Aqueous Chemical Growth Method Research Articles

Comparison of Adams-Bashforth-Moulton and Dormand-Prince Methods in Lengyel-Epstein Reaction Model Forming Zinc Oxide Nanostructures

This study adopts a numerical approach in the Lengyel-Epstein reaction model for forming zinc oxide (ZnO) nanostructures. It aims to determine the optimal approximation technique to analyze the growth of ion concentrations in ZnO nanostructures. For this purpose, ordinary differential equations are developed using the Dormand-Prince method in the Lengyel-Epstein reaction model. The results obtained from this technique are compared with the results obtained from the Adams-Bashforth-Moulton (ABM) method. After a comparative analysis of both methods, the results showed that the ABM method performs better than the Dormand-Prince method. The accuracy and stability of the ABM method are higher than those of the Dormand-Prince method. Furthermore, error analysis for both methods confirms that the results obtained from the former are more optimized. Moreover, this method also validates the results obtained from the experimental procedure by using the aqueous chemical growth (ACG) method to form the nanostructures of ZnO.

Sustainable and Low-Cost Electrodes for Photocatalytic Fuel Cells.

Water pollutants harm ecosystems and degrade water quality. At the same time, many pollutants carry potentially valuable chemical energy, measured by chemical oxygen demand (COD). This study highlights the potential for energy harvesting during remediation using photocatalytic fuel cells (PCFCs), stressing the importance of economically viable and sustainable materials. To achieve this, this research explores alternatives to platinum cathodes in photocathodes and aims to develop durable, cost-effective photoanode materials. Here, zinc oxide nanorods of high density are fabricated on carbon fiber surfaces using a low-temperature aqueous chemical growth method that is simple, cost-efficient, and readily scalable. Alternatives to the Pt cathodes frequently used in PCFC research are explored in comparison with screen-printed PEDOT:PSS cathodes. The fabricated ZnO/carbon anode (1.5 × 2 cm2) is used to remove the model pollutant used here and salicylic acid from water (30 mL, 70 μM) is placed under simulated sunlight (0.225 Sun). It was observed that salicylic acid was degraded by 23 ±0.46% at open voltage (OV) and 43.2 ± 0.86% at 1 V with Pt as the counter electrode, degradation was 18.5 ± 0.37% at open voltage (OV) and 44.1 ± 0.88% at 1 V, while PEDOT:PSS was used as the counter electrode over 120 min. This shows that the PEDOT:PSS exhibits an excellent performance with the full potential to provide low-environmental-impact electrodes for PCFCs.

Pharmacological assessment of Co3O4, CuO, NiO and ZnO nanoparticles via antibacterial, anti-biofilm and anti-quorum sensing activities.

Infectious diseases have risen dramatically as a result of the resistance of many common antibiotics. Nanotechnology provides a new avenue of investigation for the development of antimicrobial agents that effectively combat infection. The combined effects of metal-based nanoparticles (NPs) are known to have intense antibacterial activities. However, a comprehensive analysis of some NPs regarding these activities is still unavailable. This study uses the aqueous chemical growth method to synthesize Co3O4, CuO, NiO and ZnO NPs. The prepared materials were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. The antibacterial activities of NPs were tested against Gram-positive and Gram-negative bacteria using the microdilution method, such as the minimum inhibitory concentration (MIC) method. The best MIC value among all the metal oxide NPs was 0.63 against Staphylococcus epidermidis ATCC12228 through ZnO NPs. The other metal oxide NPs also showed satisfactory MIC values against different test bacteria. In addition, the biofilm inhibition and antiquorum sensing activities of NPs were also examined. The present study presents a novel approach for the relative analysis of metal-based NPs in antimicrobial studies, demonstrating their potential for bacteria removal from water and wastewater.

Green Synthesis of NiO Nanoflakes Using Bitter Gourd Peel, and Their Electrochemical Urea Sensing Application

To determine urea accurately in clinical samples, food samples, dairy products, and agricultural samples, a new analytical method is required, and non-enzymatic methods are preferred due to their low cost and ease of use. In this study, bitter gourd peel biomass waste is utilized to modify and structurally transform nickel oxide (NiO) nanostructures during the low-temperature aqueous chemical growth method. As a result of the high concentration of phytochemicals, the surface was highly sensitive to urea oxidation under alkaline conditions of 0.1 M NaOH. We investigated the structure and shape of NiO nanostructures using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). In spite of their flake-like morphology and excellent crystal quality, NiO nanostructures exhibited cubic phases. An investigation of the effects of bitter gourd juice demonstrated that a large volume of juice produced thin flakes measuring 100 to 200 nanometers in diameter. We are able to detect urea concentrations between 1-9 mM with a detection limit of 0.02 mM using our urea sensor. Additionally, the stability, reproducibility, repeatability, and selectivity of the sensor were examined. A variety of real samples, including milk, blood, urine, wheat flour, and curd, were used to test the non-enzymatic urea sensors. These real samples demonstrated the potential of the electrode device for measuring urea in a routine manner. It is noteworthy that bitter gourd contains phytochemicals that are capable of altering surfaces and activating catalytic reactions. In this way, new materials can be developed for a wide range of applications, including biomedicine, energy production, and environmental protection.

Facile synthesis of efficient Co3O4 nanostructures using the milky sap of Calotropis procera for oxygen evolution reactions and supercapacitor applications.

The preparation of Co3O4 nanostructures by a green method has been rapidly increasing owing to its promising aspects, such as facileness, atom economy, low cost, scale-up synthesis, environmental friendliness, and minimal use of hazardous chemicals. In this study, we report on the synthesis of Co3O4 nanostructures using the milky sap of Calotropis procera (CP) by a low-temperature aqueous chemical growth method. The milky sap of CP-mediated Co3O4 nanostructures were investigated for oxygen evolution reactions (OERs) and supercapacitor applications. The structure and shape characterizations were done by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) techniques. The prepared Co3O4 nanostructures showed a heterogeneous morphology consisting of nanoparticles and large micro clusters. A typical cubic phase and a spinel structure of Co3O4 nanostructures were also observed. The OER result was obtained at a low overpotential of 250 mV at 10 mA cm-2 and a low Tafel slope of 53 mV dec-1. In addition, the durability of 45 hours was also found at 20 mA cm-2. The newly prepared Co3O4 nanostructures using the milky sap of CP were also used to demonstrate a high specific capacitance of 700 F g-1 at a current density of 0.8 A g-1 and a power density of 30 W h kg-1. The enhanced electrochemical performance of Co3O4 nanostructures prepared using the milky sap of CP could be attributed to the surface oxygen vacancies, a relatively high amount of Co2+, the reduction in the optical band gap and the fast charge transfer rate. These surface, structural, and optical properties were induced by reducing, capping, and stabilizing agents from the milky sap of CP. The obtained results of OERs and supercapacitor applications strongly recommend the use of the milky sap of CP for the synthesis of diverse efficient nanostructured materials in a specific application, particularly in energy conversion and storage devices.

Synthesis of porous cobalt oxide nanosheets: highly sensitive sensors for the detection of hydrazine

A highly sensitive, reliable, and reproducible sensor for detecting hydrazine was fabricated using a porous cobalt oxide (Co2O3) nanosheets electrode. The Caffeine assisted Co2O3 nanosheets were prepared by a low-temperature aqueous chemical growth method. The morphology, phase purity, and porosity of Co2O3 nanosheets were examined via SEM, XRD, and BET techniques. SEM results reveal the hexagonal sheet-like morphology of synthesized Co2O3 nanosheets, while the XRD technique illustrates high phase purity. Furthermore, the BET technique demonstrated the increased surface area exhibited by the newly synthesized Co2O3 nanomaterial. The hydrazine sensor based on the Co3O4 nanosheet electrode demonstrated relatively high sensitivity (1.632 μA cm−2 μM−1) and a rather low detection limit (0.05 μM) due to the fast electro-oxidation of hydrazine catalyzed by Co3O4 nanosheets. The unique porous structure of Co3O4 nanosheets offers a promising probe candidate for efficient electrochemical sensors of hydrazine.

Facile Synthesis of NiO/ZnO nanocomposite as an effective platform for electrochemical determination of carbamazepine

The pharmaceutical science demand for sustainable and selective electrochemical sensors which exhibit ultrasensitive capabilities for the monitoring of different drugs. In an attempt to build a useful electrochemical sensor, we describe a most efficient method for the fabrication of NiO/ZnO nanocomposite through aqueous chemical growth method. The successfully synthesized NiO/ZnO nanocomposite is successfully employed to modify a glassy carbon electrode in order to build a sensitive and reliable electrochemical sensor for the detection of carbamazepine (CBZ), an anticonvulsant drug. The morphological texture, functionalities and crystalline structure of prepared nanocomposite were determined via FTIR, XRD, EDX, TEM, and SEM analysis. In order to examine the charge transfer kinetics, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to exploit the electrochemical properties of the synthesized nanocomposite.The NiO/ZnO nanocomposite exhibited excellent electron transfer kinetics and less resistive behavior than the individual NiO and ZnO nanoparticles. The differential pulse voltammetry and cyclic voltammetry tools were used for the fluent determination of CBZ. Certain parameters were optimized to develop an effective method including optimum scan rate 60 mV/s, potential range from 0.4 to 1.4 V and BRB as supporting electrolyte with pH 3. The developed sensor showed exceptional response for CBZ under the linear dynamic range from 5 to 100 μM. The limit of detection of proposed NiO/ZnO sensor for the CBZ was calculated to be 0.08 μM. The analytical approach of prepared electrochemical sensor was investigated in different pharmaceutical formulation with acceptable percent recoveries ranging from 96.7 to 98.6%.

Role of cobalt precursors in the synthesis of Co3O4 hierarchical nanostructures toward the development of cobalt‐based functional electrocatalysts for bifunctional water splitting in alkaline and acidic media

AbstractThe precursors have significant influence on the catalytic activity of nonprecious electrocatalysts for effective water splitting. Herein, we report active electrocatalysts based on cobalt oxide (Co3O4) hierarchical nanostructures derived from four different precursors of cobalt (acetate, nitrate, chloride, and sulfate salts) using the low‐temperature aqueous chemical growth method. It has been found that the effect of precursor on the morphology of nanostructured material depends on the synthetic method. The Co3O4 nanostructures exhibited cubic phase derived from these four precursors. The Co3O4 nanostructures obtained from chloride precursor have demonstrated improved oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) compared to other precursors due relatively higher content of Co3O4 nanostructures at the surface of material. An overpotential of 400 mV versus reversible hydrogen electrode (RHE) at 10 mA cm−2 was observed for HER. The Co3O4 nanostructures derived from the chloride precursor have shown favorable reaction kinetics via 34 mV dec−1 value of the Tafel slope for HER reaction. The Co3O4 nanostructures derived from chloride precursor have also shown an excellent HER durability for 15 hr in alkaline media. Furthermore, the OER functional characterization was carried out onto Co3O4 nanostructures derived from chloride precursor exhibited 220 mV overpotential at 10 mA cm−2 and Tafel slope of 56 mV dec−1. Importantly, the reason behind the favorable catalytic activity of Co3O4 nanostructures derived from chloride precursor was linked to one order of magnitude smaller charge transfer resistance and higher amount of Co3O4 content at the surface of nanostructures than the Co3O4 nanostructures derived from other precursors. The performance of Co3O4 nanostructures derived from chloride precursor via the wet chemical method suggests that cobalt chloride precursor could be of great interest for the development of efficient, stable, nonprecious, and environmentally friendly electrocatalysts for the chemical energy conversion and storage devices.

SnO2 nanostructure based electroanalytical approach for simultaneous monitoring of vitamin C and vitamin B6 in pharmaceuticals

Vitamins are considered as the essential nutrients because they perform vital role for normal metabolism and healthy growth. Our body cannot synthesize vitamins, therefore, they must be taken through a balanced diet because their deficiency can cause several diseases. A number of pharmaceutical formulations are available containing a range of vitamins. It is important to determine vitamin content from them through easy and efficient method. This study reports the simultaneous determination of two important water-soluble vitamins (vitamin C and B6) from multivitamin tablets with high accuracy and high sensitivity. The work is conducted in two phases; first includes the synthesis of tin oxide (SnO2) nanoparticles via aqueous chemical growth method and their characterization through Transmission electron microscopy (TEM), Energy-Dispersive X-ray (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). While second part include simultaneous electrochemical determination of vitamin C and B6 from multivitamin tablets. The cyclic voltammetry was used for the development of new method using SnO2/GCE modified electrode. In CV, two well resolved peaks obtained under optimized conditions which confirm that both vitamins can be determined at the same time. The modified electrode based on SnO2 nanoparticles was successfully applied for the determination of vitamin C and vitamin B6 in pharmaceutical samples with the limit of detection of 0.067 µM for VC, 0.048 µM for B6 respectively.

Implementation of Lengyel-Epstein Reaction Model for Zinc Oxide (ZnO) Nanostructures by Comparing Euler and Fourth-Order Runge–Kutta (RK) Methods

The current study presents Lengyel-Epstein reaction model for the analysis of the reaction kinematics of the growth of Zinc oxide (ZnO) nanostructures using the fourth-order Runge-Kutta (RK) method. The aim is to propose an improved approximation technique for the computation of the concentrations of Zinc ion and Hydroxyl ion. For this purpose, a comparison of Euler's method with the fourth-order RK method was made to gauge their effectiveness in determining the concentrations of both ions. It was determined that the fourth-order RK method gives more stable results than Euler’s method. In this regard, the comparison with Euler's method showed that the rate of convergence of the RK method is more appropriate than Euler's method. Furthermore, it was also determined that the RK method validates the experimental results for the formation of ZnO nanostructures using the aqueous chemical growth (ACG) method.

Photocatalytic degradation of methylene blue by ZnO seed layers and 1D nanorods

In the present work, the photocatalytic activity of ZnO seed layers and 1D nanorods are studied on Methylene Blue (MB) dye. ZnO thin films deposited on glass substrates by Spray Pyrolysis technique are used as the seed layers to grow 1D nanorods by Aqueous Chemical Growth (ACG) method for 10 h. The structural properties are studied by XRD measurements. Scanning Electron Micrographs confirmed the growth of 1D nanorods. The photoluminescence spectra showed a broad emission in the visible region corresponding to the structural defects. The photocatalytic experiment was conducted for 4 h in sunlight by dipping the seed layer and seed layer with 1D nanorods in a petridishes containing the dye. The dye degradation was 69 % and 80 % for seed layers and 1D nanorods respectively. The nanorods show better activity due to its higher surface area compared to the seed layer, and the increased defect concentration.

Nanostructured Co3O4 electrocatalyst for OER: The role of organic polyelectrolytes as soft templates

Designing an efficient electrocatalyst for the oxygen evolution reaction (OER) in alkaline media is highly needed but very challenging task. Herein, we used organic polyelectrolytes such as (carboxymethyl cellulose) CMC and polyacrylamide polymers for the growth of Co3O4 nanostructures by aqueous chemical growth method. The morphology and composition studies were performed on scanning electron microscopy (SEM), energy dispersive X-ray (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) techniques. The structural properties and the surface chemistry of the Co3O4 electrocatalysts were correlated to the OER performance, and the enhancement mechanism with respect to pristine Co3O4 was observed to be specifically related to the polyelectrolyte templating role.Co3O4@CMC composites displayed reduced crystallite size, producing OER overpotential as low as 290 mV at 10 mAcm−2 in 1.0 KOH and Tafel slope of 71 mVdec−1, suggesting fast transfer of intermediates and electrons during water electrolysis. On the other hand, the use of polyacrylamide and its different templating mechanism resulted in similar crystallite size, but preferential exposed faces and larger surface vacancies content, as demonstrated by HR-TEM and XPS, respectively. Consistently, this material displays cutting-edge OER performance, such as overpotential of 260 mV at 10 mAcm−2 and a low Tafel slope of 63 mVdec−1. The proposed strategy for the preparation of Co3O4 nanostructures in the presence of CMC and polyacrylamide is facile, mass production, thus it could equally contributed towards the realization of hydrogen energy. Therefore, these nanostructures of Co3O4 can be regarded as an alternative and promising materials for the different electrochemical applications including fuel cells, metal air batteries, overall water electrolysis and other energy storage devices.

A simple and efficient visible light photodetector based on Co3O4/ZnO composite

Herein, we propose for the first time visible light photodetector based on n-type ZnO nanorods decorated with p-type Co3O4 nanowires. The heterojunction was fabricated on fluorine doped tin oxide (FTO) glass substrate by low temperature aqueous chemical growth method. ZnO exhibits nanorod morphology and cobalt oxide possesses nanowire shape with sharp tail. Energy dispersive spectroscopy confirmed the presence of Zn, O, and Co elements in the heterojunction. ZnO and Co3O4 have hexagonal and cubic phases, respectively, as confirmed by XRD. The dense and perpendicular ZnO nanorods are acting as a scattering layer for visible light, while Co3O4 nanowires act as a visible-light absorber. The all oxide p–n junction can operate as visible light photodetector. Furthermore, the heterojunction also shows a reproducible and fast response for the detection of visible light. Optimization of the device is needed (presence of buffer layers, tuning a thickness of the optical absorber) to improve its functionalities.

Low Temperature Aqueous Chemical Growth Method for the Doping of W into ZnO Nanostructures and Their Photocatalytic Role in the Degradration of Methylene Blue

In this research work, we have produced tungsten (W) doped ZnO nanostructures via low-temperature aqueous chemical growth method. The morphology, crystal arrays and composition was investigated by scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and energy dispersive X-rays (EDX) respectively. The SEM results indicate the nanowire morphology before and after the doping of W into ZnO and XRD study has shown the hexagonal crystallography of W doped ZnO samples. The EDX study has confirmed the successful doping of W into ZnO crystal lattices. The photodegradation performance of methylene blue was evaluated with W doped ZnO samples and pristine ZnO in aqueous solution. The measured degradation efficiencies for the different W doped ZnO samples were 5 wt%, 10 wt%, 15 wt% and 20 wt% at pH 5 are 87.8%, 92.3%, 92.8% and 96.9%), at pH 9 (72.1%, 90.7%, 92.1%, and 96.4%) and at pH 11 (80%, 85%, 87% and 89%) for the time interval of 90 min respectively. The pH of dye solution has significant effect on the degradation efficiency. These findings show that the W doped ZnO samples have superior degradation efficiency of 96.6% in a very short interval of time. The swift degradation kinetics for the W doped ZnO samples is attributed to the reduction in the energy band gap, decrease in particle size, enhanced surface area, decrease in the recombination rate and foster charge separation process. The obtained results are exciting and providing efficient earth-abundant photocatalysts for the energy and environmental purposes.Kindly confirm the Given names and Family names for all the authors.They are correct.

An improved non-enzymatic electrochemical sensor amplified with CuO nanostructures for sensitive determination of uric acid

AbstractThis study displays the facile and fluent electrochemical determination of uric acid (UA) through exceptional copper oxide nanostructures (CuO), as an effective sensing probe. The copper oxide nanostructures were fabricated via an aqueous chemical growth method using sodium hydroxide as a reducing agent, which massively hold hydroxide source. Copper oxide nanostructures showed astonishing electrocatalytic behavior in the detection of UA. Different characterization techniques such as XRD, FESEM, and EDS were exploited to determine crystalline nature, morphologies, and elemental composition of synthesized nanostructures. The cyclic voltammetry (CV) was subjected to investigate the electrochemical performance of UA using copper oxide nanostructures modified glassy carbon electrode CuO/GCE. The CV parameters were optimized at a scan rate of 50 mV/s with −0.7 to 0.9 potential range, and the UA response was investigated at 0.4 mV. PBS buffer of pH 7.4 was exploited as a supporting electrolyte. The linear dynamic range for UA was 0.001–351 mM with a very low limit of detection observed as 0.6 µM. The proposed sensor was successfully applied in urine samples for the detection of UA with improved sensitivity and selectivity.

NiO nanostructures based functional none-enzymatic electrochemical sensor for ultrasensitive determination of endosulfan in vegetables

In an effort to develop a rapid, sensitive and improved electrochemical sensing approach for the selective oxidation of endosulfan, nickel oxide nanoparticles (NiO NPs) were anchored on glassy carbon electrode (GCE). The fabrication of NPs was accomplished via aqueous chemical growth method and subjected to different analytical tools for the determination of surface characteristics, crystallinity and elemental composition. The XRD and FESEM reveal a high crystallinity and nano seeds like morphology for the synthesized NPs with the average size of 22 nm. Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) approaches were exploited for the investigation of electrochemical behaviour of modified electrode labelled as (NiO/GCE). A significantly enhanced response of NiO/GCE for the determination of endosulfan manifested the salient role of the developed sensor in facilitating the charge transfer mechanism between the electrode’s surface and the analyte. Differential pulse voltammetry (DPV) was utilized to quantify the amount of endosulfan. The certain parameters were optimized for the fluent determination process of endosulfan such as phosphate buffer of pH 7, scan rate 80 mV/s and potential range from − 0.6 to 0.8. The DPV (Ipa) response was linear over 0.05–25 µM range with the limit of detection of 0.17 nM and limit of quantification 0.51 nM respectively. The applicability of proposed sensor was investigated in real vegetable samples that showed acceptable percent recoveries for tomato and spinach samples which were calculated to be 94, 91, 87.3% and 98, 103, 100.2% respectively.

Nonenzymatic Electrochemical Detection of 2,4,6-Trichlorophenol Using CuO/Nafion/GCE: A Practical Sensor for Environmental Toxicants.

2,4,6-Trichlorophenol (2,4,6 TCP) is one of the hazardous toxicants, which has severe impacts on the environment and human health. This study is designed to develop a highly sensitive and selective electrochemical sensor based on CuO nanostructures for the detection of 2,4,6 TCP. The CuO nanostructures were synthesized through an aqueous chemical growth method and characterized by versatile analytical techniques, for example, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, atomic force microscopy, energy-dispersive spectrometry, and X-ray diffraction. The characterization tools revealed a high crystalline nature, exceptional phase purity, nanoball morphology with an average size of around 18.7 nm for the CuO nanostructures. The synthesized material was used to modify a glassy carbon electrode (GCE) with the help of Nafion as a binder to improve its efficiency and sensitivity. The CuO/Nafion/GCE was proven to be a potential sensor for the determination of 2,4,6 TCP under optimized conditions at a scan rate of 70 mV/s, potential range of 0.1-1.0 V, and phosphate buffer of neutral pH as the supporting electrolyte. The linear range for 2,4,6 TCP was set from (1 to 120 μM) with a low limit of detection value calculated to be 0.046 μM. The developed sensor was effectively applied for water samples with acceptable recovery values from 95.9 to 100.6%.

Heterogeneous kinetics of CuO nanoflakes in simultaneous decolorization of Eosin Y and Rhodamine B in aqueous media

This study describes the heterogeneous photocatalysis of CuO nanoflakes for the effective degradation of hazardous dyes. The successful synthesis of CuO nanoflakes was carried out by exploiting aqueous chemical growth method. The synthesized material was characterized by versatile analytical tools including XRD, FE-SEM, EDX, AFM, ZP and FT-IR. The engineered CuO reveals nanoflakes texture having average size of 18.3 nm and (− 36.5 ± 3 mV) surface charge with excellent phase purity and crystalline nature. The catalytic kinetics exposed that CuO nanocatalyst exhibits an exceptional degradation over 97% for Eosin Y (EY) and Rhodamine B (RB) dyes in the aqueous medium using minimum catalyst dose of 120 and 140 μg individually and simultaneously, within 3 min of time period under sunlight. Due to ultrafine processing, cost-effective synthetic outline, supreme reduction percentage in short time and intense recyclability with an insignificant decrease in degradation abilities, the proposed nanocatalyst is extremely useful. Consequentially, the nanocatalyst presented here is more useful and realistic, hence can be suggested as an effective candidate for the successful degradation of complex dyes at the commercial level.

Efficient and Stable Co3O4/ZnO Nanocomposite for Photochemical Water Splitting

In this study, an efficient Co3O4/ZnO based composite was prepared by the low temperature aqueous chemical growth method for photoelectrochemical water splitting. Both ZnO and Co3O4 constituents are identified in the composite sample through X-ray diffraction technique. Scanning electron microscopy has shown the nanorod like morphology of ZnO with etched top surface. The energy dispersive spectroscopy has shown the presence of cobalt, oxygen and zinc as the main elements in the composite samples. The Co3O4/ZnO composite (with low content of cobalt chloride hexahydrate) shows a significant increase in the photocurrent density (3 mA/cm2 at 0.5 V vs Ag/AgCl, which is 10 times higher than the pristine ZnO). Importantly, a fast and stable photocurrent response is found at an illumination of 1 Sun of light. The superior performance of the Co3O4/ZnO composite system is attributed to the facile promotion of electron–hole charge carrier separation and favourable charge transport. Furthermore, the electrochemical impedance spectroscopy showed a small charge transfer resistance of 259.30 Ohms for the composite material and consequently a robust water splitting is obtained. The prepared composite is earth abundant, inexpensive and scalable, therefore it can be used for diverse applications.

Synergetic effect of carbon black as co-catalyst for enhanced visible-light photocatalytic activity and stability on ZnO nanoparticles

Carbon black/ZnO nanocomposites have been successfully synthesized via a simple aqueous chemical growth method. The preparation of the carbon black/ZnO nanocomposites by adding an appropriate weight of carbon black to the ZnO growth process can be favorable to improve photocatalytic degradation of methyl blue under irradiation of ultraviolet light. Compare with commercial TiO2 and ZnO nanopowders, carbon black/ZnO nanocomposites can enhance the specific surface area, the light-harvesting ability, and the charge carrier separation for achieving highly efficient photocatalysts under irradiation of both ultraviolet and visible light. The carbon black/ZnO nanocomposites exhibited a low cost and sample approach, high reusability, and high visible-light-induced photocatalytic activity.