發(fā)布時間：2018-09-09 17:27

【摘要】：氫氧電催化反應(yīng)是氫能源體系的重要反應(yīng),其熱力學(xué)和動力學(xué)直接影響水解制氫和燃料電池的能量效率和功率密度.過去十多年來,基于量子化學(xué)的理論計(jì)算在電催化劑設(shè)計(jì)及電催化反應(yīng)機(jī)理研究中得到廣泛應(yīng)用.結(jié)合文獻(xiàn)結(jié)果,本文介紹了近年來在Pt基催化劑表面氫、氧電催化反應(yīng)理論計(jì)算研究中獲得的結(jié)果和認(rèn)識.在研究中重點(diǎn)對反應(yīng)中間體吸附結(jié)構(gòu)、覆蓋度及其對反應(yīng)路徑和動力學(xué)的影響機(jī)制進(jìn)行了分析.結(jié)果指出,反應(yīng)中間體的吸附特性不僅會影響反應(yīng)控制步驟的活化能,同時通過改變表面反應(yīng)活性位的結(jié)構(gòu)和數(shù)量影響表面反應(yīng)速率.對火山頂點(diǎn)附近的Pt基催化劑,簡單計(jì)算的吸附能不足以準(zhǔn)確預(yù)測催化劑活性,必須考慮吸附質(zhì)的覆蓋度和吸附結(jié)構(gòu)的影響.在此認(rèn)識基礎(chǔ)上,根據(jù)表面反應(yīng)自由能及速率與關(guān)鍵中間體吸附能、覆蓋度及電極電勢的關(guān)系建立微觀動力學(xué)模型,利用密度泛函理論計(jì)算獲得關(guān)鍵吸附中間體在催化劑表面的電化學(xué)吸附等溫線(吸附結(jié)構(gòu)及覆蓋度與電極電勢的關(guān)系),確定反應(yīng)活性位、反應(yīng)路徑和動力學(xué),構(gòu)建催化活性與吸附能的關(guān)系曲線,預(yù)測催化劑的表面結(jié)構(gòu)及尺寸效應(yīng),并對一些重要實(shí)驗(yàn)結(jié)果進(jìn)行解釋.
[Abstract]:Hydrogen-oxygen electrocatalytic reaction is an important reaction in hydrogen energy system. Its thermodynamics and kinetics directly affect the energy efficiency and power density of hydrogen production and fuel cell. In the past decade, theoretical calculations based on quantum chemistry have been widely used in the design of electrocatalysts and the study of electrocatalytic reaction mechanism. Based on the results of literature, this paper introduces the results and understandings obtained in the theoretical calculation of surface hydrogen and oxygen electrocatalytic reactions of Pt catalysts in recent years. In the study, the adsorption structure, coverage and the mechanism of reaction path and kinetics of the reaction intermediates were analyzed. The results show that the adsorption characteristics of the reaction intermediates not only affect the activation energy of the reaction control steps, but also affect the surface reaction rate by changing the structure and quantity of the active sites of the surface reaction. For the Pt based catalyst near the peak of the volcano, the calculated adsorption energy is not enough to predict the activity of the catalyst accurately. The influence of the coverage of adsorbate and the adsorption structure must be considered. On the basis of this understanding, a micro kinetic model was established according to the relationship between the free energy and rate of surface reaction and the adsorption energy, coverage degree and electrode potential of the key intermediates. The electrochemical adsorption isotherms of the key adsorbed intermediates on the catalyst surface were obtained by using density functional theory (the relationship between the adsorption structure and the coverage degree and the electrode potential), and the reactive sites, reaction paths and kinetics were determined. The relationship curve between catalytic activity and adsorption energy was constructed, the surface structure and size effect of catalyst were predicted, and some important experimental results were explained.
【作者單位】： 湖北省化學(xué)電源重點(diǎn)實(shí)驗(yàn)室武漢大學(xué)化學(xué)與分子科學(xué)學(xué)院;
【基金】：國家自然科學(xué)基金(編號:21673163,21073137) 國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃(編號:2012CB932800)資助項(xiàng)目
【分類號】：O643.36

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