Design of gas diffusion electrode fuel cell type electrochemical device for CO2 reduction

Wang, Yucheng (2020) Design of gas diffusion electrode fuel cell type electrochemical device for CO2 reduction. Doctoral thesis, Northumbria University.

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Abstract

Using the electrochemical catalytic method, CO2 reduction reaction (CO2RR) has become practicable process with a low energy consumption. The products generated from the CO2RR are normally low carbon containing compounds, which can be directly used as fuels or feedstock for chemical industry. This is considered as a clean and sustainable cycle. However, low activity, poor selectivity and durability of electrocatalysts, limitation of CO2 mass transfer, and competing hydrogen evolution reaction (HER) in the aqueous media cause significantly reduced Faradaic efficiency (FE) towards electrochemical reduction reaction (eCO2RR). To make such technology become industrially viable, suppression of HER, good selectivity and high reaction efficiency towards desired products are under high demands.

The main achievement of this work is about the cells design for eCO2RR. Here we researched on novel, high performance and low-cost catalysts, in order to enhance the selectivity and activity of targeted products. We conducted the reactor renovation, and made a new electrochemical cell design, which was adopted advanced gas diffusion electrode (GDE) technology using carbon paper. These have enhanced the CO2 mass transfer therefore increased the FE values. We also developed a new strategy of using a porous Bi-layer GDE, and achieved dramatically increased reaction efficiency, enhanced selectivity and system durability. Several advanced nano-structured catalysts have been involved for eCO2RR, including Cu2O nano-cube, Graphene supported Cu oxides, indium metal–organic framework, commercial antinomy tin oxide and indium tin oxide. CO production using the synthesized Cu2O catalyst reached an FE value of 84.20% and a current density of 83.4 mA•cm-2 at -0.8 V vs. reversible hydrogen electrode (RHE). Formate production using ATO catalyst reached an FE value of 84.54% and a current density of 97.2 mA•cm-2 at -1.2 V vs. RHE. These new catalysts, processes and strategies has contributed significantly on future development of eCO2RR.

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