High Photocatalytic Performance Research Articles

Two-dimensional SPdAZ2 (A = Si, Ge; Z = N, P, As) monolayers with an intrinsic electric field for high-performance photocatalysis.

Two-dimensional materials exhibiting exceptional photocatalytic properties and a low carrier recombination rate have garnered significant attention. However, such attributes are relatively scarce among conventional two-dimensional materials. Two-dimensional Janus materials, owing to their intrinsic electric field, hold substantial promise in the realm of photocatalysis. In this study, we conducted a comprehensive investigation of the electronic, optical and photocatalytic properties, as well as the carrier mobility of SPdAZ2 (A = Si, Ge; Z = N, P, As) monolayers employing first-principles calculations. Employing the HSE06 hybrid density functional, we discovered that all six structures exhibit semiconductor characteristics with indirect band gaps under equilibrium conditions. Notably, SPdSiP2, SPdSiAs2, and SPdGeP2 monolayers displayed advantageous band edge positions, facilitating effective photocatalytic water decomposition. Furthermore, we computed the carrier mobility of SPdAZ2 monolayers, revealing significant variations in the electron and hole mobility along the same direction, which enhances the effective separation of electrons and holes. Finally, we explored the impact of biaxial strain and an applied electric field on the electronic properties, photocatalysis, and light absorption of SPdAZ2 monolayers. These compelling features underscore the broad potential applications of SPdAZ2 (A = Si, Ge; Z = N, P, As) monolayers in the realm of photocatalytic water decomposition.

Design of porous ZrO2 with well-tuned band structures and strong visible-light harvesting via Zn doping for enhanced visible-light photocatalysis

As one of huge-gap semiconductors, zirconium dioxide (ZrO2) has been emerging as one of popular photocatalysts for treating wastewater, and the band gap engineering of ZrO2 for efficient visible-light harvesting and high-performance photocatalysis is probably the most important challenge. In this work, porous Zn doped Zr3+-ZrO2 nanostructures with strong visible-light harvesting capacity were fabricated via a calcination process for tetracycline degradation. The obtained (Zn, Zr3+)-ZrO2 samples showed greatly narrowed band gaps and enhanced visible-light harvesting capacity. In addition, the photocatalytic performance of the (Zn, Zr3+)-ZrO2 nanostructures was studied with tetracycline degradation as a model reaction. Among these prepared samples, the optimal (Zn, Zr3+)-ZrO2-5% sample exhibited remarkably improved tetracycline degradation visible-light irradiation, and the apparent rate constant reached 0.04958 min−1, which was 7.05 times of pristine Zr3+-ZrO2. The boosted photocatalytic performance of the (Zn, Zr3+)-ZrO2 nanostructures were mainly ascribed to Zn doping effects as along as the high surface areas. Finally, possible photocatalytic mechanism, degradation pathways, and toxicity assessment were also studied. Current results indicate the significant roles of Zn doping in regulation of band gaps and morphology control of ZrO2 for high-performance photocatalytic applications.

ZIF-67 derived CoSx mediated 1D hollow carbon nitride for high photocatalytic hydrogen performance

Metal-Organic Framework (MOFs) consist of organic ligands having metal ions at the center that have many properties especially large surface area, polymetallic sites, tunable organic ligands, and porous structure. In this work, a three-dimensional MOF ZIF-67 was decorated over the g-C3N4 1D hollow tubular structure by a simple precipitation technique. The proposed CoSx co-catalyst was introduced as a free condition in the solution derived from ZIF-67 rather than loaded on the 1D g-C3N4. It is suggested that CoSx offers an active site for the reduction of water molecules after accepting the photogenerated electrons from the 1D g-C3N4. The composite reveals high hydrogen performance (13911 μmol∙g−1 h−1) in comparison with ZIF-67 (4885 μmol∙g−1 h−1) and h-CN (1229 μmol∙g−1 h−1). Additionally, the composite sample has Quantum efficiency (Q.E) of about 19.5 % for hydrogen evolution reaction (HER) at 420 nm which is significantly greater than the h-CN (1.72 %) and ZIF-67 (6.87 %) sample. The work opened a new avenue in the field of photocatalysis by suggesting noble metal-free and high-efficiency MOF heterojunction.

Enhanced photocatalytic detoxification performance of OVs-enriched Co3O4/BiVO4 benefited from S-scheme interfacial charge pairs separation mechanism

Photocatalysts possess great application prospects in the environmental and energy field, and heterojunction photocatalysts can optimize the separation and transfer of photoinduced carriers to achieve high performance photocatalysis. Herein, Co3O4/BiVO4 (CoBVO) heterojunction photocatalysts were prepared in-situ using a one-step hydrothermal method. The impact of heterojunction structure and oxygen vacancies (OVs) on the light absorption range, band structure, and photogenerated carriers separation behavior of BiVO4 were studied by characterizing the photoelectric properties of the material. The results indicate that the concentration of OVs on BiVO4 samples changes due to formation of heterojunctions. Under simulated solar light irradiation, photocatalytic performance of the synthesized catalysts was investigated using Cr(VI) and moxifloxacin as simulated contaminants, photocatalytic reduction rate constant of Cr(VI) on 2CoBVO (molar ratio of Co/Bi is 2%) is 4.4 times of that on the single BiVO4, and the photocatalytic degradation rate constant of moxifloxacin on 2CoBVO is 1.6 times of that on the reference BiVO4. S-scheme interfacial charges separation and enhanced photocatalytic performance mechanism of OVs-enriched Co3O4/BiVO4 heterojunctions were elucidated based on the experimental observations. This work provides ideas for one-step synthesis of bismuth-based composite photocatalysts, which can be applied to the photocatalytic treatment of heavy metals and antibiotics.

Effects of transition metals (Fe, Co) on the physical and photoelectrochemical hydrogen generation properties of copper oxide nanoparticulate films

The composites of some transition metal oxides are currently attracting interesting roles in various fields of technology and industry. The present work attempts to tune the properties of copper oxide (CuO) for hydrogen energy generation. Iron (Fe) and cobalt (Co) were intentionally doped at precise contents into CuO thin films. X-ray diffraction (XRD) indicated that the successful substitution of Fe and Co on the Cu sites created induces pressure (tensile) stress in the lattice. Fe doping deteriorated the films' crystallinity and increased the dislocation density from 1.82 × 10−3 to 4.36 × 10−3 nm−2, while Co codoping displayed unsystematic behavior. The scanning electron microscope (SEM) images showed that the films have smooth surfaces comprising a huge number of particles/unit area with a narrow size distribution. The energy-dispersive X-ray (EDX) analysis confirmed the presence of both Fe and Co with almost the pre-calculated ratios. The optical measurement showed that increasing the Fe contents increases the absorption coefficient of CuO and narrows its optical band gap from 1.7 to 1.55 eV. The photoluminescence (PL) intensity increases for Fe-doped CuO films whereas quenched when doped with Co. A series of photoelectrochemical (PEC) measurements were conducted to evaluate the performance of the prepared films in the production of solar hydrogen. The CuO–6%Fe film showed high photocatalytic performance for H2 generation from H2O splitting over a wide wavelength range of sunlight with long-term photostability. The photocurrent density of CuO–6%Fe film is about 155 times more than those obtained from pure CuO film. The incident photon-to-current efficiency (IPCE) and the solar-to-hydrogen efficiency (ηSTH) of CuO–6%Fe film were 5.98 % at 307 nm and 0.94 % under Xenon illumination, respectively. Hence, this work proposed an efficient and reasonable technique to enhance the performance of a CuO-based photoelectrode for solar hydrogen production.

Designing step-scheme AgI decorated Ta2O5-x heterojunctions for boosted photodegradation of organic pollutants

Step-scheme (S-scheme) AgI decorated Ta2O5-x heterojunctions have been designed and synthesized via a combination of solvothermal and chemical deposition methods for enhanced visible-light harvesting and high-performance photocatalysis. The AgI nanoparticles showed great influences on the visible-light absorption and charge separation between AgI and Ta2O5-x microspheres. The experimental results indicated that the as-prepare AgI/Ta2O5-x composites achieved enhanced photocatalytic performance towards tetracycline degradation under visible light, and the AgI/Ta2O5-x-11 sample displayed the highest photocatalytic performance and the maximum rate constant of approximately 0.09483 min−1, which was 7.22 times that of Ta2O5-x microspheres and 2.56 times that of AgI, respectively. The highly enhanced photocatalytic performance was mainly attributed to the construction of S-scheme heterostructure and formation of oxygen vacancies in Ta2O5-x microspheres. In addition, the trapping experimental and DMPO spin-trapping ESR spectra confirmed the ⸱O2− and ⸱OH species as the main radicals during tetracycline degradation. Current work indicates an S-scheme tantalum-based composites for high-performance environmental photocatalysis.

Decoration of silver on ZnS for enhancement of sunlight-driven photodegradation of reactive red azo dye and norfloxacin antibiotic

High charge carrier recombination rate is the major difficulty affecting low photocatalytic performance of the UV-responsive ZnS photocatalyst. To overcome the problem, well dispersion of noble metals on the ZnS surface can be regarded as one of the useful strategies to enhance the photocatalytic efficiency. This is due to a synergy of creation of heterojunction structure and surface plasmon resonance effect. In the present work, the surface of the hydrothermally grown ZnS photocatalyst was modified with 10 wt %silver. The hexagonal Ag/ZnS photocatalyst provided high sunlight-active photocatalytic performance toward removal of anionic azo dye and norfloxacin antibiotic with the efficiency of about 99 % and 70 %, within 120 min, respectively. The improvement of the resultant photoactivity is attributed to increasing of charge separation capacity at the interface. Well distribution of silver on ZnS surface results in the generation of the Schottky barrier at the Ag/ZnS interface. This will end up with the increment of quantum efficiency and enlargement of the photocatalytic activity. Additionally, after modification of ZnS surface by addition of silver, a red shift in the light absorption toward visible region was found. This is assigned to the effect of surface plasmon resonance (SPR) of Ag on ZnS surface. The synthesized Ag/ZnS reveals high structural stability with enhanced performance even after the fifth cycle. This work demonstrates a new avenue for creation of a silver-modified ZnS for complete degradation of toxic organic contaminants including dyes and antibiotics by use of the abundant solar energy.

Preparation of SrFe12O19/SiO2/TiO2 Photocatalysts and Degradation of Methylene Blue and Petroleum Wastewater

AbstractThe synthesis and application of magnetic photocatalysts have become a critical topic in organic waste treatment. In this study, SrFe12O19 powder, SrFe12O19/SiO2 particles and SrFe12O19/SiO2/TiO2 photocatalysts were successfully produced using coprecipitation technique, Stöber process and solvothermal method, respectively. The degradation of methylene blue dye and simulated petroleum wastewater under simulated sunlight and ultraviolet light was used to assess the photocatalytic activity of the SrFe12O19/SiO2/TiO2 composites. Results showed the high photocatalytic performance of the produced SrFe12O19/SiO2/TiO2 photocatalysts with a 1 : 4 mass ratio of SrFe12O19 to TiO2 synthesized at 170 °C, whose surface has more hydroxyl groups as the active center. At 120 min of irradiation, the photodegradation rates of methylene blue and simulated petroleum wastewater were 83.94 % and 60.77 %, respectively. The photocatalytic activity of the Fe12O19/SiO2/TiO2 with ferrite semiconductor/insulator/semiconductor structure was improved by the action of the magnetic field of SrFe12O19. The SrFe12O19/SiO2/TiO2 composite particles can be recycled easily under an external magnetic field and show good application prospects in organic wastewater degradation.

Synergetic effects of in-plane and interlayer dual regulation on sandworm-like graphitic carbon nitride for high-efficiency photocatalytic performance

Carbon nitride with tailored atomic structure has recently attracted considerable attention, however, the fast carrier recombination and incomplete visible light absorption great limited the practical application. Here, novel intramolecular synergetic effects of in-plane and interlayer dual regulation on sandworm-like graphitic carbon nitride (CN-NiC) was constructed for promoting the photocatalytic performance. Benefiting from the visible light band tail resulted from the extended π-conjugated system from carbon bridged doping, CN-NiC possesses expanded visible absorption range, and reduces the bandgap. More importantly, the Ni intercalation acts as an electron transport channel between the interlayer to reinforce the transfer of charge carriers. With this unique molecular structure, the optimized CN-NiC2 photocatalyst exhibits a high photocatalytic performance with 23.9 and 11.1-fold improvement as much as that of CN for H2 evolution and RhB degradation, respectively. In addition, the photocatalytic performance remains stable after several times cycles. This research provides an idea to obtain atomic structure tailored CN-based photocatalyst for high efficiency photocatalytic application.

Organic Ionic Liquid Grafted Nano‐CeO2: A Highly Efficient Photocatalyst for Hydroxylation of Benzene and Reduction of Cr (VI)

AbstractAn ionic liquid, namely imidazolium sulfonic acid chloride (ISAC) has been electrostatically grafted over cerium oxide nanoparticles to produce a nanocomposite, nano‐CeO2‐IL. The as‐prepared composite was characterized by various analytical techniques such as XRD, FT‐IR, SEM, TEM, XPS, BET, UV‐DRS, PL, and TGA to confirm the grafting of ISAC over CeO2 NPs. The photocatalytic process is regarded as the method of choice for the elimination of air pollutants because of its great efficiency and relatively benign working conditions. According to UV‐DRS spectra, its optical gap is 2.07 eV, which is appropriate for the visible light spectrum. The composite was investigated as a visible‐light‐driven photocatalyst for hydroxylation of benzene to phenol and heavy metal Cr (VI) reduction. Moreover, the scavenger experiments confirmed the detection of ⋅OH radicals which played a crucial role in the photocatalytic experiments. Within 60 minutes, 98.5 % of benzene was converted to phenol with 82.7 % selectivity in addition to 93.63 % Cr (VI) reduction within 30 mins. The photocatalytic reduction of Cr(VI) to Cr(III) follows a first‐order model with a rate constant of 0.027 min−1. The remarkably high photocatalytic performance of the catalyst may be ascribed to the synergistic interaction between the nano‐CeO2 catalyst and ionic liquid.

Interfacial C-O covalent bonds improving the piezo-assisted photocatalytic performance of Bi4Ti3O12@Carbon Schottky heterojunction

Rational design of piezo-assisted photocatalytic systems for simultaneously efficient ultilization of solar and mechanical energy is promising but still challenging. In this work, a novel Bi4Ti3O12@C (BTO@C) Schottky heterojunction with high piezo-assisted photocatalytic performance is rationaly designed, and the degradation reaction rate constant k for RhB reaches 0.092 min−1 in 30 min. Experimental results and density functional theory (DFT) calculations show that C-layer is tightly coated on the surface of BTO. Furthermore, C-O covalent bonds, which act as electron transfer channels, are formed at the interface of BTO and C-layer. Meanwhile, the presence of piezoelectric potential field of BTO@C under piezo-assisted photocatalytic conditions further promotes the transfer of photogenerated electrons from BTO to C-layer, which synergistically contributes to the performance enhancement. This work provides a new idea for the design and development of efficient piezo-assisted photocatalytic materials.

Successful synthesis of LaFeO3 nanoporous powders with high catalytic and photocatalytic performances: Investigation of precursor effect

Porous LaFeO3 powders with high catalytic and photocatalytic activities were successfully synthesized by sol-gel method using nitrate and chloride precursors. The precursor effect on the crystal structure, morphology, specific surface area and optical properties of the prepared powders was fully determined. Thermogravimetric and X-ray diffraction analyzes showed the formation of the orthorhombic perovskite phase (Pnma, #62) at annealing temperature of 800 and 1000 °C for powder prepared by nitride and chloride salts, respectively. The scanning electron microscopy images revealed a significant effect of precursor type on nanoparticles morphology. It was found that powder prepared from chloride salts is more porous than that prepared with nitrate salts. The estimated surface area of LaFeO3 nanoparticles ranges between 5.94 and 11.56 m2/g and the band gap varies from 2.19 to 2.27 eV. Methylene blue (MB) dye was used to investigate the catalytic and photocatalytic properties of LaFeO3 powders. Both prepared powder types showed good catalytic activity and high photocatalytic performance under visible irradiation in removing MB dye. The adsorption kinetics data of MB molecules on LaFeO3 nanoparticles are well fitted to the pseudo-first order model. Powder synthesized with chloride salts demonstrated high photodegradation efficiency of MB dye compared to that prepared by nitrate salts, which can be attributed to its relatively small band gap and high porosity. These two factors ensure a greater number of photogenerated electrons and more sites for photocatalytic reactions.

Ag3PO4/g-C3N4/Zn3(PO4)2 catalyst with ternary heterostructure and Z-scheme/type Ⅱ dual pathway mechanism for high photocatalytic performance

A novel Ag3PO4/g-C3N4/Zn3(PO4)2 photocatalyst with ternary heterostructure and Z-scheme/type Ⅱ dual pathway mechanism was synthesized. Scanning electron microscopy and transmission electron microscopy data showed that Ag3PO4, Zn3(PO4)2, and g-C3N4 were in close contact, leading to the formation of the ternary heterojunction. Under simulated solar light irradiation, the Ag3PO4/g-C3N4/Zn3(PO4)2 photocatalyst efficiently degraded rhodamine B (RhB) and displayed much higher photocatalytic activity than pure Ag3PO4, g-C3N4, Zn3(PO4)2, and Ag3PO4/Zn3(PO4)2 composite, exhibiting a RhB photodegradation efficiency of ∼91.2 % within 60 min. The quenching effects of different scavengers and electron spin resonance (ESR) experiments demonstrated that reactive h+ and·O2− species played major roles in the photocatalytic reaction. It was elucidated that excellent photocatalytic activity could be ascribed to the Z-scheme/type Ⅱ dual carrier transfer pathways. Therefore, the formation of a ternary heterostructure system is an efficient method for separating charge carriers and retaining their redox capabilities.

Defect-Regulated Two-Dimensional Superlattice of Holey g-C3N4-TiO2 Nanohybrids: Contrasting Influence of Vacancy Content on Hybridization Impact and Photocatalyst Performance.

Defect engineering provides an effective way to explore efficient nanostructured catalysts. Herein, we synthesize defect-regulated two-dimensional superlattices comprising interstratified holey g-C3N4 and TiO2 monolayers with tailorable interfacial coupling. Using this interfacial-coupling-controlled hybrid system, a strong interdependence among vacancy content, performance, and interfacial coupling was elucidated, offering key insights for the design of high-performance catalysts. The defect-optimized g-C3N4-TiO2 superlattice exhibited higher photocatalytic activity toward visible-light-induced N2 fixation (∼1.06 mmol g-1 h-1) than defect-unoptimized and disorderly assembled g-C3N4-TiO2 homologues. The high photocatalytic performance of g-C3N4-TiO2 was attributed to the hybridization-induced defect creation, facilitated hydrogenation of adsorbed nitrogen, and improvement in N2 adsorption and charge transport. A comparison of the defect-dependent photocatalytic activity of g-C3N4, g-C3N4 nanosheets, and g-C3N4-TiO2 revealed the presence of optimal defect content for improving photocatalytic performance and the continuous increase of hybridization impact with the defect content. Sophisticated mutual influence among defect, electronic coupling, and photocatalytic ability underscores the importance of defect fine control in exploring high-performance hybrid photocatalysts. Along with the DFT calculation, the excellent photocatalyst performance of defect-optimized g-C3N4-TiO2 can be ascribed to the promotion of the uphill *N hydrogenation step as well as to enhancement of N2 adsorption, charge transfer kinetics, and mass transports.

Systematic investigation of MoS2-metal sulfides (Metal = In, Sn, Cu, Cd) heterostructure via metal-sulfur bond for photocatalytic CO2 reduction

Heterojunctions between MoS2 and metal sulfides (Metal = In, Sn, Cu, Cd) were successfully constructed via the metal-sulfur bond, and their application of CO2 photoreduction into chemical values could address the problem of global warming effectively. Among all MoS2/metal sulfides, the same lamellar morphology between MoS2 and In2S3 could be ascribed for the high photocatalytic performance, which revealed the high specific surface area and benefitted for the generation of build-in electric field, thus leading to the outstanding separation and migration ability. In the opposite, the dissatisfactory photoreduction performance was emerged on the heterostructure between rod-like morphology of CdS and lamellar MoS2. Moreover, the feature of small gap between valence band minimum and Fermi level in In2S3 was remained in MoS2/In2S3 composite, which could promote more carriers to be excited. Hence, the optimal MoS2/In2S3 composite reached 10.09 μmol·h−1·g−1 of CO, 68.41 μmol·h−1·g−1 of CH4 and 6.66 μmol·h−1·g−1 of CH3OH, and the mix-coordination of CO2 adsorption and the carbene pathway over MoS2/In2S3 was revealed via in-situ DRIFTS.

Influence of bulky peripheral substituents on subphthalocyanine derivatives: Implications for photocatalytic and photoelectrochemical hydrogen production

A series of novel subphthalocyanine (SubPc) derivatives with bulky electron-donating substituents were synthesized for visible light-induced photocatalytic and photoelectrochemical hydrogen production. SubPc derivatives were decorated with bulky thiophenoxy (coded SubPc 1–2) and phenoxy (coded SubPc 3–4) substituents to compare the influence of the nature of the peripheral bulky substituents on the photophysical and photocatalytic activity of SubPc. The highest photocatalytic performance was obtained from SubPc 4, having diphenyl phenoxy substituents with an H2 production rate of 7.233 mmol g-1h−1. The photocatalytic hydrogen evolution activities of all SubPc sensitized TiO2 photocatalysts enhanced approximately four times in the presence of Pt co-catalyst. The photocatalysts showed remarkable long-term stability and reproducibility of H2 evolution over 24-hour irradiation. SubPc 4-based photocatalytic system reached a considerable catalytic activity with the H2 production of 16.022 mmol g−1 and a turnover number (TON) value of 34,089 for 24 h irradiation. Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) studies were carried out to better understand the photocatalytic abilities of SubPc derivatives and develop a symbiotic connection with experimental investigations. The results highlight the importance of peripheral substituents in modifying electron density, dipole moment, and HOMO-LUMO energy levels and improving SubPc derivative light-harvesting performance. The presence of 2,6-diisopropyl on SubPc derivatives (SubPc 2 and 4) caused a significant change in the properties, resulting in favourable electron transport characteristics and, therefore, improving photocatalytic performance. Furthermore, the incorporation of TiO2, as shown in SubPc 1@TiO2 and SubPc 2@TiO2, resulted in a modest reduction in chemical hardness, implying increased charge transfer inside the molecule and, as a consequence, enhancing its efficacy as a sensitizer. These theoretical discoveries provide a solid foundation for the customized design and optimization of SubPc derivatives for effective photocatalytic applications.

Hydrothermal synthesis of porous CdS/Bi2S3/BiOIO3 nanocomposites for solar-driven photocatalytic degradation of rhodamine B

A heterojunction structure incorporating three photocatalysts, corresponding to a ternary composite CdS/Bi2S3/BiOIO3, was proposed to address the issues of poor stability, low efficiency in utilizing visible light, and poor performance in degrading refractory organic pollutants for conventional photocatalysts. Therefore, the interconnected CdS/Bi2S3/BiOIO3 structure facilitated the transfer of electrons from Bi2S3 to BiOIO3 by reducing the band gap, as well as the transfer of h+ from BiOIO3 to Bi2S3. As a result, slow carrier recombination and a decreasing band gap were found, resulting in the good performance of RhB degradation. As a medium, CdS could improve the e- and h+ transmission efficiency between Bi2S3 and BiOIO3. According to performance measurements, after excluding the influence of adsorption, the photocatalytic activity of CdS/Bi2S3/BiOIO3 reached 94.22 % after 30 min and remained stable after five cycles. A quenching experiment illustrating the importance of superoxide and hydroxyl radicals in RhB degradation, which might be applied to other refractory organic contaminants. DRS studies demonstrated that the composite combines the benefits of CdS and Bi2S3, with better light absorption across a broader wavelength range. According to the photocatalytic mechanism, the formation of a compact, three-component heterostructure at the interface increases light absorption while decreasing electron-hole recombination. The results of corresponding novels may yield valuable insights for the development of an effective approach in the design of a high-performance photocatalysis system for the degradation of pollutants.

Saccharide-Derived Zinc Oxide Nanoparticles with High Photocatalytic Activity for Water Decontamination and Sanitation

Zinc oxide nanoparticles (ZnO NPs) with a high photocatalytic performance were prepared by using the aerobic combustion of saccharides such as glucose, fructose, dextrin, and starch with zinc nitrate. The ZnO NPs were characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray scattering spectroscopy (EDX), X-ray powder diffraction (XRPD), and UV-vis spectroscopy. The TEM images revealed that the ZnO NPs have sizes ranging from ~20 to 35 nm with a bandgap of ~3.32 eV. The XRPD pattern revealed the hexagonal wurtzite crystalline structure of the ZnO NPs. The photocatalytic properties of the ZnO NPs were studied by the photocatalytic degradation of methyl orange (MO) in deionized water (DIW) and simulated fresh drinking water (FDW) under ultraviolet light (UV-B) and sunlight illumination. The terephthalic acid photoluminescence technique was also used to study the generation of a hydroxyl radical (•OH) by ZnO NPs. The saccharide-derived ZnO NPs exhibited higher photocatalytic activity than the nonsaccharide-derived ZnO NPs. Varying the type of saccharides used during the calcination had some effect on the degree of the catalytic enhancement.

Interface engineering of 0D/2D Cu2O/BiOBr Z-scheme heterojunction for efficient degradation of sulfamethoxazole: Mechanism, degradation pathway, and DFT calculation

Constructed heterojunction has been considered an efficient strategy to enhance the migration and transfer of photoinduced charge carriers. Herein, a Z-scheme Cu2O/BiOBr heterojunction with 0D/2D structure was fabricated by microwave hydrothermal method. It was found that the optimal composites photocatalyst showed excellent activity for sulfamethoxazole (SMZ) illumination, and the removal rate reached 90.7%, which was higher than pristine Cu2O (53.0%) and BiOBr (60.0%). Subsequently, the operational parameters such as catalyst dosage, concentrations of pollutants, and pH of solution were investigated. According to the ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRs), Mott-Schottky curve, and density functional theory (DFT) analysis, the Z-scheme degradation mechanism of Cu2O/BiOBr heterostructure was proposed. Among them, the interface structure of 0-dimensions/2-dimensions (0D/2D) can significantly increase the number of heterojunctions in the composite catalyst, and Z-scheme heterostructures can accelerate the generation and migration of photoinduced charge carriers, which has a facilitation effect on improving the decomposition activity of the photocatalyst. Moreover, three possible pathways for SMZ degradation were inferred. This study provides a promising strategy for constructing novel heterojunctions with high photocatalytic performance.

Simultaneous high thermoelectric and photocatalytic performance towards single-layer ZnX2S4 (X = Al, Ga, In)

Thermoelectric generation and photocatalytic water splitting to produce hydrogen are key measures to solve energy shortage and environmental pollution. In this work, we proposed three unexplored 2D materials, ZnAl2S4, ZnGa2S4 and ZnIn2S4, and further investigated their stability, thermoelectric and photocatalytic water splitting performance. We revealed the three single-layers possess low cleavage energies of 0.23–0.28 J/m2, and simultaneously show high mechanical, thermal and dynamic stability. Besides, the single-layers are indirect semiconductors with band-gaps of 2.62/2.15/1.93 eV, and deliver thermoelectric power factors of 3.03/4.06/5.92 mW/K2m at 300 K. Also, due to the high nonlinear phonon dispersion and strong acoustic-optical interactions, they have high phonon scattering rates, as well as low lattice thermal conductivities of 1.11–3.06 W/mK. As a result, their thermoelectric figure of merit can reach 0.12/0.11/0.10 at 300 K, and increases to 0.77/0.69/0.66 at 700 K. Moreover, they also have suitable REDOX band-edges, which can drive photocatalytic water splitting to produce hydrogen and oxygen, and show high absorption coefficients of ∼ 105 cm−1 from visible to ultraviolet.