Single-step synthesis of silicon carbide anchored graphitic carbon nitride nanocomposite photo-catalyst for efficient photoelectrochemical water splitting under visible-light irradiation

Photoelectrochemical Water Splitting: A Visible-Light-Driven CoTiO3@g-C3N4-Based Photoanode Interface Follows the Type II Heterojunction Scheme

Harnessing solar energy can be efficiently used to generate hydrogen by photochemical water splitting, which is a sustainable and environmentally benign energy source. Here, a unique visible-light-driven CoTiO3@g-C3N4 (CTOCN)-based photoanode interface has been optimized and developed with modification to follow the type II heterojunction for the enhancement of photoelectrochemical water splitting. Initially, a graphitic carbon nitride-loaded CoTiO3 (with 10 wt % g-C3N4) composite was obtained using a one-pot solvothermal method. Accordingly, the type II heterojunction interface between g-C3N4 and CoTiO3 has been successfully created and confirmed by the acquired phase, morphological, and optical examinations. Thereby, heterostructure generations with interfacial interaction were enabled to decrease photogenerated electron-hole pair recombination, leading to enhanced charge transfer for water oxidation kinetics. The minimal charge transfer resistance and hole relaxation lifetime (p) shown in Nyquist and Bode plots have further confirmed the rapid electron transport across the electrode/electrolyte interfaces, which is attributed to an enhanced absorption of holes for the water splitting process. Additionally, UV-vis spectroscopy, Mott-Schottky analysis, and UPS studies were used to determine the band edge locations of g-C3N4 and CoTiO3. In comparison to previously developed nanohybrids and their equivalents, the CTOCN-d photoanode follows the type II charge transfer mechanism, resulting in a higher photocurrent density of 55.51 mA cm-2.

Photocatalytic deactivation of sulphate reducing bacteria using visible light active CuO/TiO2 nanocomposite photocatalysts synthesized by ultrasonic processing

Sulphate-reducing bacteria wreaks havoc to oil pipelines, as it is an active agent for scale formation in the oil production tubing, and plugging of reservoir rock around the oil wells, and this leads to the degradation of oil quality. In this work, we synthesized copper oxide/titanium dioxide nanocomposite photocatalysts with three different mass contents of copper oxide (10%, 20% and 30%) and used them as an effective photo-catalyst in the process of photo-catalytic deactivation of sulphate-reducing bacteria. The anchoring of copper oxide on titanium dioxide brought about the following positive attributes in copper oxide/titanium dioxide nanocomposite pertained to the photo-catalyst: (i) the material transformed to visible light active with the potential to harness the more efficient visible spectral region of the solar radiation, (ii) increased surface area on the photo-catalyst enhanced the number of active reaction sites in the material, and (iii) efficiently retarded the undesired photo-generated electron hole recombination to promote the photo-catalytic activity. Although, the photo-catalyst effective under both UV and visible light, the deactivation was found to be higher in visible radiation, particularly the nanocomposite with 20%- copper oxide on titanium dioxide showed the highest photocatalytic degradation with of Sulphate-reducing bacteria with a decay constant as high as 1.38 min ^-1 and the total depletion time as low as 8 min. It was confirmed that the bacterial deactivation was neither due to the bactericidal effect of the nanocomposite nor due to the light mediated deactivation.

A Review on Pulsed Laser Preparation of Nanocomposites in Liquids and Their Applications in Photocatalysis

The purpose of photocatalysis is to realize the conversion between solar energy and chemical energy, and it is essential to develop a high-performance photocatalyst under visible-light irradiation. The conventional methods for photocatalyst preparation are mainly wet chemical routes, and abundant yields can be obtained. However, the products are not neat and accompanied by chemical groups and impurities, which are not beneficial for the enhancement of photocatalytic performance. In recent years, as a powerful tool for nanomaterial fabrication, pulsed laser heating in a liquid medium has been utilized to prepare a variety of nanocomposites. Products with synergistic effects and high crystallinity can be rapidly prepared under pulsed laser selective heating, which is beneficial for obtaining more effective photocatalytic performance. In this review, the typical characteristics of pulsed laser heating in liquids and their prepared nanocomposites for photocatalytic applications are summarized. This review not only highlights the innovative works of pulsed-laser-prepared nanocomposites in liquids for photocatalysis but also briefly introduces the specific challenges and prospects of this field.

Nanocomposite and bio-nanocomposite polymeric materials/membranes development in energy and medical sector: A review

Nanocomposite and bio-nanocomposite polymer materials/membranes have fascinated prominent attention in the energy as well as the medical sector. Their composites make them appropriate choices for various applications in the medical, energy and industrial sectors. Composite materials are subject of interest in the polymer industry. Different kinds of fillers, such as cellulose-based fillers, carbon black, clay nanomaterials, glass fibers, ceramic nanomaterial, carbon quantum dots, talc and many others have been incorporated into polymers to improve the quality of the final product. These results are dependent on a variety of factors; however, nanoparticle dispersion and distribution are major obstacles to fully using nanocomposites/bio-nanocomposites materials/membranes in various applications. This review examines the various nanocomposite and bio-nanocomposite materials applications in the energy and medical sector. The review also covers the variety of ways for increasing nanocomposite and bio-nanocomposite materials features, each with its own set of applications. Recent researches on composite materials have shown that polymeric nanocomposites and bio-nanocomposites are promising materials that have been intensively explored for many applications that include electronics, environmental remediation, energy, sensing (biosensor) and energy storage devices among other applications. In this review, we studied various nanocomposite and bio-nanocomposite materials, their controlling parameters to develop the product and examine their features and applications in the fields of energy and the medical sector.

Porous Silicon Carbide (SiC): A Chance for Improving Catalysts or Just Another Active-Phase Carrier?

There is an obvious gap between efforts dedicated to the control of chemicophysical and morphological properties of catalyst active phases and the attention paid to the search of new materials to be employed as functional carriers in the upgrading of heterogeneous catalysts. Economic constraints and common habits in preparing heterogeneous catalysts have narrowed the selection of active-phase carriers to a handful of materials: oxide-based ceramics (e.g. Al₂O₃, SiO₂, TiO₂, and aluminosilicates-zeolites) and carbon. However, these carriers occasionally face chemicophysical constraints that limit their application in catalysis. For instance, oxides are easily corroded by acids or bases, and carbon is not resistant to oxidation. Therefore, these carriers cannot be recycled. Moreover, the poor thermal conductivity of metal oxide carriers often translates into permanent alterations of the catalyst active sites (i.e. metal active-phase sintering) that compromise the catalyst performance and its lifetime on run. Therefore, the development of new carriers for the design and synthesis of advanced functional catalytic materials and processes is an urgent priority for the heterogeneous catalysis of the future. Silicon carbide (SiC) is a non-oxide semiconductor with unique chemicophysical properties that make it highly attractive in several branches of catalysis. Accordingly, the past decade has witnessed a large increase of reports dedicated to the design of SiC-based catalysts, also in light of a steadily growing portfolio of porous SiC materials covering a wide range of well-controlled pore structure and surface properties. This review article provides a comprehensive overview on the synthesis and use of macro/mesoporous SiC materials in catalysis, stressing their unique features for the design of efficient, cost-effective, and easy to scale-up heterogeneous catalysts, outlining their success where other and more classical oxide-based supports failed. All applications of SiC in catalysis will be reviewed from the perspective of a given chemical reaction, highlighting all improvements rising from the use of SiC in terms of activity, selectivity, and process sustainability. We feel that the experienced viewpoint of SiC-based catalyst producers and end users (these authors) and their critical presentation of a comprehensive overview on the applications of SiC in catalysis will help the readership to create its own opinion on the central role of SiC for the future of heterogeneous catalysis.

Pulsed Laser in Liquids Made Nanomaterials for Catalysis

Catalysis is essential to modern life and has a huge economic impact. The development of new catalysts critically depends on synthetic methods that enable the preparation of tailored nanomaterials. Pulsed laser in liquids synthesis can produce uniform, multicomponent, nonequilibrium nanomaterials with independently and precisely controlled properties, such as size, composition, morphology, defect density, and atomistic structure within the nanoparticle and at its surface. We cover the fundamentals, unique advantages, challenges, and experimental solutions of this powerful technique and review the state-of-the-art of laser-made electrocatalysts for water oxidation, oxygen reduction, hydrogen evolution, nitrogen reduction, carbon dioxide reduction, and organic oxidations, followed by laser-made nanomaterials for light-driven catalytic processes and heterogeneous catalysis of thermochemical processes. We also highlight laser-synthesized nanomaterials for which proposed catalytic applications exist. This review provides a practical guide to how the catalysis community can capitalize on pulsed laser in liquids synthesis to advance catalyst development, by leveraging the synergies of two fields of intensive research.

Novel TiO2 Nanoparticles/Polysulfone Composite Hollow Microspheres for Photocatalytic Degradation

Nanosized titanium oxide (TiO₂) material is a promising photocatalyst for the degradation of organic pollutants, whereas the difficulty of its recycling hinders its practical application. Herein, we reported the preparation of a novel titanium oxide/polysulfone (TiNPs/PSF) composite hollow microspheres by the combination of Pickering emulsification and the solvent evaporation technique and their application for the photodegradation of methyl blue (MB). P25 TiO₂ nanoparticles dispersed on the surface of PSF microspheres. The porosity, density and photoactivity of the TiNPs/PSF composite microsphere are influenced by the TiO₂ loading amount. The composite microsphere showed good methyl blue (MB) removal ability. Compared with TiO₂ P25, and PSF, a much higher MB adsorption speed was observed for TiNPs/PSF microspheres benefited from their porous structure and the electrostatic attractions between the MB+ and the negatively charged PSF materials, and showed good degradation efficiency. For TiNPs/PSF composite microsphere with density close to 1, a 100% MB removal (10 mg L^-1) within 120 min at a catalyst loading of 2.5 g L^-1 can be obtained under both stirring and static condition, due to well dispersing of TiO₂ particles on the microsphere surface and its stable suspending in water. For the non-suspended TiNPs/PSF composite microsphere with density bigger than 1, the 100% MB removal can be only obtained under stirring condition. The removal efficiency of MB for the composite microspheres retained 96.5%, even after 20 cycles. Moreover, this composite microsphere also showed high MB removal ability at acidic condition. The high catalysis efficiency, excellent reusability and good stability make this kind of TiNPs/PSF composite microsphere a promising photocatalyst for the water organic pollution treatment.