In this work, electrochemical CO2 reduction reaction (eCO2 RR) has been performed on two intermetallic compounds formed by copper and gallium metals (CuGa2 and Cu9 Ga4 ) for the first time. Among them, CuGa2 selectively converts CO2 to methanol with remarkable Faradaic efficiency (FE) of 77.26% at an extremely low potential of -0.3 V versus RHE. The, high performance of CuGa2 compared to Cu9 Ga4 has been driven by its unique two-dimensional structure that retains surface and sub-surface oxide species (Ga2 O3 ) even in the reduction atmosphere. The Ga2O3, species have been mapped by XPS and XAFS techniques and electrochemical measurements. The eCO2 RR activity and selectivity to methanol have been decreased at higher potential due to the lattice expansion caused by the reduction of the Ga2 O3 , which has been probed by in-situ XAFS, quasi in-situ powder XRD and ex-situ XPS measurements. The mechanism of the formation of methanol from CO2 at various potentials has been visualized by in-situ IR spectroscopy and source of carbon of methanol at the molecular level confirmed from the isotope labelling experiments in the presence of 13 CO2 . Finally, to minimize the mass transport limitations and improve the overall eCO2 RR performance, PTFE-based gas diffusion electrode (GDE) has been employed in the flow cell configuration.
CO2 emissions can be recycled via low-temperature CO2 electrolysis to generate products such as carbon monoxide, ethanol, ethylene, acetic acid, formic acid and propanol. In recent years, progress has been made towards an industrially relevant performance by leveraging the development of gas diffusion electrodes (GDEs), which enhance the mass transport of reactant gases (for example, CO2) to the active electrocatalyst. Innovations in GDE design have thus set new benchmarks for CO2 conversion activity. In this Review, we discuss GDE-based CO2 electrolysers, in terms of reactor designs, GDE composition and failure modes, to identify the key advances and remaining shortfalls of the technology. This is combined with an overview of the partial current densities, efficiencies and stabilities currently achieved and an outlook on how phenomena such as carbonate formation could influence the future direction of the field. Our aim is to capture insights that can accelerate the development of industrially relevant CO2 electrolysers.
The electrochemical conversion of carbon dioxide to value-added chemicals provides an environmentally benign alternative to current industrial practices. However, current electrocatalytic systems for the CO2 reduction reaction (CO2RR) are not practical for industrialization, owing to poor specific product selectivity and/or limited activity. Interfacial engineering presents a versatile and effective method to direct CO2RR selectivity by fine-tuning the local chemical dynamics.
Electrochemical CO2 reduction is a promising way to mitigate CO2 emissions and close the anthropogenic carbon cycle. Among products from CO2RR, multicarbon chemicals, such as ethylene and ethanol with high energy density, are more valuable. However, the selectivity and reaction rate of C2 production are unsatisfactory due to the sluggish thermodynamics and kinetics of C–C coupling.
- Combining theory and experiment in electrocatalysis: Insights into materials design 10.1126/science.aad4998
- 二氧化碳电化学还原的研究进展 10.3866/PKU.WHXB201706131
- Alkaline Anion-Exchange Membrane Fuel Cells: Challenges in Electrocatalysis and Interfacial Charge Transfer 10.1016/j.jpowsour.2017.08.010
- Low-dimensional catalysts for hydrogen evolution and CO2 reduction 10.1038/s41570-017-0105
CO2 electrolysis has mainly been performed in neutral or alkaline media, but some fundamental work shows that high selectivities for CO can also be achieved in acidic media.
‘Reverse fuel cell’ converts waste carbon to valuable products at record rates
Fuel cells turn chemicals into electricity. Now, a University of Toronto Engineering team has adapted technology from fuel cells to do the reverse: harness electricity to make valuable chemicals from waste carbon (CO2).