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Graphical abstract Highlights • The CdS could be selectively deposited on {001} or {101} facets of TiO 2 nanosheet. • Z-scheme {101}TiO 2 /CdS/CDots showed significant photocatalytic 4-CP degradation efficiency. • Z-scheme {101}TiO 2 /CdS/CDots showed excellent stability and anti-photocorrosion ability. • The photocatalytic mechanisms on the nanocomposites were elucidated. Abstract Directional deposition has always been a focus issue in the construction of specific heterostructure. Herein, for the first time, we have demonstrated that the CdS could be selectively deposited on {001} or {101} facets of TiO 2 nanosheet, and two different charge transfer processes were formed. First, the selective deposition of CdS on {001} facets of TiO 2 nanosheet ({001}TiO 2 /CdS) would form the Type-II heterostructure, which seriously weakened the redox ability of {001}TiO 2 /CdS and directly resulted in the low photocatalytic performance (4-Chlorophenol (4-CP), 61.92% in 40 min) and serious photocorrosion of CdS. In contrary, the selective deposition of CdS on {101} facets of TiO 2 nanosheet ({101}TiO 2 /CdS) could construct direct Z-scheme heterostructure with significantly increased photocatalytic 4-CP degradation efficiency (96.12%), much higher than pristine TiO 2 nanosheet (87.21%). The hybrids were further modified by carbon nanodots (CDots) ({101}TiO 2 /CdS/CDots) to enhance photocatalytic performance (99.84%). The obtained direct Z-scheme {101}TiO 2 /CdS/CDots showed excellent stability and anti-photocorrosion ability. The synergistic effect between TiO 2 nanosheet, CdS and CDots was expounded through characterization analyses, and the photocatalytic reaction mechanism was proposed in detail. Toxicity assessment authenticated good biocompatibility and low cytotoxicity of {101}TiO 2 /CdS/CDots. Our discovery was expected to drive great advances in the use of TiO 2 nanosheet for environmental remediation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Synthesis of SrTiO 3 and SrTiO 3 :Er3+ nanoparticles. • Red and green emissions for SrTiO 3 nanoparticles under the excitation at 980 nm. • Enhanced photocatalytic activity of Er3+ doped SrTiO 3 nanoparticles. Abstract SrTiO 3 and SrTiO 3 :Er3+ nanoparticles were synthesized by a sol-gel method. The synthesized SrTiO 3 :Er3+ nanoparticles exhibit green and red emissions under the excitation at 980 nm. Both SrTiO 3 and SrTiO 3 :Er3+ nanoparticles exhibit photocatalytic hydrogen production under the irradiation of simulated sunlight. Moreover, SrTiO 3 :Er3+ nanoparticles show higher photocatalytic activity for hydrogen production than that of SrTiO 3 nanoparticles. The results indicate that SrTiO 3 is a good host for Er3+ and the incorporation of Er3+ is an effect way to enhance the photocatalytic activity for hydrogen production. [ABSTRACT FROM AUTHOR]

A novel anode that intimately couples anode-respiring bacteria (ARB) with a nitrogen-doped TiO 2 photocatalyst on a porous carbon foam electrode (the ICPB-anode) was fabricated and experimentally tested in an electrochemical cell. ARB are well known for obtaining energy by transferring bio-metabolized electrons to the anode, an external solid acceptor. The goal of this work was to identify if and how ARB play a role in transporting photo-generated electrons. When simulated visible-light illuminated an ICPB-anode, the current increased by ∼3 A/m 2 (∼30% of the total), due to photocatalytically generated electrons (photo-electrons). In contrast, an abiotic photocatalyst anode (photo-anode) was incapable of transfering photo-electrons. Compared to a non-photocatalytic biofilm-anode, the Coulombic efficiency increased by 15–20% with the ICPB-anode, and the effect was due to the addition of electron flow from photocatalytic water electrolysis, since oxidation of the organic electron donor was unchanged. Electrochemical impedance analyses showed that the Ohmic resistance of the ICPB-anode decreased by ∼98%, compared with the abiotic photo-anode. A redox-potential window typical of ARB’s c -type cytochromes was up-regulated when the ARB transported photo-electrons, supporting that c -type cytochromes were the significant redox proteins for transferring photo-electrons. All the results combine to show that ARB were responsible for the transport of electrons generated by photocatalysis in the ICPB-anode. [ABSTRACT FROM AUTHOR]

Titanium-dioxide (TiO 2 ) semi-conductors are promising for microbial-fuel-cell anodes, because they can accelerate the biodegradation of refractory organic pollutants while recovering electrical current. To make the coupling of TiO 2 photocatalysis and biodegradation a success, the anode’s biofilm must be protected from damage from reactive-oxygen species generated by photocatalysis. In this work, we first realized a photocatalytic bioanode using N-doped TiO 2 coated on macroporous carbon-foam that accumulated biofilm inside. Photocatalysis occurred on the outer surface, while bacteria were protected inside the foam matrix; this is a unique manifestation of intimately coupled photobiocatalysis (ICPB). Experiments focused on degradation of 4-chlorophenol (4-CP) and electrochemical characterization of the ICPB-anode. The illuminated photo-anode, non-photocatalytic bio-anode, and ICPB-anode achieved ∼10%, ∼28%, and ∼41% 4-CP degradation efficiency, respectively; clearly, the ICPB anode achieved the best performance for 4-CP removal. The corresponding mineralization efficiency of the ICPB-anode also was the highest, and current generation by the ICPB-anode was 50% greater than that of a bio-anode. Cyclic voltammetry showed that photocatalyst and biofilm had to be present together to achieve high current density, and it also suggested that the electron-transport activity of c -type cytochromes of anode-respiring bacteria played an essential role in the transport of electrons. [ABSTRACT FROM AUTHOR]

BACKGROUND Powdered photocatalyst by doping TiO2 with upconversion luminescence agents achieved visible light induced photocatalysis. However, slurry photocatalysts are difficult to recover from the treated liquor. In the present study, spherical activated carbon ( SAC)-supported and Er3+: YAlO3-doped visible-light responsive photocatalyst (Er3+: YAlO3/ TiO2-SAC) was synthesized and characterized. The photocatalytic performance of photocatalyst was examined for degradation of methyl orange ( MO) in a liquid-solid fluidized bed photoreactor under visible-light irradiation. RESULTS Two notable UV emission peaks at 320 and 360 nm were observed for Er3+: YAlO3 by visible light excitation, which were assigned to the transition of 2P3/2→ 4I15/2 and 4D5/2→ 4I11/2, respectively. An optimum 8 h photodecolorization efficiency of 65.3% was obtained from the fluidized bed with reaction rate constant 22.17 mg L−1 h−1. The degradation rate first increased and then decreased with the increasing expansion ratio, and the optimum expansion ratio was found to be 130%. CONCLUSION Optical characterization revealed that Er3+: YAlO3 could convert incident visible-light to UV, which can then be utilized by TiO2 for photocatalysis. The visible light generated by Er3+: YAlO3 emissions were not used by TiO2 because of its high band gap. The photocatalytic degradation of MO in the fluidized bed photoreactor followed the Langmuir-Hinshelwood kinetics model. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A series of metal silver (Ag) and carbon dots (CDots) co-doped BiOBr ternary systems (Ag/CDots/BiOBr) were successfully prepared by a two-step method. The CDots and Ag nanoparticles were successively introduced into BiOBr with the ionic liquid (IL) 1-hexadecyl-3-methylimidazolium bromide ([C 16 mim]Br) as the precursor. The sphere-like structure of the as-prepared ternary photocatalyst was 1–2 μm in diameter. The compositional characterization and optical and electrical properties of photocatalysts were investigated in detail. The prepared ternary photocatalysts possessed the excellent visible-light driven photocatalytic degradation for 4-chlorophenol (4-CP) with Ag content at 0.9 wt% and CDots content at 2 wt%. Additionally, the 4-CP removal efficiencies decreased in the order of 0.9Ag/2CDots/BiOBr (88.58%) > 0.9Ag/BiOBr (68.12%) > 2CDots/BiOBr (62.12%) > BiOBr (47.15%) under visible light illumination in 6 h. The dissolved organic carbon (DOC) removal and the dechlorination efficiency by the Ag/CDots/BiOBr were 62.3% and 81.5%, much higher than those by the pristine BiOBr. The coexistence of Ag and CDots on the BiOBr promoted visible light harvesting capability and prevent the recombination of photo-generated electron/hole pairs. The Ag/CDots/BiOBr photocatalytic mechanism was discussed by band structure analysis and free radical trapping experiments. [ABSTRACT FROM AUTHOR]

Intimately coupled photocatalysis and biodegradation (ICPB) has been studied for treating bio-recalcitrant pollutants. The key principle of ICPB is that photocatalysis occurs on a porous carrier’s outer surface, and biofilms are present in the interior, where they are protected from inhibition. Little is known regarding the ability of ICPB to degrade antibiotics, and a primary issue is whether or not the bacteria in the carriers’ interior can acclimate to biodegrade the products from photocatalysis of antibiotics. This study evaluated the removal and mineralization of tetracycline hydrochloride (TCH) using visible-light-induced ICPB (called VPCB) with Ag-doped TiO 2 as the photocatalyst. The biofilms inside the VPCB carriers could mineralize the photocatalytic products, which led to more than 20% enhanced removal of chemical oxygen demand (COD). By biodegrading the products of TCH photocatalysis, the biofilms lowered the competition for free radicals between TCH and its photocatalysis products; thus, VPCB accelerated TCH removal by ∼11% in the first 2 h of operation, compared with photocatalysis alone. The biofilms in the VPCB carriers evolved to being enriched in Methylibium , Runella , Comamonas , and Pseudomonas , which are known for biodegrading aromatics and being resistant to TCH. In conclusion, VPCB enhanced degradation and mineralization of TCH. [ABSTRACT FROM AUTHOR]

A group of nanosheet-assembled three-dimensional BiOCl 1−x Br x hierarchical microspheres (x = 0, 0.3, 0.4, 0.5, 0.7, 0.8 and 1.0) with layered tetragonal crystal phase were prepared by 2-methoxyethanol-assisted solvothermal route and using ionic liquids as both halogen sources and structure-directing agent. By the combination of the results including XRD, XPS and UV–vis/DR spectra, lattice substitution of halogen atoms each other and then formation of BiOCl 1−x Br x solid solution was evidenced. Additionally, the BiOCl 1−x Br x microspheres exhibited interesting composition-dependent band gaps. The simulated sunlight and visible-light photocatalytic properties including degradation, mineralization and reusability of the BiOCl 1−x Br x microspheres were evaluated by selecting p -nitrophenol (PNP) and tetrabromobisphenol-A (TBBPA) as the target pollutant compounds, finding that the balance between the suitable band gap and adequate potential of the valence band in BiOCl 1−x Br x crystals dominated their photocatalytic activity. Additionally, the BiOCl 1−x Br x microspheres with advantages such as enhanced photon utilization efficiency, larger BET surface area and favorable (110) exposed reactive surface gave the positive influence on their photocatalytic activity. Based on the results of photoelectrochemistry experiment and indirect chemical probe testing, direct • O 2 − and h VB + photooxidation for the decomposition of PNP or TBBPA was revealed. [ABSTRACT FROM AUTHOR]

Intimate coupling of visible-light-responsive photocatalysis and biodegradation (VPCB) provides novel insights into removal of inhibitory pollutants. Under these reactions, microbes are prone to photocatalytic activity. In this study, microbial responses to photocatalytic activity in VPCB used for phenol degradation were investigated. VPCB was conducted with Er 3+ :YAlO 3 /TiO 2 photocatalysts prepared at heat-treatment temperatures [HT] of 110 °C, 130 °C, and 150 °C to evaluate photocatalytic activities. The highest phenol removal rate (71.6%) was observed in photocatalysis [HT] 130, and particular microbial responses were elicited in VPCB [HT] 130. Dehydrogenase activity exhibited the highest decrease (90.7%) in VPCB [HT] 130. In this treatment, large amounts of biofilm were detached from the exterior of the carrier but the biofilm remained well protected in the interior. Extracellular polymeric substances with decreases of 65.6% and 31.4% in protein and polysaccharide levels, respectively, were not stimulated in VPCB [HT] 130 but were evidently stimulated in the other two protocols, which could be due to lower phenol inhibition. These results indicated that the most efficient removal rates of phenol and dissolved organic carbon reached 99.8% and 67.1%, respectively, in VPCB [HT] 130. [ABSTRACT FROM AUTHOR]

Much more attentions were paid to the anatase TiO 2 than rutile due to its higher photoactivety with a larger band gap. However, it is usually ignored that the relative narrow band gap of rutile TiO 2 benefits to the increasing in the responsive wavelength range. In this work, spherical activated carbon-supported Er 3+ :Al 2 O 3 -doped rutile TiO 2 (Er 3+ :Al 2 O 3 /TiO 2 -SAC) was synthesized by a sol–gel method using tetrabutyl titanate as titanium precursor, and erbium nitrate and aluminum nitrate as dopant sources. Long-wavelength visible light from a light-emitting diode source was upconverted to ultraviolet light and short-wavelength visible light by Er 3+ dopant, which could then be absorbed by the synthesized photocatalyst that contained rutile TiO 2 . This resulted in higher photocatalytic activity of samples with rutile than those with anatase. A response surface methodology based on the central composite design model was used to determine the optimum synthesis conditions: Er concentration, 0.07 mol‱; Al concentration, 0.08 mol%; and calcination temperature, 700 °C. The catalyst achieved a 90.0% removal efficiency for methyl orange (MO) with a reaction rate of 18.98 × 10 −3 min −1 at an initial MO concentration of 500 mg L −1 in 2 h under visible-light irradiation. [ABSTRACT FROM AUTHOR]

Intimately coupled photocatalysis and biodegradation (ICPB) is an attractive novel technology for the mineralization and detoxification of persistent organics. Good photocatalytic performance is essential for an advanced ICPB operation, and the photocatalyst coating and illumination conditions are strong determining factors. In this work, response surface methodology (RSM) involving the central composite design (CCD) was employed to discover optimal operating conditions, by using tetracycline hydrochloride (TCH) as the model pollutant. Polyvinyl butyral (PVB) was employed to form an adhesion layer, enhancing P25 TiO2 activity and stability. We achieved the optimal coating conditions with a mixing time of 20 h, TiO 2 dosage of 8 g/L, and PVB concentration of 0.5 wt.%. The optimum running conditions for an ICPB-reactor were found to be at a carrier volume ratio of 40% and light intensity of 6000 μw/cm2. These conditions were essential for the production of desired intermediates and functional microbial survival. At the optimized parameters ranges, ∼98% TCH removal and ∼40% mineralization was achieved, and the inhibition on Q67 illuminance was only 30.32%. This is the first work on optimizing the fabrication and operation of ICPB, which is meaningful for the application of ICPB in practical engineering. [ABSTRACT FROM AUTHOR]

Intimately coupled photocatalysis and biodegradation (ICPB) is a promising technology for treating wastewater containing antibiotics. While past work has documented the benefits of ICPB for removing and mineralizing antibiotics, its impacts on mitigating biotoxicity from products has not been studied. We fabricated an ICPB carrier by coating Ag-doped TiO 2 on the outer skeleton of sponge carriers and allowing biofilm to grow in the internal macro-pores. We used amoxicillin (C 16 H 19 N 3 O 5 S) as the model antibiotic. The amoxicillin-removal rate contents with ICPB was greater by 40% vs. photocatalysis and 65% vs. biodegradation, based on the first-order kinetic simulation. While mineralization of amoxicillin was minimal for photocatalysis or biodegradation alone, it was ∼35% with ICPB. Photocatalysis alone led to accumulation of C 14 H 21 N 3 O 2 S; biodegradation alone resulted in accumulation of C 14 H 21 N 3 O 3 , C 16 H 18 N 2 O 4 S, and C 15 H 21 N 3 O 3 ; but they were negligible after ICPB. As a result, ICPB reduced toxicity impacts measured by Staphylococcus aureas growth, Daphnia magna mobility, and teratogenicity to Zebrafish embryos. In contrast, photocatalysis alone increased each of the toxicity effects. In sum, ICPB gave greater removal and mineralization of amoxicillin, and it mitigated biotoxicity from treatment products. Image 1 • Intimate cooperation of AOP and biodegradation was achieved in an ICPB-reactor. • Cooperation accelerated the amoxicillin degradation of the sole processes. • The intimate cooperation remarkably mitigated AMO product toxicity. • AMO removal accelerated 54% and COD removal enhanced by 65% (vs. sole AOP). [ABSTRACT FROM AUTHOR]

• 3-D Ag/ZnO@CF photocatalysts with enhanced mass transfer were fabricated. • Hierarchical structure and loaded cocatalysts improved the photocarriers separation. • Phenol-Cr (VI) ester contributed to the homogeneous self-elimination of pollutants. • Synergistic removal of phenol and Cr(VI) by hetero- and homogeneous photocatalysis. Synergistic photocatalysis offers great potential for simultaneously treating organic and heavy metal pollutants. Although considerable progress has been made, this technology is seriously restricted by the poor photoactivity of heterogeneous catalysts, and the contribution from homogeneous intermoleculars has been overlooked. In this paper, the Ag/ZnO@CF with 3-D hierarchical porous structure was fabricated and used to synergistically remove phenol and Cr(VI) from water. Due to the enhanced mass transfer and cocatalysts-facilitated charge separation, 3-D photocatalysts exhibited significantly improved activity for heterogeneous photocatalysis. Furthermore, both experimental characterizations and DFT calculations evidenced the formation of phenol-chromate(VI) esters with ligand-to-metal charge transfer from benzene ring to central chromium ion under photoexcitation. Thereafter, the effects of heterogeneous and homogeneous photocatalysis on the treatment efficiency of multiplex pollutants were investigated. In an ideal scenario, 2.4 and 2.3 times higher phenol and Cr(VI) removal rate were achieved compared to single catalytic reactions. This work not only offers new material strategy for photocatalyst exploration, but also provides new insights into the multiphase homogeneous catalysis contributed by intermolecular interactions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Co-substrate strategy could favor to resist photo-H 2 O 2 stress on biofilm in ICPB. • Living cells enhanced by 19.6%, and cell morphology showed no disinfection. • Shannon index increased from 3.45 to 4.05, showed promoted microbial diversity. • The improvements caused 4-CP and COD removal to increase by ∼27% and ∼23%, respectively. Abstract Intimately coupled photocatalysis and biodegradation (ICPB) is an emerging technology for treating refractory wastewater. The prerequisite of successful ICPB is that photocatalytic reactive oxygen species (ROSs) attack refractory pollutants and yield biodegradable intermediates, but “instantly” extinct before they transfer to the biofilms. However, photocatalytic induced H 2 O 2 (a typical ROS) is different from others due to its long half-life. Photo-H 2 O 2 in ICPB could potentially damage the biofilm; however, this has not been verified to date. In this study, we show that photo-H 2 O 2 damages biofilms in ICPB, and we successfully addressed this issue using a strategy with the co-substrate (NaAC). Under H 2 O 2 stress, the living cell percentage in ICPB dropped significantly, and the cell morphology presented the disinfection of bacteria cells, with enlarged size and disappeared organelles. By adding NaAC, the living cell percentage increased by 19.6% and the bacterial intracellular structure became integrated. The Shannon index increased from 3.45 to 4.05, indicating enhanced microbial diversity. Thauera and Dechloromonas were dominant genera, which played important roles in the breaking of the aromatic ring and in dechlorinating. As a result, 4-CP removal and mineralization increased by ∼27% and ∼23%, respectively. Here, we identified the negative effects of photo-H 2 O 2 on the microbial survival of ICPB and for the first time propose an efficient co-substrate strategy to remedy this issue. [ABSTRACT FROM AUTHOR]

Intimately coupled photocatalysis and biodegradation (ICPB) shows great potential for treatment of refractory pollutants; however, no kinetics for modeling ICPB performance has been developed and the major challenge is to determine the relationship between photocatalysis and biodegradation. In this work, we developed a simplified kinetic model to predict removal and mineralization of a target pollutant (tetracycline hydrochloride; TCH) by hypothesizing that all of the biodegradable photocatalysis products are immediately bio-utilized. Combined with a second-order photocatalytic kinetic model and Monod-type biodegradation model, we observed the interactions between photocatalysis and biodegradation in ICPB. Parameters in the kinetic equations were estimated using the First Optimization software to fit the experimental data to the proposed model with nonlinear regression. Our experimental results showed that TCH and chemical oxygen demand (COD) removal were as high as 94% and 70% within 8 h, respectively. TCH was transformed to non-toxic intermediates in only 4 h. Significantly, the kinetic models could satisfactorily predict the TCH and COD removal, and agreed well with the experimental data with an R 2  > 0.92. The models confirmed that biodegradation in ICPB played a major role in accelerating TCH and its intermediates removal and mineralization, as the kinetic coefficient k 1 of ICPB was 10% greater than that of photocatalysis alone. The developed models accurately predicted the ICPB efficiencies, and revealed the mechanisms of ICPB operation. [ABSTRACT FROM AUTHOR]

Intimately coupled photocatalysis and biodegradation (ICPB) was realized in a macroporous carrier in which a photocatalyst was present on the outer surface, while a biofilm accumulated inside the carrier. In ICPB, photocatalysis products are rapidly biodegraded by a protected biofilm, leading to mineralization of the refractory organics, such as antibiotics. However, mineralization in ICPB could be compromised if the photocatalysis products remain refractory or are inhibitory. To address this, we attempted to increase metabolic activity by providing a readily biodegradable co-substrate (acetate) that could act as a source of energy and electrons to improve biotransformation and mineralization of the refractory antibiotic tetracycline (TCH). When we added acetate during ICPB of TCH, TCH removal increased by ∼5%, mineralization increased by ∼20%, and almost all photocatalysis products disappeared. Acetate addition also led to an increase in active biomass, an increase in the biomass's respiratory activity, and evolution of the microbial community to having more members able to biodegrade photocatalysis and biotransformation intermediates. Thus, providing an easily biodegradable co-substrate was an effective means for enhancing TCH removal and mineralization with the ICPB technology. [ABSTRACT FROM AUTHOR]

Constructing 0D/2D heterojunctions, especially nanodots/nanosheets heterostructure, is one of the most efficient approach to solve the drawbacks existed in 0D or/and 2D materials, such as self-aggregation, instability, low light utilization efficiency and strong recombination of photo-generated charges. Herein, an unprecedent ternary 0D/2D heterojunction of Ag/CDots/BiOCl has been prepared via a simple one-step solvothermal process. The as-prepared nanocomposites exhibited superior visible light photocatalytic activity for tetracycline (TC) degradation with 68.9% removal in 50 min, much higher than pristine BiOCl (17.0%), Ag/BiOCl (51.8%) and CDots/BiOCl (43.8%). The characterization results showed that the presence of Ag and CDots fundamentally contributed to the visible light responses of BiOCl, and enhanced electron transfer and separation, resulting in the efficient electron density increment and photocatalytic performance improvement. The synergistic effect between Ag, CDots and BiOCl was expounded, and the photocatalytic reaction mechanism was proposed in detail. The toxicity assessment authenticated the good biocompatibility and low cytotoxicity of Ag/CDots/BiOCl. The results of this study indicate 0D/2D Ag/CDots/BiOCl heterojunction is a promising photocatalyst for the remediation of current water-pollution issues. [ABSTRACT FROM AUTHOR]

As a representative artificial photosynthetic system, direct Z-scheme WO 3 /CdS is a promising photocatalyst system for water purification. However, this system is still limited due to low electron transfer efficiency and serious photocorrosion. Here, we designed and precisely fabricated a novel all-solid-state Z-scheme WO 3 /CDots/CdS system. The CDots, as a nonmetallic electron mediator, could promote interfacial charge carrier separation and eliminate photocorrosion with enhanced photocatalytic activity. The phase, morphologies, microstructures, and optical and electrical properties of as-obtained Z-scheme WO 3 /CDots/CdS heterojunctions were investigated in detail. The photocatalytic performance of as-prepared catalysts was evaluated by the decomposition of 4-chlorophenol (4-CP), rhodamine B (RhB), and tetracycline hydrochloride (TCH) and the reduction of aqueous Cr(VI) in visible light. The optimized Z-scheme WO 3 /CDots/CdS-2 photocatalyst exhibited the highest photocatalytic activity for degrading and mineralizing 4-CP (∼70.0% and 48.3% in 7 h, respectively), both of which exceeded the rates observed in WO 3 /CdS samples under the same conditions by ∼2 times. In addition, the WO 3 /CDots/CdS-2 showed excellent stability and reusability with negligible change at ∼2.2% difference for 4-CP degradation in eight cycles. The release percentage of SO 4 2− (transformed from S 2− ) and Cd 2+ was only ∼0.77% and 0.79%, respectively, when compared with the initial concentration, which was far less than for the WO 3 /CdS system (∼5.64% and 5.70%). The results indicated that a thorough and complete Z-scheme charge carrier transfer route was achieved. Toxicity assessment authenticated good biocompatibility and low cytotoxicity of WO 3 /CDots/CdS. This study showed that the Z-scheme WO 3 /CDots/CdS was a promising photocatalyst for water purification. [ABSTRACT FROM AUTHOR]

Er–Al co-doped ZnO was synthesized via a facile, one-pot and non-toxic solvothermal process. The structural properties were analyzed by X-ray diffraction and scanning electron microscopy. Furthermore, the presence of dopants in ZnO matrix was confirmed by EDX measurement. The results showed the existent of wurtzite ZnO structure and no other peaks corresponding to impure phases. UV–vis diffuse reflection spectra showed that Er–Al co-doped ZnO exhibited a red-shift of the band-edge as compared to the pristine ZnO. The photocatalytic activity of the photocatalysts was investigated by the degradation of methyl orange (MO) under visible light. It was revealed that Er–Al co-doped ZnO showed much enhanced photocatalytic activity to the pristine ZnO in the degradation of MO. [ABSTRACT FROM AUTHOR]