过渡金属与氮共掺杂碳材料电子和几何结构调控及对CO2还原活性及选择性影响规律

Direct electrochemical reduction of CO2 to fuels or chemicals using renewable electricity offers an elegant technological solution to current energy security and sustainability issues. It is desirable to develop low cost, low overpotential, high active and high selective catalyst for practical application. This proposal will focus on the development of transitional metal- and nitrogen-doped carbon nanofibers (M-N/CNF) with different structure (core-shell structure, multi-level pore structure, hollow structure, etc.) as the electrocatalysts for CO2 electroreduction reaction (CO2RR) due to the low cost, remarkable catalytic activity and high selectivity. Research efforts include: (1) to explore the composition and structure of catalytic active sites; (2) to explore the effect of elemental composition and content, nitrogen species, transition metal type and dispersion , M-Nx species and density etc. on activity and selectivity of the catalysts; (3) to explore the effects of the interaction between geometry and the formation of intermediate and its adsorption/desorption energy ; (4) to elucidate the geometric and electronic effects of different structure M-N/CNF on the mechanism of improvement for activity and selectivity. Research emphasis will be placed on the formation of activity sites and selectivity with preparation method to elucidate the relationships between the structure and performance of the catalysts and to design a new durable catalyst for the CO2RR.

利用可再生电力将二氧化碳转变成燃料或化合物为节能减排和可持续发展提供了有效解决方案。针对二氧化碳电还原反应（CO2RR）对低成本、低过电位、高活性及高选择性催化剂的应用需求，项目提出开展多孔纳米纤维过渡金属与氮共掺杂碳（M-N/CNF）作为CO2RR电催化剂，研究M-N/CNF电子结构和几何结构与催化活性、产物选择性之间“构~效”关系。通过改变M-N/CNF中元素组成及含量、氮物种形式、过渡金属种类和分散形式、M-Nx种类及密度等，调控催化活性位电子结构，实现对CO2选择性吸附、降低过电位，揭示催化活性位结构；通过几何和电子结构的调控，理论与实验结合探究中间物种形成及其吸附能、活性位结构对产物选择性影响规律，阐明不同产物的反应路径及氢析出抑制机制，提高产物的选择性。进而发展高效电催化剂的可控制备方法，研制具有高活性、高选择性的催化剂，为CO2RR催化剂的发展及应用提供科学基础。

利用可再生电力直接将二氧化碳电催化转变成燃料或化学品为当前的能源安全和可持续发展问题提供了一种有效方式，面对低成本、低过电位、高活性及高选择性的二氧化碳还原电催化剂的应用需求，项目提出开展过渡金属-氮掺杂碳（M-N/C）作为二氧化碳电催化还原催化剂的研究。重点研究了Fe-N/C、Fe-N/S-C、Fe-Co-N/C及CTF-Cu基催化剂的制备方法及在电催化二氧化碳中的应用，其中调控Fe团簇的引入可以降低从Fe-N4-C活性位点解吸CO的自由能低，使CO更易于脱附，增强催化剂的CO2RR性能；掺杂硫元素的Fe-S/N-C催化剂的活性与选择性相较于纯Fe-N-C催化剂均有显著的提升，经tafel曲线所得的tafel斜率同样验证了含硫的催化剂在电催化CO2RR动力学上更具优势；采用了在ZIF-8中掺杂Fe、Co催化剂的CO选择达到91%；构 建 了 CTF-B 约 束 Cu 催 化 剂 ， 用 于 选 择 性 和 稳 健 的CO2RR生成烃，最大FE高达81.3%。通过不同催化剂的电化学表征获得电催化二氧化碳性能的机制，有利于合理设计和高效CO2RR的结构性质研究。