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2 Reduction with Manganese to Produce Formic Acid
Published in Fangming Jin, Hydrothermal Reduction of Carbon Dioxide to Low- Carbon Fuels, 2017
Lingyun Lyu, Fangming Jin, Guodong Yao
A great deal of development effort has already been expended in the areas of reduction of CO2 concentration in the atmosphere, among which solar technology is the ideal solution (Jessop et al. 2004; Wang et al. 2011; Yadav et al. 2012). Artificial photosynthesis, in which solar energy is converted into chemical energy for renewable, nonpolluting fuels and chemicals, is regarded as one of the most promising methods. However, challenges remain in the direct conversion of solar energy into chemical energy, such as poor conversion efficiencies and poor product selectivity. Developing an efficient solar-to-fuel conversion process is a great and fascinating challenge (Indrakanti et al. 2009; Roy et al. 2010; Takeda et al. 2008; Varghese et al. 2009). In contrast to direct solar-to-fuel conversion, an integrated system should be expected to improve the efficiency of artificial solar-to-fuel conversion. Recently, some interesting integrated technologies, such as a solar two-step water-splitting thermochemical cycle based on redox of metals/metal oxides, have been reported, in which Fe/Fe3O4, Zn/ZnO, Mn(III)/Mn(II), and Mn(IV)/Mn(II) and even MgxOy/Mg have been achieved using solar energy. Thus, water splitting for hydrogen production was significantly higher than direct use of solar energy, which would be one of most promising approaches to increase artificial photosynthetic efficiency (Galvez et al. 2008; Haueter et al. 1999; Hu 2012; Uchida 2012).
Molecular Beam Epitaxial Growth of III-Nitride Nanowire Heterostructures and Emerging Device Applications
Published in Wengang (Wayne) Bi, Hao-chung (Henry) Kuo, Pei-Cheng Ku, Bo Shen, Handbook of GaN Semiconductor Materials and Devices, 2017
Shizhao Fan, Songrui. Zhao, Faqrul A. Chowdhury, Renjie. Wang, Zetian. Mi
The chemical transformation of sunlight, water, and carbon dioxide into energy-rich fuels, commonly known as artificial photosynthesis, is perceived to be one of the key sustainable energy technologies in the future energy arena (Tachibana et al. 2012). One of the key steps in artificial photosynthesis is proton reduction (hydrogen generation) through solar water splitting, which can be realized at the solid-liquid interface of nanocrystals immersed in aqueous solutions via two strategies, including the PEC approach and the photochemical (or photocatalytic) approach (Walter et al. 2010). In PEC water splitting either one or both of the electrodes can be semiconductor photocatalyst in order to capture solar energy, and a metallic conductor is commonly used for transporting the photo-generated carriers between the electrodes. Effective carrier separation and conduction in this system demands the application of external bias and highly conductive electrolyte and substrate. Photochemical dissociation of water, on the other hand, is a spontaneous and wireless approach of harnessing solar energy in which the counter electrode is mounted on the photocatalyst surface in the form of micro/nano-electrode, commonly defined as co-catalysts (Bolton and Hall, 1979; Chen et al. 2010; Walter et al. 2010).
Learning from Nature to Improve Solar Energy Conversion Devices
Published in Swee Ching Tan, Photosynthetic Protein-Based Photovoltaics, 2018
Di Sheng Lee, Yoke Keng Ngeow, Swee Ching Tan
Through millions of years of evolution, photosynthetic organisms have optimized solar energy harvesting and conversion through an intricate scaffold of proteins in which ordered assemblies of photofunctional chromophores and catalysts lie. Analogous to natural photosynthesis, artificial photosynthesis harvests light energy, separates charge, and transports charge to catalytic sites. Although biomimicry of natural photosynthesis is making good progress, artificial photosynthesis has yet to develop devices that are efficient and robust enough to compete with existing solar technologies. Nonetheless, better understanding of natural photosynthetic mechanisms and advances in chemical synthesis have led to the creations and designs of artificial photosynthetic systems that replicate natural processes, such as those of antenna, RC, and even proton pumps of natural photosynthesis.99 Artificial systems made of electron donors and acceptors to mimic natural light-driven charge separation in RCs have allowed researchers to study the effect of physicochemical properties such as donor/acceptor distance and orientation, free energy of the reaction, and electronic interactions on electron transfer efficiency.100 The next step will be to improve RC and LH complexes’ functions and to combine them. We are only scratching the surface of what Mother Nature can do, and there is still plenty to learn from nature. For example, the proteins in natural RC and LH complexes are more than a scaffold. In a RC, the protein also plays a role to control the redox properties of the pigments by varying the number of hydrogen bonds between the bacteriochlorin macrocycles and the protein backbone.101
How can carbon be stored in the built environment? A review of potential options
Published in Architectural Science Review, 2023
Matti Kuittinen, Caya Zernicke, Simon Slabik, Annette Hafner
In fully artificial photosynthesis, solar energy (photons) and CO2 are converted into chemical energy, thus mimicking natural photosynthesis. It can be used to develop carbon-negative solar fuels as well as processes for turning CO2 into ethanol (Gurudayal et al. 2017), or the photocatalytic splitting of water into hydrogen (Kim et al. 2016). Although buildings can be equipped with artificial photosynthesis systems, actual building-integrated applications were not found. The TRL for artificial photosynthesis in the production of solar fuels is reported in the range of 1–3 (Napp et al. 2017). If solar fuels can be used for the energy demands of the same building, the requirements for additional infrastructure or transports are avoided, although the CO2 emissions from the burning of fuels would remain. Therefore, we estimate that both carbon storage potential and applicability in the built environment are currently low.
Visible light irradiated photocatalytic reduction of CO2 to hydrocarbons using hybrid polyaniline/ CuO nanocomposite in aqueous system
Published in Indian Chemical Engineer, 2022
Deeksha Matthew, Vidya Shetty K
A drastic rise in greenhouse gas emissions has been observed since the beginning of the industrial revolution. Greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide, ozone, and some artificial chemicals such as chlorofluorocarbons (CFCs). Among them, CO2 contributes to the majority i.e. about 65% [1]. The current global CO2 concentration in ambient air is about 416.89 ppm [2]. It has been observed through several experimental studies that a slight shift to renewable resources can bring the CO2 concentration to a stable count. Li et al. [3] reported that there are at least three methods to reduce CO2 i.e. reduce CO2 at source; carbon capture and sequestration; artificial photosynthesis. Among them, the artificial photosynthesis involving the photocatalytic conversion of CO2 using semiconductor oxides to form value added chemicals under visible light irradiation has been gaining higher interest. Renewable fuels may be generated using solar energy by photocatalytically reducing CO2 to liquid fuels [4]. The photocatalytic conversion of carbon dioxide to formic acid [5] and further to methanol, a renewable, regenerative, and readily transportable fue1 [6] using solar energy, can potentially drive mankind towards a Methanol economy.