The output performance of the direct ethanol fuel cell (DEFC) is usually subjected to a slow motivational restriction of the anode ethanol oxidation (ER) reaction and 4E transfer of 12E transfer. By precise control of the local coordination environment (LCE) of the electrical catalyst (LCE), the kinetic reaction rate of the multi-electron reaction in the electrocatalytic reaction can be effectively improved, and the rapid transfer process of multi-electron is promoted. The LCE around the catalytically active site in the reaction plays a crucial effect on the activity, selectivity, and stability of the electrocatalyst. However, the strategy of improving the performance of the electrocatalyst performance by reasonably designed to control the performance of the electrocatalyst performance and the insufficient factors of the formation mechanism of the catalytic phase.

Studies have been effectively enhanced by metal (M) and nitrogen (N) co-doped carbon material (c), while M-N is typically considered the active site of the type of catalyst. It has also been studied by embedding other hetero atoms such as phosphorus (P), sulfur (S), boron (B), or the like, to form a synergistic M-X-C, which forms a similar atomic synergistic M-X-C, has also been studied. Since the Lce of the low-dimensional material such as a single atomic catalyst has high sensitivity, it can improve the activity of the catalyst by regulating the LCE of the catalyst. However, how to regulate the LCE of large-size catalysts such as nanomaterials and commercial materials, still not properly studied and resolved. Further, the necessary conditions that drive EOR smoothly are that the catalyst requires at least three consecutive atoms as an active site, which makes the regulatory Catalyst Lce to facilitate EOR activity to become more difficult. Conventional methods When the M-X-C catalyst is prepared by controlling the LCE, the heteroatome X is typically more inclined to C or coordinated rather than the metal M, thus greatly reduces the number of M-N active sites of such materials. Another key issue is that the commonly used carbon-based material is easily oxidized in the actual fuel cell operation, thereby reducing the stability of the fuel cell for a long time operation and hinders the commercial use prospect of the power source.

figure 1. A schematic diagram of the LCE reconstruction by fluorination drive. In this schematic, the F group is introduced into the PD / N- to impair the C-N key, and the n atom is expelled to the PD surface.

Recently, Professor Yang Yang, University of Central Florida.Nature Energy PublishedFor "Improving PD-N-C Fuel Cell Electrocatalysts THROUGH Fluorination-Driven Rearrangements of local Coordination Environment)"The research results. In this work, they increase the number of active sites of the PD-N group by introducing F in this type of catalyst in this catalyst to regulate the Lce of the catalyst in this type of catalyst. Study It is found that the formation of the NC bond can be effectively weakened by the introduction of F, and the NC bond can be effectively coordinated (Fig. 1). Compared to the conventional PD-NC catalyst to transfer the ER reaction to the ER reaction to produce B The pathway of the acid salt, the PD / N & F-C catalyst obtained by F regulation Lce allows EOR to be carried out at a 12E transfer process and completely oxidized to CO2, thereby greatly improving the selectivity and activity of EOR.

In cathode ORR, this type of PD / N & F-C compares PD-N-C catalyst exhibits faster kinetic reaction rates and higher quality specific activity. Optimized active PD-N groups effectively inhibit the migration, loss, reunion of precious metal PD. The PD / N & F-C catalyst can be used as an anode and a cathode catalyst of direct ethanol fuel cell (DEFC), and the maximum power density of the single cell reaches 0.57 W cm-2 (Fig. 2A), and can be stably operated 5900 hours (Fig. 2B) , Overcome the problems where the traditional catalyst is long-term operational activity decline. This activity and stability are a new breakthrough in direct liquid fuel cells. In addition, the authors found that the PD / PC, PD / SC, and PD / BCs can adjust the LCE of the corresponding catalyst by fing driving, thereby greatly enhances the EOR, ORR and battery performance of the catalyst. .

Figure 2. (a) As a different catalyst as a polarization curve and power density curve of the DEFC cathode and an anode; (b) with Pd / N & F-C as the catalyst DEFC stability (5900 hours).

This work provides new ideas for increasing the activity and selectivity of common catalysts, and provides new ideas to solve the problem of corrosion problems of carbon-based material catalysts commonly used in various energy equipment.

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