HYDROGEN PRODUCTION VIA CATALYTIC SPLITTING OF WATER
The hydrogen created from solar-powered water separation has the capability to be an abundant, sustainable, and clean energy resource. Originated from natural photosynthesis, synthetic solar water separating tools are currently being constructed and examined for proficiency. While the sunlight-powered water separation is a favorable route to produce sustainable hydrogen (H,) as fuels extensive applications are obstructed by the cost of the photoelectro- chemical and photovoltaic systems. Different catalysts and integrated tools have been utilized to produce hydrogen from water.33-34 Numerous scientists have achieved to improve the proficiency for direct solar water separation with cycle solar cells where surfaces have been selectively adjusted with as new record of 14% proficiency.35
Nowadays, there exists new utilized generation of hydrogen fuel cell vehicles having null emissions. The H, cars run by compressing hydrogen feds within stack of fuel cells, which can generate electricity to drive the vehicles. Fuel cells could be utilized by combining them with an electric motor to power vehicles cleanly, powerfully, and quietly. Numerous efforts have been concentrated on hydrogen as potential energies and on the utilization of water-splitting technologies as renewable and clean resources to produce hydrogen by means of solar energy. Several challenges have been constructed for developing photocatalysts, which can operate not only under UV light, nevertheless also under visible light illumination to proficiently use solar energy. Some promise resources of hydrogen are thermal-biochemical, photo-biochemical, photoelectric, photothennal, electrothermal, photonic, biochemical, thermal, and electrical. Certain kinds of energies could be resulted from renewable resources and from energy recovery procedures for hydrogen production goals.36-37
During the past years, innovative research works announced the “bionic leaf’ conception for the effective separation of water by photochemical utilization of sunlight.38 The objective has continuously been to exploit sunlight and employ it to produce liquid fuels preferably than electricity, which should be then stored in batteries. The conventional experiments were intended to employ solar power to split oxygen atoms in water from hydrogen, which is afterward transformed within isopropyl alcohol via bacteria. However, recent attempts had utilized nickel-molybdenum-zinc (NiMoZn) catalysts and the resultant reactive oxygen species (ROS) would damage the DNA of bacteria C. Liu et al.38 described the synthetic photosynthetic scheme (bionic leaf 2.0), which could be efficient for solar energy storage and chemical reduction of COv Researchers industrialized a hybrid water separating technique with biocompatible inorganic catalysts (exchange the oldest NiMoZn with a cobalt-phosphorus alloy catalysts). The nerv catalysts do not generate ROS that would damage the bacteria. The separation of water generated O, and H, at lower voltages.
The hydrogen in interaction with the Ralstoniaeutropha bacteria wras consumed to produce biomass and fuel products. The accessible technique show'ed a CO, reduction energy efficiency (REE) of about 50% once a bacteria biomass is produced and liquid alcohols are scrubbed 180g of CO, per kW h of electricity. Connecting the hybrid devices to existent photovoltaic tools could produce a CO, REE of around 10%, which exceeds that of natural photosynthetic tools.38" Coupling this hybrid device to existing photovoltaic systems can yield a CO, reduction energy efficiency of-10%, exceeding that of natural photosynthetic systems.38 Although the investigations showed that the system could be employed to create useful fuels, its potential does not limit there. The technique could nowadays transform solar energy to biomass with 10% proficiency, which is higher than 1% as shown in the quickest growing plants.
GREEN BIOCATALYSIS FOR PHARMACEUTICAL INDUSTRIES
After an initial delay stage, the pharmaceutical industries involved GChenr for economy and prestige objectives with prominence in greener artificial processes, protection of environment, and reduced solvents. During recent years, biocatalysis has been recognized as accessible and green technology that lead to produce a wide variety of pharmaceutical materials and intermediates. Biocatalysts used on broad range in pharmaceutical production provide benefits to the pharmaceutical industries in terms of costs and qualities. For this regard, there exist numerous inventions of advanced biocatalytic methods utilizing oxidases, transaminases, reductases, hydrolases, etc., winch are utilized to prepare therapeutic agents. Pioneering enzymes employed for biocatalysis provided significant economic advantages to the pharmaceutical industries.39-40 The biosynthesis in organic production in the pharmaceuticals, vitamins, flavors and fragrances, and fine chemical industries is still not completely developed;
hence, there are still further required investigations to be performed in the employment of new catalytic enzymes in organic production of drugs and other therapeutic ingredients.41^12 Recently, innovative technological and scientific advancements have unproved gene production and DNA sequencing in order to tailor biocatalysts by protein engineering and design, and the capability to rearrange enzymes within new biosynthetic routes.43'46
RECENT ADVANCEMENTS IN DEGRADABLE AND RECYCLED POLYMERS
Green economy endeavors to endorse sustainability and alternate approaches to reduce the demands for raw resource materials and energy, to improve industrial procedures, to decrease the emissions of greenhouse gas, to avoid environmental pollutions and hazards, to diminish wastes, and to recycle effectively wastes and expired products. In the initial industrial procedures, the fabrication of polymers used mostly oil raw materials, elevated energy inputs, and generated nondegradable plastics and huge quantities of wastes, hi 1930, the initial manufacturing method to make polyethylene (PE) needed temperatures exceeding 150°C and veiy high pressures above 1000 bar. Catalytic olefm polymerizations were developed in 1950s at temperatures below 100°C and with lower pressures inferior than 10 bar.47 The worldwide fabrication of plastic materials and polymers grew significantly in the last decades achieving in 2014 the incredible quantity of 315 million metric tons. The greatest producers are China with about 25% of the worldwide fabrication and the United States, Canada, and Mexico with around 20%. There exist more than 70,000 of plastics industries in Europe. Nowadays, statistics indicated 100 kg of plastics is consumed each year by one person in advanced countries.48-49
In 1980, the energy-effective catalytic copolymerization of ethylene for manufacturing linear low-density polyethylene (used in food packaging) became a million-ton business. During the last few years, the diversity of plastics enlarged considerably, and the first biodegradable plastics were presented. The plastic scattering difficulties grew rapidly, and the pollution of oceans with plastics became a critical and emergent matter of environmental pollution. This is the consequence of a deficiency of recycling and illegal removal of wastes in most of the developed countries. The GCliem of bio-based plastics and degradable polymer-based products are being in the proper way for the area of sustainable polymers.50
Nowadays, the reduction of anthropogenic carbon dioxide (C02) emissions has become a serious climate and environmental matter. The recovery of
CO, could be done on a wide range in carbon capture of power plants, bum up fossil fuels, and in steam upgrading to generate hydrogen from water and coals. It is needed to couple carbon capture materials with a technique for CO, release in order to further improve storage and transport. Several methods have been investigated for recovering CO,.51 Recently, several new catalytic mechanisms have been established to produce cyclic carbonates. One of the processes utilized active bifunctional porphyrin catalysts, which show great income number for the production of cyclic carbonates from CO, and epoxides under solvent-free circumstances.52 Another method provided that the cyclic amidine hydroiodides efficiently catalyzed the reactions of CO, and epoxides under moderate circumstances like room temperature and regular pressures, and the equivalent five-membered cyclic carbonates were attained in medium to high produces.53 The harshness of the forthcoming problems of worldwide warming have generated worldwide attempts to diminish the amount of atmospheric CO,. CO, capture and storage are being central strategies in order to meet CO, emissions reduction targets. Nowadays, there exist numerous researches and diverse technologies to capture, separate, transport, store, leak, monitor, and analyze the life cycle of CO,.54 The conversion of captured CO, into products like building materials, fuels, plastics, chemicals, and other products is being a vital issue around the world. This method can be particularly effective to reduce carbon emissions in regions where geologic storage of CO, is not applied.
ORGANIC PHOTOVOLTAIC SOLAR CELLS AND GREEN CHEMISTRY
The technology of organic photovoltaic solar cells show the aptitude to deliver cheaper electricity compared to first- and second-generation solar technologies. For the reason that numerous absorbers could be employed to generate transparent or colored organic photovoltaic devices, this technology is especially attr active to the building-integrated photovoltaic markets. Organic photovoltaic solar cells have attained proficiencies close to 12%; however, proficiency restrictions along with long-term reliability persists important obstacles. Different to the largest inorganic solar cells, organic photovoltaic cells utilize polymeric or molecular absorbers that cause a localized exciton. A graphical presentation of green solvent processable organic photovoltaics and different kinds of green solvents is presented in Figure 1.1. The absorbers are employed in aggregation with electron acceptors, like fullerene, which possesses molecular orbital energy states that aid the transport of electrons.55
The utilization of perovskite solar cells has progressed considerably the effectiveness of organic photovoltaic solar cells. Already, there are certified proficiencies of energy conversions for perovskite-based solar cells beyond the 20%.
Recently, scientists are discovering other serious region of solar cells, like the understanding of devices hysteresis and films evolution, the change of lead, and the improvement of tandem cell stacks. The stability of cells is another vital and serious matter of research.56 Researchers are trying to enhance the effectiveness of polymer solar cells by utilizing tandem structures. A wider region of solar radiation spectrum is utilized and the thermalization loss of photon energy is diminished. Earlier, the deficiency of low-bandgap polymers with outstanding performances has been the main restricting factor to achieve tandem solar cells with great performances. As a consequence of this advanced technique, devices with single junction show great external quantum proficiency higher than 60% and spectral responses that spread to 900 nm with a power conversion proficiency of around 8%. The polymers enable a solution-administered tandem solar cell with qualified 10.6% power conversion proficiency underneath standard reporting circumstances.57
FIGURE 1.1 Graphical presentation of green solvent processable organic photovoltaics and the different kinds of green solvents.
Source: Reprinted with permission from Ref. . © 2016 Elsevier.