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Electrochemical conversion of carbon dioxide (CO2) to valuable products could provide a transformative pathway to produce renewable fuels while adding value to the CO2 captured at point sources. Here, we investigate the thermodynamic feasibility and economic viability of the electrochemical CO2 reduction reaction to various carbon-containing fuels. In particular, we explore various pathways for conversion of CO2 to dimethyl ether (DME), liquid propane gas, and renewable natural gas. We compare and contrast the use of two different proton sources, including hydrogen gas and water vapor at the anode, on the capital and operating costs (OPEX) of electrochemical systems to produce DME. The results indicate that the electrical costs are the most significant portion of OPEX, demonstrating costs of 0.2–0.6 $/kWh per metric ton of DME. DME production using carbon monoxide and formic acid as intermediates proved to be the most cost-effective, demonstrating levelized costs of energy of 0.28 $/kWh with over 0.15 $/kWh of cost recovery possible through renewable hydrogen tax credits and oxygen and hydrogen gas recovery. 

Ammonia holds great promise as a carbon-neutral liquid fuel for storing intermittent renewable energy sources and power generation due to its high energy density and hydrogen content. Photo-Electrochemical Ammonia Synthesis: Nanocatalyst Discovery, Reactor Design, and Advanced Spectroscopy covers the synthesis of novel hybrid plasmonic nanomaterials and their application in photo-electrochemical systems to convert low energy molecules to high value-added molecules and looks specifically at photo-electrochemical nitrogen reduction reaction (NRR) for ammonia synthesis as an attractive alternative to the long-lasting thermochemical process. - Provides an integrated scientific framework, combining materials chemistry, photo-electrochemistry, and spectroscopy to overcome the challenges associated with renewable energy storage and transport - Reviews materials chemistry for the synthesis of a range of heterogeneous (photo) electrocatalysts including plasmonic and hybrid plasmonic-semiconductor nanostructures for selective and efficient conversion of N2 to NH3 - Covers novel reactor design to study the redox processes in the photo-electrochemical energy conversion system and to benchmark nanocatalysts’ selectivity and activity toward NRR - Discusses the use of advanced spectroscopic techniques to probe the reaction mechanism for ammonia synthesis - Offers techno-economic analysis and presents performance targets for the scale-up and commercialization of electrochemical ammonia synthesis This book is of value to researchers, advanced students, and industry professionals working in sustainable energy storage and conversion across the disciplines of Chemical Engineering, Mechanical Engineering, Materials Science and Engineering, Environmental Engineering, and related areas. 

Electrochemical nitrogen reduction reaction (NRR) for ammonia synthesis might offer an alternative means to the capital- and carbon-intensive thermochemical process (Haber-Bosch) in a clean, sustainable, and decentralized way if the process is coupled to renewable electricity sources. One of the challenges in electrochemical ammonia synthesis is finding catalysts with a suitable activity for breaking N2 triple bonds at or near ambient conditions. Improving the design of electrocatalysts, electrolytes, and electrochemical cells is required to overcome the selectivity and activity barrier in electrochemical NRR. In-situ and operando surface-enhanced Raman spectroscopy (SERS) is a well-suited technique to probe electrochemical reactions at the solid-liquid (electrode/electrolyte) interface. Operando SERS allows for the detection of intermediate species even in low abundance and is used to provide insights into NRR mechanisms using hybrid plasmonic nanostructures (e.g., Au-Pd) by combining spectroscopy and electrochemistry. A potentiostat is used to apply potential on a SERS active substrate that is then monitored by changes in a spectrum. The spectroelectrochemical cell is developed to operando probe the trace of NH3 and possible intermediate species produced at the electrode/electrolyte interface. This work would aid in understanding the reaction mechanism and ultimately designing more efficient catalysts for electrochemical energy conversion systems. This material is based upon work supported by the National Science Foundation under grant no. 1904351.