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In recent years, the growing interest in applying photoelectrocatalysis (PEC) to decompose organic pollutants has resulted in the need to search for new photoelectrode materials with high activity under visible light radiation. The presented research showed an increased photoelectrocatalytic activity under sunlight of Ti/TiO 2 sensitized with SnS quantum dots, obtained by the successive ionic layer adsorption and reaction (SILAR) method. The presence of SnS caused the enhanced absorption of visible irradiation and the reduction of recombination of generated charges by a p-n heterojunction created with the TiO 2 . The highest efficiency of photoelectrocatalytic degradation of anticancer drugs (ifosfamide, 5-fluorouracil, imatinib) was achieved for the SnS-Ti/TiO 2 photoelectrode with a SnS quantum dot size from 4 to 10 nm. In addition, a decrease of IF PEC degradation efficiency was observed with increasing pH and with the presence of Cl - , NO 3 - , HCO 3 - and organic matter in the treated solution. Studies of the PEC mechanism have shown that drug degradation occurs mainly as a result of the direct and indirect action of photogenerated holes on the SnS-Ti/TiO 2 photoelectrode, and the identified degradation products allowed for the presentation of the degradation pathway of IF, 5-FU and IMB. Duckweed ( Lemna minor ) growth inhibition tests showed no toxicity of the drug solutions after treatment.

One of the challenges in research into photoelectrocatalytic (PEC) degradation of pollutants is finding the appropriate photoanode material, which has a significant impact on the process efficiency. Among all others, photoelectrodes based on an ordered TiO 2 nanotube arrays are a promising material due to well-developed surface area and efficient charge separation. To increase the PEC activity of this material, the SILAR method was used to decorate Ti/TiO 2 nanotubes by PbS quantum dots (QD). The ifosfamide (IF) degradation rate constants was twice as higher for PbS-Ti/TiO 2 (0.0148 min -1 ) than for Ti/TiO 2 (0.0072 min -1 ). Our research showed the highest efficiency of PEC degradation of drugs using IIIPbS-Ti/TiO 2 made with 3 SILAR cycles (PbS QD size mainly 2-4 nm). The 4 and 6 of SILAR cycles resulted in the aggregation of PbS nanoparticles on the Ti/TiO 2 surface and decreased IF PEC degradation rate to 0.0043 and 0.0033 min -1 , respectively. Research on PEC mechanism has shown that the drugs are degraded mainly by the activity of photogenerated holes and hydroxyl radicals. In addition, the identified drug intermediates made possible to propose a degradation pathways of anticancer drugs and the ecotoxicity test show no inhibition of Lemna minor growth of treated solutions., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Herein, the synthesis and application of functionalized quantum dot-based protease probes is described. Such probes are composed of nontoxic ZnO nanocrystals decorated by amino groups followed by linker and labeled peptide attachment. Spherical NH 2 -terminated ZnO quantum dots (QDs) with the average size ranging from 4 to 8 nm and strong emission centered at 530 nm were prepared using the sol-gel method. The fluorescence of ZnO QDs was quenched by the BHQ1 moiety present on the N-terminal amino group of the peptide. The enzymatic cleavage of the peptide mediated by the proteinase 3 (PR3) bond resulted in an increase in the QD probe fluorescence. This observation was verified using both model and biological systems; and the picomolar detection limit was found to be more than 30 times lower than that of the previously reported internally quenched peptide (a decrease in detection limit from 43 to 1.3 pmol was observed).

In recent years, the growing interest in applying photoelectrocatalysis (PEC) to decompose organic pollutants has resulted in the need to search for new photoelectrode materials with high activity under visible light radiation. The presented research showed an increased photoelectrocatalytic activity under sunlight of Ti/TiO2 sensitized with SnS quantum dots, obtained by the successive ionic layer adsorption and reaction (SILAR) method. The presence of SnS caused the enhanced absorption of visible irradiation and the reduction of recombination of generated charges by a p--n heterojunction created with the TiO2. The highest efficiency of photoelectrocatalytic degradation of anticancer drugs (ifosfamide, 5-fluorouracil, imatinib) was achieved for the SnS-Ti/TiO2 photoelectrode with a SnS quantum dot size from 4 to 10 nm. In addition, a decrease of IF PEC degradation efficiency was observed with increasing pH and with the presence of Cl-, NO3-, HCO3- and organic matter in the treated solution. Studies of the PEC mechanism have shown that drug degradation occurs mainly as a result of the direct and indirect action of photogenerated holes on the SnS-Ti/TiO2 photoelectrode, and the identified degradation products allowed for the presentation of the degradation pathway of IF, 5-FU and IMB. Duckweed (Lemna minor) growth inhibition tests showed no toxicity of the drug solutions after treatment. [ABSTRACT FROM AUTHOR]

The growing research interest on photoelectrocatalysis has encouraged the search for new materials with high activity and the development of methods for their synthesis. The successive ionic layer adsorption and reaction (SILAR) method is an effective way to synthesize materials with photoelectrocatalytic (PEC) properties that are active under visible radiation. Therefore, studies on the impact of the parameters of the SILAR method on the properties and PEC activity of TiO 2 nanotubes sensitized with CdS quantum dots (QDs) were conducted. PEC activity was determined based on the efficiency of ifosfamide (IF) degradation, which is currently one of the most commonly detectable anticancer drugs in aquatic environment. The highest IF PEC degradation rate (0.0184 min−1) and the highest TOC removal (48%) was achieved with the CdS-Ti/TiO 2 _NO 3 −_0.1M_3c_60s photoelectrode. Among the SILAR parameters, the highest impact on the PEC IF degradation efficiency had the concentration of the Cd precursor, as well as the number and time of the cycles. Our studies showed that CdS-Ti/TiO 2 nanocomposites exhibited more than twice higher photocatalytic and PEC IF degradation efficiency than pristine Ti/TiO 2 under UV–Vis irradiation. In addition, the PEC mechanism of IF degradation using pristine Ti/TiO 2 and CdS-Ti/TiO 2 was compared, from which it was concluded that the higher PEC activity of the nanocomposites is due to the greater contribution of h+ and the generation of other oxidants caused by the presence of CdS QDs. Based on the identified degradation products, a pathway for PEC IF degradation was also proposed. ga1 • The presence of CdS QDs in TiO 2 enhances PEC degradation and TOC removal efficiency. • Precursor concentration, number of cycles, and time are the most key SILAR parameters. • The amount and size of CdS QDs determine the properties and PEC activity of electrode. • The presence of CdS increases the role of h+ and other oxidants in PEC mechanism. [ABSTRACT FROM AUTHOR]

The effect of type (AgInS2, SnS, CuS2, Bi2S3) and amount (5, 10, 15 wt%) of quantum dots (QDs) on the surface properties and photocatalytic activity of QDs-sensitized TiO2 composite, was investigated. AgInS2, SnS, CuS2, Bi2S3 QDs were obtained by hot-injection, sonochemical, microwave, and hot-injection method, respectively. To characterize of as-prepared samples high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis spectroscopy and photoluminescence (PL) emission spectroscopy were applied. The size of AgInS2, SnS, CuS2, Bi2S3 QDs were 12; 2–6; 2–3, and 1–2 nm, respectively. The QDs and QDs-sensitized TiO2 composites obtained have been tested in toluene degradation under LEDs light irradiation (λmax = 415 nm and λmax = 375 nm). For pristine QDs the efficiency of toluene degradation increased in the order of AgInS2 < Bi2S3 < CuS < SnS under 375 nm and AgInS2 < CuS < Bi2S3 < SnS under 415 nm. In the presence of TiO2/SnS QDs_15% composite, 91% of toluene was degraded after 1 h of irradiation, and this efficiency was about 12 higher than that for pristine QDs under 375 nm. Generally, building the TiO2/AgInS2 and TiO2/SnS exhibited higher photoactivity under 375 nm than the pristine TiO2 and QDs which suggests a synergistic effect between QDs and TiO2 matrix. [ABSTRACT FROM AUTHOR]

One of the most important challenges in the fabrication of ordered tantalum pentaoxide (Ta2O5) nanotube arrays (NTs) via the electrochemical method is the formation of nanotubes that adhere well to the Ta substrate. In this paper, we propose a new protocol that allows tight-fitting Ta2O5 nanotubes to be obtained through the anodic oxidation of tantalum foil. Moreover, to enhance their activity in the photocatalytic reaction, in this study, they have been decorated by nontoxic bismuth sulfide (Bi2S3) quantum dots (QDs) via a simple successive ionic layer adsorption and reaction (SILAR) method. Transmission electron microscopy (TEM) analysis revealed that quantum dots with a size in the range of 6–11 nm were located both inside and on the external surfaces of the Ta2O5 NTs. The effect of the anodization time and annealing conditions, as well as the effect of cycle numbers in the SILAR method, on the surface properties and photoactivity of Ta2O5 nanotubes and Bi2S3/Ta2O5 composites have been investigated. The Ta2O5 nanotubes decorated with Bi2S3 QDs exhibit high photocatalytic activity in the toluene degradation reaction, i.e., 99% of toluene (C0 = 200 ppm) was degraded after 5 min of UV-Vis irradiation. Therefore, the proposed anodic oxidation of tantalum (Ta) foil followed by SILAR decorating allows a photocatalytic surface, ready to use for pollutant degradation in the gas phase, to be obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • NG-ZnO/NiO were obtained via direct adsorption, solvothermal or calcination methods. • Coupling routes of QDs and ZnO/NiO affect surface and electrochemical properties. • Unique architectures improve storage efficiency and maintain structural stability. • Synergistic effect of QDs and ZnO/NiO for high performance Li- and Na-ion batteries. • Yolk-shell structure with conductive NG QDs facilitate electrochemical reactions. Surface engineering at the nanoscale to obtain robust interface between metal oxides and quantum dots is essential for improving the performance and stability of battery materials. Herein, we designed and prepared novel N-doped graphene quantum dot-modified ZnO/NiO anode materials with a well-defined yolk-shell structure for lithium and sodium-ion batteries. NG QDs were assembled on the ZnO/NiO microspheres using three different coupling strategies: solvothermal, direct adsorption and annealing under N 2 atmosphere. The presence of NG QDs deposited on the ZnO/NiO hybrids promoted enhanced electrical conductivity, lower charge-transfer resistance and provides more active sites. As a result, NG-ZnO/NiO_s anode obtained by solvothermal route exhibited high reversible delithiation capacity of 912 mAh/g at 18.6 mA g−1 and excellent cycling performance with the average delithiation capacity of 525 mAh/g at 372 mA g−1 over 400 cycles. Moreover, application of the NG-ZnO/NiO_s elecrode in Na-ion batteries revealed decent electrochemical behavior with capacity values reaching 235 mAh/g at 18.6 mA g−1. Importantly, surface properties, morphology and electrochemical behavior of obtained NG-ZnO/NiO hybrids were dependent on the combination route of NG QDs with ZnO/NiO microspheres indicating that quality of heterojunction between composite components has significant impact on the electrode performance. [ABSTRACT FROM AUTHOR]

• AgInS 2 quantum dots were prepared and loaded onto ZnO nanopyramids. • Thiol bonds promoted the heterojunction between both semiconductors. • Nanocomposites possessed higher photoactivity than that of the pristine compounds. • Photocatalytic phenol degradation and hydrogen evolution were tested. • Enhanced charge separation in nanocomposites boosted their photocatalytic activity. Despite the unique properties of single semiconductor nanomaterials and quantum dots, poor photocatalytic activity has characterized them and the fabrication of nanocomposites has become necessary to enhance their photocatalytic performance. Thus, AgInS 2 quantum dots (AIS QDs, 4.0 ± 1.6 nm), have been successfully prepared and loaded onto ZnO nanopyramids (ZnO NPy). The effect of the nominal amount of AIS QDs decorating ZnO NPy on the morphology, optical properties, structure and surface chemistry of the nanocomposites was systematically studied. Photocatalytic tests revealed that the 1%AIS@ZnO NPy sample reported the highest photoactivity for phenol degradation in aqueous phase (92 % after one hour of irradiation, λ > 350 nm) that was 4 and 68 times the reported for bare ZnO NPy and AIS QDs, respectively. Accordingly, the maximum photocatalytic hydrogen evolution, under UV–vis light, for the same sample corresponded to 17 and 21 times the estimated for pristine ZnO NPy and AIS QDs, respectively. Hence, the AIS QDs – ZnO system has been applied in the photocatalytic field for the first time in this work and a synergetic effect was confirmed owing to a strong heterojunction formation between both semiconductors that allows an enhanced charge carrier separation, improving the photocatalytic activity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Eu, Er, Tb, Yb, Ho, La (0.09–0.45 mmol) modified ZnO QDs obtained by sol-gel approach. • Modification of ZnO QDs by RE resulted in increase of photoactivity and decrease of photoluminesce. • ZnO/Er_0.09 showed the highest photocatalytic activity in phenol degradation (90%) • The photocatalytic properties of ZnO/0.09_Er can be related to new Er3+-3d/4f electronic states. • ZnO/La_0.45 showed the highest quantum yield (81%) Abstract A series of novel ZnO quantum dots modified with rare earth metals was successfully prepared by a simple sol-gel approach. The effects of types (Eu, Er, Tb, Yb, Ho, La) and amounts (from 0.09 to 0.45 mmol) of lanthanides on the optical properties, structural characterization and photocatalytic activity of ZnO/RE QDs were systematically investigated. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) with energy dispersive X-ray analysis (EDX) and UV–Vis diffuse reflectance spectroscopy were used to characterize surface properties, while photoluminescence (PL) emission spectroscopy and UV–Vis-driven degradation of phenol in aqueous phase were applied to understand optical and photocatalytic properties. The experiments demonstrated that generally modification of ZnO QDs by lanthanides resulted in increase of photoactivity while photoluminesce decrease at the same moment. The highest photocatalytic activity among all obtained nanomaterials and the lowest photoluminescence quantum yield among ZnO/Er photocatalysts were observed for ZnO QDs modified with 0.09 mmol of erbium. Increased photocatalytic activity has been shown in successive samples: ZnO/0.09_Er > ZnO/0.18_Eu > ZnO/0.09_La > ZnO/0.27_Er > ZnO/0.18_Tb > pristine ZnO QDs. The experimental results were supported by calculations based on density functional theory (DFT) which revealed atomic and electronic structure of Er/La modified ZnO QDs. [ABSTRACT FROM AUTHOR]

In this study, we report a novel method of BaZrO 3 and SrZrO 3 surface modification by two different types of quantum dots (QDs, Cu 2 O and Bi 2 O 3 ), which improved the photocatalytic performance of the obtained materials under UV-Vis light irradiation. Pristine BaZrO 3 and SrZrO 3 were prepared by the hydrothermal method. The deposition of Cu 2 O- and Bi 2 O 3 -QDs was carried out by chemical reduction. The morphology of the nanoparticles was estimated based on microscopic analysis (SEM, TEM). The perovskite structure and phase composition of polycrystals were confirmed by X-ray powder diffraction analysis (XRD). The elemental surface composition and the chemical character of detected elements were identified by X-ray photoelectron spectroscopy (XPS). The absorption ability and luminescence properties of nanocomposites were investigated by UV–Vis diffuse-reflectance spectroscopy (DRS UV-Vis) and luminescence spectroscopy. The influence of Cu 2 O/Bi 2 O 3 -QDs modification on the photocatalytic activity of BaZrO 3 and SrZrO 3 was evaluated by the phenol photodegradation process in the liquid phase under UV-Vis and toluene degradation in the gas phase under Vis irradiation. The highest photoactivity under UV-Vis light was observed for BaZrO 3 /1% Cu 2 O/33% Bi 2 O 3 and SrZrO 3 /1% Cu 2 O/33% Bi 2 O 3 samples. Research also demonstrated that single-type QD deposition (Cu 2 O or Bi 2 O 3 ) on the zirconate surface decreases the photoactivity in comparison with pristine zirconates. The mechanism of photocatalytic activity of the obtained nanocomposites was investigated by the formation of hydroxyl radicals under UV-Vis irradiation in the presence of terephthalic acid. [ABSTRACT FROM AUTHOR]

Surface distribution of quantum dots (QDs) at the semiconductor matrix caused by synthesis condition (e.g. pH of solution during coupling) could lead to different photocatalytic activity. Thus, achieving an optimal covering of semiconductor matrix by QDs has been challenging. Herein, the influence of the alkalinity level of aqueous decoration medium for the coupling of mercaptoundecanoic acid (MUA) capped CuInS 2 quantum dots (CIS) and ZnIn 2 S 4 microspheres (ZIS) on photocatalytic hydrogen evolution (PHE) performance was investigated. Aqueous decoration medium with different alkalinity levels for the formation of ZIS/CIS photocatalytic system resulted in significantly different PHE performances in the presence of (0.5 wt%) Pt co-catalyst deposition without any change in crystal structure of ZIS matrix up to pH 12.5. The photocatalytic system obtained at pH 10.5 possessed the highest performance followed by the decrease at pH 11.5 and again the remarkable increase was detected at pH 12.5 that was the pH level for uniform dispersion of CIS in aqueous medium. This work remarks the importance of the nanoparticle's aggregates on PHE performance over non-toxic ZnIn 2 S 4 /CuInS 2 photocatalytic system. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel photocatalytic AgInS 2 /Bi 2 WO 6 system was theoretically predicted and fabricated. • Fixing AgInS 2 QDs on Bi 2 WO 6 suppressed photogenerated charge carrier recombination. • AgInS 2 /Bi 2 WO 6 showed improved activity under visible irradiation and reusability. • The system allowed phenol degradation and water splitting under UV or visible light. Bismuth tungstate (Bi 2 WO 6) can work as a photocatalyst but suffers from rapid recombination of photogenerated charge carriers. Herein, density functional theory (DFT) simulations revealed that the formation of a thermodynamically stable AgInS 2 (112)/Bi 2 WO 6 (010) heterojunction could promote charge separation and enhance the photoactivity of Bi 2 WO 6. To confirm these theoretical predictions, a new type of photocatalysts in the form of Bi 2 WO 6 flower-like microspheres decorated with different amounts of AgInS 2 quantum dots (QDs) was obtained using a three-step procedure. The optimized system, obtained by embedding 1 wt% AgInS 2 QDs on a Bi 2 WO 6 matrix, possessed an enhanced photocatalytic activity for both phenol degradation and water splitting under visible light irradiation (λ > 420 nm), as well as good reusability and stability during prolonged storage. Finally, DFT calculations of the adsorption energies of reagents (O 2 , H 2 O, and H 2 molecules) on Bi 2 WO 6 and AgInS 2 /Bi 2 WO 6 surfaces showed that the surface of the AgInS 2 (112)/Bi 2 WO 6 (010) interface was more active, allowing this system to strongly interact with surrounding species such as H 2 , O 2 , and H 2 O and thereby inducing photocatalytic oxidation of OH– to •OH, reduction of O 2 to O 2 •– or reduction of H+ to H 2. [ABSTRACT FROM AUTHOR]

• XPS and theoretical studies confirmed the doping of the Bi 2 S 3 QDs by Yb and Er ions. • TiO 2 decorated by 10 wt.% of Yb-Bi 2 S 3 QDS allows to produce 1576.7 μmol H 2 /g cat. • Stability of Yb-Bi 2 S 3 QDs/TiO 2 composite in Na 2 S/Na 2 SO 3 electrolyte was proven. The formation of heterojunctions between wide- and narrow-bandgap photocatalysts is commonly employed to boost the efficiency of photocatalytic hydrogen generation. Herein, the photoactivity of urchin-like rutile particles is increased by decorating with pristine as well as Er- or Yb-doped Bi 2 S 3 quantum dots (QDs) at varied QD loadings (1–20 wt%) and doping degrees (1–15 mol%), and the best hydrogen evolution performance is achieved at Er and Yb contents of 10 mol%. Specifically, a hydrogen productivity of 1576.7 μmol g cat −1 is achieved after 20-h irradiation for TiO 2 decorated by 10 mol% Yb-doped Bi 2 S 3 QDs. Theoretical calculations show that the introduction of defects into the Bi 2 S 3 lattice through Er/Yb doping promotes the creation of new energy levels and facilitates the transport of photogenerated charges during photocatalysis. [ABSTRACT FROM AUTHOR]