Insights into the Influence of Key Preparation Parameters on the Performance of MoS2/Graphene Oxide Composites as Active Materials in Supercapacitors

Advances in energy storage and energy conversion play an essential role nowadays because the energy demands are becoming greater than ever. To overcome the actual performances of the materials used to build supercapacitors, a combination of transition metal dichalcogenides (TMDCs) and graphene oxide (GO) or reduced graphene oxide (rGO) as graphene-based structures are often studied for their excellent properties, such as high specific area and good electrical conductivity. Nevertheless, synthesis pathways and parameters play key roles in obtaining better materials as components for supercapacitors with higher technical performances. Driven by the desire to understand the influence of the structural and morphological particularities on the performances of supercapacitors based on MoS2/graphene oxide (GO) composites, a survey of the literature was performed by pointing out the alterations induced by different synthesis pathways and key parameters to the above-mentioned particularities.

Prussian Blue: A Safe Pigment with Zeolitic-Like Activity

Prussian blue (PB) and PB analogues (PBA) are coordination network materials that present important similarities with zeolites concretely with their ability of adsorbing cations. Depending on the conditions of preparation, which is cheap and easy, PB can be classified into soluble PB and insoluble PB. The zeolitic-like properties are mainly inherent to insoluble form. This form presents some defects in its cubic lattice resulting in an open structure. The vacancies make PB capable of taking up and trapping ions or molecules into the lattice. Important adsorption characteristics of PB are a high specific area (370 m2 g−1 determined according the BET theory), uniform pore diameter, and large pore width. PB has numerous applications in many scientific and technological fields. PB are assembled into nanoparticles that, due to their biosafety and biocompatibility, can be used for biomedical applications. PB and PBA have been shown to be excellent sorbents of radioactive cesium and radioactive and nonradioactive thallium. Other cations adsorbed by PB are K+, Na+, NH4+, and some divalent cations. PB can also capture gaseous molecules, hydrocarbons, and even luminescent molecules such as 2-aminoanthracene. As the main adsorptive application of PB is the selective removal of cations from the environment, it is important to easily separate the sorbent of the purified solution. To facilitate this, PB is encapsulated into a polymer or coats a support, sometimes magnetic particles. Finally, is remarkable to point out that PB can be recycled and the adsorbed material can be recovered.

Cellulose Nanocrystals: From Classical Hydrolysis to the Use of Deep Eutectic Solvents

During the last two decades, interest in cellulosic nanomaterials has greatly increased. Among these nanocelluloses, cellulose nanocrystals (CNC) exhibit outstanding properties. Indeed, besides their high crystallinity, cellulose nanocrystals are interesting in terms of morphology with high aspect ratio (length 100–1000 nm, width 2–15 nm), high specific area, and high mechanical properties. Moreover, they can be used as rheological modifier, emulsifier, or for barrier properties, and their surface chemistry opens the door to numerous feasible chemical modifications, leading to a large panel of applications in medical, electronic, composites, or packaging, for example. Traditionally, their extraction is performed via monitored sulfuric acid hydrolysis, leading to well-dispersed aqueous CNC suspensions; these last bearing negative charges (half-sulfate ester groups) at their surface. More recently, natural chemicals called deep eutectic solvents (DESs) have been used for the production of CNC in a way of green chemistry, and characterization of recovered CNC is encouraging.

Co/SBA-15 modified with TMB in the degradation of phenol

Mesoporous materials like SBA-15 offer excellent properties such as catalyst support adsorbent due to its textural characteristics and their surface chemistry. The main objective of this study was to support cobalt (20 % w) in the type ordered mesoporous material SBA-15 and expand the pore size with the introduction of a "blowing agent", such as 1,3,5-trimethylbenzene (TMB), to be evaluated in the degradation of phenol. By its physicochemical characterization, it was confirmed that this is an ordered mesoporous material with two-dimensional hexagonal structure (p6mm) with high specific area, narrow pore distribution and typical morphology of this material. The pore size of SBA-15 has been extended to 19 nm by the addition of cosolvent organic molecules (TMB) and the particle size of cobalt decreased from 18.8 nm in SBA-15 to 6.4 nm on average by supporting it in SBA-15 modified with TMB; this property seems to confer the material be more selective in the conversion of CO2, which is the reason why it has greater activity for the degradation of phenol.

Facile synthesis of a ZnO–BiOI p–n nano-heterojunction with excellent visible-light photocatalytic activity

In this paper, an efficient method to produce a ZnO/BiOI nano-heterojunction is developed by a facile solution method followed by calcination. By tuning the ratio of Zn/Bi, the morphology varies from nanoplates, flowers to nanoparticles. The heterojunction formed between ZnO and BiOI decreases the recombination rate of photogenerated carriers and enhances the photocatalytic activity of ZnO/BiOI composites. The obtained ZnO/BiOI heterostructured nanocomposites exhibit a significant improvement in the photodegradation of rhodamine B under visible light (λ ≥ 420 nm) irradiation as compared to single-phase ZnO and BiOI. A sample with a Zn/Bi ratio of 3:1 showed the highest photocatalytic activity (≈99.3% after 100 min irradiation). The photodegradation tests indicated that the ZnO/BiOI heterostructured nanocomposites not only exhibit remarkably enhanced and sustainable photocatalytic activity, but also show good recyclability. The excellent photocatalytic activity could be attributed to the high separation efficiency of the photoinduced electron–hole pairs as well as the high specific area.

Micro-sized carbon fiber: a new supporting material for microorganisms in the decomposition of nitrogen and phosphorus nutrients in wastewater with high salinity

Eutrophication, which kills fish, mussels and other animals in aquatic ecosystem, is the response tothe excess of nitrogen and phosphorus nutrients. In this study, activated carbon fiber prepared frompoly(acrilonitrile) PAN, a carbonaceous material of micro size with high specific area, has been evaluated tobe able to create microbiological membranes that could be used in the decomposition of nitrogen and phosphoruscompounds in wastewater with salinity up to 30 ppt. Utilization of carbon fiber in the sustainabletreatment of highly contaminated aquaculture wastewater with organic and inorganic pollutants was consideredas a promising application in Khanh Hoa province, Vietnam, with great treatment capacity, low system’sprice and implementation’s cost.