Search

High selectivity and fast charge separation are two important factors for photocatalytic wastewater treatment. Herein, we prepared a molecular imprinted Ag/Ag 3 VO 4 /g-C 3 N 4 photocatalyst (MIP) that exhibited great specific recognition ability along with excellent photocatalytic activity. The ultrathin g-C 3 N 4 nanosheets with high surface are used to prepare. The Z-scheme Ag 3 VO 4 /g-C 3 N 4 heterostructure and the surface plasmon resonance of the photoreduced Ag0 together contributed to the improvement of the separation efficiency of photogenerated electrons and holes. In addition, MIP provides the specific recognition ability to preferentially adsorb the target pollutant. The selectivity of photocatalysis was evaluated by the degradation of oxytetracycline and tetracycline solutions. Photoluminescence and transient photocurrent measurements further prove the improved charge separation efficiency of MIP. A plausible photocatalytic reaction mechanism is proposed based on electron spin resonance measurement and the active species trapping experiments, where indicates that the main active species of this photocatalytic process are O 2 − and h+. This research provides an effective strategy for the simultaneous enhancement of selectivity and activity via molecular imprinting. [ABSTRACT FROM AUTHOR]

The interfacial regulation strategy between semiconductors can effectively promote the separation efficiency of photogenerated carriers and enhance photocatalytic activity under the synergistic effect. Herein, AgInS 2 QDs-MoS 2 /GO (AIS-MS/GO) composites were prepared by interfacial coupling of AgInS 2 QDs (AIS), hierarchical MoS 2 and ultrathin GO. Ultrathin GO successfully solved the agglomeration problem of AIS and hierarchical MoS 2. Moreover, the photogenerated carriers were effectively separated and transferred under the synergistic effect of the AIS-MS heterojunction and ultrathin GO, thus promoting tetracycline (TC) degradation and CO 2 reduction performance. The degradation rate of tetracycline (TC) reached 96.5 %, and the yields of CO and CH 4 in the CO 2 reduction products reached 52.6 and 28.5 μmol g–1, respectively, when using the optimized photocatalyst. In-situ FTIR analysis indicated that TC is gradually degraded by small molecules on the composite surface, and has excellent dissociation ability of water molecules during the CO 2 reduction process. This work provides a new vision for the rational design of heterojunction-based photocatalysts using the interfacial regulation strategy for enhancing interfacial charge separation and photocatalytic performance. [Display omitted] • AIS-MS/GO composites were prepared via the interfacial regulation strategy. • The photogenerated carriers were effectively separated and transferred under synergistic and interfacial effects. • The aggregation problem of AIS and hierarchical MoS 2 was effectively solved. • AIS-MS/GO composites achieve a 96.5 % TC degradation rate and 35.1 % selectivity for CH 4. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic illustration of the formation of CQDs/ZnO@HNTs in the whole synthetic process. Highlights • We have experimentally demonstrated the carbon incorporated ZnO via coupling CQDs. A notable transformation of burger-like CQD s /ZnO morphology was observed and the HNTs have been introduced to improve the dispersity of hybrid photocatalysts. • From efficiently modulation of band structure of CQD s -based materials, the as-prepared CQD s /ZnO@HNTs display a remarkable optical excitation in photogenerated reactive oxygen species (ROS). • This work provides an efficient and novel strategy for element incorporated with introduced inorganic quantum dots owing to the quantum size effect. • It also developed a new sight of CQD s participated phase tuning for semiconductors, offering a beneficial route for expanding the application of VLD photodegradation based on band-tuning semiconductors and other low-dimension materials. Abstract Environmentally friendly photodegradation of refractory pollutants utilizing semiconductor photocatalysis evolution exhibits satisfactory efficiency and low energy consumption, but some of its unbefitting band position largely limits practical applications. The controllable band structure tuning via coupling low-dimensional materials with enormous potential in semiconductor photocatalysis, notably attractive carbon quantum dots (CQDs) induced for a better utilization of low-energy photoexcitation of promising inherent optical properties and photocatalytic performance on organic pollutant degradation. Here, a CQDs modified ZnO hybrid materials was synthesized and the CQDs preluded carbon-incorporated burger-like ZnO nanoparticles clusters were presented thus demonstrated a specific doping-effect. The dispersity improved by loading halloysite nanotube (HNTs) for efficiently photocatalytic activity enhancement. Furthermore, the band structure, excitation and photocatalytic reactive oxygen species (ROS) generation were detected to reveal the photochemical properties and plausible mechanism of CQDs hybrid nanomaterials system. It is observed that the superoxide radical (O 2 −), and singlet oxygen(1O 2) are the principal ROS agents under UV–vis excitations. This work not only displays a CQDs modified system of expanding photo-response range to visible light but also throws a way for quantum elemental incorporated on the influence of band-tuning for semiconductor- dominated photocatalysts. [ABSTRACT FROM AUTHOR]

One of current ideal thought to reduce the recombination of photogenerated electrons and holes from semiconductors is constructing Multi-dimensional semiconductor-carbon (S-C) heterostructures. As well as acting to photo-degrade the organic contaminant and decrease the toxicity, β-In 2 S 3 is chosen as a potential semiconductors for photocatalysts. Relative good photocatalytic properties delivered on β-In 2 S 3 , however, the fast recombination of photogenerated charge carriers are often appeared, causing reduced further application. Carbon quantum dots (CQDs) involve the introduction of plasma effect into the zero-dimensional nanomaterials in order to arouse an effect: either promoting the charge carriers transfer or plasma energy conversion of the photo-excited CQDs. However, state of the two components also encompass the poor quantum yield existed in the CQDs by its serious agglomeration. Thereby, the delivery of extraordinary ballistic electrical and thermal conductivity on single-walled carbon nanotubes (SWNTs), have shown potential for use in a variety of semiconductors decorating application. Herein, we show that a novel CQDs@In 2 S 3 /SWNTs composite in the Multi-dimensional (3D) hierarchical superstructures with an enhanced photocatalytic efficiency. The ESR analysis and free radicals trapping experiments indicated that the O 2 • − and h + were the main active species for the photocatalytic degradation. The potential photocatalytic mechanism of the three components is discussed and the direction in the plasma effect exhibited in CQDs is also considered, with a particular focus on photocatalytic area. [ABSTRACT FROM AUTHOR]

Achieving the intelligent controllability of the photocatalyst to the surrounding environment is a very meaningful work. Here, the polyacrylic acid (PAA) modified Ag/AgCl-40/CN composite was constructed to achieve an intelligent response of pH value. PAA exhibits hydrophilic properties at high pH value, increasing the adsorption capacity to tetracycline (TC) molecules. The morphology of PAA from contracted state to diastolic state, releasing the Ag/AgCl-40/CN catalyst. In addition, PAA modified Ag/AgCl-40/CN can prevent the loss of AgCl. The g-C 3 N 4 nanosheets (CN) as a carrier enhance the dispersibility of the AgCl particles. The LSPR effects of Ag nanoparticles produce more electrons acting on photocatalytic degradation. On the results of experiment, the degradation of TC by PAA@Ag/AgCl-40/CN shows an excellent degradation activity when the high pH value. Photoluminescence spectroscopy and photocurrent demonstrate that carrier separation efficiency of PAA@Ag/AgCl-40/CN is higher than CN and Ag/AgCl-40/CN. The detection of the main active substances •O 2 − and h+, revealing a reasonable mechanism for the PAA@Ag/AgCl-40/CN hybrid system. This work provides a procedure to obtain smart materials that can switch photocatalytic processes. [ABSTRACT FROM AUTHOR]

Energy band location and charge separation mechanism of SnS 2 /Au/g-C 3 N 4 system during photoreduction under sunlight irradiation. • The catalyst is prepared by facile thermal treatment and chemical deposition method. • The SnS 2 /Au/g-C 3 N 4 composites show a superior optical adsorption under UV–vis light. • The Au nanoparticle and the Z-type scheme jointly improve the separation of carrier. • The SnS 2 /3ml-Au/g-C 3 N 4 displays the best photoreduction activity and durability. The use of semiconductor photocatalytic reduction technology has higher efficiency and lower energy consumption for CO 2 reduction, but its existence of some mismatched energy band positions and relatively slow charge-hole separation greatly limits its practical application. In this paper, a SnS 2 /Au/g-C 3 N 4 embedded structure model with carbon and nitrogen hybridization is proposed to gain an in-depth understanding of the role of hybridization and precious metal modification in photocatalysis. Carriers were investigated from the perspective of kinetics through photocurrent, LSV curve, and FL spectroscopy. After modification of Au nanoparticles, the photo-excited electrons showed a slower decay process, indicating that the separation of carriers was enhanced, which was further confirmed by impedance and PL spectroscopy. SEM, AFM and TEM analysis confirmed that the 2D face-to-face SnS 2 /Au/g-C 3 N 4 embedded structure was successfully prepared and the Au nanoparticles were evenly distributed. Au nanoparticles not only act as a bridge for electron transport in 2D semiconductor materials to accelerate electron transport, but generate more excited electrons by themselves under the radiation of sunlight, which effectively improves the separation efficiency of electron-hole pairs and enhances the photocatalyst activity. DFT calculations show that the Z-type mechanism and the intercalated energy level of the SnS 2 /Au/g-C 3 N 4 embedded structure expand the light absorption and improve the carrier separation efficiency. As expected, the photocatalyst activity with CO and CH 4 the evolution rate of up 93.81 µmol·g−1·h−1 and 74.98 µmol·g−1·h−1 under visible light irradiation, respectively, while the photocatalytic activity is negligible loss after 30 h photoreduction. This work reveals the role of embedded structure and precious metal modification in the separation and transmission of electron-hole, opening up new perspective for achieving high-efficiency solar CO 2 reduction performance. [ABSTRACT FROM AUTHOR]