A Design Framework for Portable Artificial Photosynthesizer: A Future Reality

Boosting CO2 Conversion with Terminal Alkynes by Molecular Architecture of Graphene Oxide-Supported Ag Nanoparticles

The Joint Center for Artificial Photosynthesis (JCAP) is the Fuels from Sunlight Energy Innovation Hub established by the US Department of Energy in 2010 to advance research and development on systems that convert sunlight, water, and carbon dioxide into a range of commercially useful fuels. JCAP has adopted an approach in which robust concepts for complete solar-fuels generators motivate basic scientific research targeting the accelerated discovery and integration of necessary components. Through a combination of scientific, engineering, and theoretical modeling approaches, JCAP has discovered novel materials and developed solar water-splitting prototypes that exhibit performance characteristics which were inconceivable just five years ago. As JCAP continues into a second five year term, they will capitalize on its scientific achievements and sophisticated technology development during the initial funding period by focusing on artificial photosynthetic systems that produce carbon-based fuels by reducing carbon dioxide. In this talk, both the accomplishments prospects of artificial photosynthesis will be discussed. The initial five-year funding of JCAP resulted in various accomplishments that will be highlighted in this talk, including: discovery of new methods to protect light absorbing semiconductors from corrosion in aqueous solutions while still maintaining excellent electrical charge conduction to the surface; creation of an innovative high-throughput-experimentation facility with a coordinated pipeline for the rapid preparation, processing, screening, characterization, and data analysis of light absorbers and electrocatalysts; discovery of new mechanisms and materials for electrocatalytic water-splitting reactions, including earth-abundant catalysts with activity as good as those based on rare-earth metals; design, construction and testing of versatile, fully integrated test beds to facilitate the evaluation and optimization of new components and assemblies for solar-fuels generators; comprehensive multiphysics analyses and prototypes for the design of efficient and robust PEC H2 devices; life-cycle and techno-economic assessment of possible PEC systems; and standardization and development of benchmarking protocols for PEC component and device-performance validation. As JCAP moves forward into its second five-year mission, JCAP will create the scientific foundation for a scalable technology that converts carbon dioxide into renewable transportation fuels, under mild conditions, with only sunlight providing the input energy. The approach of JCAP towards meeting this objective will be introduced in this talk including the three pillars of: (1) mechanisms: discovery and understanding of highly selective catalytic mechanisms for carbon dioxide reduction and oxygen evolution operative at mild conditions of temperature and pressure; (2) materials: accelerated discovery of electrocatalytic and photoelectrocatalytic materials and useful light absorber photoelectrodes for the selective, efficient CO2 reduction into hydrocarbon fuels; and (3) prototypes: demonstration, in JCAP testbed prototypes, of artificial photosynthetic carbon dioxide reduction components and oxygen evolution components that exceed natural photosynthesis in efficiency and rival it in selectivity.

A supported catalyst and a catalytic process have been developed for the conversion of carbgas (CO2 + (100 ppm) H2O + 1% H2) as a renewable source of energy and as a measure for the control of carbon dioxide – a greenhouse gas. The carbgas was passed over a trimetallic supported catalyst consisting of ruthenium (Ru), manganese (Mn) and cobalt (Co) dispersed on a high surface area titanium dioxide support at 673 K and at atmospheric pressure with a gas space velocity of 6000–7200/h. The catalytic reaction produces methanol and propyne in a fixed bed reactor system. The catalyst simultaneously splits water into hydrogen and oxygen, and carbon dioxide into carbon and oxygen under very mild reaction conditions and at atmospheric pressure. The oxygen generated during the reaction and the addition of hydrogen during the catalytic reaction not only generates a considerable amount of energy for the reaction to proceed but also sustains the oxidation states of Ru, Mn and Co. This process maintains the specific active oxidation states of the metals during the catalytic run – a key step in the process.

Advancement of renewable energy technologies via artificial and microalgae photosynthesis

Enzyme catalytic reactions are environmentally safe catalytic reactions in organic synthesis. The efficient conversion of Carbon dioxide using enzymes will help in reducing the greenhouse gas effect and in production of useful chemicals as well. Unlike microbial processes, enzymatic biotransformation is much faster, cleaner and easier to operate. Compared to conventional processes, the enzymatic approach for conversion of Carbon dioxide has attracted a lot of attention, due to its several advantages such as high yields and selectivity under milder reaction conditions. A detailed search of published reports was done and analyzed in this paper, related to enzyme catalytic carbon dioxide conversion into useful chemicals.

Artificial photosynthesis system (APS) uses biomimetic systems to duplicate the process of natural photosynthesis that utilizes copious resources of water, carbon dioxide and sunlight to produce oxygen and energy-rich compounds and has potential to be an alternative source of renewable energy. APS like natural photosynthesis includes the splitting of water into oxygen and hydrogen, and the reduction of carbon dioxide into various hydrocarbons such as formic acid (HCOOH), methane (CH4) and carbon monoxide (CO), or even pure hydrogen fuel. These processes are accomplished by a handful of device designs, including photoelectrochemical cells or photovoltaic-coupled electrolyzers which are driven by energy extracted from sunlight photons as well as suitable catalysts. Researchers are trying to combine advantageous components from both natural photosynthesis and artificial photosynthesis to create a semi-artificial photosynthesis system, involving the incorporation of enzymes or even whole-cell into synthetic devices. However, there are several limitations to the advancement of this field which are mainly centered on the inability to establish a system that is cost-effective, long-term durable and has the highest efficiency. Artificial photosynthesis devices can also function as atmospheric cleansers by extracting the excess amount of carbon dioxide and releasing back oxygen into the environment. Although there is still a long way to go to empower society with energy supplied through artificial photosynthesis, at the same time it is both desirable and necessary. To date, the efforts to commercialize APS have been fruitful, and it will soon be a viable alternative fuel source.

Conversion of methane to syngas via plasma technology is a cost-effective approach to obtaining syngas. Methane conversion by means of ceramic electrodes was significantly increased. In plasma reformer, while electrical discharge is available in gas, very active species such as electrons, radicals, ions, atoms, and excited molecules are produced and they function as catalysts. Methane and carbon dioxide gases at atmospheric temperature and pressure in the non-thermal with TiO2-coated electrode plasma reactor with an inner diameter of 9 mm are converted to hydrogen and carbon monoxide (syngas) through one chemical step. The main objective of this research was to investigate the effects of changes in feed flow rate and feed ratio on methane conversion and product selectivity, as well as product distribution. Furthermore, the results were obtained when three synthesized catalysts were inserted in a section (3 mm) of plasma length (100 mm). The obtained results demonstrated that the voltage of 15 kV was required for methane conversion and hydrogen production. Reducing voltage and/or increasing the partial pressure ratio of methane to carbon monoxide in the reactor inlet resulted in the reduction of methane conversion rate. Moreover, according to the findings, increasing the ratio of carbon dioxide to methane would increase methane conversion and consequently, decrease the conversion of carbon dioxide. The conversion of methane and carbon dioxide was higher for co-precipitated Ce-Mn oxide support than those using the two other methods.

Upgrading biogas into added-value fuels and chemicals is seen as one of the main pathways to reduce carbon dioxide emissions from the energy sector. In particular, green methanol represents a strategical product due to its high versatility in the transportation and chemical industry. Biogas reforming is a key step in the upgrading process and it can be integrated with Power-to-X technology. The reforming can be conducted using Solid Oxide Electrolysers (SOEs). Furthermore, the outlet syngas composition can be adjusted and optimized for methanol production, via the additional production of hydrogen provided by the simultaneous steam electrolysis.This research focuses on analysing the effects of Dynelectro’s patented AC:DC operation [EP3719171A1, WO2020/201485A1, EP3947779A1] applied to biogas-fed SOE cells. The principle of this novel operating condition is to impose an alternating current over a direct current, which for SOE translates into reversing the polarization of the cell and having a regular switch between fuel cell mode and electrolysis mode. When performing steam electrolysis, the benefits of AC:DC operation are already proven to consist in reduced degradation, due to impurities removal, and enhanced temperature control during dynamic operations [Skafte, 2022]. When the SOE cell is fed with a composition of methane, carbon dioxide and steam, the main issue to solve is the high energy requirement from the steam reforming process and the steam electrolysis performed simultaneously. In fact, both reactions are endothermic at SOE operating conditions (750°C and ambient pressure), with an enthalpy difference of respectively 225 kJ/mol and 248 kJ/mol. In this regard, the AC:DC operation can provide additional heat, because of the polarization switch to fuel cell mode, and avoid the temperature drop within the SOE. Moreover, it is possible to tune the rate of co-electrolysis and biogas reforming.A mathematical model is developed to simulate biogas reforming in an AC:DC operated SOE cell. The model includes mass transport, electrochemistry, catalytic reactions and energy balance. The composition of biogas is assumed to be mainly methane and carbon dioxide. By operating both in DC and AC:DC, this gives a first indication of the extent of the expected benefits. To validate the model, laboratory experiments are performed, where single SOE cells are operated in an imitated biogas compositions and the outlet gas is analysed using gas chromatography. These experiments include current-voltage (i-V) curves and electronic impedance spectroscopy (EIS) analysis, which can be used to measure the performances of such operations by observing the cell voltage and the degradation rate.The results from ordinary direct current operation and Dynelectro’s AC:DC operation are compared in terms of syngas composition and operating voltage. The optimal composition of syngas for methanol synthesis, consisting of a ratio of hydrogen to carbon monoxide of approximately 2 and low traces of methane, is achieved. Reduced methane content in the outlet gas is shown when operating the SOE cells with AC:DC current, compared to DC operations. The latter shows a CH4 molar fraction of approximately 1%, while the former allows the CH4 concentration to go below this level, depending on the AC:DC parameters. It is found that the rate of methane and carbon dioxide conversion is dependent on the frequency and duty cycle of the AC:DC operation. The achievement of stable conditions during these operations leads to an optimized biogas to syngas conversion, and a simplified overall biogas to methanol process.

Synthesis gas is a versatile feedstock for many synthesis processes. There are several conventional reactions to produce synthesis gas i.e. steam reforming, partial oxidation, and carbon dioxide reforming but these catalytic processes have to be operated at high temperatures. Because of non-equilibrium property of low temperature plasma, it is thought to be an alternative way to drive the methane reforming reaction to synthesis gas instead of high temperature catalytic processes. In this study, synthesis gas production from methane using an ac corona discharge was conducted with and without catalysts. To study partial oxidation of methane, air was used as feed gas for reducing investment and operating cost as compared to pure oxygen. The methane conversion dropped dramatically but oxygen conversion increased with addition of ethane to the feed gas. The nitrogen in air not only acts as a dilute gas but also affects the reactions. The results show that oxygen is the most effective active species to reduce carbon formation and increases methane conversion as well as lower the specific energy consumption. For this reason, steam reforming could not be operated alone under corona discharge to convert methane into synthesis gas because of the carbon formation. For carbon dioxide reforming with methane in low temperature plasmas, methane and carbon dioxide conversions both increased with increasing voltage, gap width, and carbon dioxide to methane feed mole ratio but decreased with increasing frequency and flow rate. Under the studied conditions, methane conversion was always higher than carbon dioxide conversion. Sinusoidal and square waveforms gave negligibly different results of the reactant conversions and the product distribution of partial oxidation of methane with air and carbon dioxide reforming with methane. To find the way to increase the efficiency of producing synthesis gas, the partial oxidation of methane with carbon dioxide was carried out in the presence and absence of Pt loaded KL zeolite (Pt/KL) and Pt/ZrO₂. The results showed that the combination of catalyst and electric discharge gave a higher oxygen conversion but a little bit lower methane conversion. The presence of catalyst did not show that synergetic effect on both partial oxidation and carbon dioxide reforming. The challenging method to improve synthesis gas production efficiency by introducing water in feed steam was investigated. Combined carbon dioxide and steam reforming with methane produced higher methane conversion and CO/C₂ ratio than either carbon dioxide or steam reforming. In case of the combined partial oxidation and steam reforming, the energy consumed to convert a methane molecule decreased dramatically from 68 to 13 eV/m[subscript c] with increasing the percentage of watervapor from 0 to 50% at a CH₄/O₂ ratio of 2:1

Because of the widespread demand for a low-carbon society, the necessity of renewable energy is one of the most promising solutions for the future. In keeping pace with other environmental-friendly technologies, artificial photosynthesis is one of the latest technologies that produces chemical fuel and various energy sources without pollution. Because artificial photosynthesis uses carbon dioxide to produce chemical fuels, it has been evaluated as a promising core technology that may also provide a solution for climate change. In this study, artificial photosynthesis with a photoelectrochemical cell was designed and economic analysis on carbon monoxide and oxygen production was performed. In addition, a sensitivity evaluation was performed on the change in discount rate, benefit, and cost. The results showed that with a 10% efficiency rate and 5% discount rate on an artificial photosynthesis device, the artificial photosynthesis device generates 1.414 trillion Won of NPV. Therefore, the artificial photosynthesis device has high economic potential. As the efficiency of the device was changed to 10%, 13%, and 15%, the amount of carbon dioxide used for the reaction increased to as much as 24,309ton, 29,200ton and 36,500ton, respectively. This indicates that the artificial photosynthesis device also has a carbon dioxide reduction effect.

Reinventing the plant

Artificial photosynthesis: Promising approach for the efficient production of high-value bioproducts by microalgae

Thermodynamic analysis of syngas production via tri-reforming of methane and carbon gasification using flue gas from coal-fired power plants

Virtually all life on our planet is powered by the sun through the process of photosynthesis. Understanding the design and operating principles of natural photosynthesis is a central challenge for fundamental research because biology presents a unique paradigm and possible blueprint for the realization of artificial alternatives. All processes of natural photosynthesis, including light harvesting, charge separation and accumulation, water oxidation, and carbon fixation, embody “solutions” optimized through billions of years of evolution to challenges currently faced by scientists developing components for artificial photosynthetic devices. The present chapter provides an overview of the most important aspects of natural photosynthesis and discusses the ways in which they motivate biomimetic and bioinspired research into artificial photosynthesis.

Conversion of carbon dioxide (CO2) and water (H2O) to methanol (CH3OH) is achieved through an artificial photosynthesis procedure utilizing cobalt (Co) micro-particle based photocatalyst and solar energy in a simple, closed reactor. The photocatalyst is fabricated by exposing the surfaces of cobalt microparticles to femtosecond laser irradiation in a gold chloride (AuCl) solution. The morphology and composite of the photocatalyst surfaces were observed and detected to be a layer of cobalt dioxide (CoO) nano-flakes on which some gold (Au) nanoparticles were deposited. The Au nanoparticles harvest the Sunlight energy through a plasmonic effect. The energy absorbed by Au nanoparticles creates electrons and holes which excite the H2O and CO2 molecules adsorbed on CoO nanostructure surfaces to form excited hydrogen (H2)* and excited carbon monoxide (CO)* on the CoO surface. The excited molecules combine to form CH3OH on the CoO surface. The Au/CoO/Co nanostructured surfaces are useful for developing a low-cost method to convert solar energy to chemical energy in the form of methanol.