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A multifunctional, multiphase-supported photocatalyst was fabricated via the combination of LCD three-dimensional (3D) printing, cold plasma discharge (CPD) technology, and surface chemistry to be used for the degradation of organic pollutants in water and for the generation of hydrogen gas. BiOBr was chosen as the main catalytic phase and was used in association with a phosphor, SrAl2O4:Eu2+,Dy3+ (SAED), and a metal–organic framework, Ni-BDC. Their immobilization was realized thanks to polydopamine (PDA), which is used as a coupling agent. While BiOBr was the most active photocatalytic phase, the phosphor acted as a light-storing component for photodegradation in the dark and overall, as a boost for photoactivity. PDA also boosted the photoactivity, in parallel with its crucial role in the immobilization of the SAED/Ni-MOF/BiOBr catalyst on fractal polymer support. An in situ complexation-assisted precipitation (ISCAP) process was used, allowing the formation of the catalytic phases with nano features. The resulting hybrid photocatalysts were tested through rhodamine B (RhB) dye photodegradation upon visible light irradiation or light/dark alternating conditions to simulate more realistic variable light illumination. We found that, although used in a very small amount, the Ni-MOF had a significant impact on the photoactivity, forming a Z-scheme heterojunction with BiOBr. Finally, H2 evolution testing further established the photocatalytic activity and versatility of the supported catalysts. [ABSTRACT FROM AUTHOR]

In this paper, the sol-gel method was used to synthesize powders of LaMnO3 (LMO), La0.85Ca0.15MnO3 (LCM), and La0.85Sr0.15MnO3 (LSM). The effect of substituting Ca and Sr at the A-site on the perovskite crystal structure and electrochemical capabilities of LMO was investigated. LCM retained its orthogonal structure in comparison to the parent LMO components, whereas LSM transitioned to a rhombic structure. At 0.5 A/g, the specific capacitance of LCM and LSM electrodes is 185.5 F/g and 248 F/g, respectively. The specific capacitance of LCM was three times greater than that of the LMO electrode. Among the three samples (LMO, 22.25 m2 g−1; LSM, 31.56 m2 g−1), the LCM sample exhibited the highest specific surface area of 38.79 m2 g−1. The charge transfer resistances of the LMO, LCM, and LSM are 0.48 Ω, 0.36 Ω, and 0.38 Ω, respectively. The LCM electrode exhibits the greatest capacitance performance due to its more refined morphology, increased concentration of oxygen vacancy, and more complete utilization of the perovskite bulk structure. The above results demonstrate that Ca or Sr substitution of A-site compounds has great potential for supercapacitor applications. [ABSTRACT FROM AUTHOR]

With the advantages of short charging and discharging times, high power density, and long cycle life, supercapacitors are regarded as one of the most promising energy storage devices and have garnered massive attention in the field of energy storage. This paper prepared La1−xCaxMnO3 (x=0, 0.05, 0.1, 0.15, and 0.2) nanoparticles by the sol‐gel method. The microstructure, morphology, and electrochemical performance of the samples were characterized. The results depict that La0.85Ca0.15MnO3 has a low charge transfer resistance (0.19 Ω) and a large specific surface area (38.79 m2 g−1). The maximum specific capacitance of the La0.85Ca0.15MnO3 sample reached 248 F/g at a current density of 0.5 A/g, which is ascribable to its large specific surface area and high oxygen vacancy concentration. The anion‐intercalation mechanism was investigated by the charging and discharging process. The above results depict that Ca‐doping significantly enhances the electrochemical performance of LaMnO3 system. [ABSTRACT FROM AUTHOR]

Self-powered photoelectric devices as a new type of sensor without an external power source have a great potential advantage in the next generation of portable and wearable personal devices. The design of those devices is normally based on three kinds of strategies: a p–n junction, the Schottky junction and ferroelectric polarization. Here, a novel solution based on ion migration induced self-powered photodetectors was explored. In this work, high quality halide perovskite FAPbBr3 crystals were grown by an inverse temperature crystallization (ITC) method. An irreversible ion migration was intentionally created using a symmetrically structured Au/FAPbBr3/Au device. The resulting built-in electric field and energy band bending were proved using electrical measurements in the dark and under light. Finally, the response of the ion migration induced self-powered FAPbBr3 detector was investigated with the values of R (∼0.18 mA W−1) and EQE (∼0.055%) under light with a power density of 1 mW cm−2 and a wavelength of 397 nm. Our investigation demonstrates that ion migration, which is normally deemed a detrimental factor for device stability, can be intentionally used for self-powered photoelectric devices. [ABSTRACT FROM AUTHOR]

Hybrid nanomaterials have been produced using a combination of core–shell synthesis, 3D printing, and plasma grafting. Metal oxides, that is, ZnO and TiO2, as well as iron-based metal organic frameworks (Fe-MOF) nanoparticles were grafted permanently onto the surface of 3D-printed fractal substrates via cold plasma discharge (CPD). The aim is to produce supported photocatalysts for the degradation of organic pollutants in water. Herein, different plasma grafting strategies are developed, namely direct (using core–shell prefunctionalization) and indirect grafting. Noticeably, the latter, using poly-(vinylphosphonic acid) as an intermediate layer for self-assembly grafting, potentially opens the way for the functionalization of any polymeric surface by inorganic nanocompounds. This study mainly aims at giving insight into the plasma immobilization process, but also demonstrating the potential it offers in the domain of supported catalysis. The activity of the different hybrid materials has been assessed by monitoring the photodegradation of Rhodamine B dye (ZnO and TiO2) and the removal of Ciprofloxacin antibiotic (Fe-MOF). Also, the reusability of the hybrid photocatalysts has been demonstrated. Independently, it was found that modifying the surface of the metal oxide nanoparticles with organic coupling agentsaiming at their plasma-grafting immobilization on polymer supportsallowed enhancing their photodegradation efficiency up to 20%. Finally, a resin fractal support has been printed by liquid crystal diode-based SLA (stereolithography) and later surface-functionalized by Fe-MOF nanoparticles. This provides evidence to the possibility of using laser-based 3D printing technologies to produce supports with high surface area for the immobilization of catalysts by plasma grafting. [ABSTRACT FROM AUTHOR]

In this work, a novel heterojunction based on ZnSnO3/ZnO nanofibers was prepared by a simple electrospinning method. The crystal, structural, and surface compositional properties of ZnSnO3 and ZnSnO3/ZnO composite nanofibers were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectrometer (XPS), and Brunauer–Emmett–Teller (BET). Compared to pure ZnSnO3 nanofibers, the ZnSnO3/ZnO heterostructure nanofibers had high sensitivity and selectivity response with the fast response toward ethanol gas at low operational temperature. The sensing response of the sensor based on ZnSnO3/ZnO composite nanofibers was 19.6 toward 50 ppm ethanol gas at 225 °C, which was about 1.5 times superior to that of pure ZnSnO3 nanofibers. It can be owed mainly to the oxygen vacancies and the synergistic effect between ZnSnO3 and ZnO. [ABSTRACT FROM AUTHOR]

The combination of a phosphor with semiconductor photocatalysts can provide photoactivity in the dark. Indeed, the phosphor acts as a "light battery", harvesting photons during irradiation and later re-emitting light that can be used by the catalytic phase when in conditions of total darkness. This allows for continued activity of the composite catalyst, even in conditions of unstable light stimulation. In this study, we assess the use of a heterojunction, namely graphitic-C 3 N 4 /Ag 3 PO 4 , that enables efficient photoactivity specifically under visible light stimulation, in combination with a phosphor that exhibits green-blue phosphorescence (510 nm), that is SrAl 2 O 4 :Eu 2+ ,Dy 3+ . Our findings showed that this combination was particularly interesting, noticeably displaying significant photoactivity in darkness, after short periods of activation by visible light. After finding the right combination and optimal ratios for maximum efficiency, the resulting catalyst composite was immobilized on resin supports with a fractal surface, printed by LCD-SLA 3D printing. The immobilization was effectuated via an aqueous-phase plasma-aided grafting (APPAG) process, using cold plasma discharge (CPD) and using vinylphosphonic acid (VPA) as a coupling agent. Whereas the colloidal photocatalyst displayed a serious problem of partial physical separation between the catalytic phase, g-C 3 N 4 /Ag 3 PO 4 , and the phosphor, the immobilization of the composite catalyst on polymer supports allowed solving this issue. Photodegradation assessments confirmed that the hybrid supported phosphor-enhanced catalyst was active, notably in dark conditions, as well as fairly photostable. This study offers new prospects for the fabrication of polymer-based panels for water purification, with round-the-clock activity and that are, in addition, extremely easy to recover and reuse, by comparison with colloidal catalysts.

Inorganic photocatalysts became an essential and powerful tool for the remediation of polluted water. However, important limitations of photocatalysts in their colloidal form, especially nanosized, remain. For instance, their separation from water after use and recovery, which can be particularly demanding, time- and energy-wise. Considering such aspects, supported catalysts bear significant advantages. However, efforts still have to be made to develop processes that allow the permanent and efficient immobilization of inorganic photocatalysts in sustainable conditions, in order to maintain the advantages of supported catalysts over colloidal ones. Herein, we report the use of an aqueous-phase plasma-aided grafting (APPAG) process to produce functional and efficient hybrid photocatalysts. More specifically, based on cold plasma discharge (CPD), ZnO/Bi 2 MoO 6 heterojunctions were permanently immobilized on polymer supports generated by 3D-printing, with fractal-inspired designs. Three different approaches of the APPAG process have been successfully used for the immobilization of the inorganic phase, that is core-shell-assisted direct grafting, indirect grafting and in situ complexation-assisted precipitation (ISCAP). Noticeably, the latter technique has never been reported before to our knowledge. These three immobilization routes rely on different strategies and yield to distinct morphological specificities, but all allow using mild synthesis conditions and producing stable, active, permanently immobilized coatings of photocatalysts. Regarding the preparation of the organic supports, two sorts of additive manufacturing (AM) technologies were employed, namely fused-deposition modeling (FDM) and liquid crystal diode (LCD)-based SLA (stereolithography). The use of fractal geometries combined with AM permits the production of supports with relatively high surface areas, in a single processing step. Overall, the three plasma-based immobilization methods revealed to be efficient and the performance of the different hybrid photocatalysts have later been assessed through the photodegradation of Rhodamine B dye under simulated sunlight irradiation and visible light only, with promising results.