4-Carboxyphenyl as efficient donor group in nano Zn-Porphyrin for dye sensitized solar cells.

Dye-sensitized solar cells, represent the alternate technology in solar research due to their cost effective, easy fabrication processes, higher efficiencies, and design flexibility. In this research, dual donor group modified zinc porphyrin dyes, have been synthesized for DSSCs. The complexes of zinc porphyrin functioned as acceptor or attaching groups within each mesophenyl ring and carboxylic acid. These complexes exhibited diverse alkyl substituents and sizable electron-donating substituents, contributing to their varied chemical structures and potential applications. The dual Donor-π bridge -Acceptor group sensitizers, Zn[5,15-diphenylcarbazole-10,20-(4-carboxyphenyl) Porphyrin] (KSR-1) and Zn [5,15-thiadiazole-10,20-(4-carboxyphenyl) Porphyrin] (KSR-2) have been synthesized and adopted for DSSCs implementation. The molar absorption coefficients (ε) of KSR-2 and KSR-1 Soret bands were 0.56 x 105 mol/L/cm and 0.47 x 105 mol/L/cm, respectively. The Q bands of the KSR-1 and KSR-2 dyes were 1.10 x 105 mol/L/cm and 1.0 x 105 mol/L/cm, respectively and the molar absorption coefficient of the KSR-1 dye was greater when compared to the KSR-2 dye. The molar absorption coefficient of 0.71 x 105 mol/L/cm was visible in the KSR -1 Q-band. DFT calculations and the electrochemical characteristics of the KSR-1 and KSR-2 dyes have been studied and discussed. The exploration involved in investigating the photophysical properties and photovoltaic performance which were affected by varying the length and number of the donor entities. The wall-plug efficiency of the KSR-1 based solar panel was Voc = 0.68 V, Jsc = 8.94 mA/m2, FF = 56 and Efficiency (µ) = 3.44%. The wall-plug efficiency of the KSR-2 based solar panel was Voc = 0.63 V, Jsc = 5.42 mA/m2, FF = 53 and Efficiency (µ) = 1.83%.

Facile route of heterostructure CeO2-CuO nanocomposite as an efficient electron transport material for perovskite solar cells.

Cerium copper metal nanostructures have received extensive attention as promising electrode materials for energy storage applications due to its attractive structure, and good conductivity. Herein, CeO2-CuO nanocomposite was prepared via chemical method. The crystal structure, dielectric, and magnetic properties of the samples were characterized using by different techniques. The morphological properties of samples were inspected by field emission scanning electron microscopy (FE‒SEM) and high-resolution transmission electron microcopy (HR‒TEM) analysis implied an agglomerated with nanorod structure. The sample surface roughness and morphology were inspected using atomic force microscopy (AFM). Electron paramagnetic resonance (EPR) spectroscopy result reveals the oxygen insufficiency in the material. The variation of oxygen vacancies concentration is consistent with the changes of the saturation magnetization for the sample. Dielectric constant and dielectric losses were studied with respect to the temperature from range from 150 to 350 °C. The electrochemical study of CeO2-CuO nanocomposite shows clear oxidation and reduction peaks with covering wide potential range. In this present paper, first time we have demonstrated that the CeO2-CuO composite as an electron transport material (ETM) with copper (I) thiocyanate (CuSCN) as hole transport material (HTM) for the perovskite solar cells device fabrication. To understand the properties of perovskite like structural, optical, and morphological extensive characterizations such as XRD, UV-visible spectroscopy, and FE-SEM, was performed. For the first time, the CeO2-CuO was used as anode material for preparation low-temperature processing perovskite solar cells, results the power conversion efficiency (PCE) of 10.58% was achieved. The improvement in the device performance for the nanocomposite compared to the pure CeO2, due to unique properties of CeO2-CuO, including high hole mobility, good energy level alignment with CH3NH3PbI3 and longer life time of photo-excited carriers for facilitating the developments of industrial-scale perovskite solar cells.

Decoration of ZnO surface with tiny sulfide-based nanoparticles for improve photocatalytic degradation efficiency.

Modifying wide band gap ZnO nanoparticles surface by combine narrow bandgap semiconductors is a novel route to promote the ZnO to diverse applications. Herein, different metal sulfides (CdS, Ag2S and Bi2S3) were decorated on ZnO surface using facile a chemical route for photocatalytic application. Crystal structure, surface morphology and optical changes for the surface modified ZnO were studied by using various characterization techniques. The XRD spectra exhibited mixed phase of decorated metal sulfide nanoparticles along with strong pattens of hexagonal structure ZnO. The SEM images were confirmed that tiny CdS, Ag2S and Bi2S3 sulfide nanoparticles are well decorated on ZnO hexagonal rods surface. Band gap of the ZnO was tuned into visible region by modifying the surface by the sulfide nanoparticles. Textile industry-based crystal violet (CV) dye was used as a model pollutant to evaluate the photocatalytic activity of sulfides decorated well-crystalline ZnO photocatalysts under natural sunlight. Among the three catalysts, the Ag2S decorated ZnO achieved greatest photodegradation efficiency of 94.1% for degradation of the CV dye with rate constant value of 0.050. The highest catalytic activity may be related to Ag2S acting a significant part in reducing bandgap and boosting hole, superoxide radical, and hydroxyl radical formation, which inhibits recombination, hence enhancing the photocatalyst's efficacy, activity, and also stability.

Visible light active hybrid silver decorated g-C3N4-CeO2 nanocomposite for ultrafast photocatalytic activity and toxicity evaluation.

Development of hybrid graphitic carbon nitride (GCN) nanocomposite is an emerging research area in wastewater treatment. Herein, hybrid visible light active photocatalyst of silver decorated polymeric graphitic carbon nitride and (Ag-GCN) with cerium oxide (CeO2) nanocomposite was prepared and characterized in detail. The Ag-GCN/CeO2 photocatalyst has successfully prepared by an electrostatic self-assembly approach. The synthesized Ag-GCN/CeO2 NCs photocatalysts are characterized by various physio-chemical techniques. Using the Ag-GCN/CeO2 catalyst, the excellent photodegradation efficiency of Acid yellow-36 (AY-36) and Direct yellow-12 (DY-12) dye solution were achieved 100% within 150 min sun light irradiation. The Ag-GCN/CeO2 rate constant values of 0.048 and 0.046/min has been determined for AY-36 and DR-12 dyes, respectively. The extraordinary photocatalytic activity is due to incorporation of CeO2 with Ag-GCN which play a significant role in visible light absorption, superior reactive oxygen generation (ROS) and excellent pollutant catalyst interaction. The toxicity of the photocatalytically degraded AY-36 and DR-12 dyes were measured using the soil nematode Caenorhabditis elegans, a well-established in vivo model in biology, by analyzing survival, physiological functions, intracellular ROS levels, and stress-protective gene expressions.

A Novel Nanocomposite Based on Triazine Based Covalent Organic Polymer Blended with Porous g-C3N4 for Photo Catalytic Dye Degradation of Rose Bengal and Fast Green.

Metal free visible light active photocatalysts of covalent organic polymers (COPs) and polymeric graphitic carbon nitride (g-C3N4) are interesting porous catalysts that have enormous potential for application in organic pollutant degradation. Imine condensation for COPs, and thermal condensation for g-C3N4 were used to produce the catalysts. FT-IR, Raman, NMR, UV-Vis Spectroscopy, X-ray diffraction, and scanning electron microscopy studies were used to investigate the structural, optical, and morphological features of the metal free catalysts. We have constructed COPs with a π-electron deficient (Lewis acidic) triazine core and π -electron rich (Lewis basic) naphthalene and anthraquinone rings coupled by -O and -N donors in this study. Furthermore, the prepared Bulk-g-C3N4 (B-GCN) was converted to porous g-C3N4 (P-GCN) using a chemical oxidation process, and the generated P-GCN was efficiently mixed with the COP to create a novel nanocomposite for photocatalytic application. Using the anthraquinone-based COP and P-GCN (1:1 ratio, PA-GCN) catalyst, the highest photodegradation efficiencies for the polymeric graphitic carbon nitride of 88.2% and 82.3% were achieved using the Fast green (FG) and Rose bengal (RB) dyes, respectively. The rate constant values of 0.032 and 0.024/min were determined for FG and RB degradation, respectively. Higher activity may be related to the incorporation of COP and PA-GCN, which act significantly well in higher visible light absorption, have superior reactive oxygen generation (ROS), and demonstrate an excellent pollutant-catalyst interaction.

High Electrochemical Performance and Enhanced Electrocatalytic Behavior of a Hydrothermally Synthesized Highly Crystalline Heterostructure CeO2@NiO Nanocomposite.

A CeO2-based heterostructure nanocomposite has been attractive as an electrode material for energy storage and as an electrochemical sensor. In the present work, a CeO2@NiO nanocomposite was prepared by a simple hydrothermal method. The structural and morphological information on the heterostructure CeO2@NiO nanocomposite were obtained by using different characterization methods like X-ray diffraction, UV-visible, Fourier transform infrared, electron paramagnetic resonance, Raman, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray elemental color mapping, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Compared with pristine CeO2, the heterostructure CeO2@NiO nanocomposite exhibits a higher electrochemical performance with a specific capacitance of 317 F g-1 at a current density of 1 A g-1 in a 1 M KOH electrolyte. This device demonstrates a high energy density and a power density of 11 Wh kg-1 and 750 W kg-1, respectively. Besides, it was found that CeO2@NiO/glassy carbon electrode (GCE) shows appreciable electrocatalytic activity toward NO2- oxidation. The CeO2@NiO-modified electrode displays a linear response for NO2- oxidation between 0.001 × 10-6 and 4 × 10-3 M. Apart from high sensitivity (2260 µA mM-1 cm-2), the CeO2@NiO-modified electrode also exhibits good selectivity and long-term stability for nitrite (NO2-) detection in a water real sample, and the obtained results showed excellent recovery. The encouraging electrochemical performance of the CeO2@NiO nanocomposite provides a promising approach for the development of multifunctional electrode materials for future energy storage devices and sensors.

Ultrafast photodegradation of textile industry dyes using efficient sulfide based ternary nanocomposites.

We developed novel zinc-cadmium-bismuth sulfide (Zn-Cd-Bi2S3) and Zn-Cd-SnS nanocomposites to fabricate a heterojunction by an easy chemical technique to improve photocatalytic degradation of textile dye. Crystalline size and lattice parameter are analyzed using X-ray diffraction (XRD) spectrometer. The obtained strong diffraction peaks with various diffraction planes confirm the fabrication of a high crystal quality nanocomposite as well as the identification of its mixed crystal structure. The morphological information is studied using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (TEM). Due to its higher surface energy, the as-prepared nanocomposite displayed agglomeration by adjoining to tiny particles. The roughness of surface is studied by atomic force microscopy (AFM). Fourier transform-infrared spectroscopy (FT-IR) used to study about presence of organic functional groups on the surface of nanocomposite. Using UV-Visible and photoluminescence spectra, the impact of shifting the positions of Sn and Bi ions on the optical characteristics is investigated. Thermal property of the nanocomposite is studied by thermogravimetric-differential thermal analysis (TG-DTA) at air atmosphere. We examine and compared the photocatalytic activity of Zn-Cd-Bi2S3 and Zn-Cd-SnS nanocomposites for the crystal violet (CV) dye. Under the sun light irradiation Zn-Cd-Bi2S3 nanocomposite demonstrated a highest percentage of degradation (88.5%) within a short period (120 min). The obtained photocatalytic results indicate that the active radicals •O2-, h+, and •OH- are favourable for the photocatalytic reaction. A possible photocatalytic mechanism for the dye degradation for the photocatalyst is proposed. Due to the narrow band gap, wide range of incident light captured by the heterostructure nanocomposite and the photogenerated electrons and holes is effectively separated in the Zn-Cd-Bi2S3.

Cerium-based metal sulfide derived nanocomposite-embedded rGO as an efficient catalyst for photocatalytic application.

Reduced graphene oxide (rGO) with metal sulfides is an efficient photocatalyst for treating textile effluent. Herein, a hydrothermal technique was used to synthesize transition metal sulfide with rGO nanocomposite. Under 120 min of sunlight exposure, the cerium-nickel sulfide/rGO nanocomposite (Ce2S3-NiS2/rGO) photodegraded the methyl orange (MO) dye with an efficiency of 89.1% which is significantly higher than that of bare nickel sulfide (NiS2) and cerium sulfide (Ce2S3) photocatalysts. Moreover, another model pollutant dye bromophenol blue (BP) was treated under the same experimental condition, and it has achieved about 84.2% degradation efficiency. The combination of NiS2 and Ce2S3 improves the separation efficiency of photogenerated carriers, resulting in improved photocatalytic activity. In addition, ternary metal sulfide with rGO increases pollutant adsorption and electron-hole photogenerated pairs. Therefore, the mechanism of photocatalytic Ce2S3-NiS2/rGO is investigated in detail. This research could pave the way for the development of capable and adaptable Ce2S3-NiS2/rGO photocatalysts for environmental remediation.

Ultra-fast photocatalytic degradation and seed germination of band gap tunable nickel doping ceria nanoparticles.

Doping transition metal ions into cerium oxide (CeO2) results in interesting modifications to the material, including an increase in surface area, a high isoelectric point, biocompatibility, greater ionic conductivity, and catalytic activity. Herein, various concentrations (1-5%, 10% and 20%) of nickel (Ni) doped CeO2 nanoparticle have been made by a facile chemical process. Using a variety of cutting-edge analytical techniques, the structural, optical, and photocatalytic properties of undoped and varied concentrations (1-5%, 10%, and 20%) of Ni doped CeO2 nanoparticles have been investigated. Pure cubic fluorite structure with average crystallite sizes in the region of 12-15 nm was determined by X-ray diffraction (XRD) investigation. Transmission electron microscopy (TEM), which revealed highly homogeneous hexagonal shape of the particles with average size of 15 nm, was also used to determine microstructural information. According to the optical absorption, the band gaps of Ni doped and undoped CeO2 nanoparticles were found to be 2.96 eV and 1.95 eV, respectively. When exposed to sunlight, the narrow band gap Ni doped CeO2 nanoparticles worked as an active visible light catalyst to remove the dyes Rose Bengal (RB) and Direct Yellow (DY). The best photodegradation efficiencies for RB and DY dyes were found about 93% and 97%, respectively, using the 5% Ni-doped CeO2 catalyst. The apparent rate constant values of 0.039 for RB and 0.040 min-1 were attained for DY. As well, the treated, untreated dye solution and control solutions were utilized to assess the toxicity of commercially accessible Vigna Radiata seeds. In this study exhibits percentages of length and germination increased by 30-35% when compared to dye pollutant solution. The Ni doped CeO2 can provide a substantial alternative for current industrial waste management because of its quick photocatalytic activity and remarkable seed germination results.

2D MXene Nanomaterials as Electrocatalysts for Hydrogen Evolution Reaction (HER): A Review.

MXenes, a novel family of 2D transition metal carbide, nitride and carbonitride materials, have been gaining tremendous interest in recent days as potential electrocatalysts for various electrochemical reactions, including hydrogen evolution reaction (HER). MXenes are characterized by their etchable metal layers, excellent structural stability, versatility for heteroatoms doping, excellent electronic conductivity, unique surface functional groups and admirable surface area, suitable for the role of electrocatalyst/support in electrochemical reactions, such as HER. In this review article, we summarized recent developments in MXene-based electrocatalysts synthesis and HER performance in terms of the theoretical and experimental point of view. We systematically evaluated the superiority of the MXene-based catalysts over traditional Pt/C catalysts in terms of HER kinetics, Tafel slope, overpotential and stability, both in acidic and alkaline electrolytic environments. We also pointed out the motives behind the electro catalytic enhancements, the effect of synthesis conditions, heteroatom doping, the effect of surface terminations on the electrocatalytic active sites of various MXenes families. At the end, various possible approaches were recommended for a deeper understanding of the active sites and catalytic improvement of MXenes catalysts for HER.

MOFs-Graphene Composites Synthesis and Application for Electrochemical Supercapacitor: A Review.

Today's world requires high-performance energy storage devices such as hybrid supercapacitors (HSc), which play an important role in the modern electronic market because supercapacitors (Sc) show better electrical properties for electronics devices. In the last few years, the scientific community has focused on the coupling of Sc and battery-type materials to improve energy and power density. Recently, various hybrid electrode materials have been reported in the literature; out of these, coordination polymers such as metal-organic frameworks (MOFs) are highly porous, stable, and widely explored for various applications. The poor conductivity of classical MOFs restricts their applications. The composite of MOFs with highly porous graphene (G), graphene oxide (GO), or reduced graphene oxide (rGO) nanomaterials is a promising strategy in the field of electrochemical applications. In this review, we have discussed the strategy, device structure, and function of the MOFs/G, MOFs/GO, and MOFs/rGO nanocomposites on Sc. The structural, morphological, and electrochemical performance of coordination polymers composites towards Sc application has been discussed. The reported results indicate the considerable improvement in the structural, surface morphological, and electrochemical performance of the Sc due to their positive synergistic effect. Finally, we focused on the recent development in preparation methods optimization, and the opportunities for MOFs/G based nanomaterials as electrode materials for energy storage applications have been discussed in detail.

Structural and morphological tuning of Cu-based metal oxide nanoparticles by a facile chemical method and highly electrochemical sensing of sulphite.

A facile one-step chemical method is introduced for the successful synthesis of Cu2O, CuO and CuNa2(OH)4 crystal structures and their electrochemical properties were also investigated. X-ray diffraction studies revealed that these copper-based oxide nanoparticles display different crystal structures such as cubic (Cu2O), monoclinic (CuO) and orthorhombic [CuNa2(OH)4]. The microstructural information of nanoparticles was investigated by transmission electron microscopy. It shows attractive morphologies of different orientation such as rod like structure, nanobeads and well-aligned uniform nanorod for Cu2O, CuO and CuNa2(OH)4, respectively. Electrochemical sensing of sulphite (SO32-) on these three copper-based oxide modified electrodes was investigated. Among the three different crystal structures, CuO shows promising electrocatalytic activity towards oxidation of sulphite. A linear variation in peak current was obtained for SO32- oxidation from 0.2 to 15 mM under the optimum experimental condition. The sensitivity and detection limit were in the order of 48.5 µA cm-2 mM-1 and 1.8 µM, respectively. Finally, practical utility of CuO modified electrode was demonstrated for the estimation of sulphite in commercial wine samples.

Sunlight-driven enhanced photocatalytic activity of bandgap narrowing Sn-doped ZnO nanoparticles.

In this paper, we grab to utilize one of the trending techniques with efficient implications in wastewater treatment of organic pollutants, the photocatalytic degradation method shining out in the research field. Herein, tin (Sn)-doped zinc oxide (ZnO) nanoparticles (NPs) (Sn/ZnO) with different doping concentrations (1, 2, 3, 4, and 5 wt%) were synthesized via a simple co-precipitation assisted method and later subjected for their physico-chemical, morphological, and optical characterization. In addition, photocatalytic activity as the concerned study was investigated as to record the different doping levels of Sn/ZnO to examine the effect of doping concentration in relation with the degradation efficiency. We know that the optical bandgap of pure ZnO was 3.26 eV while it tends to increase slightly upon increasing the doping concentration. In the present investigation, methylene blue (MB) dye was used as a model pollutant to evaluate the photocatalytic activity of Sn/ZnO photocatalysts under natural sunlight. Varied doping concentrations of Sn/ZnO were compared with different characterization techniques while XRD analysis shows up 4-Sn/ZnO with sharp peak at (1 0 1) plane with smaller grain size in comparison to other Sn/ZnO samples. The morphological recognition depicts the hexagonal structure with smaller size for 4-Sn/ZnO which offers more active sites with improved photocatalytic activity, higher surface area for the transportation of pollutants. Fluorescence spectra results revealed that Sn dopant suppresses the charge carrier recombination. The lower intensity of PL indicated reduced recombination rate, which resulted in enhancing the photocatalytic activity. To investigate the possible mechanism, kinetics and reusability studies were performed. The 4% Sn-doped ZnO nanoparticle concentration showed highest photocatalytic activity when compared with other doping levels.

Facile synthesis of NiO@Ni(OH)2-α-MoO3 nanocomposite for enhanced solid-state symmetric supercapacitor application.

Electrochemical supercapacitor fabrication using heterogeneous nanocomposite is one of the most promising pathways for energy storage technology. Herein, heterostructure based nickel-molybdenum (NiO@Ni(OH)2-α-MoO3) nanocomposites have been successfully prepared on nickel foil via hydrothermal route for supercapacitor application. The mixed phases of cubic, hexagonal, and orthorhombic crystal structure for NiO, Ni(OH)2, and α-MoO3, respectively were observed by X-ray diffraction. Heterostructures of nanosheet and nanosphere morphologies were confirmed by high resolution transmission electron microscopy. Impressively, the NiO@Ni(OH)2-α-MoO3 composite working electrode exhibits a high specific capacitance of 445 Fg-1 at current density of 1 Ag-1 and shows outstanding rate capability (97.3% capacity retention after 3000 cycles at 10 Ag-1), compared to that of NiO@Ni(OH)2 nanoparticles. Notably, two-electrode symmetric supercapacitor of NiO@Ni(OH)2-α-MoO3 working electrode shows a high specific capacitance of 172 Fg-1 at 0.5 Ag-1, excellent rate capability and good cycling stability. Also, an excellent cycling stability (capacity retention of 98% after 5000 cycles) is observed for NiO@Ni(OH)2-α-MoO3 as a working electrode in the symmetric two-electrode system. The obtained attractive results demonstrate that nanocomposite anode material can be used for development of a wide-range of energy storage devices.

Visible light-driven photocatalytic dye degradation under natural sunlight using Sn-doped CdS nanoparticles.

Herein, cadmium sulfide (CdS) nanoparticles (NPs) and different concentrations (1-5 and 10 wt %) of Sn-doped CdS NPs were prepared by a chemical precipitation method using PVP as a capping agent. The synthesized NPs were characterized using various characteristic techniques such as XRD, SEM, TEM, Raman spectroscopy, UV-Vis, and photoluminescence to investigate structural, morphological, and optical properties. Optical band gap of CdS has been tuned by substitution of Sn with different concentrations. Pure CdS and Sn-doped CdS NPs were used for the photocatalytic degradation of methylene blue (MB) dye under direct sunlight irradiation. The photocatalytic activity of the Sn-doped CdS NPs is attributed to the interface actions between Sn and CdS, which significantly decreases the recombination of a photogenerated electron-hole pair. The degradation efficiencies were found to be 91.39% and 97.56% within 180 min for pure CdS and Sn-doped CdS NPs, respectively. Among the catalysts, 4% Sn-doped CdS NPs exhibit best photocatalytic degradation efficiency after 180 min of irradiation.

Synergetic Effects of Hybrid Carbon Nanostructured Counter Electrodes for Dye-Sensitized Solar Cells: A Review.

This article provides an overview of the structural and physicochemical properties of stable carbon-based nanomaterials and their applications as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The research community has long sought to harvest highly efficient third-generation DSSCs by developing carbon-based CEs, which are among the most important components of DSSCs. Since the initial introduction of DSSCs, Pt-based electrodes have been commonly used as CEs owing to their high-electrocatalytic activities, thus, accelerating the redox couple at the electrode/electrolyte interface to complete the circuit. However, Pt-based electrodes have several limitations due to their cost, abundance, complicated facility, and low corrosion resistance in a liquid electrolyte, which further restricts the large-area applications of DSSCs. Although carbon-based nanostructures showed the best potential to replace Pt-CE of DSSC, several new properties and characteristics of carbon-CE have been reported for future enhancements in this field. In this review, we discuss the detailed synthesis, properties, and performances of various carbonaceous materials proposed for DSSC-CE. These nano-carbon materials include carbon nanoparticles, activated carbon, carbon nanofibers, carbon nanotube, two-dimensional graphene, and hybrid carbon material composites. Among the CE materials currently available, carbon-carbon hybridized electrodes show the best performance efficiency (up to 10.05%) with a high fill factor (83%). Indeed, up to 8.23% improvements in cell efficiency may be achieved by a carbon-metal hybrid material under sun condition. This review then provides guidance on how to choose appropriate carbon nanomaterials to improve the performance of CEs used in DSSCs.