A Study On CO₂ Resource Utilization Electrolyser Based On Electrode Preparation Process

CO₂ direct electrolytic reduction technology can convert CO₂ into high value-added chemical raw materials.Through CO₂ resource utilization,it can not only promote carbon emission reduction,but also alleviate the temporal-spatial supply and demand contradiction of renewable energy and improve the utilization ratio of renewable energy.However,the technology has not met practical application demands,the following problems still existed:low catalytic activity and poor stability of cathode catalyst;low current density and high energy consumption of the electrolyser;high cost of anode noble metals catalyst.Therefore,based on advanced electrode preparation techniques such as catalyst preparation and regeneration,and the design and manufacture of the flow cell,the key factors affecting the CO₂ electrolyser performance were systematically optimized in this paper.The main research contents and results are as follows:1.The three-dimensional porous copper electrodes were prepared by the dynamic hydrogen bubble template method and the morphologies were regulated.The catalytic performance was examined in a self-made flow cell,and the reliability of the experimental system was verified.The results indicated that,compared with the smooth copper electrode,the 3D branch-like porous copper electrode has a larger electrochemical active surface area,smaller charge transfer resistance,and higher CO partial current density.The CO partial current efficiency increased from 0.8%to 10.9%under 2.0 V total cell voltage.The addition of surfactants in the plating solution can regulate the aperture size and microstructure of porous copper,and the stability of CO production was improved.Compared with the H-cell,the continuous flow in the flow cell can promote CO desorption and improve its selectivity.2.Taking CO with selectivitive advantage in the flow cell as the target product,gold nanoparticles were loaded on N-doped carbon by the one-step reduction method,and the effect of gold loading amount on its electrocatalytic performance was investigated in the above flow cell.The loading amount of gold showed to affect the double-layer capacitance.By regulating the gold loading amount,a total current density of 108.2 m A/cm²,and 96.9%CO current efficiency were obtained under 2.7 V total cell voltage.Through the catalytic performance comparison of pure carbon,N-doped carbon,and Au/C catalyst,it was found that the synergistic effect between gold and N-doped carbon was the key factor for the catalytic activity improving.After the catalyst was operated at 50 m A/cm² in the flow cell for 130 h,the total cell voltage increased from 2.4 V to 2.6 V,the average current efficiency and energy efficiency of CO production were 96.4%and 54.6%,respectively.3.Based on the prepared N-doped Au catalyst,the factors influencing CO₂ electrolyser performance were systematically explored from the perspective of key materials,operating conditions,and electrode preparation process.The results showed that the cathode catalyst properties,mass transfer effect and external circuit resistance had a key influence on the full electrolyser performance.Enhancing mass transfer and minimizing the external circuit resistance can facilitate the realization of high-efficient and low energy consumption catalytic reduction of CO₂.The cathode feeding mode has the greatest influence on mass transfer conditions.The external circuit resistance can be affected by temperature,electrolyte concentration,electrolyser structure,membrane and electrode preparation technology.After system optimization,the CO₂ electrolyser performance reached the international level in the low-temperature field.The total current density achieved 217.2m A/cm² at a low cell voltage of 2.2 V,with 90.6%CO current density and 60.5%energy efficiency,respectively.4.The lithium anode material was recovered as a cheap anode catalyst,its catalytic activity was repaired by heat treatment,and it was used in CO₂ electrolyser under the above optimized conditions.It was found that during heat treatment at 600 ^oC in an inert atmosphere,Li_xCo O₂ in the recycled materials can decompose to produce spinel structure Co₃O₄,which had a key effect on oxygen evolution activity improvement.The CO₂electrolyser with the recycled material anode reached available level,the total current reached 123.4 m A/cm² under 2.2 V cell voltage,and the current efficiency and energy efficiency for CO production were 91.3%and 60.9%,respectively.This paper focused on the study of efficient and stable low-cost CO₂ electrolyser,which realized the catalytic reduction of CO₂ under low cell voltage with high current density,and the mass transfer was improved.The key influencing factors of CO₂ electrolyser performance and its interaction relationship were clarified,which can provide basic research data and technical support for the application of CO₂electrolyser.The cost of anode material was reduced,which may be important to further application of CO₂ electrolyser.