heterojunction and 2D/2D structure. This study presents a promising strategy for the development of high-efficient photothermal-assisted photocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mott Schottky junction is introduced into the traditional Z-scheme heterojunction. • The high conductivity of MXene improves the transport of photogenerated electrons. • Accelerated spatial charge separation and transfer on pCN/TC and TC/Sn-Bi-MOF interfacial Schottky junction. • The photocatalytic products are highly selective for CO production. a simple electrostatic self-assembly method is adopted, in which the Z-scheme heterojunction is directly constructed with Sn-Bi-MOF (SBM) using g-C 3 N 4 (pCN) as the support platform, and the Mott Schottky junction is introduced into the heterojunction (pCN/TC/SBM). This structure not only achieves efficient and stable CO 2 conversion, besides has a high degree of selectivity for CO due to the enhanced electrodynamic migration. Under simulated sunlight, pCN/TC/SBM showed high photocatalytic activity, and the amount of CO produced was 36.33 μmol·g−1·h−1, which was 4.36 and 3.5 times that of pCN and SBM, respectively, and the quantum apparent efficiency (AQY) was 3.2 % at 420 nm. The design method not simply improves the separation of electron-hole pairs, moreover accelerates the electrodynamic migration process, which increases the yield and improves the selectivity for CO. UPS, XPS, VB, DRS, ESR and work functions were used to analyze the Fermi level arrangement and band bending of the catalyst, and the photocatalytic mechanism and electron migration path were speculated. In situ FTIR is used to illustrate the specific path of the reaction. This work provides a new strategy for the design of heterojunctions and the enhancement of the yield and selectivity of carbon dioxide reduction products. [ABSTRACT FROM AUTHOR]

The graphitic carbon nitride (g-C 3 N 4 ), as one photocatalyst which possess the suitable band gap, is better for modified TiO 2 and enhanced photocatalytic degradation of organic pollutants. In this work, the g-C 3 N 4 /TiO 2 were successfully prepared via directly calcined the mixture of melamine and P25. The as-prepared g-C 3 N 4 /TiO 2 photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and high resolution electron microscopy (HRTEM), Raman and Fourier transform-infrared spectroscopy (FT-IR). The photocatalytic performances of g-C 3 N 4 /TiO 2 composites were investigated by degradation of ciprofloxacin. The results showed that the g-C 3 N 4 and P25 were successfully composited, and the bond of C–N was well formed, the calcined temperature for as-prepared photocatalysts and the ratio of melamine and P25 were important to the degradation rate of ciprofloxacin. When the mixture of melamine and P25 with 1:2, and calcined temperature at 600 °C, the degradation rate of ciprofloxacin could reach 95% in 60 min. The enhanced photocatalytic performances could be mainly attributed to the suitable band gap structure with heterojunction of CN-P25. Finally, the possible transferred processes of photoelectrons and photoholes were proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Core-shell Mn 3 O 4 @CIS microspheres were fabricated via in situ growing CIS on the surface Mn 3 O 4. • The charge transfer of Mn 3 O 4 @CIS followed the S-scheme route to achieve strong photocatalytic reduction and oxidation. • Mn 3 O 4 @CIS showed strong photocatalytic activity for pure water cracking hydrogen production. • The spherical core–shell heterostructure could widen the light absorption range and improve the electron-hole separation efficiency. In this study, core–shell Mn 3 O 4 @CdIn 2 S 4 (Mn 3 O 4 @CIS) microspheres were prepared via synthesis of Mn 3 O 4 microspheres with Mn-MOF as precursor followed by in-situ growth of CdIn 2 S 4 (CIS) shell. The hydrogen evolution rate of the optimized Mn 3 O 4 @CIS was 2.6 mmol·g−1·h−1, which were 11.54-fold and 17.44-fold that of CIS and Mn 3 O 4 alone, respectively. The spherical core–shell structure could broaden the light absorption range and enhance the separation and migration of photogenerated carriers, thereby promoting solar energy utilization. More importantly, experimental and computational results proved that the charge migration followed an S-scheme transfer route in the interface between Mn 3 O 4 and CIS, accumulating photogenerated electrons in the conduction band of CIS for robust photocatalytic hydrogen evolution. This work provided a facile strategy for the design and fabrication of efficient photocatalysts via synchronous morphology and S-scheme heterojunction architecture. [ABSTRACT FROM AUTHOR]

Building efficient catalysts is an urgent issue in the field of photocatalytic CO 2 reduction, and Z-scheme heterojunction structures can availably suppress the recombination of photo generated carriers and improve photocatalytic performance. This study successfully prepared a new type of Bi 4 O 5 Br 2 /Bi-MOF composite photocatalyst through self-assembly method. After 5 h of simulated sunlight exposure, the optimized sample 50-Bi 4 O 5 Br 2 /Bi-MOF photocatalytic reduction of CO 2 to CO efficiency (23.78 μmol·g−1·h−1) was 5.09 times higher than pure Bi 4 O 5 Br 2 , and the CH 4 yield (5.39 μmol·g−1·h−1) was 2.52 times that of pure Bi-MOF. In addition, in the cyclic experiment, the catalyst had high stability and reusability. The Z-scheme charge transfer mechanism was confirmed through band structure analysis, Electron spin resonance (ESR), Ultraviolet photoelectron spectroscopy (UPS) and other related characterizations. This work provided an important strategy for designing efficient Z-scheme heterojunction photocatalysts. [Display omitted] • Construct Bi 4 O 5 Br 2 /Bi-MOF Z-scheme heterojunction to improve reduction performance. • Bi 4 O 5 Br 2 /Bi-MOF composite photocatalyst exhibits excellent chemical stability. • The reaction intermediates were analyzed using in-situ infrared spectroscopy. • Proving the formation of Z-scheme heterojunction through series characterizations. [ABSTRACT FROM AUTHOR]

The midgap states and amino groups resulted from bulk phase N defects and surface C defects synergistically catalyze the photocatalytic reduction of CO 2 to hydrocarbon fuels. Defect structure is one of the crucial factors for enhancing the catalytic activities of photocatalysts. However, rational design and construction of defect structures in catalysts to meet the aim of enhancing photocatalytic performance in a simple and cost-effective way is still a challenge. In this contribution, we report a strategy to construct defect structures in graphitic carbon nitride (g-CN) by simple copolymerizing of urea with polyethyleneimine (PEI). Among the prepared catalysts, u-0.05PEI presents the best photocatalytic activity for CO 2 reduction, with CO and CH 4 yields of 32.86 and 1.68 μmol g−1 in 4 h, which is about 3.2 and 2.5 times higher than that of g-CN, respectively. Characterization results show that both C and N defects are formed in the newly prepared catalysts. The C defects on the surface of u-xPEI result in the formation of more amino groups which are beneficial for CO 2 adsorption. Meanwhile, the N defects inside the samples lead to the generation of midgap states between the valance band and conduction band of u-xPEI. The midgap states greatly enlarge the light absorption extent, and enable the use of light with energy lower than the intrinsic absorption of g-CN in the photoreduction of CO 2. As confirmed by DRS, EPR, PL analysis, the excellent catalytic activity of u-0.05PEI is mainly attributed to the remarkably improved light utilization efficiency and fast charge transfer. Moreover, the reaction is performed in water without any additive or organic solvent, which makes it environmentally friendly. [ABSTRACT FROM AUTHOR]

A series of hamburger-like Ag@ZnO/C core–shell plasmonic photocatalysts have been synthesized via a simple solvothermal method for degradation of tetracycline (TC) under visible light irradiation, possessing high photocatalytic activity and good stability. The presence of localized surface plasmon resonance (LSPR) in the Ag core has increased the photocatalytic activity over an extended wavelength range. The plasmon-induced resonant energy transfer (PIRET) and direct electron transfer (DET) have facilitated the excitation and separation of photogenerated e−/h+ pairs, which has been further confirmed by electrochemical investigations. The presences of hydroxyl radicals (⋅OH), superoxide radicals (⋅O2−) and singlet oxygen (1O2) in the photocatalytic reaction system of Ag@ZnO/C photocatalyst have been demonstrated by electron spin resonance (ESR) measurements. All of the experiment results indicate that the ternary structure of Ag@ZnO/C can effectively enhance the photocatalytic activity. Furthermore, the effects of introduced Ag contents and carbon source dosage were researched by comparative photocatalytic experiments, and the potential structures of photodegradation products were studied by HPLC-MS. A series of hamburger-like Ag@ZnO/C plasmonic photocatalysts was synthesized. The photocatalysts exhibited great photocatalytic activity and stability, and the PIRET and DET have facilitated the excitation and separation of charges. The possible photodegradation mechanism was systematically presented and the potential structure of new photodegradation products was studied. [ABSTRACT FROM AUTHOR]

Fabricating 2D CN and COF based all organic van der Waals heterojunction catalyst for efficient transformation of CO 2 to hydrocarbon fuels. • 2D CN and COF based all organic heterojunction catalyst 2D CN-COF was successfully prepared. • The heterojunction arose from the interface van der Waals interaction between 2D CN and COF-TD. • The photoelectrical properties of 2D CN-COF was significantly enhanced due to the formation of heterojunction. • The CO evolution rate over 2D CN-COF is 9.2 times and 3.3 times higher than that of 2D CN and COF-TD, respectively. • The reaction was performed in the absence of any solvent and sacrificial agent. Two dimensional carbon nitride (2D CN) has attracted extensive attention due to its potential application in the field of photocatalysis. However, the poor electron-hole separation efficiency and low charge carrier migration speed confine the photocatalytic performance of 2D CN. In this work all organic van der Waals heterojunction (vdWH) catalyst (2D CN-COF) was prepared from 2D CN and triazine-based covalent organic framework (COF-TD) to efficiently enhance the catalytic activity of 2D CN. Characterization and simulation results verified the successful preparation of the catalyst. The heterojunction was originated from the intense interface van der Waals force interaction between the molecules of 2D CN and COF-TD. Furthermore, the intense π-π interaction between 2D CN and COF-TD led to the morphology transformation of COF-TD from sphere of isolated sample to elliptic sheet in 2D CN-COF. The intimate interface contact of vdWH has led to reduce bandgap, which remarkably enlarged the visible light responding region of the samples. Meanwhile, the charge carrier recombination was significantly reduced because of the formation of vdWH. The evolution rate of CO over 2D CN-COF was 9.2 times and 3.3 times higher than that of 2D CN and COF-TD, respectively. Moreover, the reaction was performed in the absence of any solvent and sacrificial agent, matching well with the idea of sustainable development. This work not only provides a new and simple strategy to fabricate 2D CN based all organic heterojunction catalyst for efficient photoreduction of CO 2 to CO and CH 4 , but also serves as a reference for other researchers to design organic heterojunction, which is based on 2D CN and COFs. [ABSTRACT FROM AUTHOR]

Synthesis of carbon nitride based catalysts containing donor-acceptor systems for photocatalytic reduction of CO 2 to CO. • Carbon nitride with donor-acceptor (D-A) systems was fabricated by C and O co-doping. • The D-A systems optimize the optical absorption and bandgap structures of carbon nitride. • The spatial separation of charge in D-A systems enhances the charge separation efficiency. • The catalyst displayed efficient CO 2 photoreduction activity and catalytic durability. Photocatalytic reduction of CO 2 to hydrocarbon fuels is an ultimate and utmost strategy to resolve the ever-increasing environmental problems and energy crisis. Our study aimed to develop a specific type of photocatalysts with increasing light utilization efficiency, reducing electron-hole recombination rate and enhancing photocatalytic activity by integrating unique donor-acceptor systems into the polymeric network of graphitic carbon nitride (g-CN). The results of the characterization showed that C and O are successfully integrated into the framework of g-CN. The O-containing and C-containing section of the as-prepared catalysts (OCCNx) play the role of donor and acceptor, respectively. The donor-acceptor systems of OCCN x offer an extra electron transfer transition mode, which dramatically extends the optical absorption range, and narrows down the bandgap of g-CN from 2.74 to 2.03 eV. Also, the donor-acceptor systems significantly improve the delocalized ability of the photoinduced charge carriers, which efficiently prolongs the lifetime of the charge carriers and reduces the electron-hole recombination rate, as all of these are all beneficial for boosting the photocatalytic activity of the catalysts. Experimental results show that OCCN 0.25 displays the best photocatalytic CO 2 reduction performance with a CO production rate of 34.97 μmol g−1 in 4 h, which is 4.3-fold higher than that obtained in the case of bulk g-CN. Moreover, the reaction is performed in water without any co-catalyst and sacrificial agent, which makes it a green and environmentally friendly reaction. Results obtained from DFT simulation agree well with the empirical results, and a possible reaction mechanism is suggested based on these calculations. [ABSTRACT FROM AUTHOR]