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Energy crises and water pollution have become the key challenges in current era of technology. In this research work, activated carbon modified BiVO4 photocatalysts have been prepared using simple hydrothermal methods for efficient hydrogen evolution through water splitting under visible light irradiation and degradation, simultaneously. The properties of the synthesized photocatalysts were studied through SEM, UV, XRD, BET and PL emission spectroscopy. The 4%AC/BiVO4 exhibited highest degradation efficiency ≈98% in 60 min and production of hydrogen energy ≈510 h−1g−1 which is much higher when compared to pure BiVO4. The enhancement in the efficiency was due to large surface area, large absorption region. High crystallinity, small band gap and synergetic effect between the composites. The activated carbon based BiVO4 composites showed high stability which shows its vital role in practical applications.

In this study, Mg2+ ions-doped ZnO nanorods were prepared via simple solvothermal method. The prepared samples were characterized by XRD, TEM/SEM, EDX, UV–visible and PL emission spectroscopy to explore the structural, morphological and optical properties, respectively. The XRD results reveal that Mg2+ ions-doped ZnO/MgO nanocomposite exhibited the hexagonal wurtzite structure of ZnO. However, the incorporation of Mg2+ ions into ZnO has shifted the XRD peaks towards lower 2Ө angles which might be due to successful incorporation of Mg2+ ions into ZnO lattice. Moreover, the prepared ZnO, MgO and MgO/ZnO nanocomposites with various Mg to Zn atomic ratios (2–11%) were used as photocatalyst for the degradation of MB and RhB dyes under visible light irradiation. The sample with 8% doping (8%MgO/ZnO) showed excellent photocatalytic performance for both dyes as compared to pure ZnO and other samples. Furthermore, the cyclic stability of 8% MgO/ZnO nanocomposite was also monitored for the degradation of RhB dye, the results show that the prepared nanocomposite has good stability and long-term durability after five consecutive cycles. The current study suggests that ZnO/MgO-based nanocomposites could be proficiently used in numerous applications especially in environmental and energy applications.

Aluminum–nickel ferrite nanostructure with a nominal composition of NiFe2-xAlxO4 (0 < x < 0.9) was synthesized by heat treatment process by employing polyvinylpyrrolidone (PVP) as a capping operator. The effects of Al3+ substitution on structural, morphological, quantitative, qualitative and magnetic properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron microscopy (XPS) and vibrating-sample magnetometry (VSM). Single-phase inverse spinel structure and decrease in average crystal size as Al concentration increases was acknowledged by XRD and EDX characterization. The decrease in average crystal size as Al3+ ions content increases is associated with structural effects of overall crystal size of nanostructure. The development of a thermally stable nickel ferrite above 500 °C was detected by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements. The magnetic hysteresis loop measurements at room temperature (RT) with an ultimate tested magnetic field of 1.8 T shows both saturation and remnant magnetization decreases as content of Al3+ ions substitution increases. The decrease in overall magnetization is due to spin non-collinearity, weakening of magnetocrystalline anisotropy and weak super-exchange interactions.

The presence of pharmaceutical wastage and their metabolites in the wastewater, even in low absorption concentration has adverse effects on society and the environment. A recyclable and economical-friendly photocatalytic technique is applicable for decontamination and sanitization of the polluted water from the anti-parasitic drugs. Here, activated carbon was synthesized which has become more efficient and suitable for degradation purpose. Peanut shell-based activated carbon (PSAC) and sugarcane bagasse (SBAC) are used for this research. In this research study, results indicate that PSAC was more profitable and energetic as compared to SBAC. XRD demonstrates that PSAC has sharp peaks at 26.8° and 65.6° but SBAC has no specific sharp peaks. SEM analytic pictures visualized that PSAC has a granular nanoporous structure that is efficacious for the Iverzine degradation rather than nano and micro layers based on SBAC. EDX spectrums confessed that PSAC has a high peak of activated carbon and very small impurity peaks of sulphur and oxygen rather than SBAC. By the investigation of FTIR spectra, SBAC and PSAC both have almost the same absorbance bonds but have different percentage transmittance. An analytic study of degradation spectrum, it has been noticed that PSAC degraded 89% of Iverzine drug but SBAC has degraded just about 63%. All the results demonstrated that PSAC was more energetic for the absorption and degradation of pharmaceuticals from water.

The discharge of various textile effluents into water is provoking numerous ecological issues that have become severe threat to human beings and aquatic lives. The removal of the effluents by photodegradation using appropriate nanoparticles (NPs) is the most promising remediation process. In this study, a facile hydrothermal approach is utilized to fabricate pure ZnO and strontium doped ZnO nanoparticles (Sr-ZnO). The fabricated nanoparticles represented hexagonal morphology and structure which was controlled with the strontium doping. The optical properties of fabricated NPs were also controlled and approached to visible light (2.52 eV) instead of the UV light. The fabricated NPs were employed for photodegradation of Rhodamine B (RHB) dye from polluted wastewater and further effect of factors like light irradiation time, pH, photocatalyst dose, dye concentration etc. was also explored to optimize the parameters. Sr-ZnO photocatalyst represent excellent RHB dye degradation as well as cyclic stability with pseudo first order kinetics. The current study proves the suitability of Sr-ZnO photocatalyst under visible light irradiation for treatment of the organic and dye polluted wastewaters.

The concern to reduce global carbon emissions has significantly improved the development of efficient solid sorbents such as activated carbon (AC). In this study, AC is developed from date stones which is one of the abundantly found agricultural waste material in gulf region. The AC was completely characterized in terms of pore volume, surface area, stability test, volatile carbon and fixed carbon contents. Impregnation of AC was performed by three different alkanolamines, namely Diethylene triamine (DETA), Pentaethylene hexamine (PEHA) and Di-ethanol amine (DEA). The alkanolamine impregnated sorbents were utilized for CO2adsorption at temperatures of 25, 30, 40, 50, 60, 70 and 100 °C and carbon dioxide (CO2) concentrations of 10, 30, 50, 70 and 92% in helium. The adsorption phenomenon was evaluated by Langmuir isotherms for all the studied adsorbents. The AC developed from date stones provided high adsorption loading capacity of CO2 i.e., 89.79 mg/g of AC at 25 °C. Thermodynamic parameters showed that the adsorption was endothermic and spontaneous in nature. Moreover, desorption profiles reveal that DETA-AC samples provided most favorable characteristics with respect to the value of desorption constant.

Herein, supported Ni/MCF-17 catalysts with the size of nickel nanocrystal in the range of 1.5–8.0 nm were synthesized and employed for COx-free hydrogen production for fuel cells via the ammonia decomposition reaction. Characterized by a variety of techniques, the results show that nickel particles are in a highly dispersed state with a uniform particle size for each catalyst. Furthermore, the influence of particle size on the catalytic performance has been investigated. It was later revealed that Ni nanoparticles with different particle sizes exhibited significant differences in catalyzing the COx-free hydrogen production reaction. Moreover, the catalyst with the Ni nanoparticle size around 3.0 nm exhibited highest catalytic activity at each reaction temperature; this could be explained by the presence of high B5 active sites on the Ni-based catalyst surface.

The contamination of ammonia in surface water should be given a critical outlook as it easily exceeds the regulated standard limit especially in rivers located in many parts of the world. Several conventional methods for the removal of ammonia have been widely used but its effectiveness in removing ammonia is not impressive. Membrane technology is gaining wider application in removal of nitrogen compounds from water and wastewater. In this study, polyvinylidene fluoride (PVDF) flat sheet membrane incorporated with adsorbent material (zeolite and gypsum) were fabricated to study its efficiency in ammonia removal. The morphology of the blended PVDF membrane by using both additive materials showed that some changes were observed at the bottom layer of the membrane where an extremely wide finger-like structure has been formed. This modified membrane exhibits hydrophobicity properties with contact angle value of 89.0 ± 0.48° and 96.3 ± 0.54° for zeolite and gypsum, respectively. Meanwhile, the crystallinity of the fabricated membrane increases from 20% for pure PVDF to 25.9% and 26.4% for the respective additive of gypsum and zeolite. Furthermore, a comparable separation performance was obtained for the blended membrane with the pure PVDF and the commercial membrane of NF1. Thus, the presence of zeolite or gypsum in the synthesized PVDF membrane could potentially enhance the removal of ammonia by becoming an adsorption material as it commonly functions.

The study presents the deposition of nanostructured indium tin oxide thin films with thicknesses of 10, 30 and 50 nm on the polylactic acid (PLA) substrate by sputtering at $$30{^{\circ }}\hbox {C}$$. The absence of ITO peaks on the X-ray diffraction patterns confirms the amorphous state of ITO films and the X-ray photoelectron spectroscopy spectrum validates the deposition of ITO films on the PLA substrate. The results of atomic force microscopy of films exhibit variation in the average roughness of 0.3–1.5 nm when the thickness is increased. It was examined that optical transmission is dependent on the thickness of films which varies from 78 to 87% in the visible spectrum of 400–700 nm and the energy band gap varies from 3.95 to 4.02 eV. The films exhibit the low sheet resistance which is due to the formation of oxygen vacancies and dangling bonds. An increase in transmittance enhances the FOM of the ITO films on the PLA substrate.

Rh@UIO-66, prepared by using the double-solvent host–guest strategy and excess reduction methods, exhibited a higher catalytic activity in AB hydrolysis compared with Rh/UIO-66 because the ultrafine Rh nanoparticles were confined to UIO-66 channels. This confinement effect played a key role in enhancing the catalytic activity for AB hydrolysis.

Magnesium hydride (MgH 2 )–carbon nanotubes (CNT) composite has been prepared by high-energy ball milling method and their experimental and kinetic hydrogen adsorption studies was assessed. Hydrogen adsorption studies were performed by Sievert’s volumetric apparatus and kinetic evaluation was conducted by surface chemistry and Langmuir–Hinshelwood–Hougen–Watson (LHHW) type mode. Powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were performed. Hydrogen adsorption capacity of commercial MgH 2 , milled MgH 2 , and MgH 2 /CNT composite are found to be 0.04, 0.057, and 0.059 g (H 2 )/g (MgH 2 ) at 673 K and hydrogen pressure of 4.6 MPa. Addition of 5 wt% of CNTs to MgH 2 proved to be very critical to enhance hydrogen adsorption as well as to improve its kinetics. It was observed that hydrogen adsorption is not in quasi-state equilibrium and is modeled using kinetic rate laws.

Template-free fabrication of graphitic carbon nitride nanotubes modified with lanthanum (La/g-CNT) for dynamic photo-catalytic CO2 reduction with CH4 has been investigated. Successful fabrication of g-C3N4 nanosheets and nanotubes were obtained with enhanced photo-activity under visible-light. Using 5 wt% La/g-CNT, CO yield of 491 µmole g-cat−1 h−1 was obtained which is 3.6 and 5.9 folds higher than g-CNS and g-CN samples. Similarly, production of H2 was highest over La/g-CNT which was 2.95 folds more than g-CNT and 5.1 times higher than using g-CN. Although, pristine g-CN has more basic sites and larger BET surface area but enhanced photo-activity over La/g-CNT can be attributed to efficient transfer of electrons over 1D structure and separation of charge carriers by La. More interestingly, effect of CH4/CO2 feed ratios was obvious, whereas, highest CO was produced at CH4/CO2 ratio of 1.0 but H2 was maximum with ratio of 2.0. Among the different reaction systems, highest CO was obtained using DRM, while CO2 reduction by H2/H2O promoted both CO and CH4 production. This was obviously due to basic characteristics, sorption competition over the catalyst surface and favorable reverse water gas shift (RWSG) reaction. The stability test further confirmed the suitability of this material which prevailed until three cycles without obvious deactivation. This work will open new opportunities to develop structured nanocalaysts for solar energy based reutilization of CO2 and CH4 for the production of renewable fuels.

Oxygen defects of nanoflower TiO2 photo-catalyst was fabricated at the presence of hydrogen at different temperatures (100–600∘C) and the concentrations of oxygen defects were firstly quantitatively analyzed by hydrogen programmed temperature reduction techniques (H2-TPR). Total oxygen defect concentration and surface oxygen defect concentration were consistent with XPS and EPR results, respectively. Even at the hydrogen thermal temperature of 600∘C, the shape of TiO2 was still kept as nanoflower structure as characterized by SEM. However, the rutile and anatase coexist in the composition of crystal phase when hydrogen reduction temperature of the TiO2 catalyst reached 400∘C to 600∘C as proved by Raman and XRD results. TiO2 sample with oxygen defects shows excellent photo-catalytic activity for degradation of Direct Blue 78(DB) regardless of ultraviolet light (the maximum degradation rate achieved within 100[Formula: see text]min was 93.27%) or visible light (the maximum degradation rate achieved within 100[Formula: see text]min was 88.25%). The photo-catalytic activity seems to be highly correlated with the surface oxygen defects of TiO2 catalyst. With surface oxygen-defect concentrations increase, the degradation ability on DB was significantly enhanced, while bulk oxygen defects had negligible effect on the photo-catalytic activity. The enhanced photo-catalytic performance of TiO2 with a fixed amount of oxygen defects was attributed to the strong capturing capability of the photo-generated electrons. In addition, the surface defects could also improve the photo-catalytic reaction efficiency.

The aim of this study is to investigate the impact of an anionic precursor [N2 gas and triethyleneamine (TEA) as nitrogen dopant source] to prepare anionic doped ZnO thin films surface morphologies, via a novel route - hydrothermal solution deposition at low temperature. The effect of dopant concentration under both with and without pH control was studied. The less populated doped ZnO crystal nearly had the same band gap as compared to undoped ZnO thin films. The photocatalytic activity of selected doped ZnO thin films were studied for the degrdation of 10 mg L-1 Methylene Blue under UV irradiation of 254nm. Based on the 1st order reaction rate constant results the morphology N2:S2-MS has shown highest degradation followed by N:S1-MS. Overall, the photocatalytic activity order is N2:S2-MS andgt; N:S1-MS andgt; N:S2-CG andgt; N:S1-CG. In general, a significant variation in surface morphologies, crystal size and population, porosity and orientation were observed. This tailored-made variation enabled the doped ZnO thin films to successfully degrade the waste methylene blue effluents.