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Recently, Gao Dunfeng, Wang Guoxiong, and Bao Xinhe of the State Key Laboratory of Catalysis of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and colleagues from Zhejiang University of Technology Wang Jianguo, etc., have made progress in the research of high-efficiency electrocatalytic reduction of carbon dioxide and found that nano-palladium electrodes are highly efficient. Catalytic reduction of carbon dioxide to carbon monoxide, and its catalytic performance and nanoparticle size have a strong dependence. The relevant results were published in the recently published "Journal of the American Chemical Society" (J.Am.Chem.Soc. 2015, 137, 4288−4291).
In recent years, the global increase in carbon dioxide emissions has posed a serious threat to the ecological environment on which people rely, so the capture, storage, and conversion of carbon dioxide have attracted widespread attention from researchers. In terms of carbon dioxide conversion, the use of traditional chemical methods to reduce carbon dioxide requires the simultaneous supply of energy and hydrogen, while electrocatalytic reduction of carbon dioxide, coupled with the electrolysis of water to obtain hydrogen from water, can directly obtain carbon monoxide and hydrocarbons in relatively mild reaction conditions. High value chemicals such as methanol and liquid fuels. At the same time, this process is combined with the use of renewable energy or surplus nuclear energy to realize large-scale energy storage, showing promising application prospects, and has now become an important research hotspot in related fields.
Pd is a typical hydrogen evolution catalyst. The CO2 reduction on the bulk Pd electrode has a high overpotential and the competitive hydrogen evolution reaction results in a low Faradaic efficiency. The team's experimental study found that in the range of 2.4–10.3 nm, the CO2 reduction selectivity and activity of Pd nanoparticles exhibited a significant size dependence. The Faradaic efficiency of CO generation at −0.89 V (vs. RHE) increased from 5.8% at 10.3 nm Pd to 91.2% at 3.7 nm Pd, while the current density at which CO was generated increased by 18.4 times. Through density functional theory (DFT) calculation, the free energy of CO2 reduction and hydrogen evolution reactions at three different reaction sites (plane, step, and angle) was analyzed, and the relationship between reaction performance and particle size was established. The conversion frequency (TOF) of the generated CO and the particle size show a volcano-type curve, indicating that the CO2 adsorption, formation of intermediate species COOH*, and desorption of CO* can be modulated by changing the size of Pd nanoparticles, thereby realizing Pd The transformation of nanoparticles from hydrogen evolution catalysts to high-efficiency CO2 reduction catalysts.
The study was funded by the National Natural Science Foundation of China and the Ministry of Science and Technology.
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