Visible Light Absorption Range Research Articles

Silver sulfide anchored bismuth molybdate p-n heterojunction nano-coating with excellent photo-thermal self-healing performance

In this research, a self-healing nano-coating with excellent photo-thermal response to near-infrared (NIR) laser is prepared. This coating incorporates silver sulfide anchored bismuth molybdate (Ag2S@Bi2MoO6) into a shape memory epoxy resin to achieve for a good photo-thermal conversion capability. The Ag2S@Bi2MoO6 p-n heterojunction could photo-generate more electron-holes pairs under the NIR laser irradiation. Also, it shows a wider absorption range of visible light, leading to effectively absorb the light energy, generate enough heat to induce the shape memory recovery in the coating, and seal the scratch. The results indicate that the temperature of EP-1 % Ag2S@Bi2MoO6 coating has reached about 88 °C, while good self-healing and anti-corrosion properties with a self-healing rate of 88.41 % have been achieved. Furthermore, calculations based on Density Functional Theory and Finite Element Method pointed out that the formation of p-n heterojunction effectively has enhanced the photo-thermal effect. This research opens a new way for developing self-healing coatings with an ultra-fast response time and high self-healing efficiency.

Ulva lactuca L. extract bio-templated fabrication of CuO/ZnFe2O4 nanocomposites for photodegradation organic dye pollutants and in vitro biological activities

In this present work, a novel CuO/ZnFe2O4 nanocomposites has been fabricated via hydrothermal-assisted synthesis using Ulva lactuca L. extract as both a reducing and capping agent A comprehensive investigation such as structural, morphological, optical, and electronic properties of the CuO/ZnFe2O4 NCs were investigated in details. The photocatalytic efficacy of the prepared CuO/ZnFe2O4 NCs was assessed for Congo red (CR) dye degradation and the experimental results demonstrate the CuO/ZnFe2O4 NCs exhibits superior photocatalytic activity (91.13% k=0.03289 min−1) compared to pure CuO and ZnFe2O4 catalysts under 120 min of visible light irradiation. Additionally, the CuO/ZnFe2O4 NCs exhibited excellent long-term recycling stability over four consecutive cycles. This enhanced photocatalytic performance of CuO/ZnFe2O4 NCs was attributed to the synergism between CuO and ZnFe2O4, which facilitate the exceptional properties such as large specific area, a wide visible-light absorption range, and efficient electron-hole separation. Furthermore, the prepared CuO/ZnFe2O4 NCs were evaluated for their in vitro antibacterial and anticancer properties. The results of the disc diffusion assay with CuO/ZnFe2O4 NCs as an antibacterial agent demonstrated a highest zone of inhibition of 18.23 ± 0.30 mm for Bacillus subtilis and 19.83 ± 0.76 mm Escherichia coli. Moreover, in vitro cytotoxicity assessments using the MTT assay indicated a 64.94% cytotoxic activity against HT-29 colon cancer cells. The multifunctional advantages of Ulva lactuca L. extract-mediated green CuO/ZnFe2O4 NCs hold significant promise for environmental remediation and in vitro-based therapeutic applications.

Preparation of Z-type Cu2SnS3/g-C3N4 heterojunction material and its synergistic photocatalytic performance with H2O2

Due to poor visible light responsiveness and easy recombination of photo generated carriers, the photocatalytic performance of a single g-C3N4 is limited. This article presents a Z-type Cu2SnS3/g-C3N4 (CTS/CN) heterojunction photocatalyst prepared by in-situ growth of CTS on the surface of g-C3N4 using a simple solvothermal method. Through SEM results, it can be seen that as the content of g-C3N4 increases, the nanosheet gaps of flower shaped microspheres on the surface of CTS/CN increase and the size becomes thinner. The UV–vis DRS experiment showed that the introduction of CTS increased the visible light absorption range of CTS/CN composite and improved its visible light absorption ability.Under the synergistic effect of H2O2, the photocatalytic degradation efficiency of CTS/70% CN towards MO reached 99% at 50 minutes，At the same time, the degradation rate constants k of methylene blue (MB), ciprofloxacin (CIP) and levofloxacin (LEV) reached 0.06289 min−1, 0.02132 min−1 and 0.02787 min−1 respectively at 100 min.In the synergistic MO system of H2O2 for photocatalytic degradation, free radical capture experiments showed that the main active species were h+and • OH. Combined with the band structure of Cu2SnS3 and g-C3N4, a Z-type photocatalytic mechanism was proposed. Under visible light, H2O2 rapidly captured the photo generated electrons of CTS/CN, promoting the transport of photo generated carriers. This study provides theoretical guidance for the design and construction of Z-type heterojunctions with superior visible light driven photocatalytic performance.

Photostability and visible-light-driven photoactivity enhancement of hierarchical C@ZnCdS/ZnS/MoS2

Zinc cadmium sulfide solid (Zn x Cd1−x S) related composites received great attention in photocatalytic hydrogen production because of their tunable bandgap and strong visible light absorption range. But sulfide-based metal materials commonly suffer from photo-corrosion issues. It is very important to construct the photocatalysts with high efficient activity and photostability for H2 production. Herein, we successively prepared ZnCdS/ZnS (ZCS/ZS) heterostructures, ZnCdS/ZnS/MoS2 (ZCS/ZS/M) heterostructures decorated ZCS/ZS with MoS2 quantum dots, then we obtained x-C@ZCS/ZS and x-C@ZCS/ZS/M heterostructures encapsulated ZCS/ZS and ZCS/ZS/M with carbon layer. The performance of the photocatalytic hydrogen production showed that sample 0.05-C@ZCS/ZS/M has a remarkable photocatalytic H2 evolution rate of 15.231 mmol·h−1·g−1 with noble metal-free co-catalysts. This rate was approximately 21 times higher than that of the pristine ZCS/ZS photocatalyst. The optimized sample reveals an excellent stability, without activity losses after 10 h. The improved photocatalytic activity can be attributed to the unique heterojunction structure formed by ZCS/ZS and MoS2. Additionally, the carbon films played a crucial role in providing excellent stability by spatially separating the sites for redox reactions, thereby inhibiting the recombination of photo-generated electron–hole pairs.

12 Connecting Sites Linked Three‐dimensional Covalent Organic Frameworks with Intrinsic Non‐interpenetrated shp Topology for Photocatalytic H2O2 Synthesis

AbstractDeveloping high connectivity (>8) three‐dimensional (3D) covalent organic frameworks (COFs) towards new topologies and functions remains a great challenge owing to the difficulty in getting high connectivity organic building blocks. This however represents the most important step towards promoting the diversity of COFs due to the still limited dynamic covalent bonds available for constructing COFs at this stage. Herein, highly connected phthalocyanine‐based (Pc‐based) 3D COFs MPc‐THHI‐COFs (M=H2, Ni) were afforded from the reaction between 2,3,9,10,16,17,23,24‐octacarboxyphthalocyanine M(TAPc) (M=H2, Ni) and 5,5′,5′′,5′′′,5′′′′,5′′′′′‐(triphenylene‐2,3,6,7,10,11‐hexayl)hexa(isophthalohydrazide) (THHI) with 12 connecting sites. Powder X‐ray diffraction analysis together with theoretical simulations and transmission electron microscopy reveals their crystalline nature with an unprecedented non‐interpenetrated shp topology. Experimental and theoretical investigations disclose the broadened visible light absorption range and narrow optical band gap of MPc‐THHI‐COFs. This in combination with their 3D nanochannels endows them with efficient photocatalysis performance for H2O2 generation from O2 and H2O via 2e− oxygen reduction reaction and 2e− water oxidation reaction under visible‐light irradiation (λ >400 nm). This work provides valuable result for the development of high connectivity functional COFs towards diverse application potentials.

Efficient photocatalytic degradation of antibiotics by binary heterojunction complex boron subphthalocyanine bromide/bismuth oxychloride

The development of stable and efficient heterojunction photocatalysts for wastewater environmental purification exhibits a significant challenge. Herien, a promising binary heterojunction complex comprising boron subphthalocyanine bromide/bismuth oxychloride (SubPc-Br/BiOCl) was successfully synthesized using the hydrothermal method, which involved the self-assembled of SubPc-Br on the surface of BiOCl via intermolecular π-π stacking interactions to compose an electron-transporting layer. The photocatalytic efficiency of SubPc-Br/BiOCl for the degradation of tetracycline and the minocycline exhibited a substantial improvement of 29.14% and 53.72%, respectively, compared to the original BiOCl. Experimental characterization and theoretical calculations elucidated that the enhanced photocatalytic performance of the SubPc-Br/BiOCl composite photocatalysts stemmed from the S-scheme electron transport mechanism at the interface between BiOCl and SubPc-Br supramolecules, which broadened the visible light absorption range, increased the carrier molecular efficiency, and accelerated the carriers. Furthermore, molecular dynamic (MD) simulations provided insights into the action trajectories of the two semiconductors, revealing that the presence of SubPc-Br enhances the water and organic pollutant adsorption capabilities of the BiOCl surface within the supramolecular array system. In conclusion, the synthesis and analysis of the binary heterojunction complex SubPc-Br/BiOCl yield valuable insights into the efficient photocatalytic degradation of antibiotics, holding great promise for diverse environmental applications.

12 Connecting Sites Linked Three-dimensional Covalent Organic Frameworks with Intrinsic Non-interpenetrated shp Topology for Photocatalytic H2O2 Synthesis.

Developing high connectivity (>8) three-dimensional (3D) covalent organic frameworks (COFs) towards new topologies and functions remains a great challenge owing to the difficulty in getting high connectivity organic building blocks. This however represents the most important step towards promoting the diversity of COFs due to the still limited dynamic covalent bonds available for constructing COFs at this stage. Herein, highly connected phthalocyanine-based (Pc-based) 3D COFs MPc-THHI-COFs (M=H2, Ni) were afforded from the reaction between 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine M(TAPc) (M=H2, Ni) and 5,5',5'',5''',5'''',5'''''-(triphenylene-2,3,6,7,10,11-hexayl)hexa(isophthalohydrazide) (THHI) with 12 connecting sites. Powder X-ray diffraction analysis together with theoretical simulations and transmission electron microscopy reveals their crystalline nature with an unprecedented non-interpenetrated shp topology. Experimental and theoretical investigations disclose the broadened visible light absorption range and narrow optical band gap of MPc-THHI-COFs. This in combination with their 3D nanochannels endows them with efficient photocatalysis performance for H2O2 generation from O2 and H2O via 2e- oxygen reduction reaction and 2e- water oxidation reaction under visible-light irradiation (λ >400 nm). This work provides valuable result for the development of high connectivity functional COFs towards diverse application potentials.

Performance Evaluation of a Multifunctional Road Marking Coating for Tunnels Based on Nano SiO2 and TiO2 Modifications

Multifunctional road marking coatings with the functions of high-temperature stability, degradation of exhaust gas, and self-cleaning are of great significance for the safe operation and environmental protection of tunnels. This article uses active acrylic resin and an organosilicon hydrophobic agent as the base material, selects expanded vermiculite and glass microspheres as insulation fillers, and uses ammonium polyphosphate, pentaerythritol, melamine, and aluminum hydroxide as high-thermal-stability systems to prepare a two-component road marking coating base material. Then, nano SiO2 and modified nano TiO2 are added as modifiers to prepare a multifunctional road marking coating for tunnels. The physical and chemical properties of multifunctional road marking coatings are evaluating based on laboratory tests including thermogravimetry and derivative thermogravimetry, differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, exhaust degradation, and contact angle tests. The results indicate that the developed multifunctional road marking coating effectively reduces the thermal conductivity of the carbon layer through physical changes in the flame retardant system and the heat resistance formed by the high breaking bond energy of nano SiO2 during the combustion process. It forms a ceramic-like structure of titanium pyrophosphate with nano TiO2 that is beneficial for improving flame retardancy without generating harmful volatile gases and has good flame retardant properties. N–V co-doping reduces the bandgap of TiO2, broadens the absorption range of visible light by nano TiO2, improves the catalytic efficiency of visible light, and achieves the degradation efficiency of the four harmful components NOx, HC, CO, and CO2 in automotive exhaust by 23.4%, 8.3%, 2.5%, and 2.9%, respectively. The solid–liquid phase separation in the multifunctional road marking coating in the tunnel causes the formation and accumulation of nano SiO2 and TiO2 particles on the coating surface, resulting in a microstructure similar to the “micro–nano micro-convex” on the lotus leaf surface and making a water droplet contact angle of 134.2° on the coating surface.

A tungsten phosphide cocatalyst enhanced bismuth tungstate photoanode with the robust built-in electric field towards highly efficient photoelectrochemical water splitting

The use of low-cost and effective cocatalyst is a potential strategy to optimize the effectiveness of photoelectrochemical (PEC) water splitting. In this study, tungsten phosphide (WP) is introduced as a remarkably active cocatalyst to enhance the PEC efficiency of a Bi2WO6 photoanode. The onset potential of Bi2WO6/WP demonstrates a negative shift, while the photocurrent density demonstrates a significant 5.5-fold increase compared to that of unmodified Bi2WO6 at 1.23 VRHE (reversible hydrogen electrode). The loading of WP cocatalyst facilitates the rapid transfer of holes, increasing the range of visible light absorption, the water adsorption ability as well as promoting the separation of photogenerated electrons and holes via the built-in electric field between Bi2WO6 and WP. This study proposes a strategy to hinder the recombination of electron-hole pairs by using WP cocatalyst as a hole capture agent, improve the photoelectric conversion efficiency, and enhance the overall photoelectrochemical properties of Bi2WO6 photoanode.

Silver (Ag) doped graphitic carbon nitride (g-C3N4) photocatalyst for enhanced degradation of Ciprofloxacin (CIP) under visible light irradiation

Pharmaceutical industry wastewater is causing an increased risk of resistant pharmaceutical micropollutants (PMP) e.g. antibiotic resistant bacteria (super bug) in the ecosystem. Amongst variety of wastewater treatment approaches, Advanced oxidation processes (AOPs) employing photocatalysis provides a cost-effective and sustainable approach for fixation of PMP in an economical and efficient manner to counter the potential risks. Until today, tremendous efforts have been made to trig the performance of photocatalytic wastewater treatment, with the key focus on development of cost-effective, efficient and a moderately stable photocatalyst. Such attempts succeeded with different types of photocatalysts using different synthesis techniques. In recent years, graphitic carbon nitride (GCN) has emerged as one of the cost effective, moderately stable, nontoxic and efficient photocatalyst, and has been scarcely studied specifically for pharmaceutical micropollutants (PMPs) degradation. Hence, considering these factors alongside the facile synthesis and moderate optical absorption of GCN, an effort was made in the present work with effective customization of GCN i.e. silver (Ag) doping to extend light absorption in visible light range which may enhance the photocatalytic performance for Ciprofloxacin (CIP) degradation. The optimization of photocatalytic performance was executed with varied Ag dopant content to obtain an optimum sample with supreme photocatalytic activity for the maximum degradation of CIP, a common antibiotic. The best Ag-doped GCN sample (0.1 AGCN) exhibits a photocatalytic degradation efficiency of 84%, which is 2.15 times greater than pure GCN (39%). The obtained results showed that the strategy of Ag doping substantially enhances the photocatalytic performance, thus offering an efficient mean for developing visible light active photocatalyst for PMP removal and encouraging further research. The photocatalytic performance of the prepared samples was evaluated by degradation of CIP under visible light irradiation. Several characterization techniques were used to characterize and analyze the prepared samples, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, UV Visible absorption, and Photoluminescence (PL) spectroscopy.

Increasing Donor-Acceptor Interactions and Particle Dispersibility of Covalent Triazine Frameworks for Higher Crystallinity and Enhanced Photocatalytic Activity.

Covalent triazine frameworks (CTFs) have recently emerged as an efficient class of photocatalysts due to their structural diversity and excellent stability. Nevertheless, the synthetic reactions of CTFs have usually suffered from poor reversibility, resulting in a low crystallinity of the materials. Here, we report the introduction of methoxy groups on the monomer 2,5-diphenylthiazolo[5,4-d]thiazole to reinforce interlayer π-π interactions of the resulting donor-acceptor type CTFs, which improved crystallinity, further increasing the visible light absorption range and allowing for efficient separation and transport of carriers. The morphology is strongly correlated to the wettability, which has a significant impact on the mass transfer capacity and photocatalytic activity in the photocatalytic reaction. To further improve crystallinity and photocatalytic activity, CTF-NWU-T3 photocatalysts in a bowl shape were prepared using a SiO2 template. The energy band structure, photocatalytic hydrogen evolution, and pollutant degradation efficiency of involved materials were investigated. The donor-acceptor type CTF-NWU-T3 with a bowl-shaped morphology, synthesized using the template method and the introduction of methoxy groups, exhibited an excellent photocatalytic hydrogen production rate of 32064 μmol·h-1·g-1. This study highlights the significance of improving donor-acceptor interactions and increasing the dispersibility of catalyst particles in dispersion to enhance the photocatalytic activity of heterogeneous photocatalysts.

Robust interaction of ZnO and TiO2 nanoparticles with layered graphitic carbon nitride for enhanced photocatalytic oxidative desulfurization of fuel oil: mechanism, performance and stability.

Sulfur compounds in fuel such as thiophene, benzothiophene and dibenzothiophene are the primary source of SO x emissions, leading to environmental pollution and acid rain. In this study, we synthesized a layered oxygen-doped graphitic carbon nitride (OCN) structure and integrated ZnO and TiO2 nanoparticles onto the OCN surface through a microwave-assisted sol-gel method. The X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) results confirmed a robust interaction between the ZnO and TiO2 nanoparticles and the oxygen-doped g-C3N4 (OCN) surface, as indicated by the formation of C-N-Ti and C-O-Ti bonds. This interaction notably improved the optoelectronic properties of the ZnO-TiO2/OCN composite, yielding increased visible light absorption, reduced charge recombination rate, and enhanced separation and transfer of photogenerated electron-hole pairs. The oxygen doping into the CN network could alter the band structure and expand the absorption range of visible light. The ZnO-TiO2/OCN photocatalyst demonstrated remarkable desulfurization capabilities, converting 99.19% of dibenzothiophene (DBT) to dibenzothiophene sulfone (DBT-O2) at 25 °C, and eliminating 92.13% of DBT from real-world fuel oil samples. We conducted in-depth analysis of the factors impacting the redox process of DBT, including the ZnO ratio, initial DBT concentration, catalyst dosage, stability, and O/S molar ratio. Radical trapping experiments established that ˙O2 -, ˙OH and h+ radicals significantly influence the reaction rate. The obtained results indicated that the ZnO-TiO2/OCN photocatalyst represents a promising tool for future fuel oil desulfurization applications.

A bicomponent synergistic MoxW1-xS2/aluminum nitride vdW heterojunction for enhanced photocatalytic hydrogen evolution: a first principles study.

The coupling of two-dimensional van der Waals heterojunctions is an effective way to achieve photocatalytic hydrogen production. This paper designs the MoxW1-xS2/AlN (x = 0, 0.25, 0.5, 0.75, 1) van der Waals heterojunction as a possible photocatalytic material. By using first-principles calculations, the effects of different Mo/W ratios on the band gap and photocatalytic hydrogen production performance of heterojunctions were investigated. The results show that the heterojunction is a direct Z-scheme photocatalyst and can achieve overall water splitting. By calculating the absorption spectrum, it is found that the heterojunction has a wider visible light absorption range when the bimetal is added, and there is still a strong absorption peak at 615 nm. With the increase of the Mo atom ratio, the absorption spectrum is red-shifted. The Gibbs free energy of the two-component Mo0.5W0.5S2/AlN heterojunction is only -0.028 eV. Our work provides a new perspective for the modification of 2D transition metal dichalcogenide photocatalytic heterojunctions.

Preparation of P-coupled g-C3N4/TiO2 photoanode and its photoelectrocatalytic degradation of sulfadiazine

In order to solve the problems of TiO2 bandgap width and low utilization rate of light energy, red phosphorus which can absorb visible light is introduced, which is complementary to the characteristics of TiO2 which mainly absorb ultraviolet light. The introduction of red phosphorus is expected to broaden the light response range of the photoelectrode to the visible region, thereby improving the efficiency of sunlight utilization. TiO2 was modified by red phosphorus sublimation precipitation. The joint introduction of P and g-C3N4 not only broadened the photoresponse range of TiO2, extended the visible light absorption range to 460nm, improved the light absorption efficiency, but also promoted the effective separation and transmission of charge, thus greatly improving the degradation efficiency of SD up to 90.28%. ꞏOH, h+ and ꞏO2- were the main active species of SD degradation, in which ꞏOH played a key role.

TiO2−x/Ag/rGO composites as effective photocatalysts for the degradation of organic pollutants

The incorporation of Ti3+ and oxygen vacancies in the TiO2−x NRs/Ag/rGO composites reduces the bandgap of TiO2 and extends the visible light absorption range due to the SPR effect of Ag NPs and the reduced light reflection in the presence of rGO.

Preparation and photocatalytic activity of CoFe2O4 nanoparticle modified rod-like Mn0.3Cd0.7S photocatalysts with S-scheme heterojunction

With the continuous progress of photocatalytic technology in environmental pollution control, the recovery of photocatalysts has gradually become a hot topic of concern. To solve this problem, a magnetically recoverable rod-shaped CoFe2O4/Mn0.3Cd0.7S with S-scheme heterojunction photocatalyst was successfully constructed. The phase composition, morphology, light absorption, and surface chemical environment of the samples were measured. The photocatalytic degradation rate of tetracycline by CoFe2O4/Mn0.3Cd0.7S is higher than that either of CoFe2O4 and Mn0.3Cd0.7S. The degradation efficiency of 1%CoFe2O4/Mn0.3Cd0.7S showed the best performance of 82.1% within 60 min. The rate constant for first-order kinetics of 1%CoFe2O4/Mn0.3Cd0.7S was about 1.72 times that of pure Mn0.3Cd0.7S. It was found that the enhanced photoactivity of the CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst was due to the wider absorption range of visible light and the improved inhibition of electron and hole recombination. It is also found that the CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst has excellent magnetic recovery ability under the external magnetic field. The photostability of as-prepared CoFe2O4/Mn0.3Cd0.7S heterojunction photocatalyst was studied, and a reasonable S-scheme electron-hole transfer mechanism was proposed according to the band structure. These advances provide a new way to improve the photoactivity of magnetic recyclable photocatalysts, and the synthetic magnetic recyclable rod CoFe2O4/Mn0.3Cd0.7S has a potential application prospect in the degradation of water pollutants.

Synergistic effect of oxygen vacancies and doped sulfur over BiOBr for efficient visible photocatalytic removal of dyes

Herein, the BiOBr co-modified with oxygen vacancies (Vo) and doped by sulfur was a promising photocatalyst (Vo-BiOBr-S), which was synthesized by a one-pot solvothermal approach. The TEM showed that Vo-BiOBr-S is a sea urchin-shaped microsphere with a diameter of about 4 μm. The photocatalytic efficiency of Vo-BiOBr-S was studied by removing rhodamine B and methylene blue, which were higher than that of BiOBr, Vo-BiOBr and BiOBr-0.8S, respectively. Additionally, the photocatalyst exhibits high degradation of aqueous solutions containing both rhodamine B and methylene blue. The photocurrent and photoluminescence tests showed that the improved photocatalytic performance of Vo-BiOBr-S was due to the accelerated charge transfer and separation by the internal electric field, which extended the visible light absorption range. Furthermore, experiments free radical trapping revealed that superoxide radicals were the principal active species in this system, contributing to the superior degradation performance of Vo-BiOBr-S. The density of states of the samples was calculated via DFT to analyse the energy band structure. The effectiveness of Vo-BiOBr-S in mineralising RhB under LED light was demonstrated through total organic carbon tests. This study presents a method to design efficient photocatalysts for use in environmental preservation.

Dispersed Bi2S3 site in a porphyrin-based metal–organic framework for photocatalytic nitrogen fixation

The development of suitable alternatives to the energy-intensive and seriously polluting Haber–Bosch process for ammonia production is crucial. Photocatalytic nitrogen fixation has attracted extensive research attention as a pollution-free, low-cost, and sustainable ammonia production process. However, most reported photocatalysts so far have relatively low conversion rates for N2 reduction. Herein, we employed a strategy based on bismuth precoordination and in-situ sulfurization strategy to grow highly dispersed bismuth sulfide (Bi2S3) on a porous coordination network (PCN) metal–organic framework. The as-fabricated photocatalyst (Bi2S3@PCN-2) with high-density heterojunctions was used for the photocatalytic nitrogen fixation for ammonia production and degradation of bisphenol A, achieving an ammonia production rate of 3880 μg h−1 g−1 and a 96.4% degradation efficiency for bisphenol A within 30 min in the absence of a sacrificial agent. The abundant porphyrin rings and highly dispersed Bi2S3 broadened the visible-light absorption range of the photocatalyst, leading to numerous photogenerated charge carriers. Additionally, the high-density heterojunctions facilitated the separation of photogenerated electron–hole pairs, resulting in excellent photocatalytic performance. This work provides a new approach for the design and preparation of bifunctional photocatalysts.

Enhancing Z-scheme photocatalytic CO2 methanation at extended visible light (>600 nm): Insight into charge transport and surface catalytic reaction mechanisms

This article reports Z-scheme photocatalytic CO2 methanation at the extended visible light (>500 nm) in absence of sacrificial electron donor/acceptor and noble metal cocatalysts. This Z-scheme photocatalyst consists of reduced graphene oxide (rGO) sandwiched between two different redox active photocatalysts (Ca-doped Bi2O3 and Cu2O). The rGO acts as a mediator by relaying electrons from Ca-doped Bi2O3 and holes from Cu2O that enables Z-scheme spatial confinement of electrons in Cu2O while holes in Ca-doped Bi2O3. This charge carrier delocalization enforces the enhanced oxidation strength of holes in Ca-doped Bi2O3 and reduction strength of electrons in Cu2O. As a result, it has exhibited methane (CH4) production rate under wider range of visible light (up to 700 nm) absorption. This Z-scheme photocatalyst therefore advents a new ‘600 nm-class photocatalyst’ for CO2 methanation. With the help of 13C isotopic measurements, first principles calculations and photoelectrochemical measurements, we have revealed the atomistic insight into the charge transport and surface catalytic reactions mechanisms to understand the rate limiting factors towards unassisted PCR.

Construction of BiOCl/Bi2WO6 Z-scheme heterojunction with close interfacial contact using CNT as electron medium

Enhancing carrier separation capabilities and extending the visible light absorption range are essential for overcoming the low photocatalytic performance of single semiconductors. In this study, by using hydrothermal and ion-exchange methods, a series of Z-scheme heterojunction BiOCl/CNT/Bi2WO6 photocatalysts with visible light response were successfully constructed by using carbon nanotubes (CNT) as an electronic medium. Under visible light irradiation, the photocatalytic performances of the samples were evaluated by the degradation of tetracycline and ciprofloxacin. The results shown that the BiOCl/CNT/Bi2WO6 heterojunction photocatalysts possessed excellent photocatalytic activity, and the kinetics reaction models of the photocatalysts followed pseudo-first-order kinetics. This excellent photocatalytic performance may be due to the acceleration of photogenerated carrier separation due to the formation of heterojunction and the CNT as an electronic medium, as well as the close contact interface between the BiOCl/Bi2WO6 heterojunction, which shortened the carrier migration path. The charge transfer mechanism in the BiOCl/CNT/Bi2WO6 Z-scheme heterojunction composites was proposed based on the results of trapping experiments, in-situ XPS and SPV. Furthermore, three degradation pathways were discussed, and toxicity assessments of intermediates showed that the toxicity after photocatalytic degradation decreased. This study could bring light on the development of promising and novel CNT-mediated Z-scheme heterojunction photocatalysts for pollutant degradation.