Facile synthesis of ZIF-8@GO composites for enhanced adsorption of cationic and anionic dyes from their aqueous solutions

In this study, zeolitic imidazolate frameworks (ZIFs) and ZIF-8-graphene oxide (ZIF-8@xGO) composites were prepared at room temperature to be used as adsorbents for cationic (methylene blue (MB)) and anionic dyes (methyl orange (MO)) from their aqueous solutions. The structural characteristics confirmed the successful preparation of amorphous ZIF-8 and its ZIF-8@GO composites at room temperature. The BET surface area of the ZIF-8@0.5GO composite was estimated to be 286.22 m2 g-1, with a mean pore diameter of 3.34 nm. The adsorption study confirmed that dye removal efficiency of ZIF-8 was significantly enhanced when blended with GO. The maximum removal efficiency of the ZIF-8@0.5GO composite was achieved within 60 min, and the removal percentages of MB and MO dyes were 95.2% and 94.6%, respectively. These values were close to those achieved by GO at 60 min (96.2% for MB and 96.3% for MO). The kinetic study confirmed that the adsorption data of MB onto GO, ZIF-8, and the ZIF-8@xGO composites fitted the non-linear pseudo-first-order kinetic model, while the adsorption of MO dye obeyed the non-linear pseudo-second-order kinetic model. Moreover, the adsorption isotherm study confirmed that the adsorption of both MB and MO dyes onto the ZIF-8 and its ZIF-8@xGO composites were fitted to the Langmuir model, which indicates a chemical adsorption process. The estimated maximum adsorption capacity of the ZIF-8@0.5GO composite towards MB and MO were 87.39 and 82.78 mg g-1, which are much higher than that achieved by pure ZIF-8 and very close to that obtained by pure GO. This indicates that our prepared ZIF-8@GO composites are comparable to pure GO. The thermodynamic study confirmed that adsorption of both the dyes onto the prepared materials is endothermic, spontaneous, and thermodynamically favorable.

Facile construction of a polypyrrole-cobalt sulfide counter electrode for low-cost dye-sensitized solar cells

A polypyrrole-cobalt sulfide composite counter electrode (CE) was prepared in this work. Firstly, polypyrrole (PPy) nanorods were prepared by an in situ polymerization method on FTO, then cobalt sulfide (CoS) nanoparticles were coated on PPy nanorods by the electrodeposition method. The DSSC with PPy-CoS CE exhibits superior photoelectric conversion efficiency than that based on platinum (Pt, one of common counter electrodes), which is 7.52%, improving more than 20% compared to Pt CE (6.19%). In addition, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements demonstrated that the PPy-CoS CE exhibited excellent catalytic performance for I3 -/I- solution.

The Recent Progress on Silver Nanoparticles: Synthesis and Electronic Applications

Nanoscience enables researchers to develop new and cost-effective nanomaterials for energy, healthcare, and medical applications. Silver nanoparticles (Ag NPs) are currently increasingly synthesized for their superior physicochemical and electronic properties. Good knowledge of these characteristics allows the development of applications in all sensitive and essential fields in the service of humans and the environment. This review aims to summarize the Ag NPs synthesis methods, properties, applications, and future challenges. Generally, Ag NPs can be synthesized using physical, chemical, and biological routes. Due to the great and increasing demand for metal and metal oxide nanoparticles, researchers have invented a new, environmentally friendly, inexpensive synthetic method that replaces other methods with many defects. Studies of Ag NPs have increased after clear and substantial support from governments to develop nanotechnology. Ag NPs are the most widely due to their various potent properties. Thus, this comprehensive review discusses the different synthesis procedures and electronic applications of Ag NPs.

Electroactive and Sustainable Cu-MOF/PEDOT Composite Electrocatalysts for Multiple Redox Mediators and for High-Performance Dye-Sensitized Solar Cells

An electrically conductive Cu-MOF, {[Cu₂(6-mercaptonicotinic acid)(6-mercaptonicotinate)]·NH₄}_n, was successfully electrodeposited on the conductive substrates via using poly(3,4-ethylenedioxythiophene) (PEDOT) as the binder. Multiple functionalities of the Cu-MOF microparticle within the Cu-MOF/PEDOT composite electrode were systematically vindicated as (1) releasing the cohesive strength among the PEDOT matrix, thus enhancing the film adhesion to substrate, (2) providing excellent intrinsic heterogeneous rate constant via lowering the reaction active energy, (3) supplying numerous active sites at the center or edges on its (-Cu-S-)_n honeycomb-like planes, (4) facilitating the electron transfer through its two-dimensional (-Cu-S-)_n plains, and (5) benefiting the penetration of the redox mediators through its porous frameworks. In multiple redox mediators (i.e., I^-/I₃^-, cobalt(II/III)-complex, and copper(I/II)-complex), the composite Cu-MOF/PEDOT electrode exhibited superior electrocatalyst activity and kept almost 100% of its initial redox peak currents after continuous cyclic voltammetric scanning for 300 cycles. As a high-performance electrocatalyst for the counter electrode in dye-sensitized solar cells (DSSCs), the composite Cu-MOF/PEDOT electrode rendered its cell a decent solar-to-electricity conversion efficiency of up to 9.45% at 1 sun and 22.80% at room light illumination. Compared to the traditional platinum electrode (7.67%), the low-cost Cu-MOF/PEDOT composite electrode has great possibility to be used for various electrochemical devices and the Internet-of-things applications.

Progress of MOF-Derived Functional Materials Toward Industrialization in Solar Cells and Metal-Air Batteries

The cutting-edge photovoltaic cells are an indispensable part of the ongoing progress of earth-friendly plans for daily life energy consumption. However, the continuous electrical demand that extends to the nighttime requires a prior deployment of efficient real-time storage systems. In this regard, metal-air batteries have presented themselves as the most suitable candidates for solar energy storage, combining extra lightweight with higher power outputs and promises of longer life cycles. Scientific research over non-precious functional catalysts has always been the milestone and still contributing significantly to exploring new advanced materials and moderating the cost of both complementary technologies. Metal-organic frameworks (MOFs)-derived functional materials have found their way to the application as storage and conversion materials, owing to their structural variety, porous advantages, as well as the tunability and high reactivity. In this review, we provide a detailed overview of the latest progress of MOF-based materials operating in metal-air batteries and photovoltaic cells.

Available photo-charging integrated device constructed with dye-sensitized solar cells and lithium-ion battery

The development of self-chargeable lithium-ion batteries is of great significance for expanding the usable range of the lithium-ion battery and it has received intensive attention from numerous researchers.