Catalytic transfer hydrodeoxygenation of lignin-derived guaiacol using formic acid (FA) as a hydrogen donor is a sustainable and secure way to obtain value-added phenol. In this work, we prepared N-doped carbon encapsulated CoNi and FeCoNi nanoparticles (CoNi@NC and FeCoNi@NC) for this reaction and found that NC shells rather than the alloy cores are the active sites. Ultraviolet photoelectron spectroscopy (UPS) results and Density Functional Theory (DFT) calculations suggested that Mott-Schottky heterostructures were constructed in CoNi@NC and FeCoNi@NC, leading to the spontaneous electron transfer from alloy cores with smaller work functions to NC shells. DFT calculations also confirm that the number of electrons transfer from alloy cores to NC shells with 1.46 a.u. and 1.59 a.u. for CoNi@NC and FeCoNi@NC, respectively. The increased electron density on NC shells improved the absorption strength of reactants and the intermediate, thereby reducing the energy barriers for the dehydrogenation of FA and hydrodeoxygenation of guaiacol. FeCoNi@NC, due to its higher surface electron density, exhibited better catalytic activity than that of CoNi@NC, 93.4% conversion of guaiacol and 87.3% selectivity to phenol can be achieved at 260 °C within 12 h, which is even better than commercially available Pd/C catalyst. The mechanistic studies revealed that guaiacol is first converted into catechol via the demethylation and hydrolysis, then to phenol via hydrogenolysis over FeCoNi@NC with the aid of FA. Moreover, the magnetically separatable FeCoNi@NC possessed high catalytic stability because NC shells protect alloy cores from the acidic solution.

使用甲酸（FA）作为氢供体对木质素衍生的愈创木酚进行催化转移加氢脱氧是获得增值苯酚的可持续且安全的方法。在这项工作中，我们为该反应制备了氮掺杂碳封装的CoNi和FeCoNi纳米粒子（CoNi@NC和FeCoNi@NC），并发现NC壳而不是合金核是活性位点。紫外光电子能谱（UPS）结果和密度泛函理论（DFT）计算表明，CoNi@NC和FeCoNi@NC中构建了莫特-肖特基异质结构，导致电子从功函数较小的合金核自发转移到NC壳。DFT 计算还证实，CoNi@NC 和 FeCoNi@NC 的电子从合金核转移到 NC 壳的数量分别为 1.46 au 和 1.59 au。NC壳上电子密度的增加提高了反应物和中间体的吸收强度，从而降低了FA脱氢和愈创木酚加氢脱氧的能垒。FeCoNi@NC由于其较高的表面电子密度，表现出比CoNi@NC更好的催化活性，在260℃下12小时内可以实现93.4%的愈创木酚转化率和87.3%的苯酚选择性，甚至优于CoNi@NC市售 Pd/C 催化剂。机理研究表明，愈创木酚首先通过去甲基化和水解转化为儿茶酚，然后在 FA 的帮助下通过 FeCoNi@NC 氢解转化为苯酚。此外，磁性可分离的 FeCoNi@NC 具有较高的催化稳定性，因为 NC 壳可以保护合金核免受酸性溶液的影响。