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The efforts of carrying forward superconducting materials to commercialization can be overcome by materials with high performance potentiated by a suitable processing technique. In this work, extreme critical currents up to 241 A @ 77 K were attained by tuning the crystal growth in a directional solidification process. Bulk rods of textured Bi-2212/2.9 wt % Ag were obtained by changing the conventional laser floating zone technique through the application of a d.c. electrical current during the crystallization process. Using an optimized composition, the electrically assisted laser floating zone (EALFZ) allowed obtaining 5800 A/cm² in rods exhibiting only 2.3 mm in diameter, the highest value reported so far for bulk samples. This behavior is a consequence of the texture enhancement and radial phase distribution, exceeding a 2-fold increase in J c compared with samples grown without electrical current. Morphological and structural observations are discussed and correlated with the results from the electrical characterization. Applications on extremely efficient electrical current leads working at temperatures below 77 K using the above-described materials grown by EALFZ are anticipated. [ABSTRACT FROM AUTHOR]

Nanocrystalline diamond (NCD) films are attractive for many applications due to their smooth surfaces while holding the properties of diamond. However, their growth rate is generally low using common Ar/CH4 with or without H2 chemistry and strongly dependent on the overall growth conditions using microwave plasma chemical vapor deposition (MPCVD). In this work, incorporating a small amount of N2 and O2 additives into CH4/H2 chemistry offered a much higher growth rate of NCD films, which is promising for some applications. Several novel series of experiments were designed and conducted to tailor the growth features of NCD films by fine-tuning of the gas-phase compositions with different amounts of nitrogen and oxygen addition into CH4/H2 gas mixtures. The influence of growth parameters, such as the absolute amount and their relative ratios of O2 and N2 additives; substrate temperature, which was adjusted by two ways and inferred by simulation; and microwave power on NCD formation, was investigated. Short and long deposition runs were carried out to study surface structural evolution with time under identical growth conditions. The morphology, crystalline and optical quality, orientation, and texture of the NCD samples were characterized and analyzed. A variety of NCD films of high average growth rates ranging from 2.1 μm/h up to 6.7 μm/h were successfully achieved by slightly adjusting the O2/CH4 amounts from 6.25% to 18.75%, while that of N2 was kept constant. The results clearly show that the beneficial use of fine-tuning of gas-phase compositions offers a simple and effective way to tailor the growth characteristics and physical properties of NCD films for optimizing the growth conditions to envisage some specific applications. [ABSTRACT FROM AUTHOR]

Efficient energy storage from intermittent renewables can rely on the conversion of temporary energy excess by alkaline electrolysis, yielding oxygen and green hydrogen, which can be stored and used on demand. Electrodes made of laser-induced graphene (LIG) materials offer many advantages over the traditional graphene processing routes, due to inherent simplicity and low cost-benefit. Despite poorly studied, LIG electrodes are promising for water splitting when properly doped/modified with metals. However, proper design and processing optimization should be considered. The present study is devoted to the laser processing effects on the LIG electrode performance towards water splitting in alkaline media. Promising guidelines were obtained for hydrogen production, showing high electrochemical activity, while the microstructural degradation can be minimised by selecting suitable laser processing conditions, such as 3.6 W of laser power, 100 mm/s of laser scan rate, 36 mJ/mm of energy density and 2 laser scans. • Laser processing affects the LIG electrode performance during water splitting. • Effects of laser power, scan rate, energy density and laser scans were studied. • Low laser power is an essential processing parameter for the LIG's stability. [ABSTRACT FROM AUTHOR]

Laser-induced graphene from paper (paper-LIG) was applied in non-enzymatic electrochemical sensing of uric acid (UA) in human urine. Paper-LIG was formed by CO 2 laser modification of paper into a 3D graphene arrangement. Kinetic analysis of paper-LIG electrodes returned effective heterogeneous electron transfer standard rate constants of 1.4 × 10−3 cm s−1 and 7.8 × 10−4 cm s−1 for [Ru(NH 3) 6 ]2+/3+ and [Fe(CN) 6 ]4−/3− redox probes, respectively. These electrodes were able to detect and quantify uric acid in PBS within the 10–300 μM range at pH between 5.6 and 7.4. At pH 7.4, a linear response (R2 = 0.999) from 10 to 250 μM was achieved, with a limit of detection of 3.97 μM and a sensitivity of 0.363 μA cm−2 μM−1. Paper-LIG electrodes denoted adequate selectivity in synthetic urine as well as in ascorbic acid (AA) and dopamine (DA)-containing electrolytes. Determination of urinary UA content in human samples returned a concentration of c.a. 1.8–1.9 mM, within the range for healthy individuals. Recoveries of samples spiked with 50 and 100 μM UA were 100.6% and 95.4%, respectively, with satisfactory reproducibility and stability. These cheap, lightweight, flexible, and eco-friendly paper-LIG biosensors for non-enzymatic quantification of UA in human urine pave the way to widespread application in the detection of other important biomarkers. [Display omitted] • "Green" graphene electrodes by CO 2 laser irradiation of paper ("paper-LIG"). • Uric acid (UA) quantification at clinically relevant concentrations and pH (5.6–7.4). • Limit of detection of 3.97 μM and a sensitivity of 0.363 μA cm−2 μM−1 (pH = 7.4). • Adequate selectivity in synthetic urine, as well as in ascorbic acid and dopamine-containing electrolytes. • Recoveries of 100.6% and 95.4% for human urine samples spiked with 50 and 100 μM UA. [ABSTRACT FROM AUTHOR]

A promising concept of consumable anode materials for high-temperature pyroelectrolysis process, which is expected to overcome the environmental and economical impacts of classical extractive metallurgy, relies on substituted magnetite-based ferrospinels, presenting high electrical conductivity, appropriate refractoriness, and redox stability. The present work aims assessment of the processing effects on structural, redox, and electrical properties of Fe2.3Al0.2Mg0.5O4 spinel, prepared by conventional solid-state route ( SSR) and laser floating zone ( LFZ) method. The observed trends for high-temperature electrical conductivity behavior indicated that the electronic transport is only slightly affected by the preparation method, suggesting the minor effects from the grain boundaries. For scaled-up ferrospinel-based consumable anodes the impact of oxidation during thermal cycling on electrical properties and electrode integrity can be minimized even in air, by using relatively fast cooling/heating rates. [ABSTRACT FROM AUTHOR]

Laser‐induced graphene (LIG) produced by irradiation of paper (paper‐LIG)holds substantial promise for flexible devices. This article presents paper‐LIG humidity and temperature sensors fabricated by single‐step irradiation of common filter paper with a pulsed UV laser (355 nm). The influence of the process parameters on the conversion of cellulose fibers into LIG is discussed based on the resulting morphology, structure, conductivity, and chemical composition, revealing a distinct barrier to transformation and a propagation behavior not seen under CO2 laser irradiation. The obtained material is constituted by a porous, electrically conductive network of fibers. The paper‐LIG relative humidity (RH) and temperature sensors with sensitivities of up to 1.3 × 10−3%RH−1 and ‐ 2.8 × 10−3 °C−1, respectively, are examined in terms of their linearity, reproducibility, and response time. A detailed discussion on the response mechanism is presented in the context of literature, pointing towards the absorption of water molecules in the interlayer spacing of graphene as the main reason for the increase in resistance with RH. Additionally, a contribution from variable range hopping along the ab plane of graphene at high RH is suggested. These results demonstrate the potential of paper‐LIG for low‐cost, sustainable, and environmentally friendly sensing. [ABSTRACT FROM AUTHOR]

Among the many potential applications of graphene and graphene-based materials, their use as protective films or as additives in coatings for corrosion protection has seen an increased level of interest in the last decade. Much of this interest is motivated by the need to implement additional functionalities, to enhance anti-corrosion performance and to ultimately extend the service life of metallic structures. Pristine graphene films, with their impermeable nature allied to flexibility and mechanical strength, appear as particularly attractive candidates for barrier films against corrosive agents, while graphene-based materials such as graphene oxide and reduced graphene oxide offer a wide range of opportunities for their dispersion in polymeric matrices for composite anti-corrosive coatings. Simultaneously, considerable progress in the development of scalable graphene and graphene-based materials production techniques has been made during the last several years. Currently, a broad range of graphene materials with different morphologies and properties is available, making the need for an adequate fit between the production method and the desired application even more evident. This review article aims to give the reader a general overview of the recent trends in both the production of graphene and graphene-based materials, and their implementation in different anti-corrosion solutions. Moreover, the present work provides a critical look on this subject, highlighting the areas in need of further exploration. [ABSTRACT FROM AUTHOR]

Optical fiber technology has rapidly progressed over the years, providing valuable benefits for biosensing purposes such as sensor miniaturization and the possibility for remote and real-time monitoring. In particular, tilted fiber Bragg gratings (TFBGs) are extremely sensitive to refractive index variations taking place on their surface. The present work comprises a case-study on the impact of different methods of analysis applied to decode spectral variations of bare and plasmonic TFBGs during the detection of N-terminal B-type natriuretic peptide (NT-proBNP), a heart failure biomarker, namely by following the most sensitive mode, peaks of the spectral envelopes, and the envelopes' crossing point and area. Tracking the lower envelope resulted in the lowest limits of detection (LOD) for bare and plasmonic TFBGs, namely, 0.75 ng/mL and 0.19 ng/mL, respectively. This work demonstrates the importance of the analysis method on the outcome results, which is crucial to attain the most reliable and sensitive method with lower LOD sensors. Furthermore, it makes the scientific community aware to take careful attention when comparing the performance of different biosensors in which different analysis methods were used. [ABSTRACT FROM AUTHOR]

Laser‐induced graphene (LIG) is inexpensive, fast, and easy to produce when compared to many other forms of graphene. Within the biosensing field, LIG electrodes are most often produced via infrared (IR) laser irradiation of polyimide sheets. Nevertheless, the usage of ultraviolet (UV) laser to produce LIG provides advantages in terms of sensor miniaturization because of its inherently higher scribing resolution. Yet, studies on the electrochemical performance of UV LIG, its relation with morphological and structural aspects as well as its comparison with IR LIG are still lacking. This work shows that both LIGs present swift electron transfer kinetics constituting excellent electrodes for electroanalysis. Extreme sensitivities of 93 and 58 µA µm−1 cm−2 at physiologically relevant dopamine (DA) concentrations are found for IR and UV LIG, respectively. Such sensitivities and good selectivity are achieved in the presence of physiologically relevant concentrations of ascorbic and uric acids, contrasting to the related literature employing IR LIG where such interferents are below the physiological range. Despite providing lower sensitivity, UV LIG is still an excellent material for DA biosensors, with the above‐mentioned advantages in terms of miniaturization. To our knowledge, these are among the highest sensitivities reported for voltammetric measurement of DA using carbon‐based materials. [ABSTRACT FROM AUTHOR]

Monitorization of gait‐related parameters is of the utmost importance to prevent complications in several diseases, ensuring affordable healthcare for the growing amount of chronic, lifestyle‐related diseases and also for improving motion performance. Sensorized insoles allow to both pressure data and gait timings to be extracted non‐intrusively in a point of care paradigm. Laser‐induced graphene (LIG) offers a path to the integration of sensors in different kinds of materials, including cork, a common insole material. In this work, piezoresistive sensors are developed by providing conductivity to natural cork and agglomerate cork through the direct synthesis of LIG by UV irradiation. Highly isotropic conductive LIG regions with less than 100 Ω sq−1 are patterned and their piezoresistive response for up to 1132 kPa is assessed with sensitivities up to 0.02 kPa−1. A low‐cost prototype insole is devised and tested, proving the potential of this kind of functional cork as a green alternative for gait analysis platforms. [ABSTRACT FROM AUTHOR]

In chemical vapor deposition of graphene, low nucleation density and large domain sizes are desirable. In the particular case of growth on copper, throughout recent years, several works have reported the oxidation of the substrate through various means, which leads to a reduced nucleation density. In this work, an in situ oxidation and reduction treatment is explored, establishing its connection with the removal of carbon impurities from the copper bulk, as well as clarifying the role of these impurities as graphene nucleation sites. The extent of the contribution of these impurities to the growth of graphene is inferred by experiments using carbon-13 methane feed. The effect of the oxidation and reduction treatment on the substrate's surface roughness is also addressed. Lastly, the synthesis recipe based on this treatment is supplemented with a growth stage splitting, an increased argon flowrate and a short etching stage, resulting in millimeter sized hexagonal graphene domains (diameters 2–3 mm) with improved electrical transport properties. Thus, the deposition process presented here stands out on account of its streamlined nature, which makes it an attractive candidate for industrial scale-up. Image 1 [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) is a widely versatile semiconductor with major importance from the technological point of view, presenting the advantage of being grown by a large number of techniques and having one of the richest varieties of morphologies. Due to the special interest in this semiconductor, several approaches have been employed to control the production of its nanostructures. Herein, we report the development of a vapour-based method, designated as laser-assisted flow deposition (LAFD), capable of producing ZnO micro and nanocrystals with different morphologies and with a high crystalline and optical quality. This new process allows a high yield of ZnO production, showing great prospects for scalable applications. In the present work, we review in detail the main growth parameters and their relationship with the produced morphologies, in addition to their influence on the structural and optical properties. Furthermore, an assessment of the possible growth mechanisms that may be involved in this new method is reported. Some potential applications of the ZnO structures produced by LAFD were also evaluated, with focus on the photocatalysis and photovoltaic fields. Additionally, the possibility of synthesizing ZnO composite nanostructures as well as the growth of other metal oxides using this technique was explored. [ABSTRACT FROM AUTHOR]

Abstract Graphene has emerged as a novel material with enhanced electrical and structural properties that can be used for a multitude of applications from super-capacitors to biosensors. In this context, an ultra-sensitive biosensor was developed using a low-cost, simple and mask-free method based on laser-induced graphene technique for electrodes patterning. The graphene was produced on a polyimide substrate, showing a porous multi-layer structure with a resistivity of 102.4 ± 7.3 Ω/square. The biosensor was designed as a 3-electrode system. Auxiliary and working electrodes were made of graphene by laser patterning and the reference electrode was handmade by casting a silver ink. A molecularly-imprinted polymer (MIP) was produced at the working electrode by direct electropolymerization of eriochrome black T (EBT). As proof-of-concept, the MIP film was tailored for chloramphenicol (CAP), a common contaminant in aquaculture. The resulting device was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy readings against a redox standard probe. The limit of detection (LOD) was 0.62 nM and the linear response ranged from 1 nM to 10 mM. These analytical features were better than those produced by assembling the same biorecognition element on commercial graphene- and carbon-based screen-printed electrodes. Overall, the simplicity and quickness of the laser-induced graphene technique, along with the better analytical features obtained with the graphene-based electrodes, shows the potential to become a commercial approach for on-site sensing. Highlights • Ultra-sensitive graphene-based biosensor developed by a low cost and mask-free method using laser-induced graphene technique. • Detection of chloramphenicol with a LOD of 0.62 nM. • Combination of molecularly-imprinting technology with laser-induced graphene. • Promising approach for future quantitative biosensing. [ABSTRACT FROM AUTHOR]

The interplay of unique cation arrangement and redox coupling in ferrospinels offers a wide range of magnetic and catalytic properties, evaluated mostly for low and intermediate temperature applications. This work focuses on high-temperature properties of magnesium-substituted magnetite, for prospective high temperature applications such as electrodes for pyroelectrolysis, energy conversion, catalysis, etc. The effects of silica and zirconia additions to (Fe,Mg) 3 O 4 are studied, with emphasis on structural, electronic transport and redox properties. Up to at least 2% Zr 4+ can be dissolved in the spinel lattice by sintering in inert atmosphere at 1773 K, resulting in a moderate conductivity decrease and lower tolerance against oxidative decomposition. Silica additions are accommodated by magnesium exsolution and formation of (Fe,Mg) 2 SiO 4 and (Mg,Fe)O phase impurities rather than by the substitution in spinel lattice, as confirmed by combined structural, microstructural and electrical conductivity studies. Minor amounts of silica in ferrospinels do not result in the conductivity decrease and apparently provide more stable thermo-chemical expansion behaviour, being favourable for prospective high-temperature applications, including anode materials in silicate-based melts. [ABSTRACT FROM AUTHOR]

Driven by environmental challenges and global movement to carbon-lean technologies, the pyroelectrolysis process for iron extraction from oxide melts is being proposed as an interesting alternative to the traditional steelmaking. Still, one of the critical issues impacting the prospects of this technology includes the development of appropriate anode materials, taking into account the extremely aggressive nature of oxide melts at very high temperatures. Here we propose a unique concept of consumable anode for pyroelectrolysis process, based on multicomponent ferrospinel-based ceramics. The electrochemical studies and post-mortem XRD/SEM/EDS analysis of the electrolysis cells have demonstrated that ceramic spinel anodes can sustain significant current densities for making the process feasible, while their consumption by interaction with Si-containing species from the molten electrolyte was found to be moderate. [ABSTRACT FROM AUTHOR]

An innovation is reported in the synthesis of a hybrid carbon structure resulting from the simultaneous growth of graphene and nanocrystalline diamond (NCD) by the microwave plasma chemical vapor deposition technique. This strategy allows to take advantage of the complementary electronic behavior of each carbon allotrope, a key feature in new nanostructured materials for electronics under the graphene/insulator all-carbon approach. The graphene-diamond hybrid structures were grown on copper and transferred to a glass substrate to be further characterized. Raman analysis puts in evidence the signature of both phases and the high crystallinity of the graphene layer, based on band intensity and width measurements. Raman mapping and SEM observations show a uniform distribution of the NCD clusters, confirmed by AFM/EFM measurements. Additionally, HRTEM analysis permitted to detail the diamond nanocrystalline structure, revealing a close link to the graphene layer on the basis of which a diamond on graphene nucleation mechanism is proposed. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and characterization of directionally solidified Y-doped zirconia–barium zirconate eutectic materials by the laser floating zone technique (LFZ) is presented in the search for novel mixed ionic conductors by protons and oxide ions. Emphasis is placed on the control of the LFZ conditions that promote the solubilization of Y in both eutectic phases, and how the dopant influences the ionic conductivity. Fast growth under constitutional supercooling conditions leads to the development of ZrO2–dendrites above the solidification interface, which are dipped into a finer-interpenetrated network of ZrO2 and BaZrO3. Yttrium-doping of the ZrO2 fluorite-type lattice is favored by the high thermodynamic stability of BaZrO3. However, even low Y-substitution levels in BaZrO3 lead to dominating protonic conduction in the composite under humidified atmospheres below 500°C. At higher temperatures, the proton incorporation is unfavorable, and the total conductivity of the composite is determined by the hole conduction in the Ba(Zr,Y)O3, and/or oxide–ion conductivity through the (Zr,Y)O2. [Copyright &y& Elsevier]

Laser-induced graphene (LIG) is a foam-like porous material consisting of few-layer graphene obtained by laser irradiation of a wide range of carbon-containing substrates. Among these, the ability to synthesize LIG from paper and other cellulose-related materials is particularly exciting, as it opens the door to a wide assortment of potential applications in the form of low-cost, flexible, and biodegradable devices. Here, the synthesis of this material, dubbed paper-LIG , on different types of filter papers and xylan biopolymer is discussed. In particular, we report the formation of paper-LIG by single-step irradiation, providing an improvement over the conventional multiple lasing approach and giving an explanation of the conditions that allow this simplified synthesis. All the relevant process parameters are covered, assessing their effect on the resulting electrical properties, structure, and morphology. Additionally, we demonstrate the application of LIG obtained from xylan, an abundant and often underutilized biopolymer, for temperature sensing. These results provide a better understanding of the conditions required for the synthesis of highly conductive LIG from paper and related materials, paving the way for its application, with reduced cost and low environmental impact, in fields ranging from biomonitoring to consumer electronics. [Display omitted] • Synthesis of laser-induced graphene from filter paper by a single irradiation step • Synthesis of laser-induced graphene by irradiation of filter paper containing activated charcoal • Laser-induced graphene from a xylan substrate, valorizing this underutilized natural product • Temperature sensor employing laser-induced graphene obtained from modified xylan [ABSTRACT FROM AUTHOR]

The properties of directionally solidified eutectic (DSE) zirconia–mullite composites are presented. These materials combine two oxide ion conductors in eutectic microstructures stable over broad temperature (570–1415°C) and pO2 (10−20 to 105 Pa) ranges, which are pertinent for their application as high temperature (>1200°C) solid electrolytes, e.g. in Nernstian sensors. X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy results reveal a composite structure comprising eutectic crystals of mullite and zirconia, and an intergranular amorphous phase rich in Al–Y–Si–O. The amorphous phase is crystallised upon annealing at 1400°C, and the resulting composites have a composition close to the nominal eutectic consisting of 79vol.% mullite and 21vol.% zirconia. The electrical conductivity of these materials is rationalized in terms of percolation, fraction and properties of each phase, attaining values in excess of 0.01S/cm at 1370°C and displaying Arrhenius behaviour with activation energy of 70kJ/mol. The broad electrolytic domain of these solid electrolytes is demonstrated by conductivity measurements carried out from 600°C to 1370°C in O2, air, Ar and 10%H2 +90%N2 atmospheres. [ABSTRACT FROM AUTHOR]

Niobium oxides have been reported as an alternative to tantalum, and its oxide, for the production of capacitors, but these materials still require a further and exhaustive study. Understanding the dynamics of the oxidation process from NbO to Nb2O5 is essential to explain and control the properties of a niobium oxide based capacitors. In situ XRD analysis of NbO powders was performed from 100 to 1100°C, which showed a temperature range where only amorphous phase is present. The capacitor anodes, formed from the same type of NbO powders, were then heat-treated in air from room-temperature (RT) to 550°C and recorded with a video camera to see the colour shift. The presence of core–shell structures and the increase of the shell thickness/amount with temperature are visible in SEM. Finally, in situ spectroscopy studies were performed, in order to observe the interference spectra which are responsible for the observed colours. [ABSTRACT FROM AUTHOR]

Carbon-based electrodes have demonstrated great promise as electrochemical transducers in the development of biosensors. More recently, laser-induced graphene (LIG), a graphene derivative, appears as a great candidate due to its superior electron transfer characteristics, high surface area and simplicity in its synthesis. The continuous interest in the development of cost-effective, more stable and reliable biosensors for glucose detection make them the most studied and explored within the academic and industry community. In this work, the electrochemistry of glucose oxidase (GOx) adsorbed on LIG electrodes is studied in detail. In addition to the well-known electroactivity of free flavin adenine dinucleotide (FAD), the cofactor of GOx, at the expected half-wave potential of −0.490 V vs. Ag/AgCl (1 M KCl), a new well-defined redox pair at 0.155 V is observed and shown to be related to LIG/GOx interaction. A systematic study was undertaken in order to understand the origin of this activity, including scan rate and pH dependence, along with glucose detection tests. Two protons and two electrons are involved in this reaction, which is shown to be sensitive to the concentration of glucose, restraining its origin to the electron transfer from FAD in the active site of GOx to the electrode via direct or mediated by quinone derivatives acting as mediators. [ABSTRACT FROM AUTHOR]

Laser‐induced graphene (LIG) can be obtained by irradiation of a polymer by a laser source. The present work demonstrates that it is possible to obtain this kind of material using an ultraviolet laser instead of the typical infrared source. Using this approach, a fourfold decrease in the penetration depth (5 µm) is achieved, while the spatial resolution is doubled. Electromechanical strain LIG sensors are patterned in polyimide substrates with different thicknesses and their performance to strain, bending, and force inputs is measured. A low‐cost arterial pulse wave monitor is built, exploring the high force sensitivity of the sensors produced on the thinner substrates. Laser‐induced graphene is obtained by irradiation of polyimide by an ultraviolet laser instead of the typical infrared source, with a fourfold decrease in the penetration depth and doubled spatial resolution. Electromechanical strain sensors are patterned in substrates with different thicknesses and their performance is measured. A low‐cost arterial pulse wave monitor is built, exploring the higher sensitivity of thinner substrates. [ABSTRACT FROM AUTHOR]

With a bandgap energy of ≈3.3 eV at room temperature, zinc oxide (ZnO) exhibits physical properties that make it a potential candidate for several technological applications. Sustainable development requires, among other actions, removal of organic pollutants by employing non‐toxic structures, which can be achieved considering the photocatalytic properties of ZnO. In this work, high optical and structural quality ZnO crystals with distinct morphologies (nanotetrapods and microrods) are produced by laser‐processing. By adding silver to the growth precursors it is possible to produce ZnO/Ag composites in a single and short step, boosting a synergetic conjugation of the properties of both materials. The ZnO structures produced with and without silver are fully characterized by electronic microscopy and optical spectroscopy. Moreover, their photocatalytic activity is analyzed using methylene blue as a model‐test contaminant, revealing that the nanotetrapods exhibit a better performance than the microrods. This effect is further enhanced by the presence of silver on the ZnO surface, hindering the photoinduced carriers' recombination, as corroborated by the photoluminescence results. ZnO micro and nanocrystals with different morphologies (nanotetrapods and microrods) are produced by laser‐assisted flow deposition method and their photocatalytic activity is tested, reveling a better performance for the nanotetrapods. By adding silver to the precursor rods, ZnO/Ag composites are formed in a single and short step. Nanotetrapods grown in the presence of silver evidence the best performance in the degradation of the dye when compared to the remained crystals. [ABSTRACT FROM AUTHOR]

ZnO microrods were grown by laser assisted flow deposition technique in order to study their luminescence behaviour in the near band edge spectral region. Transmission electron microscopy analysis put in evidence the high crystallinity degree and microrod's compositional homogeneity. Photoluminescence revealed a dominant 3.31 eV emission. The correlation between this emission and the presence of surface states was investigated by performing plasma treatments with hydrogen and nitrogen. The significant modifications in photoluminescence spectra after the plasma treatments suggest a connexion between the 3.31 eV luminescence and the surface related electronic levels. [ABSTRACT FROM AUTHOR]