Light-driven Photocatalytic Activity Research Articles

Defective WO3 nanoplates controllably decorated with MIL-101(Fe) nanoparticles to efficiently remove tetracycline hydrochloride by S-scheme mechanism

Here, a series of S-scheme hybrid MIL-101(Fe)/WO3 samples were designed and prepared by tightly immobilizing MIL-101(Fe) nanoparticles on the surface of WO3 nanoplates via a simple solvothermal reaction. The in situ loading of MIL-101(Fe) promoted charge separation because of the successful construction of the S-scheme, significantly enhancing the photocatalytic activity to efficiently remove tetracycline hydrochloride (TCH). This smart structural design endowed the synthetic MIL-101(Fe)/WO3 hybrid sample with highly efficient visible light-driven photocatalytic activity and good photostability. The optimized MIL-101(Fe)/WO3(1:1) hybrid photocatalyst exhibited the highest photocatalytic efficiency with a photodegradation efficiency of up to 93.8%. Dissimilar to certain reports, the photocatalytic activity over hybrid MIL-101(Fe)/WO3 samples was majorly driven by photogenerated holes (h+). In addition, the S-scheme photocatalytic mechanism was fully demonstrated by systematic characterizations including active species capture experiments and electron paramagnetic resonance analyses. This study sheds light on the design and synthesis of S-scheme hybrid photocatalysts for highly efficient applications of photocatalysis for removing TCH.

Decorating 2D Ti3C2 on flower-like hierarchical Bi2WO6 for the 2D/2D heterojunction construction towards photodegradation of tetracycline antibiotics

Constructing 2D/2D heterojunction in traditional metal oxide photocatalyst is considered to be a practical strategy for boosting visible light-driven photocatalytic activity remarkably. This work fabricated 2D/2D heterojunction by decorating 2D Ti3C2 on nanosheet units in 3D flower-like Bi2WO6 hierarchical structure and significantly improved efficiency of photocatalysis degradation of tetracycline hydrochloride (TC-HCl) as a model antibiotic. It is possible to contribute to the constructed interfacial connection between [Bi2O2]2+ layer and Ti3C2 as well as the resulting electron dislocation of Bi-O bonds, which extended light harvesting range, improved photo-generated holes oxidation and accelerated charge transfer. The best rate constant degradation of TC-HCl and TOC removal efficiency were achieved on 3 %-Ti3C2/Bi2WO6 sample, which were 7 times and 3.5 times that of original Bi2WO6 sample. To gain more insight details about photocatalytic process, reactive species were also investigated and a logical mechanism of TC-HCl degradation was presented. This work demonstrated an intriguing exploration strategy of photo-degradation catalyst and was expected to promote the environmental application of solar-driven antibiotics degradation technology.

Visible light-driven photocatalytic activity of Cu2O/ZnO/Kaolinite-based composite catalyst for the degradation of organic pollutant

Herein, we design to synthesize a novel Cu2O/ZnO/kaolinite composite catalyst by co-precipitation method. The synthesized composite catalysts were labeled as 5CZK, 10CZK, 15CZK, and 20CZK which represent 5, 10, 15, and 20% of Cu2O, respectively, on ZnO/kaolinite. The photocatalyst samples were characterized with different instruments. Moreover, the methylene blue (MB) dye was used as a target organic pollutant and the degradation was evaluated under visible light irradiation. The highest performance for the degradation of MB was achieved by 10CZK catalyst and degrades 93% within 105 min. However, ZnO (Z), Cu2O/ZnO (CZ), 5CZK, 15CZK, and 20CZK composite catalysts, degrades 28, 66, 76, 71, and 68% of MB dye, respectively. The enhanced degradation efficiency of 10CZK composites catalyst could be due to the higher adsorption properties from metakaolinite and the light-responsive properties of the Cu2O/ZnO samples under visible light. Hence, the resulting composite catalyst could be applicable for environmental remediation.

Construction of a double Z-scheme Bi2O3–CuBi2O4–CuO composite photocatalyst for the enhanced photocatalytic activity

Herein, a ternary Bi2O3–CuO–CuBi2O4 photocatalyst was synthesized by the solvothermal deposition via the adjustment of Cu/Bi concentration ratio. The Bi2O3–CuO (5%) with the 5% of Cu/Bi concentration ratio exhibited dramatically high solar/visible light-driven photocatalytic activity, and the photocatalytic rate was 2.69/2.06 and 2.39/1.75 folds of pure Bi2O3 photocatalysts toward rhodamine B (RhB) and methylene blue (MB) photodegradation, which was ascribed to the high solar absorption and low interface resistance. In addition, the •O2− and •OH radicals were defected to be the active species for the dye degradation, and then the Z-scheme heterojunction scheme was proposed to explain the photocatalytic result. The prepared sample photoelectrode also displayed the attractive photoelectric conversion capacity. The investigation indeed confirms that the novel ternary Bi2O3–CuO–CuBi2O4 photocatalysts exhibit wide application prospect in wastewater remediation.

Multifunctional magnetic C3N4-rGO adsorbent with high hydrophobicity and simulated solar light-driven photocatalytic activity for oil spill removal

In this study, magnetic reduced graphene oxide (rGO)-based adsorbents with and without C3N4 (C3N4-Fe-rGO and Fe-rGO) were synthesized via a fast and simple thermal method with polyvinylidene fluoride as a polymer binder and were used for adsorption and photocatalytic degradation of toluene as an aromatic compound in oil. The physical and chemical properties of prepared adsorbents were analysed by XRD, FESEM, FTIR, TEM, BET-BJH, TGA, WCA, VSM, DRS, PL, EDX, and RAMAN. The results showed higher intake of toluene on Fe-rGO (adsorption capacity 1.387 g/g) compared to C3N4-Fe-rGO (adsorption capacity 1.313 g/g), despite more hydrophobicity and higher selectivity of C3N4-Fe-rGO. Study on adsorption isotherms and adsorption kinetics of both samples indicated the highest agreement with Toth adsorption isotherm and quasi-first-order kinetic model. The results of TGA analysis showed better temperature resistance of the C3N4 containing adsorbent than Fe-rGO. BET analysis also illustrated the existence of slit-shaped meso pores for both adsorbents originating from 2D structure of rGO and C3N4. Considering optical properties, PL analysis indicated negligible electron-hole recombination rate in both samples. However, DRS analysis confirmed higher absorption of light and red shift to visible light region for C3N4-Fe-rGO. Regarding the sole photocatalysis rout, it was found that C3N4-Fe-rGO could degrade higher amounts of toluene (8%) compared to 0.7% of Fe-rGO. Scavenger tests finally were studied and superoxide and hydroxyl radicals were confirmed as the main reactive species in toluene photocatalytic degradation in this work.

BiSnSbO6–TiO2 composites enhance LED light-driven photocatalytic antibacterial activity

A new type of BiSnSbO6–TiO2 composite photocatalytic antibacterial material with heterojunction structure was synthesized by solid phase sintering and characterized by XRD, SEM, TEM, FT-IR and UV–vis diffuse reflectance spectroscopy methods. The photocatalytic antibacterial experiments were carried out under LED light irradiation, and the experimental results showed that BiSnSbO6–TiO2 composite had significantly stronger photocatalytic antibacterial performance against bacteria and fungi than BiSnSbO6 and TiO2 alone. The antibacterial efficiency of 500 mg/L BiSnSbO6–TiO2 composite against E. coli, S. aureus, Bacillus subtilis and P. aeruginosa could reach 71.33%, 100%, 100% and 100%, respectively. The antibacterial efficiency of 125 mg/L BiSnSbO6–TiO2 composite against Candida albicans reached 61.16% under light conditions. The feasibility of removing pathogenic microorganisms from livestock and poultry effluent by composite material under LED light was investigated. In addition, SEM was used to observe the structural changes of the bacteria, and the bacterial morphology was wrinkled and broken, leading to the death of the bacteria. Meanwhile, the antibacterial mechanism was explored through free radical scavenging experiments, and it was found that ·OH, H+, e− played a major role in the photocatalytic antibacterial process. Finally, BiSnSbO6–TiO2 composite was confirmed to have no cytotoxicity by cytotoxicity test. This experiment provides a new type of environment-friendly photocatalytic composite material which can be excited by LED light and has broad application prospect in practical antibacterial field.

Hydroxyl-Decorated Diiron Complex as a [FeFe]-Hydrogenase Active Site Model Complex: Light-Driven Photocatalytic Activity and Heterogenization on Ethylene-Bridged Periodic Mesoporous Organosilica

A biomimetic model complex of the [FeFe]-hydrogenase active site (FeFeOH) with an ethylene bridge and a pendant hydroxyl group has been synthesized, characterized and evaluated as catalyst for the light-driven hydrogen production. The interaction of the hydroxyl group present in the complex with 3-isocyanopropyltriethoxysilane provided a carbamate triethoxysilane bearing a diiron dithiolate complex (NCOFeFe), thus becoming a potentially promising candidate for anchoring on heterogeneous supports. As a proof of concept, the NCOFeFe precursor was anchored by a grafting procedure into a periodic mesoporous organosilica with ethane bridges (EthanePMO@NCOFeFe). Both molecular and heterogenized complexes were tested as catalysts for light-driven hydrogen generation in aqueous solutions. The photocatalytic conditions were optimized for the homogenous complex by varying the reaction time, pH, amount of the catalyst or photosensitizer, photon flux, and the type of light source (light-emitting diode (LED) and Xe lamp). It was shown that the molecular FeFeOH diiron complex achieved a decent turnover number (TON) of 70 after 6 h, while NCOFeFe and EthanePMO@NCOFeFe had slightly lower activities showing TONs of 37 and 5 at 6 h, respectively.

Visible light-driven photocatalytic activity of wide band gap ATiO3 (A = Sr, Zn and Cd) perovskites by lanthanide doping and the formation of a mesoporous heterostructure with ZnS QDs

Charge carrier recombination and wide band gap energy are still the main challenges in the visible-light-driven photocatalytic applications of titanate perovskites, ATiO3. Herein, three strategies are rationally used to achieve a titanate-based photocatalyst with high photocatalytic performance under visible light. In the first step, SrTiO3, ZnTiO3, and CdTiO3 perovskites were synthesized and their photocatalytic activity was evaluated in the degradation of methylene blue (MB) and bisphenol A (BPA). Then, a dysprosium cation (Dy3+) was doped into an ATiO3 crystalline lattice. Systematic investigations indicate that Dy doping in SrTiO3 and CdTiO3 extends the ligand to metal charge transfer absorption edge to visible wavelengths leading to the activation of doped perovskites under visible light. Higher visible-light-driven photocatalytic performance (73.29% for MB and 52.57% for BPA) and higher total organic carbon (TOC) removal (59.20% for MB and 39.53% for BPA) have been achieved by Dy doped CdTiO3 compared to other photocatalysts. Finally, we prepared a Dy-CdTP/ZnS QD mesoporous type-II heterostructure by the in situ growth of ZnS QDs on a flower-like Dy-CdTP. This design accelerates the separation and transfer of photogenerated electron-hole pairs. The surface area of the Dy-CdTP/ZnS QD heterostructure was ∼11.6 times greater than that of Dy-CdTP, offering a large surface area for the adsorption of organics, and abundant active sites for photocatalytic degradation. Taking advantage of the large surface area and considerable suppressing of the charge carrier recombination, the optimized Dy-CdTP(0.6)/ZnS QD photocatalyst exhibits excellent and stable performance for the degradation of MB (98.25%) and BPA (89.12%) with their considerable mineralization under visible light.

Crystal Facet Engineering and Hydrogen Spillover-Assisted Synthesis of Defective Pt/TiO2-x Nanorods with Enhanced Visible Light-Driven Photocatalytic Activity.

Hydrogen spillover can assist the introduction of defects such as Ti3+ and concomitant oxygen vacancies (VO) in a TiO2 crystal, thereby inducing a new level below the conduction band to improve the conductivity of photogenerated electrons and the visible light absorption property of TiO2. Meanwhile, crystal facet engineering offers a promising approach to achieve improved activity by influencing the recombination step of the photogenerated electrons and holes. In this study, with the aim of achieving enhanced visible light-driven photocatalytic activity, rutile TiO2 nanorods with different aspect ratios were synthesized by crystal facet engineering, and Pt-deposited TiO2-x nanorods (Pt/TNR) were then obtained via reduction treatment assisted by hydrogen spillover. The reduction treatment at 200 °C induced the formation of surface Ti3+ exclusively, whereas surface Ti3+ and VO were formed by performing the reduction at 600 °C. The Pt/TNR with a higher aspect ratio reduced at 200 °C exhibited the highest activity in photocatalytic H2 production under visible light irradiation owing to the synergistic effect of the introduction of Ti3+ defects and the spatial charge carrier separation induced by crystal facet engineering.

Biosynthesis of rod shaped Gd2O3 on g-C3N4 as nanocomposite for visible light mediated photocatalytic degradation of pollutants and RSM optimization

To investigate visible light-driven photocatalytic activity, novel heterogeneous catalysts were constructed employing graphitic carbon nitride (g-C3N4) and gadolinium oxide (Gd2O3). Each catalyst was prepared separately. To begin, melamine was used to synthesize g-C3N4. Gd2O3 was prepared via green synthesis by utilizing Cocos nucifera coir extract as a capping agent. Then the prepared g-C3N4 and Gd2O3 were combined in order to form Gd2O3/g-C3N4 nanocomposite. The sole aim of the fabrication of this nanocomposite is to degrade organic pollutants such as amaranth (AM) and congo red (CR) dye, utilizing visible light. The Gd2O3/g-C3N4 nanocomposite was found to be an efficient catalyst in the degradation of AM and CR dye. The prepared nanocomposite was characterized utilizing various techniques like X-ray diffraction, Fourier transform-infra red (FT-IR), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS) and Photoluminescence emission (PL) spectroscopy. The surface area and the surface charge were examined with the aid of BET analysis and Zeta potential respectively. Scanning electron microscope (SEM) and a Transmission electron microscope (TEM) were used to investigate the synthesized nanocomposite's morphology. In contrast with g-C3N4, Gd2O3 and Gd2O3/g-C3N4 have a larger surface area. The Gd2O3/g-C3N4 nanocomposite's PL emission spectra confirmed the lower electron-hole (e-_h+) pair recombination rate. The Gd2O3/g-C3N4 nanocomposite has proved to be an outstanding catalyst with a degradation efficiency of 95% towards CR. Furthermore, the experiments were optimized using Response surface methodology (RSM). These findings revealed that the dye concentration, pH, and catalyst dosage are important parameters in the photocatalytic degradation process. The high correlation co-efficient for the second order polynomial model demonstrated that the data predicted using RSM was in agreement with the experimental results. This work adds to the understanding of g-C3N4-based rare earth metal oxide nano-photocatalysts for efficient organic pollutant degradation.

Novel N,C,S-TiO2/WO3/rGO Z-scheme heterojunction with enhanced visible-light driven photocatalytic performance

Novel N,C,S-TiO2/WO3/rGO Z scheme photocatalyst was successfully synthesized from graphite, TIOT, and ammonium metatungstate precursors. Material characteristics such as crystal structure, surface morphology, functional groups, specific surface area, elemental composition, band gap energy, and electron-hole recombination were characterized by XRD, TEM, BET, SEM/EDX, FT-IR, UV–VIS, and PL methods. The as-synthesized novel N,C,S-TiO2/WO3/rGO Z-scheme heterojunction photocatalyst exhibited visible light-driven photocatalytic activity (the band gap energy = 2.24 eV), could generate both effective electrons and holes, and presented the lowest electron-hole recombination rate compared to all individual components. Different factors impacting the photocatalytic decomposition of Direct Blue 71 (DB 71) by the N,C,S-TiO2/WO3/rGO system were studied. The results showed that pH of the solution, catalyst load, DB 71 initial concentration, and reaction time affected the DB 71 photocatalytic degradation efficiency. The DB 71 degradation completed after 100 min with a typical efficiency of over 91%, which was much better than other photocatalytic systems. The DB 71 degradation process followed the pseudo-first-order kinetics model with coefficients of determination > 0.95 for all conditions. The photocatalyst was easily regenerated, and exhibited a very good stability, with a photocatalytic degradation efficiency of over 83.0% after 3 cycles.

Synthesis and Enhanced Light Photocatalytic Activity of Modulating Band BiOBrXI1-X Nanosheets.

The photocatalysis technique has been proven to be a promising method to solve environmental pollution in situations of energy shortage, and has been intensively investigated in the field of pollutant degradation. In this work, a band structure-controlled solid solution of BiOBrXI1−X (x = 0.00, 0.05, 0.10, 0.15, 0.20, 1.00) with highly efficient light-driven photocatalytic activities was successfully synthesized via simple solvothermal methods. The phase composition, crystal structure, morphology, internal molecular vibration, optical properties, and energy band structure were characterized and analyzed by XRD, SEM, HRTEM, XPS, Raman, and UV Vis DRS. To evaluate the photocatalytic activity of BiOBrXI1−X, rhodamine B was selected as an organic pollutant. In particular, BiOBr0.15I0.85 displayed significantly enhanced photocatalytic activity by virtue of modulating the energy band position, optimizing redox potentials, and accelerating carrier separation. Moreover, the enhancement mechanism was elucidated on the basis of band structure engineering, which provides ideas for the design of highly active photocatalysts for practical application in the fields of environmental issues and energy conservation.

Fabrication of CdS/Ti3C2/g-C3N4NS Z-scheme composites with enhanced visible light-driven photocatalytic activity.

The Ti3C2 and g-C3N4NS were obtained first, and the CdS/Ti3C2/g-C3N4NS Z-scheme composites were prepared via a facile hydrothermal synthesis, and their photocatalytic properties were investigated. The g-C3N4NS with a high surface area displayed higher adsorption and degradation capacity. Compared with Ti3C2/g-C3N4NS and CdS, the visible light photocatalytic activity of CdS/Ti3C2/g-C3N4NS composites was improved. The as-synthesized CTN-4:1 composite exhibited outstanding photocatalytic performance for degradation of orange II, approximately 3.2 and 10.7 times higher than that of Ti3C2/g-C3N4NS and CdS, respectively. The fabrication of CdS/Ti3C2/g-C3N4NS Z-scheme heterostructure using Ti3C2 as electron transfer medium improved the separation ability of the photoinduced e--h+ pairs, thereby leading to the improvement of visible light-driven photocatalytic activity. This finding provides new insights into the construction of high efficiency Z-scheme heterostructure photocatalyst.

Enhanced Visible Light-driven Photocatalytic Activities of Ag3PO4 Modified Electrochemically Anodized TiO2 Nanotube Arrays

Enhanced Visible Light-driven Photocatalytic Activities of Ag3PO4 Modified Electrochemically Anodized TiO2 Nanotube Arrays

Layered Ti3C2 MXene and silver co-modified g-C3N4 with enhanced visible light-driven photocatalytic activity

Novel Ag/g-C3N4/Ti3C2 heterojunction (ACN/TC) was synthesized via one-step calcining the mixture of Ag+-melamine superamolecule and Ti3C2. With robust interfacial contact of ACN/TC heterojunction, the introduction of Ag nanoparticles could induce localized surface plasmon resonance and improve the visible light responsivity. Besides, layered Ti3C2 was served as electron sink and co-catalyst to provide rapid charges transfer channel and enhance O2 adsorption, thereby accelerating the separation of photogenerated charges and production of radicals. The optimized ternary heterojunction (ACN/TC-15) exhibited that the photocatalytic removal rate of Rhodamine B (RhB) and Tetracycline hydrochloride (TC) reached 99.2% and 92.1% under visible light (λ > 420 nm) irradiation, respectively. Besides, extending to λ > 510 nm light irradiation, the removal rate of RhB and TC still 85.6% and 79.5%, respectively. During the TC degradation, the superoxide radical (·O2−) was determined as the main oxidative species. Besides, the possible degradation pathway of TC was proposed. This work not only showed a simplified method for the preparation of Ag/g-C3N4/Ti3C2 composite, but also provided insights into Ti3C2 MXene as co-catalyst to improve the photocatalytic degradation of organic pollutants.

Visible Light-Driven Photocatalytic Activity and Kinetics of Fe-Doped TiO2 Prepared by a Three-Block Copolymer Templating Approach.

Fe-doped titania photocatalysts (with 1, 2.5, and 3.5 wt. % Fe nominal content), showing photocatalytic activity under visible light, were prepared by a soft-template assisted sol–gel approach in the presence of the triblock copolymer Pluronic P123. An undoped TiO2 photocatalyst was also prepared for comparison. The photocatalysts were characterized by means of X-ray powder Diffraction (XRPD), Quantitative Phase Analysis as obtained by Rietveld refinement, Diffuse Reflectance (DR) UV−Vis spectroscopy, N2 adsorption/desorption at −196 °C, electrophoretic mobility in water (ζ-potential), and X-ray photoelectron spectroscopy (XPS). The physico-chemical characterization showed that all the samples were 100% anatase phase and that iron was present both in the bulk and at the surface of the Fe-doped TiO2. Indeed, the band gap energy (Eg) decreases with the Fe content, with Tauc’s plot determined values ranging from 3.35 (undoped TiO2) to 2.70 eV (3.5 wt. % Fe). Notwithstanding the obtained Eg values, the photocatalytic activity results under visible light highlighted that the optimal Fe content was equal to 2.5 wt. % (Tauc’s plot determined Eg = 2.74 eV). With the optimized photocatalyst and in selected operating conditions, under visible light it was possible to achieve 90% AO7 discoloration together with a TOC removal of 40% after 180 min. The kinetic behavior of the photocatalyst was also analyzed. Moreover, the tests in the presence of three different scavengers revealed that the main reactive species are (positive) holes and superoxide species. Finally, the optimized photocatalyst was also able to degrade phenol under visible light.

Bimetallic silver/bismuth-MOFs derived strategy for Ag/AgCl/BiOCl composite with extraordinary visible light-driven photocatalytic activity towards tetracycline

The rod-like Ag/AgCl/BiOCl materials were successfully fabricated by calcination of the self-sacrificial template of silver/bismuth bimetallic-organic frameworks (BMOFs) under air atmosphere in order to achieve more desirable photocatalytic activity towards tetracycline (TC). The microstructures, content, morphologies, photogenerated electron-hole pair, and photocatalytic activities were characterized for all obtained catalysts. Ag/AgCl/BiOCl obtained through the silver/bismuth BMOFs derived strategy enhanced light absorption ability in visible light region with modified energy band structures, further decreasing the recombination efficiency of photo-induced carriers with enhanced performance during photocatalysis process. TC degradation evaluations driven by visible light revealed that Ag/AgCl/BiOCl possessed superior photocatalytic activity compared to BiOCl, as well as some reported in the literature. Additionally, Ag/AgCl/BiOCl demonstrated remarkable stability during TC photocatalytic reactions, maintaining above 84% initial photocatalytic activity after second cycle. In general, Ag/AgCl/BiOCl material benefited TC degradation from aqueous solutions. Our work opens up new perspectives for advanced uniform-sized photocatalytic catalyst using bimetallic MOFs as self-sacrificial templates.

Fabrication of novel Ag4Bi2O5-x towards excellent photocatalytic oxidation of gaseous toluene under visible light irradiation

In this work, a novel oxide combined with bismuth (Bi) and silver (Ag) was prepared via simple ball milling. This substance was optimized by adjusting the amount of pre-source. Preliminary characterization results confirmed the successful synthesis of Ag4Bi2O5. Subsequently, gaseous toluene was selected as model compound to evaluate the photocatalytic activity of Ag4Bi2O5 photocatalyst. According to the degradation results, Ag4Bi2O5 performed excellent visible light-driven photocatalytic activity with high stability. For the oxidation process of gaseous compound, reactive oxygen species (ROS) were responsible for the achievement, and the formation of oxygen vacancies on Ag4Bi2O5 were involved in the generation of ROS to promote the transfer of photogenerated electrons, and improving photocatalytic activity. DFT calculations revealed the theoretical band gap of Ag4Bi2O5 bulk is 1.758 eV. And the work function of Ag4Bi2O5 (112)ov was ca. at 4.447 eV. The material was easily fabricated and a reliable path was provided for the synthesis of new and efficient photocatalyst for the remediation of polluted indoor air.

A Composite Material of Hydrothermal Prepared Blue Fescue-Like CQDs/Sn-Doped ZnO with Enhanced Visible Light-Driven Photocatalytic Activity

Novel Blue Fescue-like CQDs/Sn-doped ZnO composite photocatalyst was successfully synthesized via a gentle hydrothermal method. The hierarchical CQD/Sn-doped ZnO samples are assembled by many hexagonal prism-shaped nanoneedles. In addition, the photocatalytic performance of all samples was obtained by degrading rhodamine B(RhB) under visible light irradiation. The degradation results indicate that the photocatalytic activity of CQDs/Sn-doped ZnO is better than Sn-doped ZnO, CQDs/ZnO, pure CQDs and pure ZnO. The stability and reusability of CQDs/Sn-doped ZnO were confirmed by cyclic degradation experiments. It can be considered that the effective photocatalytic performance is attributed to the adsorption and transfer of electrons by CQDs.

Yolk-Shelled Gold@Cuprous Oxide Nanostructures with Hot Carriers Boosting Photocatalytic Performance.

Plasmonic Au nanoparticles (NPs) have been commonly used to enhance the photocatalytic activity of Cu2O. Till now, core-shell Au NP@Cu2O composites have been reported in previous studies. Yet, these Au@Cu2O composites only exhibit visible light response. Other special Au nanostructures, such as Au nanorods (NRs) or Au nanobipyramids (NBPs), which possess near-infrared light absorption, were rarely used to endow the near-infrared light response for Cu2O. In this work, for the first time, we used Au NPs, Au NRs, and Au NBPs and employed a handy and universal method to synthesize a series of yolk-shelled Au@Cu2O composites. The results showed that the yolk-shelled Au@Cu2O composites had much higher photocatalytic activity than their solid-shelled ones and pure Cu2O. More importantly, yolk-shelled Au NR@Cu2O and Au NBP@Cu2O composites indeed presented excellent near-infrared light-driven photocatalytic activity, which were impossible for Au NP@Cu2O and pure Cu2O. This outstanding performance for yolk-shelled Au NR@Cu2O and Au NBP@Cu2O could be attributed to the transfer of abundant hot electrons from Au NRs or Au NBPs to Cu2O, and the timely utilization of hot holes on Au through the rich pore channels on their yolk-shelled structure. Furthermore, yolk-shelled Au@Cu2O also showed better stability than pure Cu2O, owing to the migration of the oxidizing holes from Cu2O to Au driven by the built-in electric field. This work may give a guide to fabricate controllable and effective photocatalysts based on plasmonic metals and semiconductors with full solar light-driven photocatalytic activities in the future.